Parking system, function - GF54.65-P-0006FQM
MODEL 218 as of model year 2015 with CODE 235 (Active Park Assist)
Function requirements, general
- Terminal 15 ON
The status of circuit 15 is sent by the electronic ignition lock control unit via the chassis CAN 1, front SAM control unit and chassis CAN 2 to the parking system control unit.
Parking system, general
The parking system uses the ultrasonic measuring procedure to register the distance between the vehicle and an obstacle. While driving at speeds of v < 36 km/h, parallel or perpendicular parking spaces on both sides of the vehicle in the direction of travel are measured, stored and the vehicle is moved in and out of a parking space semi-automatically upon the request of the driver.
Semi-automatic exiting of perpendicular parking spaces is not available.
The parking system warning indicator instrument panel and the rear parking system warning indicator notifies the driver of the respective distance between the vehicle and the obstacle. An acoustic warning can also be issued via the warning buzzer.
In certain situations, warnings from the parking system are suppressed, e.g. when reversing through narrow passages (driveway). There is an obstacle within the detection range but, based on the current steering wheel position, a collision will not take place.
Parking system operation is dependent on speed and direction of travel, and therefore the following input factors have to be determined:
- Direction of travel and vehicle speed
- Driving stage engaged
Direction of travel and vehicle speed:
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 via chassis CAN 1, front SAM control unit and chassis CAN 2 to the parking system control unit and to the instrument cluster. The parking system control unit calculates the vehicle speed and defines the direction of travel. At the same time the instrument cluster also calculates the speed to be displayed and sends it over the chassis CAN 2 to the parking system control unit.
Engaged drive position:
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 parking system control unit via chassis CAN 2.
The parking system includes the following subfunctions:
- Measuring procedure function sequence
- Self-test function sequence
- Behavior in the event of overvoltage and undervoltage function sequence
- Deactivate and activate function sequence
- Function sequence for monitoring reverse travel
- Function sequence for monitoring forward travel
- Parking space recognition function sequence
- Function sequence for display of possible parking spaces on instrument cluster
- Function sequence for semi-automatic parking
- Function sequence for semi-automatic parking space exit
Illustration of the principle for measuring procedure
Measuring procedure function sequence
The parking system is based on the ultrasonic measuring procedure. As such, the parking system control unit actuates the distance sensors directly.
These then emit ultrasonic waves. The ultrasonic waves reflected by an obstacle are received again by the distance sensors. The parking system control unit directly reads in the signals of the distance sensors and evaluates them. In principle a distinction is made between two measurements. On the one hand the direct measurement resulting from a direct echo and on the other hand the indirect distance measurement which is achieved via a cross echo (illustration of the principle). Echoes can usually also be received from adjacent distance sensors due to the large distance sensor detection angles; these are known as cross echoes. These occur at the obstacle due to scattered reflection. With the help of the triangulation method, the distance from the vehicle to an obstacle can be calculated from two echo signals. The propagation times of the signals from the direct measurement and from the cross measurement are required for this method. A long signal propagation time therefore corresponds to a large distance, and a short signal propagation time corresponds to a short distance to the obstacle.
The parking system cannot work correctly in certain cases due to the function principle (transmitting and receiving sound waves). So for example, when approaching a strong sound absorbent obstacle (e.g. a vehicle covered in snow) it is possible that false data may be displayed.
Shows model 218.3
The distance sensors are activated according to the direction of travel.
The distance sensors responsible for monitoring the front area (A) and the front corner protection area (B) are activated when the vehicle is moving forward.
The distance sensors responsible for monitoring the rear corner protection area (C) and the rear area (D) are also activated when the vehicle is moving backward.
The monitored front area is max. s = 100 cm.
The monitored rear area is max. s = 120 cm.
If the distance between the vehicle and an obstacle is less than s = 20 cm (c, e), the parking system will for technical reasons no longer receive any defined data.
Below a speed of v = 36 km/h, the area to the right and left of the vehicle is measured in the horizontal depth up to a distance of s = 400 to 450 cm (parking space detection) and stored in the parking system control unit for s = 15 m.
