The main purpose of the ECS is to adapt the suspension of the car into the driving conditions taking account the speed, surface of the road, cornering, stopping requirements and acceleration. The aim is to increase safety and driving comfort. The basic driving characteristics of the car can be changed from a soft, smooth ride to a hard driving experience of a sports car and everything between. All should happen quickly and continuously. The driver has an option for select for manual selection by pushing a button to drive continuously in sport, normal or comfort mode.
The purpose of an accelerometer is to measure the car body motion and, in some cases, the vertical motion of the front wheels. The car body motion is measured by two accelerometers located very close to the upper fixing point of the front shock absorbers and springs. The wheel hub sensors are located at the other end of the shocks and springs next to the wheel. The idea is to measure the difference in vertical motion between the wheel and the body. In more modern systems the wheel hub sensors have been replaced by position sensors, which directly measure the distance between the wheel and body.
Most systems also include one accelerometer in the middle or rear part of the car's to measure pitch of the car. The aim of this feature is to reduce the inclination of the car when accelerating and braking.
Today the majority of new cars in the luxury and upper middle class range, including some Sport Utility Vehicles (SUVs) , have air suspension. The volume of the air in the air cushions in all corners of the car can be controlled. This is done by controlling the flow of the air in and out of the additional air reservoirs. The system includes a special air compressor, one or two air reservoirs, four shock absorber units with air springs and traditional shock absorbers, 2 to 5 stand-alone accelerometers and the electronic control unit (ECU) .
The alternative solution is to control the flow of oil inside traditional shock absorbers. The flow of oil is controlled by special electrically controlled valves inside the shock absorber. The system contains 3 or 5 stand alone accelerometers.