Reversing camera (RFK), function - GF54.65-P-0005FQM
MODEL 218 as of model year 2015 with CODE 218 (Rear view camera)
Function requirements, general
- Terminal 15 ON
- Function enabled via the COMAND controller unit operating menu
The electronic ignition lock control unit sends the circuit 15 status over the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
To do so, the COMAND controller unit sends the enable signal for the function over the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
If the trunk lid or liftgate is not closed, the picture on the Audio/COMAND display is overlaid with a warning message. The guide lines are hidden from view. The rear SAM control unit transmits the status of the trunk lid or the liftgate (open or closed) via the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
During initial startup and after replacing the reversing camera or the trunk lid, the reversing camera must be coded again using the diagnosis tester. 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, generation of dynamic and static guide lines and sending image data to the Audio/COMAND display. The images recorded by the reversing camera with an extended angle of vision of ∠ > 180° are processed accordingly by the integrated control unit. The current driving path, based on the vehicle dimensions, vehicle speed and steering wheel angle, is shown in the Audio/COMAND display.
The reversing camera function comprises the following subfunctions:
- Function sequence for activating/deactivating reversing camera
- Function sequence for picture capture/picture output of reversing camera
Function sequence for activating/deactivating reversing camera
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 reversing camera function over the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
Engagement of gear range "R" activates the reversing camera.
Gear range "R" is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then sends the status "gear range R engaged" to the front SAM control unit via the drive train CAN, CDI control unit or ME-SFI control unit and chassis CAN 1. The front SAM control unit transmits the "Reverse gear engaged" signal to the reversing camera via chassis CAN 2.
The reversing camera evaluates the input factors and activates or deactivates the reversing camera function.
The reversing camera is deactivated under the following conditions:
- Vehicle speed during forward travel v > 12 km/h
- Route during forward travel s > 10 m
- Time period t > 255 s with gear range "R" not engaged
- Gear range "P" engaged
- Circuit 15 OFF
Additional function requirements for picture recording and picture display on the reversing camera
- Reversing camera activated
Function sequence for picture capture/picture output of reversing camera
The reversing camera sends the request to display the image data via the chassis CAN 2, front SAM control unit and interior CAN to the COMAND controller unit, processes the recorded camera images and then sends the processed image data over the LVDS line to the COMAND controller unit. The COMAND controller unit activates the Audio/COMAND display via the telematics CAN and sends the processed image data via the LVDS line to the Audio/COMAND display. The processed image data is then shown on the Audio/COMAND display.
The reversing camera uses the wheel angle and stored vehicle parameters (lane and exterior contour of the vehicle) to calculate guide lines to be superimposed onto the pictures shown.
The Electronic Stability Program control unit calculates the wheel angle based on the position of both front wheels and sends corresponding information to the reversing camera via chassis CAN 1, front SAM control unit and chassis CAN 2.
The reversing camera can be operated in the following modes which can be selected by the driver:
- Maneuvering mode
- Trailer mode (with code (550) Trailer hitch)
- Wide-angle mode
The relevant selection is made using the control menu for 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 function does not apply if the reversing camera was previously operated in trailer mode.
Maneuvering mode:
The maneuvering mode assists the driver when reversing while parking. To do so, dynamic guide lines are shown in the display in addition to the pictures recorded by the reversing camera.
Display of dynamic and static guide lines (when wheels are turned in), shown on model 222.0
Virtual steering angle (yellow guide lines):
The virtual steering angle (yellow guide lines) is shown as soon as the driver engages gear range "R". It indicates to the driver the path that the vehicle would follow with the current steering wheel angle. This curve is automatically adapted to the situation as the wheel angle changes. The distance between the virtual steering angle yellow guide lines corresponds to slightly more than the width of the vehicle.
Parking procedure:
To park, the driver must adjust the steering wheel angle until one of the outer yellow guide lines virtually touches the parking space marking. The parking space marking can be for instance 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 (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. When doing so, the driver can check using the virtual vehicle width (white guide lines) whether the vehicle is straight in relation to the parking space and whether the parking space is wide enough.
The white guide lines symbolize the width of the vehicle beyond the outside mirrors.
The distance lines inform the driver of the distances between the rear area 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 in the Audio/COMAND display in addition to the pictures recorded by the reversing camera.
The status of the trailer recognition is sent by the trailer recognition control unit over the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
Display of distance lines in the trailer mode, shown on model 222.0
Virtual steering angle (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.
Distance line around the ball head (red guide line):
The distance line (red guide line) is shown with a radius of s = 0.30 m around the ball head.
All guide lines are hidden during an attempted correction (forward travel) and shown again when the gear range "R" is engaged again, taking into consideration the following parameters:
- Time period t < 255 s
- Vehicle speed v < 12 km/h
- Route s < 10 m forward travel
The picture displayed disappears when these parameters are exceeded. The reversing camera then remains in standby mode.
The direction of travel is defined using the wheel rotation direction. The Electronic Stability Program control unit sends the relevant information to the reversing camera via chassis CAN 1, front SAM control unit and chassis CAN 2.
The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends the relevant information to the instrument cluster via chassis CAN 1, front SAM control unit and chassis CAN 2. The instrument cluster calculates the vehicle speed to be displayed and sends this over chassis CAN 2 to the reversing camera.
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.
View of the area to the rear of the vehicle in wide-angle mode
| Electrical function schematic, reversing camera | PE54.65-P-2051-97XAK |
| Overview of system components of parking assistance systems | GF54.00-P-9997FQM |