Self-test function sequence
During the self-test the following components are checked for proper operation:
- Parking system control unit
- Distance sensors
- Rear parking system indicator
- Parking assist electrical lines
Parking system control unit self-test:
The parking system control unit performs a self test after the ignition is switched on (circuit 15 ON). In the process, the hardware of the parking system control unit is tested.
Selecting gear range "R" does not have any impact on the self-test of the parking system control unit.
Distance sensor self-test:
A self-test of the distance sensors (e.g. for connection) is only performed when a distance sensor is "pulsed" (activated) (ultrasonic waves are transmitted).
Engaging gear range "R" has an impact on the self-test of the distance sensors. If reverse gear or gear range "R" has been engaged, all distance sensors are tested. If reverse gear or gear range "R" has not been engaged, only the front distance sensors are tested.
Distance sensor test for subsequent vibrations:
A distance sensor test for subsequent vibrations (acoustic/physical function of the distance sensor) is performed cyclically.
Function test on parking system warning indicators:
When the ignition is switched on (circuit 15 On), the parking system control unit fully actuates all display elements in the parking system warning indicators for approx. t = 1 s.
If there are no malfunctions or faults, the two yellow horizontal "standby" bars light up in the parking system warning indicators. The parking system control unit carries out further self-tests at regular intervals.
The following states can be recorded here:
- Operational problem
- System error(s)
If a malfunction or system error occurs, the parking system is deactivated and the LED in the parking system button in the upper control panel control unit lights up.
The parking system control unit transmits the appropriate request via the chassis CAN 2, front SAM control unit and LIN instrument panel to the upper control panel control unit, which actuates the LED in the parking system button via the instrument panel LIN.
Malfunction:
A malfunction can be caused by a temporary external disturbance (e.g. a jackhammer on a construction site, a steam jet or by driving through an automatic car wash). If a malfunction occurs during operation, this is displayed by the lighting up of the red display elements in the rear parking system warning indicator or in the parking system instrument panel warning indicators.
To do this, the parking system control unit actuates the parking system warning indicators directly.
If a malfunction persists, the cause thereof is identified while driving by means of a self-test. If the malfunction is still present, this is interpreted as a system error.
A warning sound is not emitted.
System fault(s)
A system fault can have the following causes:
- Defective component
- Error in communication
- Overvoltage or undervoltage
If a system error is detected, depending on whether or not reverse gear or gear range "R" has been engaged, the red display elements in the rear parking system warning indicator or in the parking system instrument panel warning indicator illuminate. A warning tone is also emitted for t = 2 s.
To do this, the parking system control unit actuates the parking system warning indicators directly. In addition, the parking system control unit transmits the request to output a warning to the instrument cluster via chassis CAN 2. The instrument cluster then directly actuates the warning buzzer. After another t = 3 s, the parking system switches off, a fault is entered in the fault memory of the parking system control unit and the LED in the parking system button illuminates.
If the system error occurs again after an ignition cycle, the described scenario is repeated.
Behavior in the event of overvoltage and undervoltage function sequence
The parking system behavior in the event of overvoltage or undervoltage is shown in the following table.
| On-board power supply voltage U < 9.0 V | On-board power supply voltage U > 16.0 V | Undervoltage with reset | Undervoltage without reset (start pulse) |
|---|---|---|---|
| Parking system nonfunctional | Parking system nonfunctional | The function is activated again after a reset | Display of distance |
| Parking system warning indicators, dark | Parking system warning indicators, dark | No function test for parking system warning indicator display | Start pulse has no influence on parking system |
| No function test, if voltage returns to normal | No function test, if voltage returns to normal | - | No function test for parking system warning indicator display |
| LED in the parking system button ON | LED in the parking system button ON | - | - |
Additional function requirements for activation and deactivation
- Self-test completed successfully
- Drive position "D" or "R" is engaged
Deactivate and activate function sequence
The parking system can be manually deactivated or activated by pressing the parking system button in the upper control panel.
