Vehicle Sensorsย ๐:
In a way, sensors are the sensory organs of the vehicle. A fundamental component of electronic control systems, they must record physical or chemical variables and convert them into electrical signals.
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In recent years, there has been an explosion in the number of different types of sensor. Many new types of sensor have been seen in particular in the area of safety and convenience electronics. Essentially, sensors can be categorized as follows:
1. ๐๐จ๐ฌ๐ข๐ญ๐ข๐จ๐ง S๐๐ง๐ฌ๐จ๐ซ๐ฌ (๐๐ข๐ฌ๐ญ๐๐ง๐๐/๐๐ง๐ ๐ฅ๐ ๐ฌ๐๐ง๐ฌ๐จ๐ซ๐ฌ)
Position sensors are used to capture the position of
* the throttle valve,
* of the accelerator or brake pedal,
* of the distance and angular positions in diesel injection pumps,
* of the fill level in the fuel tank,
* of the steering angle,
* of the angle of tilt, etc.
The ultrasonic and radar sensors used to determine distances from obstacles for modern driver assist systems also belong in this category.
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Speed and velocity sensors are used to determine
* the speed of crankshafts,
* camshafts and
* diesel injection pumps or
* wheel speeds.
Yaw rate sensors also belong in this category. They detect the rotational movement of the vehicle about its own axis and are needed for ESP.
3. ๐๐๐๐๐ฅ๐๐ซ๐๐ญ๐ข๐จ๐ง S๐๐ง๐ฌ๐จ๐ซ๐ฌ
Acceleration sensors record the acceleration of the car body and are used in passive safety systems (airbags, seat belt tensioners, roll bars) and driving stability systems such as ABS and ESP, as well as in chassis control.
4. ๐๐ซ๐๐ฌ๐ฌ๐ฎ๐ซ๐ S๐๐ง๐ฌ๐จ๐ซ๐ฌ
Pressure sensors are used to capture a wide variety of pressures including
* suction or charging pressure,
* fuel pressure, brake pressure,
* tire pressure,
* hydraulic reservoir pressure (for ABS and power steering),
* refrigerant pressure (air conditioning system),
* modulation pressure (automatic transmission) and so on.
5. ๐๐๐ฆ๐ฉ๐๐ซ๐๐ญ๐ฎ๐ซ๐ S๐๐ง๐ฌ๐จ๐ซ๐ฌ
Temperature sensors are used to capture temperatures, e.g. in the context of measuring
* suction or charge air temperature,
* ambient and interior temperatures,
* evaporator temperature (air conditioning system),
* coolant temperature,
* engine oil temperature,
* Tyre air temperature and so on.
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Force and torque sensors are used to measure forces such as
* pedal force,
* drive,
* brake and steering torque forces or
* the weight of the occupants of a vehicle (for adaptive restraint systems).
7. ๐ ๐ฅ๐จ๐ฐ M๐๐ญ๐๐ซ๐ฌ
Flow-meters are used to capture the fuel requirement and the amount of air drawn in by the engine.
8. ๐๐๐ฌ S๐๐ง๐ฌ๐จ๐ซ๐ฌ
Gas sensors capture the composition of the exhaust gas (oxygen sensor, NOx sensor) or detect hazardous substances in the fresh air supply.
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* ๐๐ฎ๐ฅ๐ฌ๐ S๐๐ง๐ฌ๐จ๐ซ, C๐ซ๐๐ง๐ค๐ฌ๐ก๐๐๐ญ
The crankshaft sensor captures the engine speed and the position of the crankshaft. The control unit uses these values to calculate the injection pulse and the ignition pulse.
* ๐๐๐ฆ๐ฌ๐ก๐๐๐ญ ๐ฉ๐จ๐ฌ๐ข๐ญ๐ข๐จ๐ง
The camshaft sensor is located at the cylinder head and scans a ring gear at the camshaft. This information is used, for example, for the start of injection, for the signal to activate the solenoid valve for the pump/nozzle injection system and for cylinder-specific knock control.
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The air mass meter is installed between the air filter housing and the intake manifold. It measures the air mass drawn in by the engine. This variable provides the basis for calculating the fuel quantity that must be supplied to the engine.
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Air temperature sensors capture the temperature of the ambient air. The values measured are used to control various systems (e.g. the air conditioning system) or as correction values for the injection system. The installation location is determined by the air temperature to be measured. The sensor for the intake air temperature, for example, is located in the air duct for the intake air.
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The coolant temperature sensor is screw-mounted in the cooling system. The gauge tip protrudes into the coolant and records its temperature. The control unit uses this value to adapt the amount of fuel injected to the engine temperature.
* ๐๐ก๐ซ๐จ๐ญ๐ญ๐ฅ๐ ๐ฉ๐จ๐ฌ๐ข๐ญ๐ข๐จ๐ง
Throttle valve sensors are attached to the throttle valve axle. They monitor the opening angle of the throttle valve. From the values, the engine electronics calculate the fuel quantity which is injected based on other factors.
* ๐๐ง๐จ๐๐ค S๐๐ง๐ฌ๐จ๐ซ๐ฌ
Knocking is an uncontrolled form of combustion in a petrol engine. As continuous knocking can damage the engine, it must be checked and regulated. The engine control unit evaluates the voltage signals received from the knock sensor and regulates the ignition point in a range just below what is known as the knock limit. Knock sensors are permanently monitored by the control unit.
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The intake pipe pressure sensor measures the intake pipe vacuum downstream of the throttle valve and forwards this value to the engine control unit as an electrical signal. This is combined with the value of the air temperature sensor so that the air mass drawn in can be calculated.
