The Kynix Blog - Sensor

Introduction Linear Displacement Sensor, also called Linear Transducer or Linear Potentiometer Sensor, is a device used to monitor and measure linear position, which convert mechanical physical quantities into electrical signals. Linear potentiometer is a type of variable resistance sensor, designed to measure the displacement of a slider or wiper in a linear direction. Also known as a slider or pot, linear potentiometers produce a changing rate of resistance, dependent on the position of a slider or wiper. LVIT Linear Position Sensor Technology Catalog Introduction Ⅰ Linear Displacement Sensor Working Principle Ⅱ Linear Potentiometer Sensor Design Parameters Ⅲ Linear Transducer Applications Ⅳ Linear Displacement Sensor Types Recommendation Ⅴ Linear Potentiometer Sensor Installation Ⅵ Linear Transducer Operating Requirements Ⅶ Linear Displacement Sensor Use Matters Ⅷ FAQ Ⅰ Linear Displacement Sensor Working Principle The function of the linear displacement sensor is to convert the linear mechanical displacement into an electrical signal. In order to achieve this effect, the sensor slide rail is connected to a steady-state DC voltage, allowing a small current of microamperes to flow, and the voltage between the slide and the starting end is proportional to the length of the slide. Using the sensor as a voltage divider can minimize the requirements for the accuracy of the total resistance of the sliding rail, because the resistance change caused by the temperature change will not affect the measurement result. The linear displacement sensor is actually a sliding rheostat. Using the sensor as a voltage divider can minimize the requirements for the accuracy of the total resistance of the sliding rail, because the resistance change caused by the temperature change will not affect the measurement result. Figure 1. KTC 300mm Linear Displacement Sensor Ⅱ Linear Potentiometer Sensor Design Parameters For the general linear displacement sensor:Wear resistance life: >100X106 timesLinear accuracy error: <0.05%Repeatability error: <0.005mmMaximum moving speed: 10m/sImpact factor: IEC 68-2-29:1968 50gVibration factor: IEC 68-2-6:1982 20gMaximum allowable voltage: DC60V/5KΩ～20KΩ; DC36V/2KΩ～4KΩ; DC24V/1KΩTemperature drift coefficient: <1.5ppm/℃ Figure 2. KTR-75mm Linear Displacement Transducer Ⅲ Linear Transducer Applications 1) KTC, KTM, LS tie rod structure is a general structure, with optional pull ball universal head or universal head, can reduce the adverse effects caused by the installation of non-neutral. They are suitable for injection molding machines, textile machinery, woodworking machinery, etc.2) KPC and KPM fixed belts at both ends are hinged and sporty, suitable for swinging, and in measurement systems where the sensor body cannot be fixed, and the sensor will move with the measurement movement.3) KTF and KFM slider types are suitable for the application of the smallest installation length size. With the extension arm, it can eliminate the adverse effects of installation misalignment.4) KTR type is a miniature self-recovery rod structure, no need to tow and install.5) KPF type can also detect the internal displacement of the cavity. Figure 3. KPM Linear Displacement Sensor Ⅳ Linear Displacement Sensor Types Recommendation 🔺Tie Rod TypeUniversal drawbar conductive plastic film series, effective stroke 75mm ~ 1250mm, 4mm buffer stroke at both ends, precision 0.05%~ 0.04%FS. The surface of the shell is anodized, anti-corrosion.Built-in conductive plastic measuring unit, no temperature drift, long life, and automatic electrical grounding function. The sealing grade is IP67, DIN430650 standard plug and socket, which can be applied to most general occasions.The tie rod ball joint has 0.5mm automatic centering function, and the allowable extreme movement speed is 10m/s.🔺Sliding TypeGeneral-purpose slider conductive plastic film series, effective stroke 75mm～3000mm, 4mm buffer stroke at both ends, precision 0.05%～0.02%FS. The surface of the shell is anodized, anti-corrosion.Built-in conductive plastic measuring unit, no temperature drift, long life, and automatic electrical grounding function. The sealing level is IP54 (IP57 when installed downwards), DIN430650 standard plug and socket, which can be used in most general occasions, especially the length direction is limited, the alignment is difficult.The tie rod with the ball head has 10mm automatic correction function, and the allowable limit motion speed is 10m/s. Figure 4. KPC Linear Displacement Sensor Ⅴ Linear Potentiometer Sensor Installation 1) The installation of the linear displacement sensor should balance two ends. Do not tighten the fixing bracket screws before the limit position is determined. The linear displacement sensor fixing bracket screws can be locked after adjusting the stroke.2) The pull-ball universal head of the tie-rod displacement sensor allows a centering deviation with a radius of 1mm. Of course, the shorter the specification, the smaller the centering deviation is recommended.3) After fixing the linear displacement sensor, when retracting the tie rod, the cylindrical body of the universal ball head should be able to have gaps in the four radial directions. Or adjust the mounting position of the universal head or the mounting bracket position near the extended end.4) If there is a big misalignment when the pull rod is pulled out, adjust the mounting bracket near the end of the plug. This can be used as an auxiliary review method.5) The mounting rod of the pull ball universal head and the pull rod are allowed to tilt at an angle of 12°. However, if the centering deviation and tilt deviation are both large during installation, the stability and service life of the electronic ruler will be affected. So further adjustment is required.6) The slider electronic ruler can reduce the workload of adjusting the neutrality, but the auxiliary extension rod cannot be cancelled. Because the stability and service life due to the poor neutralization will occur, and even damage the sensor.7) After all adjustments are made, tighten the mounting screws to make the grounding resistance less than 1. Measure the resistance between the cover screw of the potentiometer sensor and the mounting bracket with a multimeter in the 200 block.8) When using a four-wire system or wiring with a shielded wire, the grounding end of the linear potentiometer should be connected, and the fourth end or shielding wire should be grounded at the end of the electric control box correctly. Figure 5. KTM Linear Displacement Sensor Ⅵ Linear Transducer Operating Requirements 🔺The supply voltage should be stable.Industrial power supply requires ±0.1% stability. For example, the reference voltage is 10V, and the fluctuation of ±0.01V is allowed under the fluctuating voltage. Otherwise, it will cause the displayed trap to fluctuate. 🔺Prevent electrostatic interference.Electrostatic interference and FM interference can easily make the digital display of the linear displacement sensor jump. Separate the strong current line of the equipment from the signal line of sensor in a wire duct. The potentiometer should use a grounding support, and its shell (the resistance between the end cover screw and the support should be less than 1Ω) must be well grounded. The signal line should be shielded and well grounded where at one end of the electrical box.In the case of electrostatic interference, the voltage measurement of the general multimeter is normal, but it shows the digital beating, even the phenomenon is the same when the high-frequency device is interfered. To verify whether it is electrostatic interference, use a power cord to short-circuit the cover screw of the sensor with a certain point of metal on the machine. However, it is difficult to eliminate high-frequency interference by the above-mentioned methods, which occurs frequently in robots and inverters. Stopping the robot or the inverter power saver can test it. 🔺WiringLines "1" and "3" are power lines, and "2" is the output line. Once the above line is connected wrongly, there will be large linear errors, resulting in poor control accuracy, and display bounce easily. 🔺The power supply capacity should be sufficient.If the power supply capacity is too small, the following situations are likely to occur: the mold clamping movement will cause the display of the glue injection ruler to jump, or the melt movement will cause the display of the mold clamping potentiometer sensor to fluctuate. Especially when the power supply of solenoid valve drive power supply is combined with the sensor, the above-mentioned situation is prone to occur. In severe cases, the voltage fluctuation can be measured with the voltage file of a multimeter. If the problem cannot be solved, even if the electrostatic interference and high-frequency interference are eliminated, the neutrality is also bad. At this time, you can check the power supply efficiency. 🔺Installation angleThe angle tolerance is ±12°, and the parallelism tolerance is ±0.5mm. If both are too large, it will cause the display number to jump. In this case, the angle and parallelism must be adjusted. 🔺Prevent short circuit.During the working process of the displacement sensor, the data is regularly displayed at a certain point or no data. In this case, it is necessary to check whether the connection line insulation is damaged and the ground short circuit caused by regular contact with the machine's metal casing. 🔺Avoid aging.For the linear displacement sensor that has been used for a long time, the seal is aging, there may be a lot of impurities, such as oil and water mixture, which affect the contact resistance of the brush, and cause the display number. It can be considered as the early damage of sensor. Figure 6. KTF Linear Displacement Sensor Ⅶ Linear Displacement Sensor Use Matters 1) If the potentiometer sensor has been used for a long time, and the seal has been aging, there are a lot of impurities mixed in, and the water mixture and oil will seriously affect the contact resistance of the brush, which will cause the displayed number to jump continuously. At this time, it can be said that the electronic ruler of the linear displacement sensor has been damaged and needs to be replaced.2) If the capacity of the power supply is small, there will be many situations. Therefore, the power supply should have sufficient capacity. Because insufficient capacity will cause the following situation: The movement of the melt will change the display of the sensor to cause the fluctuations,  resulting in a large error in the measurement result.If the driving power of the solenoid valve and the power supply of the linear displacement sensor are at the same time, the above situation is more likely to occur. In serious cases, the voltage range of the multimeter can even measure the relevant fluctuations of the voltage. If the situation is not caused by high-frequency interference, electrostatic interference, or insufficient neutrality, then it may be caused by the small power supply.3) FM interference and electrostatic interference may cause the digital scale of the linear displacement sensor to jump. The signal line of the sensor and the strong current line of the equipment should be separated from the wire duct. Use the grounding support to have good contact with the ground. The signal wire needs to use a shielded wire, and a section of the electrical box should be grounded to the shielded wire.If there is high-frequency interference, the voltage measurement with a multimeter will usually display abnormally. When there is electrostatic interference, the situation is the same as that of high-frequency interference. To prove whether it is electrostatic interference, you can use a power cord to short-circuit the cover screw of the sensor with some metal on the machine. As long as it is short-circuited, the e-interference will be eliminated immediately. However, if you want to eliminate high-frequency interference, it is difficult to use the above method. Frequency-conversion power savers and robots often have high-frequency interference, so you can try to stop them to verify the interference.4) The power supply voltage must be stable. The industrial voltage needs to meet the stability of ±0.1%. For example, if the reference voltage is 10V, a fluctuation of ±0.01V can be allowed. If it is not, it will cause a display fluctuation. But if the amplitude of the display fluctuation at this time does not exceed the amplitude of the fluctuation voltage, then the potentiometer sensor is normal.5) As for the linear displacement sensor installation, the parallelism can be allowed to have an error of ±0.5mm, and the angle can be allowed to have an error of ±12°. However, if both are too large, then the display number will be bounced. So the parallelism and angle must be adjusted.6) During the connection process, be sure to pay more attention, the wires of the potentiometer sensor cannot be connected wrongly.   Ⅷ FAQ 1. What is a linear displacement sensor?A linear displacement sensor is a device used to monitor and measure linear position. They can also be called Linear Position Sensors or Linear Transducers. They are available in different sizes to measure different stroke lengths.   2. How does a linear displacement sensor work?Linear displacement transducers are linear sensors that work on the magnetostrictive principle, whereby a torsional strain pulse is induced in a specially designed magnetostrictive waveguide by the momentary interaction of two magnetic fields.   3. What is the linear displacement?Therefore; “Linear Displacement” can be defined as the movement of an object in a linear fashion along a single axis in a straight line, for example; from side to side or up and down. ... Linear Displacement is usually measured in millimetres or inches and has a positive and negative direction.   4. What are linear sensor potentiometers?A linear potentiometer is a type of position sensor. They are used to measure displacement along a single axis, either up and down or left and right. Linear potentiometers are often rod actuated and connected to an internal slider or wiper carrier.   5. What is the difference between linear potentiometer and rotary potentiometer?This potentiometer is similar in function to the rotary potentiometer. The only difference between these two, as the name suggests, is the linear motion of the knob, instead of rotary, for adjusting the resistance.   6. How does a potentiometer sensor work?Potentiometers work by varying the position of a sliding contact across a uniform resistance. ... A potentiometer has the two terminals of the input source fixed to the end of the resistor. To adjust the output voltage the sliding contact gets moved along the resistor on the output side.   7. What does a potentiometer sensor measure?A potentiometer sensor measures the distance or displacement of an object in a linear or rotary motion and converts it into an electrical signal.   8. How does a potentiometer measure displacement?To measure the displacement of the body, this body, which is moving, is connected to the sliding element of the potentiometer. As the body moves, the position of the slider located on the potentiometer also changes so the resistance between the fixed point and the slider changes.

