Design

Design

Steering wheel angle sensor module (SAS)




After initiation, with the ignition key in position II and when the steering wheel is turned 4.5 degrees in any direction, the steering wheel angle sensor module (SAS) continuously transmits information about the steering wheel angle position to the brake control module (BCM) to calculate the intended direction of travel. The steering wheel angle sensor module (SAS) also transmits information to the suspension module (SUM).
Communication between the steering wheel angle sensor module (SAS) and the brake control module (BCM) occurs on the high speed side of the controller area network (CAN). The steering wheel angle sensor module (SAS) is integrated in the steering wheel module (SWM).
The steering wheel angle sensor module (SAS) is powered via the steering wheel module (SWM).

Steering wheel angle sensor




The steering wheel angle sensor is incorporated with the SRS contact reel, which in turn is installed on the steering wheel module (SWM). A code wheel is mounted inside the steering wheel angle sensor which follows the movements of the steering wheel. 9 optical digital sensors and 2 analog photo diodes read off the code wheel. The signal must create a specific pattern. This information is transmitted to the steering wheel angle sensor module (SAS) which uses these signals to calculate the steering wheel angle, speed and number of turns. In total, the steering wheel angle sensor can measure a range of +/- 720 degrees, although the steering wheel can only be turned a maximum of +/-540 degrees.
Due to the reliance of the DSTC (Dynamic stability and traction control) system on information from the steering angle sensor it is extremely important that the contact reel has been centered correctly and that only an original Volvo steering wheel is used.