GF54.65-P-0006LE Parking System, Function

GF54.65-P-0006LE Parking System, Function
- with CODE (230) Advanced Parking Guidance
- with CODE (220) PARKTRONIC

General function requirements
^ Circuit 15 On

The status of circuit 15 is transmitted by the EIS [EZS] control unit to the PTS control unitN73 via the chassis CAN (CAN E)N62

Parking system, general
The parking system uses an ultrasonic measuring system for recording the distance to an obstacle and with code (230) Exclusive parking assist also for measuring and storing parking spaces. It assists the driver when parking and in maneuvering situations at speeds of v < 16 km/h.

The distance between the vehicle and the obstacle is indicated to the driver visually and acoustically.

In certain situations warnings from the parking system are suppressed, e.g. when reversing through narrow passages (driveway). There is in fact an obstacle in the recording range but a collision will not take place due to the current steering wheel position.

The parking system function consists of the following partial functions:
^ Measuring procedure function sequence
^ Self-test function sequence
^ Behavior in the event of overvoltage and undervoltage function sequence
^ Activate and deactivate function sequence
^ Reverse travel function sequence (front and rear monitoring range active)
^ Forward travel function sequence (front monitoring active)
^ Parking space recognition function sequence (with code (230) Exclusive parking assist)
^ Display of potential parking spaces function sequence (with code (230) Exclusive parking assist)
^ Parking Guidance function sequence (with code (230) Exclusive parking assist)

Component Identification:

Measuring procedure function sequence
The whole system is based on the ultrasonic measuring procedure. The following components are actuated by the PTS control unit in the process:
- Outer left front PTS ultrasonic sensor (B8/1)
- Center left front PTS ultrasonic sensor (B8/2)
- Inner left front PTS ultrasonic sensor (B8/3)
- Inner right front PTS ultrasonic sensor (B8/4)
- Center right front PTS ultrasonic sensor (B8/5)
- Outer right front PTS ultrasonic sensor (B8/6)
- Outer right rear PTS ultrasonic sensor (B8/7)
- Inner right rear PTS ultrasonic sensor (B8/8)
- Inner left rear PTS ultrasonic sensor (B8/9)
- Outer left rear PTS ultrasonic sensor (B8/10

As a result of this these emit an ultrasonic signal. The signal reflected by an obstacle is received and evaluated. The driver is informed about the respective distance between the vehicle and obstacle via the PTS warning indicator in the instrument cluster (A1) and the rear PTS warning indicator (A44/3).

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. The large opening angle of the sensors means that as a rule reflected echoes can also be reflected by adjacent distance sensors, the so-called cross echoes. These occur at the obstacle due to scattered reflection.
The distance between the vehicle and obstacle can be calculated from two echo signals using the triangulation method. The propagation times of the signals from the direct measurement and from the cross measurement are required for this method.

The parking system cannot work correctly in certain cases due to the function principle (transmitting and receiving sound waves). For example, incorrect values may be displayed when the vehicle approaches an obstacle which absorbs sound very effectively (a snow-covered vehicle).

The outer left front PTS ultrasonic sensor and outer right front PTS ultrasonic sensor serve corner safeguarding (B) in the swivel range of the front of the vehicle. This monitored range guarantees a minimum distance of s = 15 cm at this point which is realized on the software side. No PTS ultrasonic sensors are fitted for corner safeguarding in the swivel ranges of the vehicle rear as these areas can be seen using the outside mirrors.

The monitoring ranges are activated depending on the direction of travel:
- With forward travel the front monitoring range (A, B) is monitored
- With reverse travel the front monitoring range (A, B) and rear monitoring range (C) is monitored.

The monitoring range in front of the vehicle is a maximum of s = 100 cm (c), the monitoring range behind the vehicle a maximum of s = 120 cm (e).
If the distances to the vehicle are less than s = 20 cm (a1, c1), for technical reasons the parking system does not receive any more defined values.

On vehicles with code (230) Exclusive parking assist below a speed von v < 36 km/h the monitoring range of parking space recognition (D) on the right and left of the vehicle is measured up to a distance of s = 4 m to s = 4.5 m (d). These values are stored in the PTS control unit while driving past for a distance of s = 15 m.

The range of the sensors may vary depending on environmental conditions.