* ๐๐ฑ๐ฒ๐ ๐๐ง S๐๐ง๐ฌ๐จ๐ซ๐ฌ
The oxygen sensor measures the residual oxygen content in the exhaust gas in order to ensure an optimum combustion mixture at all times. Depending on the type of sensor, a chemical element (titanium dioxide/zirconium dioxide) and the residual oxygen content of the exhaust gas bias a voltage, which is then used by the control unit as a measured variable.
EXAMPLES OF SENSORS FROM CAR BODY ELECTRONICS:
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The wheel speed is used by driving safety systems such as ABS and ASR as a speed value as well as by GPS systems to calculate the distance traveled. A fault will cause these systems to fail, significantly impairing safety.
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The transmission sensor captures the transmission speed. The speed signal is used by the control unit for precision control of the shift pressure during shifting and to decide which gear should be engaged when.
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Distance sensors are used to capture driving speed. They are mounted on the transmission or rear axle. The information obtained is required for the speedometer, cruise control, and converter slip control.
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For reasons of operational safety and for increased comfort, levels such as engine oil, coolant and washer fluid are monitored with level sensors. The level sensors send a signal to the engine control unit which activates an indicator lamp.
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The brake wear sensors are located on the brake linings and are subject to the same wear. A visual signal tells the driver that the wear limit has been reached.
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The sensor information provides the basis for the function of numerous active and passive safety systems. Thanks to significant progress in the development of new sensors, there has been a constant increase in the capabilities of safety and driver-assist systems in recent years. Sensors thus have a key role to play in increasing safety on our roads.
Some of the safety systems are
1.๐ ๐จ๐ซ๐ฐ๐๐ซ๐ ๐๐จ๐ฅ๐ฅ๐ข๐ฌ๐ข๐จ๐ง ๐๐ฏ๐จ๐ข๐๐๐ง๐๐ ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ
It alerts the driver when the vehicle is getting close to another vehicle in front of it. It employs various sensors such as cameras, RADAR or LIDAR to sense the objects or other vehicles in front of the vehicle. A forward-collision warning system provided with autonomous braking can reduce the speed of the vehicle thereby mitigating the effect of a collision.
2. ๐๐๐๐ฉ๐ญ๐ข๐ฏ๐ ๐๐ซ๐ฎ๐ข๐ฌ๐ ๐๐จ๐ง๐ญ๐ซ๐จ๐ฅ
The adaptive cruise control maintains the vehicle's pre-set speed. It automatically slows down the vehicle in heavy traffic to maintain a safe gap. Forward-mounted sensors keep track of the distance to the vehicle at the front. The vehicle accelerates to maintain the preset cruise speed as the traffic speeds up.
3. ๐๐๐ง๐ ๐๐๐ฉ๐๐ซ๐ญ๐ฎ๐ซ๐ ๐ฐ๐๐ซ๐ง๐ข๐ง๐ ๐๐ง๐ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐ข๐จ๐ง ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ
This system employs cameras to track the position of the vehicle within the lane and alert the driver if the vehicle is in danger. Certain systems offer haptic warnings such as seat or steering vibrations, while others provide audible and/or visual warnings.
4. ๐๐ฅ๐ข๐ง๐๐ฌ๐ฉ๐จ๐ญ ๐๐๐ญ๐๐๐ญ๐ข๐จ๐ง ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ
This sensor network system monitors the blind spots at the front, side and rear areas of the vehicle. Most of the systems provide visual alerts appearing on or near the side-view mirrors upon detecting the blind spot.
An audible alert is activated when the driver signals a turn, and the vehicle is headed towards the blind spot on the turning side.
Certain systems may also activate the steering controls or brake to maintain the vehicle in its lane.
5. ๐๐๐ซ๐ค ๐๐ฌ๐ฌ๐ข๐ฌ๐ญ ๐๐ง๐ ๐๐๐๐ค๐จ๐ฏ๐๐ซ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐ข๐จ๐ง ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ
assists drivers to park and back up their vehicles. Rear object detection systems make use of sensors and cameras to enable the driver to look for the objects in the rear side of the vehicle while backing up.
6. ๐๐๐๐ฉ๐ญ๐ข๐ฏ๐ ๐ก๐๐๐๐ฅ๐ข๐ ๐ก๐ญ
it alerts drivers to visualize objects better on dark, curved roads. The headlight pivots in the direction of a moving vehicle to illuminate the road ahead based on the vehicleโs speed and steering wheel movement.
7. ๐ ๐๐ญ๐ข๐ ๐ฎ๐ ๐ฐ๐๐ซ๐ง๐ข๐ง๐ ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ๐ฌ
it employs sophisticated algorithms to monitor the steering control and other behaviors such as blink duration and blink rate of the driver. This system is designed to warn the driver if it detects drowsiness or inattention.
8. ๐๐ฎ๐ซ๐ฏ๐ ๐ฌ๐ฉ๐๐๐ ๐ฐ๐๐ซ๐ง๐ข๐ง๐ ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ
it monitors the vehicle as it approaches bends in the road by using a global positioning system and digital map. Curve speed sensors alert the driver if the system senses that the vehicle is nearing a curve at an over speed.
* ๐๐ง๐ฏ๐ข๐ซ๐จ๐ง๐ฆ๐๐ง๐ญ๐๐ฅ ๐ฉ๐ซ๐จ๐ญ๐๐๐ญ๐ข๐จ๐ง
Sensors make modern vehicles not only safer but also cleaner. They supply the basic information for clean and effective fuel combustion in the engine, thereby enabling exhaust emissions values and fuel consumption to be reduced significantly. Finally, they support the reliable functioning of high-efficiency exhaust re-treatment systems. Examples include the controlled 3-way catalytic converter, the diesel particulate filter or the DeNOx catalytic converter.
