Reversing camera (RFK), function - GF54.65-P-0005GN
MODEL 166 as of model year 2016 with CODE 218 (Rear view camera)
MODEL 292 with CODE 218 (Rear view camera)
Block diagram
Function requirements, general
- Circuit 15 ON
- Liftgate closed
The electronic ignition lock control unit transmits the status of circuit 15 via chassis CAN 2 to the reversing camera.
If the liftgate is not closed, the picture shown on the Audio/COMAND display is covered by a warning message. The guide lines are hidden from view. The rear control unit sends the status of the liftgate (open or closed) over the interior CAN, the electronic ignition lock control unit and chassis CAN 2 to the reversing camera.
During initial startup and after replacing the reversing camera or the liftgate, the reversing camera must be re-coded using the diagnosis unit. The reversing camera is calibrated automatically after initial startup.
Reversing camera, general
The reversing camera is an optical parking and maneuvering aid. Its tasks include a surrounding field recording of the rear driving area, the generation of dynamic and static guide lines and the sending of the picture data to the COMAND controller unit. The pictures recorded by the reversing camera with an extended angle of vision of ∠ > 180° are processed accordingly by the reversing camera.
The current driving path, based on the vehicle dimensions, vehicle speed and front wheel angle, is shown in the Audio/COMAND display.
The reversing camera encompasses the following subfunctions:
- Function sequence for activating/deactivating reversing camera
- Function sequence for actuating the rear camera cover
- Function sequence for picture recognition, picture output
Function sequence for activating/deactivating reversing camera
The reversing camera can be automatically activated or deactivated by engaging gear range "R".
Automatic activation/deactivation of the reversing camera must be enabled at the corresponding operating level of the COMAND controller unit. To do so, the COMAND controller unit sends the status of the function via interior CAN, electronic ignition lock control unit and chassis CAN 2 to the reversing camera. If the gear range "R" is engaged, the reversing camera is activated.
The fully integrated transmission control unit transmits the information about the engaged gear range via the drive train CAN, the CDI control unit (with diesel engine) or the ME-SFI [ME] control unit (with gasoline engine), chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the reversing camera.
The reversing camera function is now activated or deactivated.
Function sequence for actuating the rear camera cover
In order to protect it from dirt, the camera lens is protected by a camera cover. The camera cover is automatically opened or closed to match the status of the reversing camera (activated or deactivated).
The camera cover is opened and closed when requested by the reversing camera. The reversing camera sends this over chassis CAN 2, the electronic ignition lock control unit and the interior CAN to the rear control unit. The rear control unit then actuates the rear camera cover motor directly. The status of the camera cover (open or closed) is registered by the switch for the rear camera cover motor. The rear control unit reads in the status of the rear camera cover motor switch and sends this over the interior CAN, electronic ignition lock control unit and the chassis CAN 2 to the reversing camera.
To clean the camera lens, the camera cover can be opened through the COMAND controller unit operating menu. During this process, no picture is shown on the Audio/COMAND display. The COMAND controller unit sends the request "service mode" via interior CAN, electronic ignition lock control unit and chassis CAN 2 to the reversing camera. Further course of signals corresponds to the automatic opening and closing of the camera cover.
Function sequence for picture recognition, picture output
If the reversing camera is activated by engaging reverse gear, an appropriate request is transmitted for activation of the COMAND controller unit via chassis CAN 2, the electronic ignition lock control unit and the interior CAN to the COMAND controller unit.
The reversing camera then transmits the recorded pictures to the COMAND controller unit in the form of CVBS signals. The COMAND controller unit then activates the Audio/COMAND display over the telematics CAN (CAN A). The COMAND controller unit processes the images and transmits the image data via the LVDS line to the Audio/COMAND display.
To optimize the display of the pictures shown, in addition to the optical compensation in the lens, an electronic compensation through the reversing camera is also carried out.
The reversing camera also calculates the guide lines (lane and exterior contour of vehicle) that are superimposed onto the displayed pictures, taking the front wheel angle and stored vehicle parameters into account. The current front wheel angle is recorded by the electric power steering control unit. The electric power steering control unit then transmits this angle over chassis CAN 2 to the reversing camera.