IntroductionAs we all know, Tire Pressure Sensor is a small programmable electronic device for driving safety. So what is the role of car tire pressure sensor? Just to prevent car accidents? Of course more than that, it can also extend the service life of the tires and even reduce the wear and tear of the suspension system. So this sensor should not be underestimated. Therefore, what exactly is the tire pressure sensor monitoring? How does it send signals to the vehicle controller? What is the difference between built-in and external sensor? Here gives a detailed introduction.TPMS Tire Pressure Monitoring Systems InstallationCatalogIntroductionⅠ Tire Pressure Sensor Working PrincipleⅡ Tire Pressure Sensor LocationⅢ Types of Tire Pressure Sensor Comparisons3.1 Original Second-generation Tire Pressure Sensors3.2 OEM Tire Pressure Sensors3.3 HUF TPMS Sensors3.4 Second-generation Tire Pressure SensorsⅣ Tire Pressure Sensor FaultsⅤ Tire Pressure Monitoring System ResetⅥ FAQⅠ Tire Pressure Sensor Working PrincipleThe tire pressure sensor signal is sent to the antenna receiver by sending a wireless signal of 433MHz or 355MHz, and the receiver sends the tire pressure data to the BCM (body control module) through the LIN (serial communication network), and finally compares with the BCM preset tire pressure data. If the tire pressure is too low, BCM will send a signal to the meter through the gateway via the high-speed CAN (serial communication protocol), showing the result. With the development of technology, the tire pressure sensor fully supports high-definition accurate monitoring of tire temperature, tire pressure and battery status to ensure driving safety at all times. The general-purpose tire pressure sensors on the market can replace all original sensors, copy the data of the original tire pressure sensors, and can repeat programming indefinitely.Figure 1. Tire Pressure Sensor Working PrincipleInstalling a tire pressure sensor is a direct type of tire pressure monitoring. Use the sensor installed in each tire to directly measure the tire pressure, then use the wireless transmitter to send the pressure information to the central receiver module, finally display the tire pressure data. When the tire pressure is too low or when there is a gas leak, the system will alarm automatically.In addition, there is also indirect tire pressure monitoring. Its working principle is: when the air pressure of a certain tire decreases, the weight of the vehicle will make the rolling radius of the tire smaller, causing its speed to be faster than other wheels. By comparing the rotational speed between the tires, in order to achieve the purpose of monitoring the tire pressure, the indirect tire alarm system actually relies on the tire's rolling radius to monitor the air pressure. Ⅱ Tire Pressure Sensor LocationThe tire pressure monitoring sensor is installed on the tire, usually at the valve position. The tire pressure monitoring display is usually placed on the center console. A lot of electronic devices are installed in the middle of the center console, which has a certain impact on radio frequency interference, especially the electronic eye. The tire pressure sensor can be divided into built-in type and external type according to the location where it is installed.The following is a display drawing of the location of the tire pressure sensor in a car:Figure 2. Tire Pressure Sensor Location Display Drawing1: Right-front wheel pressure monitoring sensor2: Central information display (can display tire inflation pressure info)3: Right-rear tire pressure monitoring sensor4: Remote control signal receiver5: Left-rear tire pressure monitoring sensor6: Combination instrument7: Dynamic stability control system8: Left-front tire pressure monitoring sensor🔺External Tire Pressure SensorFigure 3. External Tire Pressure SensorUsually, some of the original tire pressure sensors that the car is equipped with can display the current tire pressure, while others only give an alarm when the tire is out of air. For the external tire pressure sensor, the valve core has not played much role.The external tire pressure sensor is very simple to replace the battery. The battery can be opened by disassembling it with a wrench or other tools. The service life of the external battery is much shorter than that of the built-in battery due to structural design.🔺Built-in Tire Pressure SensorFigure 4. Built-in Tire Pressure SensorThe built-in sensor has obvious feature, that is, it can avoid being stolen and external interference, and it can be used for a longer time.But why can the original car tire pressure monitoring battery last for 8-10 years, while the latter can only be used for about 5 years? This is mainly due to the different working principles.In the original car, the tire pressure sensor is usually in a dormant state after the vehicle is stationary for 30 minutes. When the vehicle speed exceeds 30KM/hour, the sensor sends a signal to the receiver once a minute. The transmission frequency is about 433MHz, and the additional tire pressure sensor will emit a signal every 5 seconds or so when the tire rotates. So it is very power-consuming to use it.For driving safety, of course, the shorter the signal transmission interval, the better. However, tire leaks are generally slow. If it is a puncture, the tire pressure sensor will not play any role. Therefore, the sending interval of 1 minute is very reasonable, which can greatly improve the battery life.The principle is not complicated whether it is built-in or external sensors. The sensor sends the tire pressure data to the receiver via a wireless signal, and then displays it. Based on the above analysis of various tire pressure sensors, we can get such a result, that is, the stability of the original sensor is greater than that of the later installation. The built-in type is better than the external type in terms of use time and safety. Ⅲ Types of Tire Pressure Sensor Comparisons3.1 Original Second-generation Tire Pressure SensorsThe third-generation tire pressure of the original factory has been officially certified by Audi, with complete packaging and certificates. It is the most formal product. The service life of the qualified product of the original factory is more than six years.Advantages: High production standards. The various accessories used, including button batteries, have strict standards, and the accuracy of tire pressure data and transmission stability are very reliable.Disadvantages: After a lengthy supply chain, the cost rises. For example, a kind of tire pressure sensor is ordered from somewhere: the price is 400+, and the installation also requires modules, gas nozzles, and wiring harnesses, therefore, the price must be increased. 3.2 OEM Tire Pressure Sensors (off the official assembly line)Everyone knows that each OEM has its own dedicated supporting supplier, and the product will be installed and used in the car after very strict testing when it arrives at the OEM. This process will screen out a batch of products that do not meet the requirements of the OEM. , It may also be that the production date is too long. When the battery power does not meet the original factory requirements, it is treated as industrial waste.Advantages: Cheap priceDisadvantages: Sensor quality cannot be guaranteed. The production date is too long, the product does not have any packaging, the appearance and function (accuracy, sensitivity, etc.) cannot be guaranteed, and there is no after-sales service generally. 3.3 HUF TPMS SensorsThe comparison chart between HUF and the original tire pressure sensor shows that except for the different product codes, everything else is the same.Figure 5. Tire Pressure Sensor ComparisonAdvantages: The production standard is the same as the original product, except for the difference in marking and packaging. Because there is no Audi supply channel, the price is lower than the original product. Except that, the quality can be guaranteed by independent sellers.Disadvantages: Unofficial channels and no certificates. 3.4 Second-generation Tire Pressure SensorsThe sub-factory tire pressure sensor is a highly modeled product. Some small manufacturers have developed closely based on the original product. There are many brands and types of products. The appearance of this type of product is quite different from the above three types.Advantages: Cheap price.Disadvantages: The production standard is low, and the tire pressure data accuracy, transmission stability, and service life cannot be guaranteed. Although it can be used when installed, it is easy to have problems. Ⅳ Tire Pressure Sensor FaultsHow do I know if my tire pressure sensor is bad? The tire pressure sensor faults may be caused by the sensor running out of power, the sensor signal failure, and the sensor circuit failure. Due to different car usage conditions, you can check according to the following failure reasons:1) First of all, the air pressure is not high. If it is, the tire pressure needs to be reset; if not, it is a monitoring failure, but this possibility is small. Generally, the tire sensor is faulty, which will cause the brake system to turn the TPMS (tire pressure monitoring system) light on, and you can go to the repair shop to reset.Figure 6. Tire Pressure Sensor Light2) The Volkswagen series cars can supplement the standard air pressure, and then press the tire pressure monitoring button for a few seconds to reset. Other car models can use the decoder to reset or automatically reset after driving a certain distance when the standard air pressure is supplemented.3) The vehicle tire pressure is strictly the air pressure inside the tire, so the height of the tire has an important influence on the performance and power of the car. When you test a tire pressure sensor failure, you can check it.4) If the tire pressure sensor is out of power, it is easy for the tire pressure to be falsely reported. At the same time, the tire pressure value may be very unstable from high to low, and the brightness of the tire pressure display will decrease. When these problems occur, you can try to replace the tire pressure sensor battery to test.Over time the (Tire Pressure Monitoring System) TPMS sensors can go bad or the batteries can go dead. Here shows you how to replace TPMS sensors at home without a tire machine. Just look at the following video:How To Replace TPMS (Tire Pressure Monitoring System) Sensors? Ⅴ Tire Pressure Monitoring System Reset1) Press the button at the lower right corner of the multifunction steering wheel to calibrate the tire pressure monitoring system. You need to press the operating button to select "Vehicle Setting".2) Press the SEL/RESET button, the tire pressure monitoring system calibration will appear on the display.3) Press the SEL/RESET button, the display will switch to the personalized setting interface, and then select "Calibration".4) Press the SEL/RESET button, the "Calibration Start" message will appear on the multi-information display, and disappear after two seconds.Figure 7. Car Tire Pressure Sensors Ⅵ FAQ1. What does it mean when tire pressure sensor fault comes on?The “tire pressure sensor fault” message is an indication that there is a problem with the tire pressure monitoring system. ... If the tire is overinflated or underinflated, this could cause damage to the tire and/or hazardous driving conditions. 2. How much does it cost to fix a tire pressure sensor fault?Generally speaking, the TPMS sensor replacement cost is going to fall somewhere between $230 and $750 in most cases. And unlike some other auto repairs, it's the parts, not the labor, that are going to get you. TPMS sensors can cost anywhere from $180 to $680 alone. 3. Can you drive with a bad tire pressure sensor?No, driving with the TPMS Light on is not safe. It means one of your tires is underinflated or overinflated. ... This can cause undue wear on the tire, potentially lead to a tire failure, and cause a blowout dangerous to you and other drivers on the road. 4. How do I test my TPMS sensor?It is important check the TPMS system before working on a customer's vehicle. Using a TPMS diagnostic tool, select the vehicle's make, model and year manually – or for faster service, scan the vehicle's VIN barcode located on the placard on the vehicle doorjamb to read the sensor information. 5. How long do tire pressure sensors last?The lithium ion batteries inside tire pressure sensors may last anywhere from five to 10 years. Five to six years is a more typical lifespan for older TPMS sensors. The lithium ion batteries inside TPMS sensors may last anywhere from five to 10 years. 6. Can you drive without tire sensors?Yes you can. If you are in canada, there is no law about tpms (tire pressure monitoring system), so there is no problem to drive without it. In USA, this is forbidden. Over this, you will have a light on in your dash if you wheel don't have sensor, but no other issue. 7. How much should it cost to replace a tire sensor?The service kit costs $5-$10 per wheel on most vehicles. A special TPMS tool and additional time are also needed to check and reset the sensor system. In the event pressure sensors need to be replaced, the cost ranges from $50-$250 each depending on vehicle type. 8. How do you fix a tire pressure sensor?Press the TPMS reset button and hold it until the light blinks three times, then release it. Start the car and let it run for 20 minutes to reset the sensor. You'll usually find the tire pressure monitor reset button beneath the steering wheel. Check your user's manual if you're having trouble locating it. 9. How do I know if my tire pressure sensor is bad?Drive for a little bit. The light should go off as the sensor reads the new pressure levels. If the light stays on, you should have us check your tires for a leak or another issue that may not be immediately visible. If the tire pressure is stable, then it could be a bad sensor. 10. Why do tire pressure sensors fail?Some tire pressure sensors have been known to fail as a result of corrosion. ... This can result in valve stems breaking off or cracking, causing the tire to go flat. Other reasons for failure include wiring faults, issues with keyless entry systems, and TPMS module failure, however these are all far less common faults. 11. Can you turn off tire pressure sensor?The U.S. Department of Transportation has mandated that all vehicles manufactured after 2008 include a tire pressure monitoring system (TPMS). Although you cannot disable the TPMS in a General Motors (GM) vehicle, you can reset the system if you recently checked your tires and inflated them properly. 12. Can I replace just one TPMS sensor?You can replace just one sensor. However, when you replace a TPMS sensor you have to "register" it on the vehicle. That is, the vehicle ECU has to be programmed to know that it has a new sensor with a new ID. 13. Is it worth it to replace TPMS sensors?The only time when the TPMS sensor replacement cost might not be worth it is when your car isn't worth much at all. If you have an older car that isn't worth a whole lot of money, paying to have bad TPMS sensors replaced might not be in your best interests. 14. Can you replace battery in TPMS sensor?Most TPMS sensors run on batteries that are built into the sensor and these batteries are not replaceable. The life expectancy of the lithium ion batteries in a TPMS sensor is anywhere from 5-10 years. ... If one of your TPMS sensors fails and needs replacement, you can replace it individually. 15. How do I get the TPMS light to go off?Drive the car at 50 mph for about 10 minutes.This should reset the sensor, and the next time you start the car the TPMS light should be off. Without starting the car, turn the key to the “On” position. Press the TPMS reset button and hold it until the light blinks three times, then release it.

