Detection Of Straight-Ahead Position In Operation

During operation, the swivel module moves to the straight-ahead position as follows:

• E46, E83, E63: zero-position sensor with level change: each time the flank is passed through (each time the level changes) in the defined direction, the nominal values are compared to the actual values. The number of steps required between the flank and the straight-ahead position is defined. If the swivel module has seized or become obstructed, there will be more steps to the level change than calculated. The stepper motor controllers take this difference into account ("lost steps" = steps moved by the stepper motor WITHOUT a corresponding change in the position of the swivel module). If the step losses (= "lost steps") exceed a permissible range, the level change is passed through repeatedly. The stepper motor controllers recognise the required number of steps. The swivel module is detected as having seized based on the number of steps completed (the reference values and actual values are then recalibrated by repeated swivelling of the headlight). The stepper motor controller also detects whether the swivel module is obstructed. If the swivel module is obstructed, the stepper motor controller attempts to move the headlight into the straight-ahead position. If the headlight cannot be moved into the straight-ahead position, the stepper motor controller switches off the headlight (switch-off conditions: sleep mode and restart detected; the fog lights are switched on as emergency lighting).
• If the zero-position sensor is defective, the headlight is moved into the straight-ahead position based on the coded replacement values (from the mechanical reference point).