Component Identification:

Self-test function sequence
The PTS control unit carries out a self-test after switching on the ignition (circuit 15 ON).
The following components are checked for proper operation:
- PTS control unit
- Rear PTS warning indicator
- Front PTS ultrasonic sensors
- Rear PTS ultrasonic sensors
- All electrical lines of the parking system

The PTS warning indicator in the instrument cluster and the rear PTS warning indicator are actuated fully for t = approx. 1 s after the self-test. If no malfunctions or faults exist, two yellow horizontal "stand-by" bars in the instrument cluster and two yellow vertical "stand-by" bars in the rear PTS warning indicator light up. The PTS control unit performs further self-tests at regular intervals.

The PTS control unit distinguishes between a malfunction and a system error. In the event of a system error or a system fault the parking system is deactivated and the light-emitting diode in the PTS OFF switch (S6/2s12) lights up.

The following states can be recorded:
^ System disturbance
^ System error(s)

System disturbance
A system disturbance can be caused by a temporary external disturbance (e.g. a jackhammer on a construction site, a steam jet or by driving through a washing facility). If a system fault occurs during operation, this is indicated by the red display elements in the respective warning indicator in question lighting up.

If a system disturbance is present for an extended period of time, the cause of the system disturbance is identified during driving operation by means of a self-test. If the system disturbance is still present, this is interpreted as a system fault.

A warning sound is not emitted.

System fault
A system fault can have the following causes:
- Defective component
- CAN communication fault
- Overvoltage or undervoltage

If a system error is detected, the red display elements in the respective warning indicator in question are actuated. An acoustic warning is also emitted for t = 2 s
The parking system switches off after a further t = 20 s and a fault is entered in the fault memory of the PTS control unit.

The license plate bracket attached to the bumper varies depending on the national version. Due to the different dimensions and geometries of the license plate brackets it is necessary to adapt the parking system to the conditions in each case. The national version can be adapted by means of an IS tester in order to prevent malfunctions due to modified license plate brackets

Behavior in the event of overvoltage and undervoltage function sequence
The behavior of the parking system in the event of overvoltage or undervoltage can be seen in the following table.

Additional function requirements for activation and deactivation
^ Self-test completed successfully
^ Parking brake not operated

The status of the parking brake is recorded via the electric parking brake switch (S76/15). The signal from the electric parking brake switch is read in by the electric parking brake controller unit (A13) and transmitted to the central gateway control unit (N93) via the front end CAN (CAN G). From here the signal reaches the PTS control unit via the chassis CAN.

Activate and deactivate function sequence
If gear range "D" or "R" is engaged and the accelerator pedal sensor (B37) is operated when the parking brake is applied, the parking brake is released by the electric parking brake controller unit. Once the parking brake is released the PTS control unit activates the parking system.

The intelligent servo module for DIRECT SELECT (A80) transmits the current transmission selector lever position to the CDI control unit (N3/9) (with diesel engine) or ME-SFI control unit (N3/10) (with gasoline engine) via the drive train CAN The accelerator pedal position is read in by the CDI control unit or ME-SFI control unit via the accelerator pedal sensor.
The CDI control unit or ME-SFI control unit transmits the accelerator pedal position and the current transmission selector lever position to the central gateway control unit via the chassis CAN.
The central gateway control unit passes on all the relevant information to the electric parking brake controller unit via the front end CAN.
If all the parameters are met, the electric parking brake controller unit releases the parking brake by actuating the integrated electric motor. Once the parking brake is released the electric parking brake controller unit transmits the status of the parking brake to the central gateway control unit via the front end CAN; from here the signal reaches the PTS control unit via the chassis CAN.

The parking system can be deactivated or activated manually using the PTS OFF switch.

The operation of the PTS OFF switch in the cockpit switch group (S6/2) is read in by the upper control panel control unit (N72/1) via the instrument panel LIN (LIN 1) and transmitted to the central gateway control unit via the interior CAN (CAN B). This transmits the status to the PTS control unit via the chassis CAN.

When the parking system is activated, depending on the light status of the rain/light sensor (B38/2), the rear PTS warning indicator is actuated with a certain brightness. The rain/light sensor is read in by the overhead control panel control unit (N70) which transmits the light status to the central gateway control unit via the interior CAN. This transmits the light status to the PTS control unit via the chassis CAN.

If the rain/light sensor detects "Day" the rear PTS warning indicator is actuated with 100 % brightness. In the case of "Night" the rear PTS warning indicator is actuated with 30 % brightness. The brightness of the front warning indicator is effected by way of the brightness control of the instrument cluster.
In driving mode the parking system switches to stand-by mode between v = 40 km/h and v = 16 km/h, i.e. the PTS control unit, warning indicator and distance sensors are supplied with voltage but the warning indicators are not yet actuated.