The front SAM control unit reads in the status of parking system button via the instrument panel LIN and sends it via chassis CAN 2 to the parking system control unit.
If the parking system has been manually switched off using the parking system button, it is automatically switched back on again when circuit 15 is reactivated.
The brightness of the parking system warning indicators is dependent on the ambient brightness. The ambient brightness is sensed by the rain/light sensor. The rain/light sensor sends information on the ambient brightness (dusk/dawn level) over the wiper/inside rearview mirror-LIN to the front SAM control unit. The front SAM control unit sends this information over the chassis CAN 2 to the parking system control unit. If the light sensor detects "Night", the rear parking system display is actuated at 60% brightness. If the light sensor detects "Day", the rear parking system display is actuated at 100% brightness.
When the parking system is deactivated, only the LED in the parking system button lights up. The parking system control unit transmits an appropriate request via the chassis CAN 2, front SAM control unit and LIN instrument panel to the upper control panel control unit, which actuates the LED in the parking system button via the instrument panel LIN. When driving the parking system switches to standby mode between v = 60km/h and v = 16 km/h. In other words, the parking system control unit, the parking system warning indicators and the distance sensors are still supplied with power but the parking system warning indicators are switched to "dark".
Additional function requirements for monitoring reverse travel
- Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h (calculated from the wheel speed)
- Backward movement of vehicle (defined via the wheel rotation direction)
- No trailer recognized (with code (550) Trailer hitch)
The "Trailer detected" status is sent by the trailer recognition control unit via the interior CAN, front SAM control unit and chassis CAN 2 to the parking system control unit.
Function sequence for monitoring reverse travel
During reverse travel the areas in front of and behind the vehicle are monitored. When the lower limit speed of v = 16 km/h is dropped below, the parking system changes to measuring mode. When obstacles are detected in front of or behind the vehicle, the driver is first warned visually by the display elements in the parking system warning indicators lighting up. When dropping below a distance of s = 30 cm, the warning is then intensified by an intermittent tone and subsequently by a continuous signal. When the upper speed limit of v = 18 km/h is exceeded, the parking system goes over into stand by mode again. The parking system control unit actuates the parking system warning indicators directly. If the distance from the obstacle is less than s = 30 cm, the parking system control unit transmits the request to output a warning via the chassis CAN 2 to the instrument cluster. The instrument cluster then actuates the warning buzzer.
Additional function requirements for monitoring forward travel
- Vehicle speed v = 0 to 18 km/h or vehicle speed v = 16 to 0 km/h (calculated from the wheel speed)
Function sequence for monitoring forward travel
When driving forwards the area in front of the vehicle is monitored. When the lower limit speed of v = 16 km/h is dropped below, the parking system changes to measuring mode. When obstacles are detected in front of the vehicle, the driver is first warned visually by the illumination of the warning segments of the parking system instrument panel warning indicator. When dropping below a distance of s = 30 cm, the warning is then intensified by an intermittent tone and subsequently by a continuous signal. When the upper speed limit of v = 18 km/h is exceeded, the parking system goes over into stand by mode again. The parking system control unit actuates the instrument cluster parking system warning indicator directly. If the distance from the obstacle is less than s = 30 cm, the parking system control unit transmits the request to output a warning via the chassis CAN 2 to the instrument cluster. The instrument cluster then directly actuates the warning buzzer.
Additional function requirements, parking space recognition
- Antilock braking system (ABS) and Electronic Stability Program (ESP®) have not intervened for t = 5 s
- Vehicle speed v < 36 km/h (calculated from the wheel speed)
The Electronic Stability Program control unit sends the status of the ESP® chassis CAN 1, front SAM control unit and chassis CAN 2 to the parking system control unit.
Parking space recognition function sequence
The parking space detection function is used for simple locating of suitable parallel or perpendicular parking spaces. The parking space detection function is implemented via the outer front distance sensors. These monitor the area left and right of the vehicle and therefore have a larger range than the rest of the distance sensors.