IntroductionThe Temperature Sensor, a measuring instrument, uses various physical properties of a substance to convert the thermal quantity into the physical quantity, including expansion, resistance, capacitance, electromotive force, magnetic properties, frequency, optical characteristics and thermal noise. Many materials and components change with temperature, so there are quite a few materials that can be used as temperature sensors. Here are four temperature sensors in detail.Temperature Sensors ExplainedCatalogIntroductionⅠ Temperature Sensor Types Overview1.1 What is Thermocouple?1.2 What is Thermistor Sensor?1.3 What is Resistance Temperature Detector (RTD)?1.4 What is IC Sensor?1.5 Temperature Sensor Cons and ProsⅡ How to Test: Measuring IndexesⅢ FAQⅠ Temperature Sensor Types OverviewThere are many types of temperature sensors, which can be divided into contact type and non-contact type according to the measurement method; thermistor and thermocouple according to the characteristics of sensor materials and electronic components.The contact temperature sensor needs to maintain thermal contact with the measured medium, so that the two can perform sufficient heat exchange to reach the same temperature. This type of sensor mainly includes resistance type, thermocouple, PN junction temperature sensor and so on. The non-contact temperature sensor does not need to be in contact with the measured medium, but achieves the purpose of temperature measurement through the heat radiation or convection of the measured medium.Here is a detailed introduction to the commonly used four: Thermocouples, Thermistors, Resistance Temperature Detector (RTD), IC Sensor.Figure 1. Temp Sensors (Resistance Changes with Temperature)1.1 What is Thermocouple?Thermocouples are the most commonly used temperature sensors in measurement. Its main advantages are wide temperature range and adaptability to various atmospheric environments, and it is strong, low in price, does not require power supply, and is also the cheapest. The thermocouple consists of two different metal wires connected at one end. When one end of the thermocouple is heated, there is an electric potential difference in the thermocouple circuit, and the measured electric potential difference can be used to calculate the temperature.Figure 2. Metal JunctionsThe thermocouple sensor has two contacts. The measurement end (sometimes called the hot end) is where the two metals connect. The reference junction (also called the cold end) is connected to the measurement circuit. When there is a temperature difference between two ends, an mV signal proportional to the temperature difference is generated. The mV value increases with increasing temperature. The relationship between mV and temperature is non-linear.The thermocouple connector can be constructed by connecting the thermal junction to the outer sheath for grounding or ungrounding (insulating from the sheath). A grounded thermocouple responds faster, but the thermocouple will contact the processing voltage. Therefore, it is important to isolate the measurement circuit to prevent the formation of ground loops and to avoid measurement errors.Figure 3. Thermocouple for Temperature MeasurementInside the temperature component, the thermocouple is usually embedded in magnesium oxide (MgO) and a metal sheath, then insert it into the thermowell or protective tube. This helps protect the sensor from environmental pollution. When magnesium oxide is contaminated with water and salt, even thermocouples that are not grounded will eventually be grounded.As above mentioned, the relationship between voltage and temperature is nonlinear, so it is necessary to make a second measurement for the reference temperature (Tref), and use the test equipment software or hardware to process the voltage-temperature conversion inside the instrument to finally obtain the thermocouple temperature (Tx). Thermocouple is the simplest and most versatile temperature sensor, but its sensitivity is relatively low, which is easy to be affected by environmental interference signals, and the temperature drift of the preamplifier. So it is not suitable for measuring small temperature changes, that is, it is not suitable for high-accurate measurement and application.In actual use, the thermocouple measuring circuit can measure any temperature except 0°C. The measuring circuit must measure the temperature of the cold junction and restore the temperature to 0°C. This kind of electrical compensation is called cold junction compensation (or reference junction compensation). Most thermocouple measurement circuits do this.If the application requires a thermocouple instead of a thermistor, a higher-grade thermocouple is better. In addition, their cost difference is small, and high-quality wire can provide higher stability.🔺Table 1: Thermocouple Types and Application RangesThermocouple TypeApplication Range (℃ / ℉)E95-900℃ (200-1650℉)J95-760℃ (200-1400℉)K95-1260℃ (200-2300℉)N95-1260℃ (200-2300℉)R870-1450℃ (1600-2640℉)S980-1450℃ (1800-2640℉)T0-350℃ (32-660℉) 1.2 What is Thermistor Sensor?The main component of the thermistor sensor is the thermistor, which absorbs heat radiation around.Thermistors are made of semiconductor materials, mostly with a negative temperature coefficient, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor. However, the linearity of the thermistor is extremely poor and has huge effects with the production process. So the manufacturer cannot give a standardized thermistor curve.The thermistor is very small and responds quickly to temperature changes. But it needs to use a current source, and its small size also makes it extremely sensitive to self-heating errors.Figure 4. Thermistor SensorThe thermistor measures the absolute temperature on the two lines, with better accuracy, but it is more expensive than a thermocouple, and the measurable temperature range is also smaller than that of a thermocouple. A commonly used thermistor has a resistance value of 5kΩ at 25°C, and a temperature change of 1°C causes a resistance change of 200Ω. Note that the lead resistance of 10Ω only causes a negligible error of 0.05°C. It is very suitable for current control applications that require fast and sensitive temperature measurement. Small size is benefit for applications with space requirements, but care must be taken to prevent self-heating errors.Figure 5. Resistance-TemperatureThe thermistor also has its own measurement tips. With small size, it can quickly stabilize, and will not cause thermal load. However, it is not strong enough, and large currents can cause self-heating. Since the thermistor is a resistive device, any current source will cause heat on it due to power. Power is equal to the product of current squared and resistance. Therefore, a small current source must be used. If the thermistor is exposed to high heat, it will cause permanent damage. 1.3 What is Resistance Temperature Detector (RTD)?RTD is a precision temperature sensor, made of high-purity conductive metal (such as platinum, copper or nickel) or alloy. Its resistance increases with increasing temperature and decreases with decreasing temperature, similar to a thermistor. RTD is like a thermoelectric converter, converting temperature changes into voltage changes. By passing a constant temperature current through the temperature sensor, an output voltage that increases linearly with temperature can be obtained. The most suitable metal for RTD is a pure metal that remains stable within a given temperature range. The resistance-temperature change relationship is preferably linear. The larger the temperature coefficient (it is defined as the resistance change caused by unit temperature), the better, and it must be able to resist thermal fatigue and respond sensitively to temperature changes. A typical RTD has a protective sleeve and a probe. The protective sleeve is mainly used to protect the RTD from being damaged by the measured medium, which is usually made of stainless steel, carbon steel, inconel or cast iron, and its use temperature can reach 1100°C.Figure 6. Resistance Temperature Detector (RTD)It is currently the most accurate and stable sensor, and its linearity is better than thermocouples and thermistors. However, RTD is also a temperature sensor with slow response speed and more expensive price. So it is most suitable for applications that have strict requirements on accuracy, but speed and price are not critical. 1.4 What is IC Sensor?IC sensors can work in a temperature range of -55°C to +150°C, and precise one can operate at temperatures up to +200°C. It is commonly used in fitness tracking applications, wearable products, computing systems, data loggers, and automotive applications. The most common integrated IC temperature sensors are analog output devices, digital interface devices, remote temperature sensors, and those integrated ICs with thermostat functions.Figure 7. IC Sensors (Thermometer)Analog output devices (usually output voltage, but some also output current) are most like passive solutions when they need an ADC to process the output signal. Digital interface devices most often use a two-wire interface (I2C or PMBus) and have a built-in ADC. In addition to including a local temperature sensor, remote temperature sensors also have one or more inputs to monitor the remote diode temperature—they are most often placed in highly integrated digital ICs (for example, processors or field programmable gate arrays FPGA). When reached the temperature threshold, the thermostat can provide a simple alarm.Here are the details of two common types:🔺Analog Output Temperature SensorThe integrated sensor is made using silicon semiconductor integration process, so it is also called a silicon sensor or a monolithic integrated temperature sensor. It is a dedicated IC that integrates a temperature sensor on a chip and can take temperature measurement and then output analog signals. The main features of this sensor are single function (only measuring temperature), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc., which are suitable for long-distance temperature measurement, control and measurement. What’s more, non-linear calibration doesn’t required, and the peripheral circuit is simple.🔺Digital Output SensorDigital temperature sensor is the product of microelectronics technology, computer technology and automatic test technology (ATE). The intelligent temperature sensor contains temperature sensor, A/D converter, signal processor, memory (or register) and interface circuit. Some products also come with multiplexers, central controller, random access memory and read-only memory. The characteristic of the intelligent temperature sensor is that it can output temperature data and related temperature control quantities, adapts to various microcontrollers (MCU). It realizes the test function through software on the basis of hardware, and its intelligent harmony also depends the level of software development.1.5 Temperature Sensor Cons and Pros🔺Table 2: Advantages and Disadvantages of thermocouples, RTDs, thermistors and IC sensors.CriteriaThermocoupleRTDThermistorIC SensorTemperature-250℃ to +750℃-100℃ to +500℃-267℃ to +2316℃-55℃ to +200℃AccuracyBestDepends on calibrationGoodGoodLinearityGoodWorstGoodBestSensitivityLessBestWorstGoodCircuityComplexDepends on accuracy/power requirementsComplexSimplestPower ConsumptionHigh when takingLow-highLowest Ⅱ How to Test: Measuring Indexes1) Measurement accuracy: 0.01 level2) Resolution 0.1uV and 0.1mΩ3) Scan switch parasitic potential: ≤0.4μV4) Temperature range: Water tank: (room temperature +5~95)°C; Oil tank: (95 ~ 300)°C; Low & constant temperature bath: (-80 ~ 100)°C; High temperature furnace: (300~1200)°C5) Temperature control stability: better than 0.01℃/10min (oil tank, water tank, low temperature constant temperature tank); 0.2℃/min (tube type verification furnace)6) Total uncertainty: For thermocouple verification, measurement uncertainty is better than 0.7 ℃, repeatability error <0.25 ℃; For thermistor verification, measurement uncertainty is better than 50 mk, repeatability error <10 mk7) Working power supply: AC220V±10%, 50Hz, and well protected grounding.8) High temperature furnace power: about 2kW9) Constant temperature bath power: about 2kW10) Power of microcomputer measurement and control system: <500 Ⅲ FAQ1. What is temperature sensor and how it works?How do temperature sensors work? They are devices to measure temperature readings through electrical signals. The sensor is made up of two metals, which generate electrical voltage or resistance once it notices a change in temperature. ... Temperature is the most common physical measurement type in industrial applications. 2. What happens when a temperature sensor goes bad?If the coolant temperature sensor goes bad it can send a false signal to the computer and throw off the fuel and timing calculations. ... This will cause the computer to think the engine is cold, even when it is not, and as a result will use more fuel than necessary. 3. Which temperature sensor is best?The most well-known are Pt100 (with a resistance of 100 ohms at 0°C) and Pt1000 (with a resistance of 1,000 ohms at 0°C). The Pt1000 offers better accuracy and a larger tolerance to long wire lengths than the Pt100. Compared to thermocouples, resistance sensors offer better accuracy and a more linear response. 4. What is the application of temperature sensor?Within our homes, temperature sensors are used in many electrical appliances, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters. 5. How do I know if my temperature sensor is bad?What Signs May Signal Your Coolant Temperature Sensor May Be Failing.Poor Fuel Economy.Irregular Temperature Readings.Black Smoke from Your Exhaust.Your Engine is Overheating.Your Check Engine Light is On. 6. How important sensors are nowadays?Intelligent sensor systems are omnipresent in our everyday lives. They provide security, save lives and improve our quality of life. As more and more areas of life are automated and networked, the importance of innovative sensor technologies will also increase in the future. 7. What should I consider when choose a temperature sensor?Several factors must be considered when selecting the type of sensor to be used in a specific application: temperature range, accuracy, response time, stability, linearity, and sensitivity. 8. What is the value range of a temperature sensor?The effective operating range is -50 to 250 °C for glass encapsulated thermistors or 150°C for standard thermistors. 9. What are the pros and cons thermocouple?Advantages and disadvantages of thermocoupleAdvantages of thermocouple: Simple working principle, Short response time, Low price, Wide temperature ranges, Rugged construction, Self-powered, Small size.Disadvantages of thermocouple: Nonlinearity, Accuracy, Interference can cause errors. Old technology, Needs calibration, Corrosion. 10. What is difference between PT100 and RTD?There is no difference a PT100 is a version of a RTD (resistance temperature detector). What is an RTD? A resistance temperature detector, also known as an RTD or resistance thermometer, is a type of temperature sensor. ... A PT100 sensor is the most common type of Resistance Thermometer (RTD).