The reversing camera function enables the driver to select between the following parking modes:
- Maneuvering mode
- Trailer mode (with CODE 550 (Trailer hitch))
- Wide-angle mode
The relevant selection is made via the system menu of the COMAND controller unit in the appropriate control level.
If the reversing camera was previously operated in maneuvering mode, the maneuvering mode is activated again when the "R" gear range is engaged. This does not apply when the reversing camera was previously operated in trailer mode.
Maneuvering mode:
The maneuvering mode assists the driver when reversing while parking. In doing so, dynamic guide lines are also shown on the Audio/COMAND display in addition to the pictures recorded by the reversing camera.
Display of dynamic and static guide lines (with wheels turned in), shown on model 222
Virtual tire track (yellow tracked lines):
As soon as the driver engages gear range "R", the yellow tire tracks are shown. They indicate to the driver the path which the vehicle would follow with the current steering wheel angle. These curves are automatically adapt as the front wheel angle changes.
Parking procedure:
To park, the driver must now adjust the steering angle so that the right or left outside line of the yellow tire track in the Audio/COMAND display is touching the relevant parking space marking. This parking space marking can, e.g. be another vehicle or a line on the asphalt. The driver must then continue reversing and adapting the steering wheel angle until the parking space markings run parallel to the current direction of travel.
Virtual vehicle width (static, white guide lines):
Next the driver must turn the steering wheel back into the straight-ahead position in order to drive in a straight line up to the final park position in the parking space. While doing so, the driver can check - using the white guide lines - whether the vehicle is in a straight position relative to the parking space, and whether the parking space is wide enough.
The white guide lines symbolize the vehicle width including the outside mirrors.
The distance lines inform the driver of the distances between the virtual bumper and obstacles.
Trailer mode (with code 550 (Trailer hitch)):
Trailer mode supports the driver when reversing to a trailer by zooming to the trailer hitch's ball head.
When reversing, special guide lines are also shown on the Audio/COMAND display in addition to the pictures recorded by the reversing camera.
Display of distance lines in trailer mode, shown on model 222
Trajectory of ball head for continued reversing (yellow guide line):
The virtual steering angle (yellow guide line) and the distance line (red guide lines) are shown as soon as the driver engages gear range "R". The virtual steering angle indicate to the driver the path which the vehicle would follow with the current steering wheel angle. This curve is automatically adapted to the situation as the steering angle changes. The length of the guide line corresponds to approx. s = 1 m.
The distance line is a fixed display on the Audio/COMAND display, and notifies the driver about the distance within a radius of 0.30 m around the ball head of the trailer hitch.
The guide lines are hidden on the Audio/COMAND display during a correction attempt (forward travel) and re-displayed when gear range "R" is engaged again, taking the following parameters into consideration:
- Time period t < 15 s
- Vehicle speed during forward travel v < 10 km/h
- Distance during forward travel s < 10 m
If these parameters are exceeded, the image of the rear area recorded by the reversing camera is removed from the Audio/COMAND display. The reversing camera then remains in standby mode.
The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit transmits this information via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the instrument cluster. The instrument cluster calculates the vehicle speed from this information and transmits this via chassis CAN 2 to the reversing camera.
Shutoff criteria:
The reversing camera is deactivated under the following conditions:
- Vehicle speed during forward travel v > 10 km/h
- Route during forward travel s > 10 m
- Time period t > 15 s with gear range "R" not engaged
- Gear range "P" engaged
- Circuit 15 OFF
Wide-angle mode:
The wide-angle mode supports the driver when reversing in unclear traffic areas. The reversing area is shown via the Audio/COMAND display in a three-part view with an angle of ∠ > 180°. The provides the driver, e.g. when reversing out of a narrow lane, to have a good view of a traversing road in good time.
Display of reversing area in wide-angle mode, shown on model 292
| Electrical function schematic for reversing camera | PE54.65-P-2051-97NBA | |
| Overview of system components of parking assistance systems | MODEL 166 as of model year 2016 with CODE 218 (Rear view camera) with CODE 235 (Active Parking Assist) with CODE 501 (360° camera) MODEL 292 with CODE 218 (Rear view camera) with CODE 235 (Active Parking Assist) with CODE 501 (360° camera) |
GF54.00-P-9997GN |