The light-emitting diode in the PTS OFF switch lights up when the parking system is deactivated.
The parking system is also activated again if it was deactivated on the last trip by means of the PTS OFF switch.

Additional function requirements for reverse travel
^ v < 16 km/h
^ Reverse gear engaged

The vehicle speed is recorded by the left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3) and right rear rpm sensor (L6/4). The status of the latter is transmitted by the ESP control unit (N47-5) (without model 221.095/195) or by the regenerative braking system control unit (N30/6) (model 221.095/195) to the PTS control unit via the chassis CAN.

The reverse travel function is requested by engaging "gear range R". The status of the transmission selector lever position is made available by the intelligent servo module for DIRECT SELECT on the drive train CAN (CAN C) and passed on by the CDI control unit or by the ME-SFI control unit on the chassis CAN. The central gateway control unit reads in this information, generates from this the status "gear range R engaged" and transmits it to the PTS control unit via the chassis CAN.

Reverse travel function sequence (Front and rear monitoring ranges active)
The parking system changes to measuring mode when the limit speed of v < 16 km/h is dropped below. If obstacles are detected in front of or behind the vehicle, this is displayed optically by the corresponding display elements lighting up in the warning indicator or instrument cluster. When the distance drops below a distance s < 30 cm, the warning is emitted initially as an intermittent tone and then as a continuous signal (see table below). The parking system changes to stand-by mode again when the vehicle speed v > 18 km/h is exceeded.

On vehicles with code (550) Trailer hitch the area to the rear of the vehicle is not monitored when a trailer used. The trailer recognition control unit (N28/1) transmits the status "Trailer recognized" via the interior CAN to the central gateway control unit which transmits the status to the PTS control unit via the chassis CAN.

Display of front monitoring range

Display Of Front Monitoring Range:

Display Of Rear Monitoring Range:

Additional function requirements for forward travel
^ v < 16 km/h

The vehicle speed is recorded through the rpm sensors. Their status is transmitted by the Electronic Stability Program control unit to the PTS control unit via the chassis CAN.

Forward travel function sequence (Front monitoring active)
When the lower limit speed of v < 16 km/h is dropped below the parking system changes to measuring mode.
If obstacles are detected in front of the vehicle, the driver is first alerted visually by illumination of the corresponding display elements in the warning indicator. When the range drops below a distance of s < 30 cm, the warning is emitted initially as an intermittent tone and then as a continuous signal (see previous table).

The parking system changes to stand-by mode again at a vehicle speed v > 18 km/h.

Additional function requirements, parking space recognition
^ No trailer operation
^ No control intervention function of the following systems within the last t = 5 s:
- Antilock brake system (ABS)
- Electronic Stability Program (Electronic-Stability-Program) (ESP)

Parking space recognition function sequence
Parking space recognition enables suitable longitudinal parking spaces to be found. When driving at a speed of v < 40 km/h the parking spaces are always measured on both sides (right and left of the vehicle) by the outer left front PTS ultrasonic sensor or outer right front PTS ultrasonic sensor in the bumpers. The outer left front PTS ultrasonic sensor and outer right front PTS ultrasonic sensor record the range on the left and right of the vehicle, for this purpose they show a larger measuring range than the remaining front PTS ultrasonic sensors.

Here the range of these ultrasonic sensors has been extended to s = 4 m to s = 4.5 m. The PTS control unit reads in this data, evaluates it and stores it over a distance of s = 15 m.
It is calculated whether the parking space is suitable for the vehicle from the stored vehicle dimensions and deviations of the recorded parking space.

The Parking Guidance recognizes a longitudinal parking space according to the following criteria:
- Free area limited to the rear (e.g. by a vehicle)
- Parallel to the course of the road
- At least b = 1.5 m wide
- Be at least l = 1.3 m longer than the vehicle

Parking space recognition only recognizes a free space which is geometrically suitable for parking, not whether this free space actually also represents a parking space.

Component Identification:

The trajectory specifies path to be driven from into the parking space. The trajectory consists of two arcs.

Display of potential parking spaces function sequence
With active parking guidance the PTS control unit transmits the request for the readiness indicator to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN (CAN F). The P symbol with a black background appears in the instrument cluster.
The display for active parking guidance appears in the instrument cluster as of a speed v <35 km/h. As a result unnecessarily hard braking maneuvers in urban traffic are prevented by operating instructions.