At a speed of v = 0 to 18 km/h the parking system operates in mixed mode between obstacle and parking space detection. As of v > 18 km/h, the parking system changes to parking space detection mode and remains active up to v = 36 km/h.
Shows model 218.3
The range of the outer front distance sensors amounts to a maximum of between s = 400 to 450 cm depending on environmental influences (e.g. rain, snowfall, air humidity, extreme temperatures of e.g. T = -40 or +85 °C, air pressure, hot engine air).
The data from the outer front distance sensors is read in and evaluated by the parking system control unit. It is calculated whether the parking space is suitable for the vehicle from the stored vehicle dimensions and deviations of the recorded parking space.
Minimum size of a parallel parking space (parallel to the direction of travel):
- At least s = 150 cm wide
- At least s = 100 cm longer than the vehicle
Minimum size of a perpendicular parking space:
- At least vehicle width + s = 100 cm
- At most vehicle width + s = 250 cm
For parallel parking, two boundary points are always required (front and rear). During perpendicular parking, two boundary points are needed (on the side).
After the driver has engaged gear range "R", the "Start Park Assist?" query and the warning notice "Pay attention to surroundings" appear in the multifunction display of the instrument cluster. In addition, the symbol of the OK button for "Yes" (activate) and/or the "Back" button for "No" (do not activate) appears in the multifunction display. The driver can then start or cancel the Active Parking Assist function using the left multifunction steering wheel button group.
The steering wheel electronics directly reads in the control signals from the left multifunction steering wheel button group and transmits this via the steering LIN to the steering column tube module. The steering column tube module control unit sends the control signals over chassis CAN 1, front SAM control unit and chassis CAN 2 to the instrument cluster. Depending on the response to the message, the instrument cluster sends the status of the Active Park Assist to the parking system control unit via chassis CAN 2.
Active Park Assist detects an empty space which is geometrically suitable for parking. However, it cannot detect whether the empty space is actually a parking space.
Illustration showing principle of parking space detection; shown on model 222.0
The trajectory, which consists of two arcs, forms the path to be taken into the parking space.
Parking space detection display in instrument cluster
Additional function requirements for display of possible parking spaces on instrument cluster
- Transmission not in neutral position or gear range "D" engaged
- Vehicle speed v = 0 to 30 km/h (calculated from the wheel speed)
The fully integrated transmission control unit transmits the currently engaged gear range via drive train CAN, CDI control unit or ME-SFI control unit, chassis CAN 1, front SAM control unit and chassis CAN 2 to the parking system control unit.
Function sequence for display of possible parking spaces on instrument cluster
When Active Parking Assist is searching for a parking space, a P symbol (6) is shown on the instrument cluster. As soon as an appropriate parking space is detected by Active Parking Assist, a left directional arrow (7) or a right directional arrow (8) also appears in addition to this symbol that indicates the side of the vehicle on which the parking space is located.
Parking spaces are always looked for on both sides of the vehicle. However, only parking spaces on the passenger side are pointed out by default. To also allow parking spaces on the driver side to be displayed, the driver must actuate the turn signal in the appropriate direction.
The parking system control unit sends the request to activate the display in the multifunction display over the chassis CAN 2 to the instrument cluster.
The steering column tube module control unit reads in the switch position of the combination switch directly and sends the position information via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the parking system control unit.
Changes to the parking situation after parking space detection are not considered by Active Park Assist.
Additional function requirement for semi-automatic parking
- Speed v < 10 km/h (without code (498) Japan version) or v < 7 km/h (with code (498) Japan version) (calculated from the wheel speed)
- Suitable parallel and perpendicular parking space detected
Function sequence for semi-automatic parking
If the Active Park Assist has detected a suitable parallel or perpendicular parking space and the parking procedure has started, various driving instructions and messages are shown to the driver in the instrument cluster. The driver can now take the hands off the steering wheel. The Active Park Assist steers the vehicle into the parking space by means of targeted steering movements. All the driver has to do is accelerate.
