Reversing camera (RFK), function - GF54.65-P-0005CAM

MODEL 207.3/4 as of model year 2014 with CODE 218 (Rear view camera) 

Function requirements, general 

• Terminal 15 ON
• Function enabled via the COMAND controller unit operating menu
• Reverse gear (with transmission 711, 716) or gear range "R" (with transmission 722.9, 725) engaged
• Trunk lid closed

The electronic ignition lock control unit sends the circuit status of circuit 15 via 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 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 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 COMAND controller unit. The pictures recorded by the reversing camera with an extended angle of vision of ∠ > 130° are processed accordingly by the reversing camera. The current driving path is then shown in the Audio/COMAND 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 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 function over 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 722.9, 725) is engaged.

Vehicles with transmission 722.9 or 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 722.9, 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 v > 12 km/h
• Driving distance during forward travel s > 10 m
• Time period t > 255 s with reverse gear not engaged or gear range "R" not engaged
• Gear range "P" engaged (with transmission 722.9, 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 COMAND controller unit, processes the recorded camera images and then sends the processed image data via the Composite Video Baseband Signal (CVBS) line (up to 30.11.2014) or the Low Voltage Differential Signal (LVDS) line (as of 01.12.2014) 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.

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
• Trailer mode (with CODE 550 (Trailer hitch))
• Wide-angle mode (as of 01.12.2014)

The relevant selection is made via the system menu of the COMAND controller unit in the appropriate control level.

If the reversing camera was being operated in maneuvering mode, maneuvering mode is activated again when gear range "R" (with transmission 722.9, 725) or reverse gear (with transmission 711, 716) 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. 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 

Virtual steering angle (yellow guide lines):

As soon as the driver engages gear range "R" (with transmission 722.9, 725) or reverse gear (with transmission 711, 716), the virtual steering angle (yellow guide lines) is displayed. They 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 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 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.

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 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. To do so, special guide lines are shown in the display in addition to the pictures recorded by the reversing camera.

Display of distance lines in the trailer mode, shown on model 222 

Virtual steering angle (yellow guide lines):

As soon as the driver engages gear range "R" (with transmission 722.9, 725) or reverse gear (with transmission 711, 716), the virtual steering angle (yellow guide lines) and the distance line (red guide line) are displayed. 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 the guide lines are hidden for an attempted correction (forward travel) and shown again when the reverse gear or gear range "R" is engaged again taking the following parameters into consideration:

• t < 255 s
• v < 12 km/h
• s < 10 m forward travel

The displayed picture 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 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 from this information and transmits this via chassis CAN 2 to the reversing camera.

Wide-angle mode (as of 01.12.2014):

The wide-angle mode supports the driver when reversing in unclear traffic areas. The reversing area is shown in the Audio/COMAND display as a three-part view with an angle of ∠ > 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 (as of 01.12.2014); illustration shows model 222 

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.

	Electrical function schematic, reversing camera		PE54.65-P-2051-97EAF
	Overview of system components of parking assistance systems		GF54.00-P-9997CAM