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

MODEL 205, 253 with CODE 218 (Rear view camera) 

Function requirements, general 

• Terminal 15 ON
• Function enabled through control menu on the head unit
• Reverse gear (transmission 716) or gear range "R" (transmission 722, 724, 725) engaged
• Trunk lid or liftgate closed

The electronic ignition lock control unit sends the status of circuit 15 over the user interface CAN to the reversing camera.

The head unit sends the function enable over the user interface CAN 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 sends information on the status of the trunk lid or the liftgate (open or closed) over the interior CAN, electronic ignition lock control unit and user interface CAN to the reversing camera.

During initial startup and after replacing the reversing camera or the trunk lid or the liftgate, 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 head unit. 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 is shown on the Audio/COMAND display in the form of guide lines based on the vehicle dimensions, vehicle speed and steering angle.

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 recognition, picture output 

Function sequence for activating/deactivating reversing camera 

When reverse gear or gear range "R" is engaged, the reversing camera is activated.

Vehicle with transmission 716:

Engaging the reverse gear is recorded by the manual transmission main shifter shaft position sensor. The CDI control unit or the ME-SFI [ME] control unit reads in the signal of the manual transmission main shifter shaft position sensor directly, uses it to generate the "Reverse gear engaged" signal and transmits this to the electronic ignition lock control unit via the drive train CAN, the powertrain control unit and the chassis FlexRay.

Vehicle with transmission 722, 724, 725:

Gear range "R" is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit over the drive train CAN, powertrain control unit and chassis FlexRay.

The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the transmission variant and sends this via the user interface CAN 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
• Route 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, 724, 725)
• Circuit 15 OFF

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 to the camera cover control unit via the user interface CAN, electronic ignition lock control unit and 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.

To allow the camera lens to be cleaned, the camera cover can be opened using the control menu of the head unit. During this, no image is shown in the Audio/COMAND display. The head unit sends the "Service mode" request to the reversing camera via 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 output 

• Reversing camera activated

Function sequence for picture recognition, picture output 

The reversing camera sends the request to display the image data via the user interface CAN to the head unit, processes the recorded camera images and then transmits the processed image data via the LVDS line to the head unit. The head 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 steering wheel 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 wheel angle sensor. The steering column tube module control unit reads in the signals from the steering wheel angle sensor directly and sends information regarding the steering wheel angle via the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the reversing camera.

The reversing camera function can be operated in the following modes which the driver can select:

• Maneuvering mode
• Trailer mode (with CODE 550 (Trailer hitch))
• Wide-angle mode

The corresponding selection is made on the head unit's control menu in the appropriate control level.

If the reversing camera was previously operated in maneuvering mode, the maneuvering mode is activated again when reverse gear or 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 

Virtual steering angle (yellow guide line)

The virtual steering angle (yellow guide lines) is shown as soon as the driver engages reverse gear or the 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 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 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 trailer mode (with CODE 550 (Trailer hitch)); shown on model 222 

Virtual steering angle (yellow guide line)

The virtual steering angle (yellow guide line) and the distance line (red guide line) are shown as soon as the driver engages reverse gear or the 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 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:

• 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 vehicle speed is calculated from the wheel speed.

The Electronic Stability Program control unit sends the corresponding information via the chassis 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 the user interface CAN 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 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 reversing area in wide-angle mode, shown on model 222 

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