  In daily production and life, ultrasonic ranging sensors are mainly used for non-contact automatic parking distance control (PDC) of automobiles, obstacle avoidance robots, construction sites and industrial working environments that require liquid level, well depth, pipeline length, etc. In general, there are two commonly used ultrasonic distance measurement methods:   - The ultrasonic ranging system based on single chip microcomputer or embedded equipment;   -  An ultrasonic ranging system based on CPLD (complex programmable logic device). In order to understand the design and application of ultrasonic ranging sensor, let us first understand the working principle of ultrasonic sensor. Introducing ultrasonic sensor & taking HC-SR04 as an example   Catalog   I What is ultrasonic sensor? II Methods for ultrasonic ranging III Principles for ultrasonic ranging IV Conclusion FAQ   I What is ultrasonic sensor?      Figure 1. Working principle of ultrasonic sensor ranging An ultrasonic sensor is a sensor that converts an ultrasonic signal into another energy signal (usually an electrical signal).  Ultrasonic is a mechanical shock wave generated in elastic media with a frequency greater than 20 kHz. Because of its strong directivity, slow energy consumption and relatively long propagation distance, it is often used in non-contact ranging.  In addition, ultrasonic has the big ability to penetrate liquid and solid, especially in the sunshine opaque solid. When an ultrasonic hits an impurity or an interface, itwill produce a significant reflection to form an echo,  and when it hits a moving object will cause a phenomenon called Doppler Effect.  Therefore, ultrasonic ranging has a good adaptability to the environment, and ultrasonic distance measurement can be well compromised in real time, precision, and price. II Methods for ultrasonic ranging At present, there are various methods for ultrasonic ranging:    -  round-trip time detection;   -  phase detection;   -  acoustic amplitude detection. The principle is that the ultrasonic sensor emits ultrasonic waves of a certain frequency, propagates through the air medium, and is reflected back after reaching the measurement target or the obstacle. After being reflected, the ultrasonic receiver receives the pulses, and the time it takes, is the round-trip time, which is related to the distance traveled by ultrasonic waves. Measuring the wave propagation time to get the wave propagation distance: Assuming that s is the distance between the measured object and the range finder, the time measured is t / s, and the velocity of ultrasonic propagation is expressed as v／m·s－1, then there is a relation (1): s=vt／2       (1) When the accuracy is required, the influence of temperature on the ultrasonic propagation speed needs to be considered, therefore the ultrasonic propagation speed is corrected according to relation (2) to reduce the error. v=331．4+0．607T        (2) Where T is the actual temperature, the unit is °C; v is the propagation speed of ultrasonic wave in the medium, and the unit is m/s. Figure 2. Working principle of ultrasonic ranging sensor   III Principles for ultrasonic ranging   The principle of ultrasonic ranging is to transmit ultrasonic waves in a specific direction through an ultrasonic transmitter, and start timing at the same time as the transmission. When ultrasonic waves propagate in the air and hit an obstacle, they will immediately return and be received by the ultrasonic receiver, and stop timing immediately. The ultrasonic ranging sensor uses the principle of ultrasonic echo ranging and uses precise time difference measurement technology to detect the distance between the sensor and the target. It has the advantages of small angle, small blind area, high measurement accuracy, non-contact ranging, waterproof, anti-corrosion, and low cost. Ultrasonic ranging sensors are usually used in a way that one transmitter corresponds to one receiver, but there are also multiple transmitters corresponding to one receiver. Therefore, the ultrasonic distance sensor can measure the return and return time of the ultrasonic wave to determine the distance of the object. This is how the ultrasonic distance sensor works. For the ultrasonic distance sensor, we recommend to use the Korean Hagisonic ultrasonic distance sensor module HG-C40U.   Figure 3. Ultrasonic distance sensor module HG-C40U   Ultrasonic distance sensor module has two optional transmission modes:   -  Free operation mode: when there is power supply, the sensor itself can send trigger and burst signals and it is usually for basic applications;   -  External trigger mode: the external system (controller or processor) controls trigger signals for advanced applications. These two modes are suitable for a variety of purposes.   In addition, the sensors also involve the choice of two input power supplies:   -  Low voltage (5V) for the processor circuit, the distance to the obstacle can be measured is 3.5m;   -  High voltage (12V) for the controller circuit, the distance to the obstacle can be measured is 5m. The data is transmitted by UART (universal asynchronous receiver-transmitter) with a resolution of less than 5mm. On the other hand, users can select different setting modes according to their own environment needs. Such as free-running / UART triggering / external trigger settings, etc.  At the same time, on the basis of baud rate of UART communication, the user can also decide whether to set up the circular buffer or not. The output signal uses high performance ASIC (application-specific integrated circuit) chip to ensure stable transmission and sensitive reception, and the communication between sensor and PC uses "interface board" (RS232, power regulator). The data show that the real received ultrasonic wave can be amplified in real time by using the monitor program on PC, the distance value can be output by UART (ASCII, mm), and then the detection signal can be converted into the rectangular TTL level signal (square wave) in real time. IV Conclusion Ultrasonic sensors are reliable, cost-effective and efficient solutions for distance sensing, level and obstacle detection. Once you understand how ultrasonic sensors work and which ultrasonic technology is most suitable rather than excellent, you can make more informed decisions about the correct sensor system for your application.   FAQ   1. What type of sensor is ultrasonic sensor? ultrasonic / level sensors measure the distance to the target by measuring the time between the emission and reception. An optical sensor has a transmitter and receiver, whereas an ultrasonic / level sensor uses a single ultrasonic element for both emission and reception.   2. How many types of ultrasonic sensors are there? four types. All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type).   3. What is the range of ultrasonic sensor? For ultrasonic sensing, the most widely used range is 40 to 70 kHz. The frequency determines range and resolution; the lower frequencies produce the greatest sensing range. At 58 kHz, a commonly used frequency, the measurement resolution is one centimeter (cm), and range is up to 11 meters.   4. Can ultrasonic sensor detect human? Finally, ultrasonic sensors assist in detecting people for autonomous navigation of robots. Ultrasonic sensors can be used to set multiple tripwire distances to help navigate around people. Additionally, the high read rate allows you to quickly detect when a person may enter your robot's path.   5. Is ultrasonic sensor harmful? Occupational exposure to ultrasound in excess of 120 dB may lead to hearing loss. Exposure in excess of 155 dB may produce heating effects that are harmful to the human body, and it has been calculated that exposures above 180 dB may lead to death.   6. How do ultrasonic sensors work? Ultrasonic sensors work by emitting sound waves at a frequency too high for humans to hear. They then wait for the sound to be reflected back, calculating distance based on the time required. This is similar to how radar measures the time it takes a radio wave to return after hitting an object.   7. Why is ultrasonic sensor used? Ultrasonic sensors are used primarily as proximity sensors. They can be found in automobile self-parking technology and anti-collision safety systems. ... Ultrasonic sensors are also used as level sensors to detect, monitor, and regulate liquid levels in closed containers (such as vats in chemical factories).   8. Where are ultrasonic sensors used? Ultrasonic sensors have been used throughout many applications and industries. They are used within food and beverage to measure liquid level in bottles, they can be used within manufacturing for an automated process and control maximising efficiency on the factory floor.   9. Is ultrasonic sensor waterproof? Most ultrasonic distance sensors aren't waterproof which can be a problem if you need your project to withstand the elements outdoors. ... This sensor is suitable for outdoor applications such as car reversing sensors, security alarms, industrial inspection, etc.   10. Is ultrasonic sensor analog or digital? Usually, ultrasonic sensors are integrated with an Analog-to-Digital converter (ADC).   11. How do ultrasonic sensors measure distance? As the name indicates, ultrasonic sensors measure distance by using ultrasonic waves. The sensor head emits an ultrasonic wave and receives the wave reflected back from the target. Ultrasonic Sensors measure the distance to the target by measuring the time between the emission and reception.   12. How accurate is the ultrasonic sensor? The more accurate ultrasonic sensors can achieve 0.1 – 0.2% of the detected range under perfectly controlled conditions, and most good ultrasonic sensors can generally achieve between 1% and 3% accuracy.   13. What can ultrasonic sensors detect? Ultrasonic sensors can measure the distance to a wide range of objects regardless of shape, color or surface texture. They are also able to measure an approaching or receding object.   14. Are ultrasonic sensors affected by smoke? Ultrasonic sensors are superior to infrared sensors because they aren't affected by smoke or black materials, however, soft materials which don't reflect the sonar (ultrasonic) waves very well may cause issues.   15. Which is better ultrasonic or IR sensor? Ultrasonic sensors work using sound waves, detecting obstacles is not affected by as many factors. If reliability is an important factor in your sensor selection, ultrasonic sensors are more reliable than IR sensors. If you're willing to compromise reliability for cost, infrared sensors are ideal for your application.  