The parking system control unit calculates the required steering angle from the size of the parking space and the position in relation to the space. The actual steering angle is recorded by the steering angle sensor. The steering column tube module control unit reads in the data from the steering angle sensor directly and sends information on the steering wheel angle via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the parking system control unit. The parking system control unit sends corresponding steering commands to the electrical power steering control unit via chassis CAN 2. The electrical power steering control unit then actuates the electric power steering actuator motor accordingly. The steering gear converts the rotation movement of the electric power steering actuator motor into a parallel movement. The parking system control unit monitors the gear rack travel of the steering gear when this takes place. This is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis CAN 2 to the parking system control unit.
The parking system control unit transmits the appropriate requests to issue driving instructions and messages to the instrument cluster via chassis CAN 2.
The following driving instructions or messages can be displayed:
- "Park Assist Active - Please accelerate independently, pay attention to surroundings"
- "Park Assist Active - Please engage gear range R, pay attention to surroundings"
- "Park Assist Active - Engage gear range D, pay attention to surroundings"
- "Park Assist complete"
- "Park Assist canceled"
- "Park Assist inoperative"
- "Park Assist only up to 10 km/h" (without code (498) Japan version)
- "Park Assist only up to 7 km/h" (with code (498) Japan version)
Following a gear range change, the driver must move the vehicle until it brakes automatically (maneuvering point or target parking position reached).
Reverse travel or forward travel monitoring is active during parking. The Electronic Stability Program control unit calculates the required braking torque and actuates the traction system hydraulic unit accordingly upon reaching the maneuvering points or the target parking position. The parking system control unit sends information about the remaining distance to the specified obstacle to the Electronic Stability Program control unit via chassis CAN 2, the front SAM control unit and chassis CAN 1.
Any changes to the remaining distance to the obstacle are also taken into account (e.g. a person walking into the path of the vehicle). Depending on the current driving situation, however, it is not always possible to prevent a collision in such cases.
Delimitation at the side of the parking space is defined by a recognized obstacle (e.g. a curb or pole). If an obstacle is not detected at the side, the active parking assist aligns the vehicle flush with the front or rear obstacle.
When doing this, the angled position of the vehicle in the parking space is corrected by means of appropriate maneuvering movements. The wheels are moved to the straight ahead position once the parking procedure has been completed. As soon as the vehicle is secured, the message "Park Assist complete" appears for t = 5 s in the multifunction display of the instrument cluster. In addition, the instrument cluster actuates the warning buzzer. A chime sounds.
The vehicle is secured by engaging of gear range "P" by the driver or by the standstill coordinator in the Electronic Stability Program control unit.
The target position of the vehicle is generally as far into the parking space as possible.
The following situations will result in deactivation of the Active Parking Assist:
- Exceeding the permissible speed
- Turning the steering wheel ("hands-on detection");
To do this, the parking system control unit monitors the gear rack travel of the steering gear and recognizes active turning on the steering wheel due to the modification to the gear rack travel. The gear rack travel is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis CAN 2 to the parking system control unit.
- Defect on an electrical component in the power steering
- Defect on an electric or hydraulic component of the brake system
- Faulty CAN signals
- Driver's door and driver seat-belt buckle open at same time
- Deactivation of the parking system
In the event of deactivation of the Active Park Assist due to the circumstances listed, reactivation requires a change of gear or gear range. If the vehicle is outside the previously calculated trajectory, it must be manually steered to a starting position from which a new trajectory can be calculated.
Additional function requirements for semi-automatic exit of parking space
- Vehicle has been parked semi-automatically
- Semi-automatic parking space exit function is activated in "Park Assist" menu of instrument cluster
- Speed v < 10 km/h (without code (498) Japan version) or < 7 km/h (with code (498) Japan version) (calculated from the wheel speed)
- Turn signal must be set
The instrument cluster sends the status of the Active Parking Assist to the parking system control unit via chassis CAN 2.
Function sequence for semi-automatic parking space exit
The semi-automatic parking space exit function must be preceded by semi-automatic parking of the vehicle. This ensures that the vehicle is positioned parallel to a parking space boundary. This information is required as the Park Assist first requests "straight to the rear" vehicle movement to exit the parking space. If the vehicle was positioned in the parking space at an angle, the rim could be damaged by the curb, for example.