Only parking spaces on the passenger-side of the vehicle are displayed as standard. In order to also get parking spaces displayed on the driver-side (e.g. in one-way streets), the turn signal indicator must be set towards the driver-side.

If an appropriate parking space has been detected, the PTS control unit transmits the request for a visual indicator to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN. The display appears in the form of a stored blue P symbol (10). In addition to this P symbol a direction arrow (11 or 12) appears which indicates on which side of the vehicle the parking space is located. Delimitation at the side of the parking space is established by a recognized obstacle (e.g. a curb or pole). If no obstacle to the side is recognized, one's own vehicle is aligned with the front or rear obstacle (e.g. vehicle). The target position of one's own vehicle is generally as far back and deep in the parking space as possible.

Changes in the parking situation after parking space recognition are no longer taken into account by the system.

Parking guidance function sequence
If the PTS control unit recognizes that the vehicle is at a standstill, the parking space last recognized and stored is defined as the desired parking space. Once reverse gear is engaged, the PTS control unit transmits the request to display the warning message to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN:

"Pay attention to all the vehicle surroundings. Confirm with OK"

Only when pressing the OK button (S110s6) has been transmitted by the steering column tube module (N80) to the PTS control unit via the chassis CAN, does the PTS control unit transmit the presentation data for parking guidance to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN.

The vehicle must be driven straight back a short distance if necessary, depending on the distance of the vehicle to the parking space. This is signaled by a green lane behind the vehicle. The vehicle must be reversed until an information tone can be heard. This signals the starting position reached before the parking process and is shown by a white clamp behind the vehicle. The PTS control unit receives the movement data from the ESP control unit via the chassis CAN.

When the vehicle is stationary the red actual lane (13) is shown with the yellow specified lane (14). The red actual lane must overlap the yellow specified lane; to do this, the steering wheel must be turned. Turning the steering wheel is read in by the steering angle sensor (N49) of the steering column tube module and transmitted to the PTS control unit via the chassis CAN. The PTS control unit changes the display of the red actual lane at the same time as the steering wheel is turned.

If the red actual lane is congruent with the yellow specified lane, the lane (15) is shown green and an information tone sounds. If the representation of the lane is located within the parking space (16), a white retaining clamp (17) with an arrow for the holding position is displayed at the end of the green lane
The vehicle must be driven backwards up to the holding position displayed with the adjusted steering angle. If the holding position is reached, the PTS control unit transmits the request to output an information tone to stop the vehicle to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN.

Once the vehicle has come to a standstill a yellow specified lane and a red actual lane are displayed again. The red actual lane must overlap the yellow specified lane; to do this, the steering wheel must be turned. Turning the steering wheel is read in by the steering angle sensor () of the steering column tube module and transmitted to the PTS control unit via the chassis CAN. The PTS control unit changes the display of the red actual lane at the same time as the steering wheel is turned.
If the red actual lane is congruent with the yellow specified lane, the green lane is shown with a white retaining clamp with an arrow for the holding position and an information tone sounds. The vehicle must be driven backwards up to the holding position displayed with the adjusted steering angle. If the holding position is reached, the PTS control unit transmits the request to output an information tone to stop the vehicle and the message "Parking Guidance ended" for t = 5 s to the central gateway control unit via the chassis CAN and further on to the instrument cluster via the central CAN.

Once the vehicle is stationary an acoustic warning can sound from the PARKTRONIC depending on the parking situation (e.g. with an insufficient distance to the rear obstacle). The Parking Guidance changes to maneuvering mode in which the vehicle is displayed in the parking space without lanes.

The vehicle does not always have to be parallel with the curb in the parking space at the end of the second steering angle. In small parking spaces Parking Guidance tries to guide the vehicle so that the vehicle stops as deep as possible in the parking space. The vehicle can then be positioned in the parking space by suitable maneuvering (with the aid of PARKTRONIC and parking space display).

If the system detects an obstacle when reversing on the proposed parking curve, the driver is warned; for this purpose, Parking Guidance is overlaid by a warning message.
If the Parking Guidance detects that the obstacle has been removed again the display goes back into normal mode and the Parking Guidance can be finished as usual.
If the vehicle drives over the position recognized as critical, the warning mode will end and the Parking Guidance changes again into normal mode.