Warm hints: The word in this article is about 5400 words and  reading time is about 25 minutes This article is equal to a comprehensive course about automobile sensors which including the basic introduction of automobile sensors, their types, applications, functions, and market analysis, etc.   Electronic technology has become the leading factor in the direction of the development of a new generation of automobiles, and sensors are the core components of electronic technology. More and more modern cars have used sensors more and more, in order to improve the economic, dynamic and emission performance of automobile engines, improve the braking performance, steering performance and safety performance of the vehicle. The key to achieve these goals lies in the electronic and intelligent vehicle, the prerequisite is the timely acquisition of all kinds of information, which is bound to require a large number of sensors in the car.   Catalogs I. An Overview of Automobile Sensors II. The Development History of Automobile Sensors III. Types of Automobile Sensors and Their Functions IV. Sensors Used in Automobile Engines and Their Functions 4.1 Automobile Temperature Sensor 4.2 Automobile Pressure Sensor 4.3 Air Flow Sensor 4.4 Fuel Flow Sensor 4.5 Engine Speed Sensor 4.6 Gas Concentration Sensor-oxygen Sensor V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control   System VI. Sensor Application in Automobile Safety System VII. Other Major Automotive Sensors VIII. Automotive Sensors Market Size--Its Market Trend FAQ I. An Overview of Automobile Sensors   The automobile sensor is the input device of the automobile computer system. It takes all kinds of working condition information in the car, such as speed, temperature of various medium, engine operation condition and so on, and convert it into the device or device that can be input signal according to certain law. Simply speaking, the sensor transfers the non electric quantity to the electrical signal to transmit to the ECU, so that the car is in the best working state.     An Overview of Automobile Sensors In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. Automobile sensors are responsible for the acquisition and transmission of information in these systems. The information collected by the sensors is processed by the computer (electronic control unit), and the instructions sent to the actuator are formed to complete the electronic control. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system itself according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control. Automotive sensors usually consist of three parts: sensing element, converting element, and measuring circuit.   （1）the sensitive element is the part that can be measured directly (or response), and is about to be converted into a non electric or other quantity that is determined to be determined by the sensing element of the sensor. （2）the conversion element converts the above non electric quantity into electrical parameters. （3）The function of the measurement circuit is to convert the electrical parameters input by the conversion element to the measurable quantity of voltage, current, or frequency, in order to display, record, control and handle the parts. Measurement circuit The sensor is at the interface between the research object and the test system, namely the first of detection and control. The sensor is a window to perceive, obtain and detect information. All the information obtained in the process of scientific research and automated production must be obtained by the sensor and converted into an easy transmission and processing electrical signal. Its role and status are particularly important. The following figure is the list of correspondence between the human body and machine, which helps us further understand its function.   In modern automotive electronic control, sensors are widely used in various systems of engine, chassis, and body. The vehicle sensors are responsible for the acquisition and transmission of information in these systems. The computer (electronic control unit ECU) sends out instructions to the actuator after the signal is processed in a hurry, and the electronic control is implemented. The sensor is a very important device in the electronic control and self-diagnosis system. It can identify the changes in the outside world and the changes of the system itself in time and then control the work of the system according to the information of the change. Each system control process relies on sensors to feedback information and achieves automatic control.     II. The Development History of Automobile Sensors   In the 1960s, there were only oil pressure sensors, oil sensors, and water temperature sensors on cars. They were connected with meters or indicator lights. After the 1970s, in order to control emissions, a number of sensors were added to help control the vehicle's power system, as the catalytic converters, electronic ignition, and fuel injection devices needed to maintain a certain air-fuel ratio to control emissions during the same period. Until the 1980s, ABS and airbags improved vehicle safety.   The Development History of Automobile Sensors Sensors are used today to determine the temperature and pressure of various fluids, such as intake temperature, air inlet pressure, cooling water temperature, and fuel injection pressure, and sensors used to determine the speed and position of various parts (such as speed, throttle opening, camshaft, crankshaft, angle and speed of the transmission, the position of the exhaust recirculation valve (EGR), etc.); and for measurement.   Sensors for engine load, detonation, broken fire, and oxygen content in exhaust gas; sensors to determine the seat position; sensors to determine wheel speed, road elevation difference, and tire pressure in the anti-lock braking system and suspension control device; and to protect the airbags of the front occupants, not only need more collision sensors and acceleration sensors.   The researchers also use the anti-collision sensors (ranging radar or other ranging sensors) to determine and control the lateral acceleration of the car, the instantaneous speed of each wheel and the required torque, so that the braking system is a part of the vehicle stability control system.   III. Types of Automobile Sensors and Their Functions   （1）According to the relationship of energy, sensors can be classified into two types: active and passive based on their energy relations. Most of the sensors used in cars belong to passive sensors, which require additional input power to produce electrical signals, so the sensor is actually an energy controller.    （2）According to the classification of signal conversion according to the signal conversion classification, it can be divided into one kind of non electricity conversion into another kind of non electricity, such as elastic sensitive element and pneumatic sensor; the other is the transducer converted from non electricity to electricity, such as thermocouple temperature sensor, piezoelectric accelerometer and so on.    （3）Classification according to input quantity according to input quantity is classified according to the measurement, which can be divided into displacement, velocity, acceleration, angular displacement, angular velocity, force, torque, pressure, vacuum degree, temperature, current, gas composition, concentration sensor and so on. For example, the following air flow sensor: Air flow sensor （4）According to the working principle classification according to the working principle of the sensor, there are resistance, capacitance, strain, inductance, photoelectric, photosensitive, piezoelectric, thermoelectric sensor, etc.   （5）According to the output signal classification, according to the sensor output signal, there are analog and digital sensors. Simulation system adoption and digital system adoption   IV. Sensors Used in Automobile Engines and Their Functions Electronic control of engines has been considered to be one of the main technology fields of automobiles. The sensor of engine control system is the core of the whole automobile sensor, and there are many kinds, including temperature sensor, pressure sensor, position and speed sensor, flow sensor, gas concentration sensor and detonation sensor, etc. These sensors provide the engine's work condition information to the engine's electronic control unit for accurate control of the engine working condition, in order to improve engine power, reduce fuel consumption, reduce exhaust emissions and perform fault detection. Sensors Used in Automatic Inductive Door   4.1 Automobile Temperature Sensor   Temperature sensor like automobile temperature sensor is mainly used to detect engine temperature, suction gas temperature, cooling water temperature, fuel temperature, and catalytic temperature. Water temperature state indicatior The temperature sensor has three main types: thermistor, wire wound resistor, and thermal couple resistor. These three types of sensors have their own characteristics, and their applications are also slightly different. The thermistor temperature sensor has high sensitivity and good response characteristics, but it has poor linearity and low temperature.   Among them, the universal temperature range is -50 C to 30 C, the precision is 1.5%, the response time is 10ms, the high-temperature type is 600 to 1000, the precision is 5%, the response time is 10ms; the precision of the wire-wound resistance temperature sensor is high, but the response characteristic is poor; the precision of the thermocouple resistance temperature sensor is high and the temperature range is wide, but it needs to be used together with the amplifier and cold end treatment.   Other practical products have ferric oxygen sensor (temperature range from -40 to 120, 2%), metal or semiconductor membrane air temperature sensor (temperature range from -40 to 150, 2%, 5%, response time 20ms).   4.2 Automobile Pressure Sensor The pressure sensor is the most used sensor in automobiles. It is mainly used to detect air pressure of airbags, the fluid pressure of transmission system, injection pressure, engine oil pressure, inlet pipe pressure, the fluid pressure of air filtration system, and so on. At present, the more commonly used vehicle pressure sensors are capacitive, piezoresistive, differential transformer, and surface acoustic wave.   The capacitive pressure sensor is mainly used to detect negative pressure, hydraulic pressure, and air pressure. The measurement range is 20kPa to 100kPa. Its characteristics are high input energy, good dynamic response characteristics, and good environmental adaptability.   The performance of the piezoresistive pressure sensor is affected by temperature, and it needs another temperature compensation circuit, but it is suitable for mass production; the differential transformer type pressure sensor has a large loss. The acoustic surface wave pressure sensor has the characteristics of small volume, lightweight, low power, low power, high reliability, high sensitivity, high resolution, and digital output. It can be used in the pressure detection of the automobile air suction valve and can work steadily at high temperatures.   4.3 Air Flow Sensor The flow sensor is mainly used for measuring the airflow and fuel flow of the engine. The intake volume is one of the basic parameters for fuel injection calculation. The Mass Air Flow Sensor (MAF) is a computer-controlled sensor that calculates the volume and density of the air taken in by the engine. This in turn ensures the right amount of fuel is used for optimized operating conditions. If this sensor is faulty, the car may stall and the fuel usage will be higher than necessary.   The function of the airflow sensor is to perceive the size of the airflow and transform it into an electrical signal to transmit to the electronic control unit of the engine. The measurement of airflow is used in the engine control system to determine combustion conditions, control air-fuel ratio, start, and ignition. There are 4 types of airflow sensors: rotary wing, Carmen vortex, hot wire, and hot film. The main technical indicators of the airflow sensor are: the working range is 0.11m3/min to 103m3/min, the working temperature is -40 to 120 degrees, and the accuracy is more than 1%.   4.4 Fuel Flow Sensor The fuel flow sensor is used to detect the flow rate of fuel, mainly with a water wheel and circulating ball. The dynamic range is 0 ~ 60kg/h, the working temperature is -40 to 120, the precision is 1%, and the response time is < 10ms. The position and speed sensor of position and speed sensor crankshaft and speed sensor is mainly used to detect engine crankshaft angle, engine speed, throttle opening, speed, and so on. It provides a reference point signal for ignition time and injection time and provides an engine speed signal at the same time.   4.5 Engine Speed Sensor Engine Speed Sensor is attached to the crankshaft and monitors the spinning speed of the crankshaft, which controls the fuel injection and timing of the engine.    Electromagnetic crankshaft position sensor At present, the position and speed sensors used in automobile are mainly AC generator type, magnetoresistance type, Holzer effect type, reed switch type, optical type, semiconductor magnetic transistor and so on. The measurement range is from 0 to 360 degrees, the precision is better than 0.5 degrees, and the bending angle is up to 0.1 degrees. There are many kinds of speed sensors, such as sensitive wheel rotation, sensitive power transmission shaft and sensitive differential driven shaft. When the speed of the vehicle is higher than 100km/h, the general measurement error is larger. The non contact photoelectric speed sensor should be used, the speed range is 0.5km/h to 250km/h, the repetition precision is 0.1%, and the distance measurement error is better than 0.3%.   4.6 Gas Concentration Sensor-oxygen Sensor A gas concentration sensor is mainly used to detect gas and exhaust emissions in vehicle bodies. The most important thing is the oxygen sensor. It detects the oxygen content in the exhaust gas of the car. According to the oxygen concentration in the exhaust, the air-fuel ratio is measured, and the feedback signal is sent to the microcomputer control device to control the air-fuel ratio to converge to the theoretical value.   The commonly used germanium oxide sensors (using the temperature of -40 to 900, 1%), chromium oxide concentration cell type gas sensor (using temperature 300 to 800 C), solid electrolyte chromium oxide gas sensor (using temperature 0~400, precision 0.5%), and two oxide oxygen sensor and two oxidation oxygen sensor. The Oxygen sensor measures the amount of unburdening oxygen that is present in the exhaust pipe and will indicate if the fuel is burning rich or lean. A faulty oxygen sensor will cause the car to idle poorly and jerk as well as cause high fuel consumption. Gas concentration sensor Compared with the germanium oxide sensor, the titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer. titanium dioxide oxygen sensor Among them, the stable oxidation of calcium oxide is deposited by reactive sputtering. Working electrodes and reference electrodes are made by thick film technology. The output voltage of the ideal A/F point is abrupt, the ratio of air to air is higher, the output voltage of the oxygen sensor decreases when the oxygen concentration is added in the exhaust gas; when the air-fuel ratio becomes lower and the oxygen concentration in the exhaust gas decreases, the output voltage of the oxygen sensor is increased.    The electronic control unit recognizes the mutation signal and corrections the injection volume, so as to adjust the air-fuel ratio accordingly and make it change near the ideal air-fuel ratio. At present, the NOx sensor is more and more strict for the diesel exhaust emission of NOx and PM. To cope with this limitation, it is not enough to improve the combustion mode of diesel engines. Therefore, post-processing technology is more and more valued. The selective reduction catalyst (SCR) method is one of the NOx purification techniques. The NOx in the tail gas can be selectively adsorbed to the catalyst. By spraying urea to the catalyst, the NOx can be decomposed into nitrogen, water, and discharge by reduction reaction.    The sensor in urea SCR can detect whether the dosage of urea water needed for SCR is suitable. This sensor is essential for reducing agents using nitrogen oxides (NOx) as urea water purifiers. Knock sensor detonation sensor is used to detect engine vibration, by adjusting ignition advance angle and avoiding detonation. Detonation can be detected in three ways, namely cylinder pressure detection, engine block vibration, and combustion noise.    The detonation sensors have magnetostrictive and piezoelectricity. The use temperature of the magnetostrictive detonation sensor is -40 C ~125 C and the frequency range is 5~10kHz; the piezoelectric detonation sensor has a sensitivity of 200mV/g at the center frequency 5.417kHz and has good linearity in the range of 0.1g~10g. titanium dioxide oxygen sensor has characteristics like basic structure, lightness, cheapness, and strong resistance to lead pollution. The two zirconia micro ion sensor consists of calcium oxide stable oxidation plasma, porous platinum thick film working electrode, palladium/oxidation, and thick film parameter electrode, water layer, electrode contact, and guard layer.     V. Application of Vehicle Sensor in Vehicle Chassis Electronic Control  System   Chassis sensors are sensors distributed in the transmission control system, the suspension control system, the power steering system, and the braking system. They are different in different systems, but the working principle is the same as the sensor in the engine, which is mainly used in the following.   Suspension sensors are used to control and control vehicle dynamics by interfering and adjusting the characteristics of vehicle suspension components. The continuous damping control system (ADC) consists of 4 control units, CAN, 4 wheel vertical acceleration sensors, 4 body vertical acceleration sensors, and 4 damper proportional valves.    