The semi-automatic parking space exit function is activated by actuating the turn signal indicator in the direction (left or right) in which the parking space is to be exited. The steering column tube module control unit reads in the switch position of the combination switch directly and sends the position information via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the parking system control unit. At the same time, the parking system control unit evaluates the transmission position. If "P" gear range is not engaged, the parking system control unit transmits the "Start Parking Assist?" query over chassis CAN 2 to the instrument cluster. The symbol of the OK button for "Yes" (activate) and/or the "Back" button for "No" (do not activate) is shown in the multifunction instrument cluster display. The driver can then start or cancel the Active Parking Assist function using the left multifunction steering wheel button group. The steering wheel electronics directly reads in the control signals from the left multifunction steering wheel button group and transmits this via the steering LIN to the steering column tube module. The steering column tube module control unit sends the control signals over chassis CAN 1, front SAM control unit and chassis CAN 2 to the instrument cluster. Depending on the response to the message, the instrument cluster sends the status of the Active Park Assist to the parking system control unit via chassis CAN 2.
After starting the parking space exit procedure, various driving instructions or messages are shown to the driver in the multifunction display of the instrument cluster. The driver can now take the hands off the steering wheel. The Active Parking Assist steers the vehicle out of the parking space by means of targeted steering movements. All the driver has to do is accelerate.
The parking system control unit sends corresponding steering commands to the electrical power steering control unit via chassis CAN 2.
Then the electric power steering control unit actuates the electric power steering actuator motor correspondingly (full steering angle). The steering gear converts the rotation movement of the electric power steering actuator motor into a parallel movement. The parking system control unit monitors the gear rack travel of the steering gear when this takes place. This is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis CAN 2 to the parking system control unit. The parking system control unit transmits the appropriate requests to issue driving instructions and messages to the instrument cluster via chassis CAN 2.
The following driving instructions or messages can be displayed:
- "Park Assist Active - Please accelerate independently, pay attention to surroundings"
- "Park Assist Active - Engage gear range D, pay attention to surroundings"
- "Park Assist Active - Please engage gear range R, pay attention to surroundings"
- "Park Assist complete"
- "Park Assist canceled"
- "Park Assist inoperative"
- "Park Assist only up to 10 km/h" (without code (498) Japan version)
- "Park Assist only up to 7 km/h" (with code (498) Japan version)
Following a gear or gear range change, the driver must move the vehicle until it brakes automatically (maneuvering point reached). Reverse travel or forward travel monitoring is active during parking space exiting.
The Electronic Stability Program control unit calculates the required braking torque and actuates the traction system hydraulic unit accordingly when the maneuvering points are reached. The parking system control unit sends information about the remaining distance to the specified obstacle to the Electronic Stability Program control unit via chassis CAN 2, the front SAM control unit and chassis CAN 1.
If the Active Parking Assist has positioned the vehicle so that the driver can drive directly out of the parking space, the parking system control unit sends the request to issue the message "Parking assistance completed" via chassis CAN 2 to the instrument cluster.
The following situations lead to deactivation of the Active Park Assist:
- Exceeding the permissible speed
- Turning the steering wheel ("hands-on detection");
To do this, the parking system control unit monitors the gear rack travel of the steering gear and recognizes active turning on the steering wheel due to the modification to the gear rack travel. The gear rack travel is recorded by the electric power steering torque sensor. The electrical power steering control unit reads in the signals from the electric power steering torque sensor directly and transmits information about the steering rack movement of the steering gear via the chassis CAN 2 to the parking system control unit.
- Defect on an electrical component in the power steering
- Defect on an electric or hydraulic component of the brake system
- Faulty CAN signals
- Driver's door and driver seat-belt buckle open at same time
- Deactivation of the parking system
| Electrical function schematic of parking system | PE54.65-P-2054-97XAC |
| Overview of system components of parking assistance systems | GF54.00-P-9997FQM |