Adaptive Front Lighting System (AFS) Headlamps
Adaptive Front Lighting System (AFS) Headlamps
The AFS headlamp is similar in its construction to the xenon headlamp described previously. The projector module is constructed and operates as described for the xenon headlamp with the addition of the AFS system which allows the projector module to be moved vertically and horizontally. The following description covers the additional differences to the xenon headlamp with AFS.
The AFS is a system to improve driver visibility under differing driving conditions. AFS provides a larger visible area which is illuminated when cornering by adjusting the position of the beam distribution on the road. Horizontal adjustment is made automatically to the most suitable orientation for the driving conditions using steering angle and information from other vehicle sensors.
AFS is only available with xenon headlamps and also includes the dynamic headlamp leveling system described in the 'Headlamp Leveling'. The bi-xenon module within the headlamp is controlled by actuator motors which rotate the projector module on its vertical and horizontal axes to adjust the beam output to suit the cornering conditions and vehicle inclination. Only the bi-xenon lamp projector module swivels, the halogen high beam lamp unit remains static.
The AFS is controlled by an AFS control module which is located at the bottom of the left hand 'A' pillar. The module is connected to and controls an AFS power module located on the base of each headlamp. Signals from the AFS control module are processed by the AFS power module which powers stepper motors to adjust the vertical and horizontal alignment of the projector module. The AFS power module also controls and regulates the operation of the static bending lamp (if fitted) which is requested by the AFS control module but controlled by the LCM.
AFS Concept
The AFS xenon headlamp construction is similar to the non-AFS xenon headlamp assembly. The AFS headlamp has a xenon control module located on the underside of the lamp assembly. An additional AFS power module is located in front of the xenon control module. The AFS power modules supply the correct voltage to stepper motors which control the positioning and movement of the AFS projector module.
The AFS assembly contains an additional carrier frame which provides the location for the AFS actuators. The remaining lamps are as described previously. The AFS headlamp also incorporates a static bending lamp.
The carrier frame is attached to the AFS vertical actuator. The projector module has a central pivot point which allows the module to move horizontally in response to operation of the AFS horizontal actuator.
The AFS actuators are bi-polar (2 phase) dc stepper motors which are driven by a power output from the AFS power module. Each stepper motor receives its position information from the AFS control module via the applicable AFS power module. When the actuators are powered to their requested positions, a holding current is applied to maintain the actuator position.
The actuators do not supply a positional feedback signal to the AFS control module. Each stepper motor requires referencing each time the AFS system becomes active. When the AFS system is active, each vertical actuator is driven in the low beam position and each horizontal actuator is driven to an inboard position until a mechanical stop in the actuator is reached. Once the stop is reached a step counter in the AFS control module is set to zero and the actuator is then powered to the operating position as determined by the AFS control module software.
The AFS control module receives front and rear suspension height data to provide dynamic headlamp leveling adjustment via the vertical actuator motor. The AFS control module also receives vehicle speed signals from the ABS module to adjust the projector module vertically to increase the beam range as the vehicle speed increases.
AFS Control Module
The AFS control module is located at the bottom of the left hand 'A' pillar, behind the trim panel.
The AFS control module is a dual functionality unit which also incorporates software to control the dynamic headlamp leveling. The AFS control module is connected to the high speed CAN bus and receives inputs from other vehicle systems on the status of the following parameters: Steering angle
^ Vehicle speed
^ Headlamp status
^ Engine running
^ Reverse gear selected
^ Automatic lighting on.
The AFS will only operate when the AFS control module receives an engine running signal on the CAN bus. When the engine running signal is received the AFS control module performs an initialisation routine.
The AFS will also function when the lighting control switch is in the AUTO position and the AFS control module receives a lights on signal from the rain/light sensor and an engine running signal.
The AFS control module then monitors the inputs from the other vehicle systems to control the AFS functionality according to cornering angles and vehicle speed.
The AFS control module is connected to each AFS power module on a private LIN bus. The power modules read operating values supplied from the AFS control module and control the output drivers for the stepper motor actuators inside the headlamp assembly.
AFS Control Module Connector C2193 (V8 Petrol) or C3145 (Td6 Diesel) Pin Details