According to the vehicle movement and the information detected by these sensors, the optimal damping coefficient of each wheel suspension damper is calculated, the height of the car is adjusted automatically, the change of the vehicle posture is suppressed, and the control of vehicle comfort, handling stability and driving stability is realized. The system is realized by the electronic control of the steering angle of the wheel.    The common system has the active front-wheel power steering system ESP, the active front-wheel superposition steering system AFS, and the active rear-wheel steering system RWS. The sensors used mainly include the speed sensor, engine speed sensor, torque sensor, and so on, which make use of these sensors to make the power steering control system realize steering control light, improve response characteristic, reduce engine loss, increase output power, save fuel and so on.   Whether it is ESP, AFS, or RWS, the principle of it is the driver's manipulation instruction, which senses the condition of the road surface by the sensor, and passes the network to the electronic controller and the actuator in the form of the electrical signal.   （1）The anti-lock braking sensor of the ABS system mainly uses the wheel angular velocity sensor to detect wheel speed. When the slip rate of each wheel is 20%, the brake oil pressure is controlled, the braking performance is improved, and the vehicle handling and stability are ensured. In this system, the wheel speed sensor is a very important part of ABS. It needs to provide reliable and precise wheel speed to ECU in time. The sensors have electromagnetic, Holzer, and magnetoresistance.   （2）TCS system, when the driving torque of the vehicle driving wheel is too large, the driving wheel will move relative to the ground. It is generally hoped that the slip rate of the driving wheel should not exceed 20%. This system of control for driving wheel skating is called the TCS system. It is developed on the basis of ABS. In most cars, TCS and ABS share an ECU. They identify and judge the driving condition of a vehicle based on the signal input by sensors.   （3）ESP electronic stabilization system ESP is an active safety system with good maneuverability and direction stability by adjusting the size and matching of the longitudinal force of the wheel to control the yaw motion of the car. The basic principle of ESP is to identify the expected motion state of a driver by means of sensors and operational logic. In order to identify the driver's expectation of the car and know the actual motion state of the car, the ESP system needs more sensors than ABS and TCS. They are hydraulic sensors of steering wheel sensor, vehicle yaw rate sensor, lateral acceleration sensor, and brake master cylinder.     VI. Sensor Application in Automobile Safety System   Safety is the primary factor for automobile consideration, and there are many sensors for safety, such as micro accelerometers for automobile airbags, surface micromachined gyroscopes of angle measurement rate, etc. Microaccelerometer micro accelerometer is usually composed of a parallel cantilever beam, one end of the beam is fixed on the frame and a small mass block (about 10mg) is suspended at the other end.    When there is no acceleration, the mass block is not moving. When there is a vertical acceleration, the mass block is moving, the acceleration is sensitive to the acceleration, and the signal is converted to the output by C/V transformation and phase-sensitive demodulation. According to the detection mode, the micro accelerometer has several kinds of piezoresistive, capacitive, tunnel, resonant, and thermal forms.   The capacitance micro accelerometer has high sensitivity, low noise, small drift and a simple structure. It is widely used in automobile airbag systems and anti-skid systems. The mass of capacitance micro accelerometer mass block moves downward when it has acceleration and changes the distance from another electrode on the frame. The displacement of mass movement can be obtained by measuring the change of capacitance.    The main structure is divided into suspension. The arm swing type and comb-like folded beam type are changed into other types. The structure of the former is relatively simple, and the bulk silicon processing method is mostly used. The simple pendulum type structure consists of the upper and lower fixed electrodes and the movable sensitive silicon cantilever beam electrode, the anisotropic corrosion of the semiconductor plane process, and the encapsulation of the electrostatic sealing technology. The latter can be regarded as the combination of the cantilever beam and the combination.    The design is much more complicated. The micromachining method is mainly based on surface sacrificial layer technology. The isotropic properties of the polysilicon material can guarantee the symmetry of the micromechanical properties, the precision of the batch processing is high, and the sensitive parts of this structure are small in size, and the monolithic integration of the peripheral circuits is realized. Micromachined gyroscope (MEMS) micromachined gyroscope (MEMS) is a vibrational angular rate sensor, which has attracted much attention in the application and development of automobiles. It is mainly used in GPS signal compensation and chassis control system for automobile navigation.   There are two vibration modes in the micromechanical gyroscope, one is the transverse vibration mode, that is, the mode of driving vibration, which is usually called the reference vibration, which will produce additional motion under the action of the Coriolis force; the other is the normal vibration mode, the sensitive vibration mode, the detection of the additional movement of the Coriolis force, and the angular rate information contained in the Coriolis force. According to the material used, the micromachined gyroscope is divided into two kinds of quartz and silicon vibrating beams. The quality factor of quartz material has the highest Q value, the top characteristic of the gyroscope is the best, but the quartz processing is difficult and the cost is very high.    Silicon material has complete structure, good elasticity, and easy to get high Q value micromechanical structure, which has become the mainstream of low-cost research and development at present. The structure of the silicon micromachined gyroscope, the vibration beam structure, the double frame structure, the plane-symmetric structure, the transverse fork structure, the comb tuning fork structure, the beam island structure are used. The driving modes for the reference vibration are electrostatic, piezoelectric, and electromagnetic driving. The detection methods of additional vibration caused by the Coriolis force are capacitive detection, piezo detection, and piezoresistive. Testing.    The gyroscope design with electrostatic drive and capacitance detection are the most common. Some of the products have been developed successfully. Vehicle monitoring and self-diagnosis sensor in-vehicle monitoring and self-diagnosis, the main application of vehicle sensors will be tire pressure monitoring, followed by sensors applied to cooling, braking, and other systems.    In addition, such as the use of light sensors in the luminance control system, the use of magnetic sensors and airflow velocity sensors in the driving system, the use of indoor temperature sensors, suction temperature sensors, air volume sensors, sunshine sensors, and humidity sensors in the automatic air conditioning system, and the use of azimuth sensors and speed sensors in the steering system.    The collision sensor is the main control signal input device in the airbag system. The effect is when the vehicle collides on the road, the collision sensor is used to detect the intensity signal of the car collision, and the signal is entered into the airbag computer. The airbag computer determines whether the inflatable element is detonated to inflate the airbag according to the signal of the collision sensor. After the transformation of many countries, many cars are also equipped with side airbags. When the car has a lateral collision, the airbag will also be inflated, so a system equipped with a lateral airbag is equipped with a collision sensor on the left and right sides of the car.    This is more humane in ensuring the safety of vehicle users. The lateral tilt angle sensor is an effective method to prevent the car from turning over the car during driving. It is an important measure to improve the safety of the car, especially the high gravity cars, such as the off-road vehicle and the double-deck passenger car, which is more necessary.   Take an example, an angle sensor made with the principle of gravity. The mass of the swing part is m, and the distance between the center of gravity and the shaft is L. When the car body tilts or curves, it can make the swing part deflect. The force analysis in Figure 1 is an ideal state without any friction. The force F is the result of the joint action of the sliding force F1 and the centripetal force F2. The force F is proportional to the tilting force, and the beta-generated deflection angle is proportional to the tilting force. The resultant force T of the gravitational G and F in the oscillating part is the tension of the pendulum, and the swing angle of beta =tg-1 (F/G) is independent of L. When the mass m is fixed, the beta is only related to F and is proportional.   In fact, due to the existence of friction on the shaft, the longer the L is, the larger the swing torque is, the higher the accuracy. Angle sensor is usually used as a sampling element in the control system, and its performance plays an important role in the whole system. The potentiometer angle sensor has been widely used in all kinds of control systems, but its disadvantage is the existence of sliding wear and electrical noise of the contact. The magnetic sensitive resistance angle sensor is a new pure resistive element made of semiconductor technology. It is characterized by no contact.    When the swing partial deflection, the flux of the magnetic resistor is changed to make the resistance of the magnetic sensitive resistance several times. The above changes fundamentally eliminate the electrical noise and improve the accuracy. All kinds of angle sensors have a damping function so that there is a short delay in response to the measured angle, which is beneficial for the control system.   VII. Other Major Automotive Sensors   Alcohol detection MEMS system is a new type of integrated alcohol sensor, which can adsorb oxygen according to the oxygen concentration in the environment and change the resistance value. In normal conditions, the element can keep a certain resistance value after the oxygen is adsorbed in the air, and once the air contains alcohol, the oxygen element on the surface of the element will react with the alcohol to reduce the resistance value.    By measuring the resistance value, we can detect the alcohol concentration in the breath. The alcohol detection MEMS sensor will be embedded in the sealed shell of the diameter 8mm, together with the signal processing circuit and so on, and will be embedded in the steering wheel together. Once the driver's exhaled gas contains alcohol, a safety alarm will be issued.    When the raindrop is hit on the glass of the induction zone, the intensity of the light reflected by the raindrop will change because of the rainfall or moisture content on the glass and changes the brushing frequency of the wiper. Or through the infrared electronic rainfall sensor to induce the amount of rainfall, and automatically adjust the speed of the wiper with the change of speed to improve the driver's driving convenience to make the driving safer.    The tire pressure monitoring system installs highly sensitive sensors on each tire to monitor the tire condition at any time in the driving state and transmit it wireless to the receiver through a sensor to enable the driver to grasp the condition of the tire at any time, to ensure the safety of the car, to prolong the service life of the tire and to reduce the consumption of the fuel. The most advanced direct tire pressure monitoring solutions include advanced warning systems, pressure, temperature, voltage and motion detection.   When the oil viscosity sensor changes the oil, it usually depends on the time or mileage specified by the manufacturer. A few manufacturers have adopted a more advanced way to calculate the oil exchange interval by recording engine speed and temperature.     VIII. Automotive Sensors Market Size--Its Market Trend   Because of the important role of automotive sensors in the automotive electronic control system and the rapid growth of the market demand, all countries in the world have paid great attention to its theoretical research, new material application, and new product development. The development trend of automotive sensor technology in the future is miniaturization, multi-function, integration, and intelligence.   The microsensor with low cost and high performance can be designed by means of micro electro mechanical system (MEMS) technology and computer-aided design technology. At the current level of technology, micromachining technology has been able to produce microstructures with different levels of 3D, and then produce tiny sensor sensors with very small sizes. Because the components are relatively small, the use is relatively convenient and efficient, making the economy improved.    Multifunction means that a sensor can detect 2 or more two characteristic parameters or chemical parameters, thus reducing the number of sensors and improving the reliability of the system. Integration refers to the use of IC manufacturing technology and fine processing technology to make IC sensors. Intelligentization refers to the combination of sensors and large-scale integrated circuits with CPU, which is intelligent, to reduce the complexity of ECU, to reduce its volume, and to reduce the cost.    In addition, the development of new materials is an important basis for sensor technology. Now new materials, such as optical fiber, nanomaterials, superconducting materials, have opened a new world for the development of sensors. With the development of research, more and more new sensor materials will be developed. The function of the sensor is not only related to its material, but also to its processing technology.    Micromachining technology has been increasingly used in the sensor manufacturing process. With the development of modern manufacturing technology, more advanced manufacturing technologies will be applied to the manufacture of automotive sensors. The principle of the sensor is based on various physical, chemical, biological effects, and laws, which enlightens people to further explore sensitive functional materials with new effects and to develop new sensors with new principles. This is an important way to develop low-cost, high-performance, multi-functional, and miniaturized sensors. FAQ   1. What is a sensor in automobile? Automobile sensors are intelligent sensors which can be used to control and process the pressure of oil, temperature, level of emission, coolant levels, etc. There are different types of sensors used in automobiles, but knowing the working of these sensors is essential.   2. How many sensors does a car have? Currently, each vehicle has from 60 to 100 sensors on board and we can expect that number to rise as cars get 'smarter'.” In fact, recent industry figures suggest the number of sensors is projected to reach as many as 200 per car based on current trends.   3. What is the importance of sensors in the automobile? Sensors monitor vehicle engines, fuel consumption and emissions, along with aiding and protecting drivers and passengers. These allow car manufacturers to launch cars that are safer, more fuel efficient and comfortable to drive.   4. How do vehicle sensors work? Using echo-times from sound waves that bounce off nearby objects, the sensors can identify how far away the vehicle is from said object, and alert the driver the closer the vehicle gets. Electromagnetic sensors create an electromagnetic field around the bumper, and offer an alert whenever objects enter it.   5. How many sensors does a F1 car have? 300 sensors. With help from over 300 sensors on each car, McLaren's F1 ECU deals with over 1000 input parameters and transmits more than 1.5GB of live data back to the garage during an average 300km grand prix.   6. Where are sensors located on cars? Depending on the vehicle engine model, you often have 1 to 4 exhaust gas temperature sensors. The sensors are installed on the exhaust pipe and the exhaust manifold, and sometimes also on the turbocharger. The sensors are often quite expensive and can be difficult to reach and replace; they often rust and get stuck.   7. How long do car sensors last? Newer oxygen sensors are supposed to work efficiently for 60,000 to 90,000 miles, depending on the model of your car. If your mechanic determines that your car's problem is due to a bad or failing oxygen sensor, the replacement shouldn't take long and you'll be ready to tackle many more miles on the road.   8. Do all cars have sensors? Modern cars have an increasing amount of sensors. Most cars have an oxygen sensor and a throttle position sensor, but parking sensors are optional. Professional mechanics agree that one of the most important evolutions to come about in recent years is the expansion of sensors to monitor mechanical systems.   9. How do I know if my upstream or downstream oxygen sensor is bad? A decrease in fuel efficiency can be a telltale sign that an O2 sensor is not performing as it should. This can happen because of a fuel mixture that is either too lean or too rich. Such a swing in A/F ratio is a sign that an upstream or control sensor is faulty.   10. What does a car do when the oxygen sensor is bad? If your oxygen sensor is failing, then its readings will be inaccurate, again, resulting in a sub-optimal fuel-to-air composition. Your car's performance isn't the only thing that is harmed by a malfunctioning oxygen sensor - it can do damage to the environment as your car's emissions will increase drastically.  

