Reversing Camera (RFK), Function - GF54.65-P-0005LF
Model 222 up to model year 2018 with code 218 (Rear view camera) except code 235 (Parking Pilot with PARKTRONIC)
Shown on model 222
Function requirements, general
- Terminal 15 ON
- Function enabled through corresponding COMAND controller unit operating menu
The electronic ignition lock control unit sends the status of circuit 15 to the reversing camera control unit via user interface CAN.
The COMAND controller unit sends the function enable over the user interface CAN to the reversing camera control unit.
If the trunk lid is not closed, the picture in the Audio/COMAND display is overlaid with a warning message. The guide lines are hidden from view.
The rear SAM control unit sends information regarding the status of the trunk lid (open or closed) via interior CAN, electronic ignition lock control unit and user interface CAN to the reversing camera control unit and to the instrument cluster.
During commissioning and after replacing the reversing camera control unit or the trunk lid, the reversing camera control unit must be coded again using the diagnosis tester. The reversing camera is calibrated automatically after initial startup.
Reversing camera, general
The reversing camera control unit is an optical parking 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 pictures recorded by the reversing camera using 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 actuating the camera cover
- 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. The COMAND controller unit sends the status of the reversing camera function to the reversing camera control unit over the user interface CAN.
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 reversing camera control unit over the drive train CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN.
The reversing camera control unit 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 for forward travel s > 10 m
- Time period t > 255 s when gear range "R" not engaged
- Gear range "P" engaged
- Circuit 15 OFF
Function sequence for actuating the 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 control unit. The reversing camera control unit sends the corresponding request to the camera cover control unit over the user interface CAN, electronic ignition lock control unit and the interior CAN. The camera cover control unit then actuates the rear camera cover motor directly. The status of the rear camera cover (open or closed) is detected from the rear camera cover motor switch. The camera cover 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 user interface CAN to the reversing camera control unit.
To clean the camera lens, the camera cover can be opened through the COMAND controller unit operating menu. During this, no image is shown in the Audio/COMAND display. The COMAND controller unit sends the "Service mode" request to the reversing camera control unit over the user interface CAN. The further course of signals corresponds to that for the opening of the camera cover when the reversing camera is activated.
The camera cover is automatically closed from a speed of v > 30 km/h (irrespective of any calibration procedure) or after switching off circuit 15. During a calibration procedure, it is possible that the camera cover remains open for the duration of the calibration even after the reversing camera function has been deactivated. The camera cover is not closed until after the calibration is complete.
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 control unit sends the request to display the image data over the user interface CAN to the COMAND controller unit, processes the recorded camera images and then sends the processed image data over the HSVL line to the COMAND controller unit. The COMAND controller unit activates the Audio/COMAND display over the telematics CAN and sends the processed image data over the HSVL line to the Audio/COMAND display. The processed picture data is then shown on the Audio/COMAND display.
The reversing camera control unit uses the steering wheel angle and stored vehicle parameters (lane and exterior contour of the vehicle) to calculate guide lines that are then superimposed on the displayed pictures.
The steering angle is recorded by the steering wheel angle sensor.
The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information regarding the steering wheel angle over the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the reversing camera control unit.
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), 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 as the steering 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 alter the steering wheel angle until one of the outer yellow guide lines virtually touches the parking space marking. The parking space marking can, for example, 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 (white guide lines):
The white guide lines symbolize the vehicle width including 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 shown in the Audio/COMAND display in addition to the pictures recorded by the reversing camera.
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.
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
- Driving distance 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 corresponding information over the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the reversing camera control unit.
The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit sends the corresponding information via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster calculates the vehicle speed to be displayed and sends it via user interface CAN to the reversing camera control unit.
Wide-angle mode:
The wide-angle mode supports the driver when reversing in unclear traffic areas. The reversing area is shown on 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
The wide-angle mode also includes object detection for objects that are moving relative to the vehicle. When the vehicle is stationary, only moving objects are detected; during forward or reverse travel the detection of static objects is also possible. These are represented by a bar display below the object.
| Electrical function schematic, reversing camera | PE54.65-P-2051-97SEA | ||
| Overview of system components of parking assistance systems | GF54.00-P-9997LF |