As in the human body, there are organs in a motor vehicle that are necessary for perceiving the environment or one's own “body”. While people have to be satisfied with their eyes, ears, skin, nose and mouth, a vehicle can access countless sensors that are necessary for its function.
In principle, sensors measure various chemical and physical parameters and often convert them into electrical signals via further intermediate stages. The electrical signals are an essential part of electronic regulation and control systems and are indispensable for the safety and comfort of the vehicle. The electrical variables that are sent by the sensors include not only current and voltage, but also other variables such as frequency and period, phase or pulse duration of an oscillation, as well as resistances, capacitance and inductance. The electrical signals picked up by the sensor are processed by a microcomputer, a control unit, which in turn controls the actuators responsible for the output.
The world of sensors
The world of sensors has become larger and larger in recent years, thanks in part to an increasing need for safety and comfort and thus increasing demands on vehicles. We now expect the very latest technology in every new vehicle, from collision warning systems to
Lane change holders. And especially this new type of sensor, which takes care of the external environment, has grown steadily in recent years. This includes radar sensors, ultrasonic sensors or image sensors that can read and interpret traffic signs.
In the past, sensors that focused on the drive or the chassis were mainly used in cars. Up to 50 sensors are now installed in modern cars. Bosch is the world's leading manufacturer of so-called MEMS (Micro-Electro-Mechanical-System) sensors. The versatile MEMS have fine structures made of silicon inside, which move a tiny bit when the housing is moved. The electrical properties change as a result of the displacement, are measured and converted into a data stream. You can measure acceleration, rotation rates, pressure, mass flow and the earth's magnetic field in all three axes.
Sensors - types and functions
In addition to the electronic logic, the MEMS contain tiny mechanical elements. The individual parts in these sensors are so tiny that some of them are 17 times thinner than a human hair. MEMS can take on many functions: They are responsible for the parking assistance systems or for triggering the airbags and can also check seat occupancy and, if necessary, send a signal to buckle up. In a vehicle, the sensors can be divided into three categories: The drive train combines all sensors that are essential for the function of the vehicle, for example lambda probe, speed sensor, pressure sensor or angle / position transmitter. Sensors that are important for comfort in the car and especially for passengers are air quality sensors, pressure sensors for central locking or the rain sensors for windshield wiper control. The third category concerns driving safety: steering wheel angle sensors, acceleration sensors for the airbag or ESP and ABS are among the safety sensors of a vehicle.
There are also different types of sensors: The simplest type of sensor is a switch with two operating levels: "On" and "Off". Passive sensors are mostly simple resistors or capacitors, for example a temperature sensor. They usually output the signals as an analog voltage. Active sensors, on the other hand, are operated with electricity and usually send out a square-wave signal, for example the Hall sensor.
Sources: Text green car magazine, video: green car magazine
Cover picture: Climate sensors in the car - Copyright Syda Productions @ fotolia.com
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