Warm hints: this article reading time is about 15 minutes. This article is mainly about learning several kinds of industrial weapons - sensors. Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, systems engineering, computer technology, electronics, hydraulic pressure technology, and automatic control, among which automation is based on control theory and computer technology.   CatalogI、Automation TechnologyII、Physical SensorIII、Fiber Optic SensorIV、Bionic SensorV、Infrared SensorVI、Electromagnetic SensorVII、Magneto-optical Effect SensorVIII、How to Choose Industrial SensorsFAQ I. Automation Technology Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, system engineering, computer technology, electronics, hydraulic pressure technology, automatic control, etc., of which automation and control theory and computer technology The most influential technology. There are a lot of special equipment in automation technology, just like the different weapons, the author made a count of the automated weapons below.II. Physical SensorPhysical sensorSensor (Sensor) is a common but very important device. A sensor is a device, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. For the sensor, the input can be divided into static and dynamic according to the input state. We can get the static characteristics of the sensor based on the relationship between the output and the input based on the steady-state of each value.  The main indicators of the static characteristics of the sensor are linearity, hysteresis, repeatability, sensitivity, and accuracy. The dynamic characteristics of a sensor refer to the response characteristics of the input over time. Dynamic characteristics are usually described using automatically controlled models such as transfer functions. In general, the signal received by the sensor has a weak low-frequency signal, and the amplitude of the external interference sometimes exceeds the measured signal. Therefore, eliminating the noise in series becomes a key sensor technology. The physical sensor is a sensor that detects physical quantities by the use of certain physical effects. The sensor can convert measured physical volume into a form of energy to facilitate the processing of the signal device. The output signal and the input signal have a definite relationship. The main physical sensors include photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, pyroelectric sensors, and optical fiber sensors.  As an example, let us look at the more commonly used photoelectric sensors. This kind of sensor converts the optical signal into an electrical signal. It directly detects the radiation information from the object and can also convert other physical quantities into an optical signal. The main principle is the photoelectric effect: When the light is irradiated to the material, the electrical effect on the material changes, and the electrical effects here include electron emission, conductivity, and potential current. Obviously, a device that can easily produce such an effect becomes a major component of a photoelectric sensor, such as a photoresistor.  In this way, we know that the main working process of a photoelectric sensor is to receive the corresponding light, convert the light energy into electricity through a device such as a photosensitive resistance, and then obtain the required output by amplification and denoising electric signal. The output electrical signal here has a certain relationship with the original optical signal, which is usually close to a linear relationship so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be compared to optical sensors. The range of applications of physical sensors is very extensive. We look at the application of physical sensors from the perspective of biomedical sciences. It is not difficult to infer that physical sensors have important applications in other aspects. For example, blood pressure measurement is the most common type of medical measurement. Our usual blood pressure measurement is an indirect measure of the blood pressure in the vessel by measuring the relationship between blood flow and pressure detected by the body surface. The sensors needed to measure blood pressure usually include an elastic diaphragm that transforms the pressure signal into a deformation of the diaphragm and then converts it into a corresponding electrical signal based on the strain or displacement of the diaphragm. At the peak of the electrical signal, we can detect systolic pressure. After passing through the inverter and the peak detector, we can get the diastolic pressure. The average pressure can be obtained through the integrator. Let us look again at breath measurement technology. Respiratory measurement is an important basis for the clinical diagnosis of lung function and is essential in surgery and patient monitoring. For example, when using a thermistor sensor for measuring respiratory rate, mount the sensor's resistance on the outside of the front end of a clip, clip the clip over the nose, and pass the heat as the flow of breathing gas flows from the thermistor surface Sensitive resistance to measure the frequency of breathing and the status of hot gas. Another example of the most common body surface temperature measurement process. Although it seems easy, it has a complex measurement mechanism. The body surface temperature is determined by various factors such as the local blood flow, the heat conduction of the underlying tissue, and the heat dissipation of the epidermis. Therefore, the measurement of the skin temperature must take into account various influences.  Thermocouple sensors are more commonly used in the measurement of temperature, usually rod-shaped thermocouple sensors and thin-film thermocouple sensors. Because the size of the thermocouple is very small and the accuracy is relatively high, it is possible to measure the temperature at a certain point accurately. With the help of later analysis statistics, a more comprehensive analysis result can be obtained. This is incomparable with the traditional mercury thermometer, but also shows the broad prospects for the application of new technologies to scientific development. From the above introduction, it can be seen that physical sensors have a variety of applications just in biomedical applications. The development direction of the sensor is a multifunctional, imaged, intelligent sensor. Sensor measurement as an important means of data acquisition is indispensable for industrial production and even family life, and physical sensors are the most common family of sensors. The flexible use of physical sensors will inevitably create more products and better benefits. III. Fiber Optic SensorFiber optic sensorIn recent years, sensors have evolved in the direction of sensitivity, precision, adaptability, compactness, and intelligence. In the process, fiber optic sensors are a new addition to the sensor family. Optical fiber has many excellent properties, such as anti-electromagnetic interference and atomic radiation performance, fine diameter, soft, lightweight mechanical properties, insulation, non-inductive electrical properties, water resistance, high-temperature resistance, corrosion resistance, chemical properties, etc. It can reach people's eyes and ears in unattainable places (such as high-temperature areas), or in areas harmful to humans (such as nuclear radiation area), but also can transcend human physiological boundaries and receive sensory organs Unforeseen outside information. Optical fiber sensors are new technologies that have emerged in recent years. It can be used to measure a variety of physical quantities, such as sound fields, electric fields, pressures, temperatures, angular velocities, and accelerations, as well as measurement tasks that are difficult to accomplish with existing measurement techniques. In tight spaces, fiber optic sensors show unique capabilities in environments with strong electromagnetic interference and high voltage. At present, there are more than 70 optical fiber sensors, which are roughly divided into optical fiber sensors and optical fiber sensors. The so-called optical fiber sensor itself is the optical fiber directly to receive the outside world was measured. The external measured physical quantity can cause the length, refractive index, and diameter of the measuring arm to change so that the light transmitted within the fiber changes in amplitude, phase, frequency, polarization, and the like. The light transmitted by the measuring arm interferes (compares) with the reference light of the reference arm to change the phase (or amplitude) of the output light, and the change in the measured light can be detected based on this change. The phase of the transmission in the optical fiber is highly sensitive to external influences, and the interferometric technique can detect the physical quantity corresponding to the slight phase change of 10 negative quadratic arcs. For the optical fiber’s winding and low loss characteristics, we can disc a long fiber optic into a small diameter optical fiber ring in order to increase the length, to obtain higher sensitivity. An optical fiber acoustic sensor is a kind of sensor using the optical fiber itself. When the fiber is a little tiny external force, it will produce micro-bending, and its light transmission capacity has undergone great changes. Sound is a kind of mechanical wave. Its effect on the optical fiber is to stress and bend the optical fiber. By bending, the sound intensity can be obtained. Compared with laser gyro, FOG has high sensitivity, small size, and low cost. It can be used in the high-performance inertial navigation systems of aircraft, ships, and missiles. Another major category of fiber optic sensors is the use of fiber optic sensors. The structure is rough as follows: The sensor is located at the end of the fiber. The fiber is just the transmission line of light, and the physical quantity to be measured is transformed into the change of the amplitude, phase, or amplitude of the light. In this sensor system, conventional sensors are combined with optical fibers. The introduction of optical fibers offers the possibility of implementing probing telemetry. This fiber-optic transmission sensor has a wide range of applications and is easy to use, but its accuracy is slightly lower than that of the first type of sensor. Fiber optic sensors have become a rising star in sensor families with their numerous advantages and have played their own unique role in various measurements and become an indispensable part of the sensor family. IV. Bionic SensorBionic sensorA bionic sensor is a new sensor using a new detection principle, which uses immobilized cells, enzymes, or other bioactive substances and transducers to form a sensor. This kind of sensor is a new type of information technology developed in recent years by the mutual penetration of biomedicine and electronics and engineering. This sensor is characterized by high performance and long life. In bionic sensors, biometric sensors are more commonly used. Bionic sensors in accordance with the media used can be divided into enzyme sensors, microbial sensors, organelle sensors, tissue sensors. In the picture, we can see that there is a close connection between the biomimetic sensor and all aspects of the biological theory and it is a direct result of the development of the biological theory. Among biosensors, urea sensors are a recently developed type of sensor. The following is an example of a urea sensor biosensor sensor application. The urea sensor is mainly composed of two parts, a biofilm, and an ion channel. The biofilm can feel the effects of external stimuli, the ion channel can receive the information of the biofilm and amplify and deliver it. When the sensory site inside the film is affected by an external stimulating substance, the permeability of the membrane will change, allowing a large number of ions to flow into the cell to form the transmission of information. Among them, the important component of the biofilm is the membrane protein, which can produce a conformal network change, change the permeability of the membrane, and transmit and amplify the information. The biofilm ion channels, which are composed of amino acid polymers, can be replaced by polymers of polyamine acids (L-glutamic acid, PLG), which are easily synthesized in organic chemistry, and are more chemically stable than the enzyme. PLG is water-soluble, which is not suitable for motor modification. However, PLG and polymer can synthesize block copolymers to form sensor films for sensors. The principle of the ion channel of the biofilm is basically the same as that of the biofilm. After the block copolymer film is fixed on the electrode, if a substance that changes the inductive network of the PLG is added, the permeability of the film changes, and thus a current is generated. Changes in the current from the changes can be carried out on the detection of stimulating substances. The urea sensor has been tested and proved to be a biometric analog sensor with good stability. The lower limit of detection is 10 orders of magnitude of a negative third power. It can also detect irritant substances, but for the time being it is not suitable for the measurement of living organisms. At present, although many biomimetic sensors have been developed successfully, the stability, reproducibility, and mass productivity of biomimetic sensors are obviously insufficient. Therefore, biomimetic sensing technology is still in its infancy. Therefore, in addition to continuing to develop a new series of biomimetic sensors And improve the existing series, the biomembrane immobilization technology and solid-state biomimetic sensor deserved further study. In the near future, biomimetic sensors that simulate the functions of the organism will appear, which may exceed the sensitivity of human facial features and improve the robot's vision, taste, touch, and ability to operate on objects. We can see the broad prospects for biomimetic sensor applications, but these require the further development of biotechnology, and we'll see this day coming. V. Infrared SensorInfrared sensorInfrared technology has been developed to the present, as we all know. This technology has been widely used in modern science and technology, national defense and agriculture, and other fields. Infrared sensing systems are infrared-based measurement systems that can be divided into five categories based on function:  (1) radiometers for radiation and spectroscopic measurements; (2) search and tracking systems for searching and tracking infrared targets, determining Its spatial position and its movement are tracked; (3) The thermal imaging system can produce a distribution image of the entire target infrared radiation; (4) Infrared ranging and communication systems; (5) Hybrid systems, refer to the above categories A combination of two or more in the system. Let us look at the composition of the infrared system, the main optical system, and auxiliary optical system, on the basis of which the key components of infrared are discussed in detail. In fact, the working principle of the infrared sensor is not complicated, the working principle of each part of a typical sensor system is as follows: (1)The target object. According to the infrared radiation characteristics of the target to be set, the infrared system can be set. (2)Atmospheric attenuation. When the target's infrared radiation passes through the Earth's atmosphere, the infrared radiation emitted by the infrared source will be attenuated due to the scattering and absorption of gas molecules and various