Suspension Height Sensors

Four suspension height sensors are used in the adaptive dynamics system, two for the front suspension and two for the rear suspension. A front suspension height sensor is attached to each side of the front subframes and connected by a sensor arm and sensor link to the related lower lateral arm of the front suspension. A rear suspension height sensor is attached to each side of the rear subframe and connected by a sensor arm and sensor link to the related upper control arm of the rear suspension.

The RH suspension height sensors are dual output, with separate outputs for the adaptive damping system and for the AFS (adaptive front lighting system). The LH suspension height sensors are single output, for the adaptive damping system only.

On each suspension height sensor, the sensor arm and sensor link convert linear movement of the suspension into rotary movement of the sensor shaft. The suspension height sensors measure suspension displacement at each corner of the vehicle and output a corresponding analogue signal to the ADCM. The algorithms in the ADCM calculate the position, velocity and frequency content of the signals and use the results for wheel control.

Each suspension height sensor is connected to the ADCM via three wires, which supply ground, 5 V supply and signal return.

The sensing element consists of an array of Hall effect devices arranged to measure the direction of the magnetic field of a small magnet attached to the end of the sensor shaft. As the sensor shaft rotates, so do the lines of magnetic flux from the magnet. The signals from the Hall effect elements are processed by means of a dedicated integrated circuit to generate an output voltage that varies as the sensor shaft is rotated. The sensor has a measurement range of ± 40° around its nominal position and the nominal sensitivity is 57 mV/° of shaft rotation.