Initialization of the Integral Active Steering

The ICM control unit calculates the higher-level control functions for the Integral Active Steering. The output signals of this control function are the reference steering angles, that should be set at the front and rear axle.

This is performed by the AS and HSR actuator control units together with the actuators. The actual angle set at the front and rear axle is sent to the ICM control unit as acknowledgment. The control circuit of the driving dynamics control system closes once this information has been received.

To determine this information correctly, the Integral Active Steering must be initialized. During this initialization procedure, the center of the steering gear at the front axle is determined and the corresponding signal values are stored (for example).

NOTE: The Integral Active Steering must be initialized under the following circumstances:

the ICM, AS or steering column switch cluster control unit has been replaced or
the steering angle sensor in the steering column switch cluster has been calibrated or
the steering gear has been replaced or
if requested by the diagnostic system due to a fault code memory entry in the test schedule.

During the calibration the diagnostic system issues several prompts to steer from one limit position to the other. The internal combustion engine should be running and the vehicle should be standing on the ground of the workshop when calibration is in progress. These marginal conditions most closely resemble the conditions under which the customer operates the vehicle and deliver the best initialization results. If the front wheels are resting on revolving and sliding supports, or are suspended in mid air if the vehicle is raised, this may lead to unsatisfactory results.