gases, and various sol particles. (3) Optical receiver. It receives a portion of the target's infrared radiation and transmits it to the infrared sensor. Equivalent to a radar antenna, often used as an objective lens. (4) Radiation modulator. Radiation from the target under test is modulated into alternating radiant light to provide the target orientation information and to filter out large areas of interfering signals. Also known as a reticle and chopper, it has a variety of structures. (5) Infrared detector. This is the heart of the infrared system. It is the use of infrared radiation and the physical interaction between the physical effects of detecting infrared radiation sensors, in most cases is the use of this interaction presented by the electrical effects. Such detectors can be divided into two types of photon detectors and thermal detectors. (6) Detector cooler. Since some detectors must work at low temperatures, the corresponding system must have refrigeration equipment. After cooling, the equipment can shorten the response time and increase detection sensitivity. (7) Signal processing system. The detected signal is amplified, filtered, and extracted from these signals. This information is then converted into the required format and finally delivered to the control device or display. (8) Display device. This is the terminal device of the infrared device. Commonly used displays include oscilloscopes, kinescopes, infrared sensitized materials, indicating instruments, and recorders. Here gives a video of infrared sensors:Working principle of infrared sensorAccording to the above process, the infrared system can complete the measurement of the corresponding physical quantity. The infrared system is the core of infrared detectors, according to the detection mechanism of different, can be divided into two categories of heat detectors and photon detectors. The heat detector is used as an example to analyze the principle of the detector. The thermal detector is the use of radiant heat effect, so that the detection element causes the temperature to rise after receiving radiation, and thus makes the detector temperature-dependent performance changes. By detecting a change in one of these properties, radiation can be detected. In most cases, radiation is detected by thermoelectric changes. When the element receives the radiation and causes a non-electrical physical change, the corresponding change in the amount of electricity can be measured by appropriate transformation. Infrared sensors have played an important role in modern production practices. With the improvement of detection equipment and other parts of technology, infrared sensors can have more performance and better sensitivity. VI. Electromagnetic Sensor Magnetic sensors are the oldest sensors and compass is the earliest application of magnetic sensors. However, as a modern sensor, in order to facilitate the signal processing, a magnetic sensor is required to convert the magnetic signal into an electrical signal. The earliest applications were magnetoelectric sensors manufactured on the principle of electromagnetic induction. This magnetic sensor has made an outstanding contribution to industrial control. But today it has been replaced by a new type of magnetic sensor based mainly on high-performance magnetically sensitive materials.The shape of an electromagnetic sensorAmong the electromagnetic effect sensors used today, the magnetic rotation sensor is an important one. Magnetic rotation sensor mainly by the semiconductor magnetoresistive components, permanent magnets, fixtures, enclosures, and other components. A typical structure is a pair of magnetoresistive elements mounted on a permanent magnet stimulation, the input and output terminals connected to the fixture, and then installed in the metal box, and then sealed with plastic to form a closed structure, the structure has good reliability. Magnetic rotation sensor has many advantages of semiconductor magnetoresistance element. In addition to having high sensitivity and a large output signal, it also has a strong speed detection range, which is due to the development of electronic technology. In addition, this sensor can also be used in a wide temperature range, has a long working life, resistance to dust, water, and oil, and therefore withstand a variety of environmental conditions and external noise. Therefore, this kind of sensor has received widespread attention in industrial applications. Magnetic rotary sensors are widely used in factory automation systems because they have satisfactory characteristics and do not require maintenance. Its main application is the machine tool servo motor rotation detection, factory automation robotic arm positioning, hydraulic stroke detection, factory automation related equipment position detection, rotary encoder detection unit, and a variety of rotating detection unit. Modern magnetic rotation sensors mainly include four-phase sensors and single-phase sensors. In the course of work, four-phase differential rotation sensor with a pair of detection unit to achieve differential detection, the other to achieve the inverted differential detection. In this way, four-phase sensor detection capability is four times single-element. The two-element single-phase rotation sensor also has its own advantages, that is, small and reliable features, and the output signal can detect low-speed movement, anti-environmental impact, and anti-noise ability, low cost. Therefore, single-phase sensors will also have a good market. Magnetic rotary sensors also have great potential for use in household appliances. In the reversing mechanism of the cassette recorder, a magnetic resistance element can be used to detect the end of the magnetic tape. Most home video recorders have a variable speed and high-speed playback function, which can also be used magnetic spindle sensors to detect the spindle speed and control, to obtain a high picture quality. The positive and negative rotation of the motor in the washing machine and the high and low-speed rotation functions can be detected and controlled by the servo rotation sensor. Electromagnetic proximity switch. This switch can be sensed into the metal area of their own test objects, control their own internal circuit on or off. The switch generates its own magnetic field. When a metal object enters the magnetic field, it will cause a change in the magnetic field. This change can be turned into an electrical signal by switching the internal circuitry. The electromagnetic sensor is a widely used high-tech, both at home and abroad have invested some research efforts in research, the application of this sensor is penetrating into the national economy, national defense construction and people's daily life in all fields, with the information The arrival of society, its status and role will certainly be more prominent. VII. Magneto-optical Effect SensorMagneto-optical effect sensorModern electric measurement technology is maturing day by day, has the advantages of high precision, easy to real-time processing connected to a microcomputer, etc., has been widely used in the measurement of electrical and non-electrical measurements. However, the electrical measurement method is susceptible to interference. In the AC measurement, the frequency response is not wide enough and there are certain requirements on voltage and insulation. With the rapid development of laser technology, the above problems have been solved. Magneto-optic effect sensors are high-performance sensors using laser technology. Laser is another new technology that has been rapidly developed in the early 1960s. Its appearance signals that people have mastered and utilized light waves and entered a new stage. Due to the low monochromaticity of ordinary light sources in the past, many important applications are limited. The advent of lasers makes radio technology and optical technology by leaps and bounds, penetrate each other and complement each other. Today, many sensors have been fabricated using lasers that solve many of the unsolved technical problems that make them suitable for use in hazardous, flammable places such as coal, oil, and gas storage. For example, optical fiber sensors made of laser can measure the situation of crude oil injection, cracking oil tank parameters. It is not necessary to supply power at the place of measurement. This is particularly applicable to the petrochemical equipment group that requires strict safety and explosion protection measures. It can also be used to implement optical method telemetry chemistry in some aspects of large-scale steel plants. The principle of magneto-optic effect sensor mainly utilizes the polarization state of light to realize the function of the sensor. When a beam of polarized light passes through the medium, if there is an external magnetic field in the beam propagation direction, the light will rotate through the plane of polarization by an angle, which is the magneto-optical effect. That is, the applied magnetic field can be measured by the angle of rotation. Under certain experimental setups, the angle of deflection is proportional to the intensity of the output, and the laser diode LD is illuminated by the output light to obtain the digitized light intensity that is used to measure a particular physical quantity.Magneto-optical effect sensorSince the late 1960s, RC Lecraw has raised great concerns after his research report on magneto-optical effects was presented. Japan, the Soviet Union, and other countries have conducted research, and domestic scholars have also explored it. Magneto-optical sensor with excellent electrical insulation properties and anti-interference, wide frequency response, safety, and explosion-proof and other characteristics, and therefore for some special occasions electromagnetic parameters of measurement, has a unique effect, especially in the power system high voltage and current The measurement aspect shows its potential advantages. At the same time, by developing the software and hardware of the processing system, automatic real-time measurement of the welding machine and the robot control system can also be realized. In the use of magneto-optic effect sensors, the most important thing is to choose magneto-optical media and lasers. Different devices have different capabilities in terms of sensitivity and working range. With the advent of high-performance lasers and new types of magneto-optical media in recent decades, the performance of magneto-optical effect sensors has become stronger and the applications have become more widespread. Magneto-optical sensor, as a specific purpose sensor, can play its own function in a particular environment. It is also a very important industrial sensor.  VIII. How to Choose Industrial SensorsModern sensors vary widely in principle and structure. How to select a sensor based on a specific measurement purpose, measurement object, and measurement environment is the first problem to be solved when performing a certain amount of measurement. When the sensor is determined, the matching measuring method and measuring equipment can be determined. The success or failure of measurement results depends to a large extent on the reasonableness of the choice of sensors. The influencing factors are:  (1) Determine the type of the sensor according to the measurement object and the measurement environment. (2)Selection of the sensitivity. (3)Frequency response. (4) Linear range. (5)Stability.(6) Accuracy. FAQ 1. What sensor means?a device that responds to a physical stimulus (such as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control) .2. What is the purpose of a sensor?A sensor converts the physical action to be measured into an electrical equivalent and processes it so that the electrical signals can be easily sent and further processed. The sensor can output whether an object is present or not present (binary) or what measurement value has been reached (analog or digital). 3. How do sensors work?Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed. 4. What can sensors detect?Broadly speaking, sensors are devices that detect and respond to changes in an environment. Inputs can come from a variety of sources such as light, temperature, motion and pressure. 5. What are the importance of sensors in our daily life?Intelligent sensor systems are omnipresent in our everyday lives. They provide security, save lives and improve our quality of life. As more and more areas of life are automated and networked, the importance of innovative sensor technologies will also increase in the future. 6. How do we classify sensors?Classification of Sensors:Active and Passive Sensors. Contact and Non-Contact Sensors.Absolute and Relative Sensors.Analog and Digital Sensors.Miscellaneous Sensors. 7. How are sensors used to collect data?With a sensor, a machine observes the environment and information can be collected. A sensor measures a physical quantity and converts it into a signal. Sensors translate measurements from the real world into data for the digital domain. 8. What is the difference between sensor and transducer?The main difference between sensor and transducer is that a transducer is a device that can convert energy from one form to another, whereas a sensor is a device that can detect a physical quantity and convert the data into an electrical signal. 9. Why do we need a temperature sensor?Within our homes, temperature sensors are used in many electrical appliances, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters. 10. How sensors are connected?A sensor device directly connected to a computer. A connected sensor is a sensor that also has a way to send data to either a local network or the Internet. Diagram of a sensor receiving waves on the left and broadcasting a wireless signal on the right to a router. A sensor device wirelessly connected to a network. 11. Can a transducer be a sensor?A Sensor is defined as a device which measures a physical quality (light, sound, space) and converts them into an easily readable format. If calibrated correctly, sensors are highly accurate devices. Not all transducers are sensors but most sensors are transducers. 12. What is the difference between active and passive sensors?Active sensors have its own source of light or illumination. In particular, it actively sends a pulse and measures the backscatter reflected to the sensor. But passive sensors measure reflected sunlight emitted from the sun. When the sun shines, passive sensors measure this energy. 13. What are the basic characteristics considered in the process of sensor selection?Sensor selection criteria include temperature, size, protection class, and whether the sensor requires a discrete or analog input. Also consider sensor repetition accuracy, sensor response speed, and sensing range. 14. What are the applications of sensors?Sensors are central to industrial applications being used for process control, monitoring, and safety. Sensors are also central to medicine being used for diagnostics, monitoring, critical care, and public health. 15. How do you check the accuracy of a sensor?To find out the accuracy of sensor you have to take several readings by your sensor on that particular one input parameter (like. temperature). after accumulating those sensor output values evaluate the standard deviation as per law, which indicate the accuracy level of your sensor. You May Also Like GPS and inertial sensors for driverless applicationsA New Technology for Advancing Opticals,Sensors Even Resistant SupercapacitorsSensors are Always In a State of Rapid ProgressComprehensive Analysis of Fiber Optic Sensor