Reversing Camera (RFK), Function - GF54.65-P-0005RDM
Model 172.4
as of model year 2017
with code 218 (Rear view camera)
Illustration shows model 172.4
Function requirements, general
- Terminal 15 ON
- Function enabled via operating menu of radio
- Reverse gear (with transmission 711, 716) or gear range "R" (with transmission 725) engaged
- Trunk lid closed
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.
The radio sends the enable signal for the function via the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
If the trunk lid is not closed, the picture shown on the Audio/COMMAND display is covered by a warning message. The guide lines are hidden from view. The rear SAM control unit sends the status of the trunk lid (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 aid. Its tasks include the recording of images of the area to the rear of the vehicle, the generation of dynamic and static guide lines and the transmission of the image data to the radio. The pictures recorded by the reversing camera with an extended angle of vision of ∠ gt 180° are processed accordingly by the reversing camera. The current driving path is then shown in the Audio/COMMAND display based on the vehicle dimensions, vehicle speed and the steering angle. The reversing camera function comprises the following subfunctions:
- Function sequence for activating/deactivating reversing camera
- Function sequence for picture recognition, picture output
- Function sequence for actuating the camera cover
Function sequence for activating/deactivating reversing camera
Automatic activation/deactivation of the reversing camera must be enabled at the corresponding operating level of the radio. The radio sends the status of the function via the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
The reversing camera is activated when reverse gear (with transmission 711, 716) or gear range "R" (with transmission 725) is engaged.
Vehicles with transmission 725:
The fully integrated transmission control unit sends the information on the engaged gear range via the drive train CAN, CDI control unit or ME-SFI control unit and chassis CAN 1 to the front SAM control unit. Vehicles with transmission 711 or 716:
Engagement of reverse gear is defined via the status of the backup lamp switch, which is read in directly by the front SAM control unit. The front SAM control unit uses the status of the backup lamp switch (with transmission 711, 716) or the information on the engaged gear range (with transmission 725) to generate the "Reverse gear engaged" signal, irrespective of the transmission variant involved, and sends this signal via chassis CAN 2 to the reversing camera.
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 ∠ gt 12 km/h
- Driving distance during forward travel S gt 10 m
- Time period t gt 255 s with reverse gear not engaged or gear range "R" not engaged
- Gear range "P" engaged (with transmission 725)
- Circuit 15 OFF
Additional function requirements for picture recording and picture display on the reversing camera
- Reversing camera activated
Function sequence for picture recognition, picture output
The reversing camera sends the request to display the image data via chassis CAN 2, the front SAM control unit and interior CAN to the radio, processes the recorded camera images and then transmits the processed image data via the LVDS (Low Voltage Differential Signal) line to the radio. The radio activates the Audio/COMMAND display via the telematics CAN and transmits the processed image data via the LVDS line to the Audio/COMMAND display. The processed image data is then shown on the Audio/COMMAND display.
To optimize the display of the pictures shown, electronic distortion correction is conducted by the reversing camera in addition to the optical distortion correction by the lens.
The reversing camera uses the steering angle and stored vehicle parameters (lane and exterior contour of the vehicle) to calculate guide lines which are superimposed on the display. The steering angle is recorded by the steering angle sensor. The steering column tube module control unit reads in the signals from the steering angle sensor directly and sends information on the steering angle to the reversing camera via chassis CAN 1, the front SAM control unit and chassis CAN 2.
The reversing camera function enables the driver to select between the following parking modes:
- Maneuvering mode
- Wide-angle mode
The corresponding selection is made via the system menu of the radio in the appropriate operating level.
If the reversing camera was being operated in maneuvering mode, maneuvering mode is activated again when gear range "R" (with transmission 725) or reverse gear (with transmission 711, 716) is engaged.
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); illustration shows model 172.4
Virtual steering angle (yellow guide lines):
As soon as the driver engages gear range "R" (with transmission 725) or reverse gear (with transmission 711, 716), the virtual steering angle (yellow guide lines) is displayed. 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 steering angle changes. The distance between the virtual steering angle (yellow guide lines) corresponds to slightly more than the width of the vehicle.
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.
Parking procedure:
To park, the driver must adjust the steering 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 angle until the parking space markings run parallel to the current direction of travel.
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.
Wide-angle mode:
The wide-angle mode supports the driver when reversing in unclear traffic areas. The reversing area is shown in the Audio/COMMAND display as a three-part view with an angle of ∠ gt 180°. This gives the driver a clear view of crossing roads in good time, e.g. when reversing out of narrow streets.
Display of area to rear of vehicle in wide-angle mode; illustration shows model 172.4
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. This movement is represented by a bar display below the object.
Function sequence for actuating the camera cover
In order to protect the camera lens from dirt, it is covered by a camera cover.
The camera cover is automatically opened or closed according to 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 request via chassis CAN 2, the front SAM control unit and interior CAN to the camera cover control unit. 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 directly and sends this via the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera.
The camera cover can be opened to clean the camera lens over the radio or COMMAND controller unit control menu. During this, no image is shown in the Audio/COMMAND display.
The radio or the COMMAND controller unit sends the "service mode" request via the interior CAN, front SAM control unit and chassis CAN 2 to the reversing camera. 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 gt 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.
| Electrical function schematic, reversing camera | PE54.65-P-2051-97TAA | ||
| Overview of system components of parking assistance systems | GF54.00-P-9997RDM |