Parallel And Perpendicular Park Assist (PPPA)
The PPPA system with pull out assist is active only when the status of the ignition is ON, the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) position, the manual transmission gear selector lever is in the Reverse R or is not in Reverse R and the vehicle speed is less than about 11 km/h (7 mph). The front and rear park assist features of this system can be manually disabled and enabled by the vehicle operator using the Park Assist OFF push button in the instrument panel switch pod. In vehicles equipped with this option, the system is enabled from the factory as a default.
Reasons for disabling the system include trailer towing and off road use. With a trailer attached to the vehicle the audible and visual park assist alerts would be incessant whenever the gear selector lever was in the Reverse (R ) position due to the Proximity of the trailer to the rear of the vehicle. Similarly, operating the vehicle off road may cause the park assist alerts to become distracting due to the Proximity of large trees or boulders and the extreme front and rear approach angles that may be encountered while maneuvering on off road trails or terrain.
When the system is disabled, a PARK ASSIST SYSTEM OFF graphic and textual message will appear in the EVIC display of the IPC at the beginning of each ignition ON cycle, whenever the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) positions, or whenever the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions. When the system is enabled, a PARK ASSIST SYSTEM ON graphic and textual message will appear in the EVIC display of the IPC at the beginning of each ignition ON cycle, and a PARK ASSIST READY graphic and textual message will appear in the display whenever the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) positions and the vehicle speed is less than about 11 km/h (7 mph), or whenever the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions and the vehicle speed is less than about 11 km/h (7 mph).
The microcontroller based, 12 channel PAM is the central component of the park assist system. It supplies voltage to the park assist sensors, receives and analyzes data from the sensors, calculates and communicates the proper display information to the EVIC display, calculates and communicates the proper audible outputs to the RRM, performs system diagnostics and communicates with other electronic modules in the vehicle or with a diagnostic scan tool over the CAN data bus. The PAM operates on battery voltage received through a fused ignition (RUN) fuse in the PDC and is grounded through a take out of the body wire harness secured to the body sheet metal.
Six ultrasonic park assist sensors in the front bumper fascia and six sensors in the rear bumper fascia allow the park assist system to locate and identify the Proximity of nearby obstacles. These sensors each generate ultrasonic sound pulses when triggered by the PAM, then signal the PAM when an echo of the reflected sound pulses is received. The detection distance range from the front of the vehicle is about 1.2 m (47 in), or from the rear of the vehicle is about 2 m (80 in). The detection height range from the ground is about 0.2 m (7.8 in) to about 0.8 m (31 in). The detection area extends somewhat around both front and rear corners of the vehicle. In the PPPA system, the four sensors on the outboard right and left ends of the front and rear fascias have increased range over the other eight sensors and are not interchangeable.
In vehicles with an automatic transmission, the PPPA has an available autonomous brake warning feature. When the transmission gear selector position is Reverse (R ), an object is detected at the rear of the vehicle at a vehicle velocity based distance value and the ultrasonic sensors are capable of detecting an object the PAM sends an electronic brake and release message to the ABM over the CAN data bus network. The autonomous brake warning is aggressively performed by the ABM to reduce vehicle speed and pre-fill the brake hydraulic system in an effort to warn and to give the vehicle operator more time to react to a detected object at the rear of the vehicle.
The autonomous brake warning feature is an alert function, not a comfort function; therefore, the brake application will be sharp and sudden to disturb, rather than smooth and discrete. This feature is enabled from the factory as a default, but can be manually disabled or enabled by the vehicle operator using the customer programmable features settings menu of the RRM.
The EVIC display unit provides the vehicle operator with a graphical representation of the vehicle along with numerous illuminated arc sections that indicate the relative location and range of detected objects. The display is visible directly in front of the vehicle operator and operates based upon the electronic message inputs received from the PAM over the CAN data bus. There are three regions at the front or rear of the vehicle designated for arc alerts: Center, Left and Right. The Front Center region consists of five zones, the Rear Center region consist of six zones, while the Right and Left regions at the front and rear both consist of two zones. The zones range from furthest to nearest from the vehicle. The arc sections are illuminated in an amber color until the nearest zone is reached, at which point the arc sections become illuminated red in color.
Meanwhile, the RRM generates audible indications of a detected object by emitting a series of chime tones that grow progressively higher in frequency as the vehicle gets closer to the object. As the vehicle comes within about 30 cm (12 in) of the object, the audible warning changes from a high frequency series of chime tones to a single continuous tone. If the audio system is active when the RRM receives a chime request message from the PAM, the audio output will be muted automatically while the park assist audible warnings are being generated.
The semiautomatic parallel and perpendicular parking feature is designed to assist the vehicle operator, not to substitute for the vehicle operator. The vehicle operator must stay in full control of the acceleration and braking of the vehicle. The driver initiates the parallel and perpendicular parking feature by using the Parallel And Perpendicular Park Assist ON push button in the instrument panel switch pod.
Once the parallel and perpendicular park feature is turned on, an Active Park Sense Search screen pops up in the EVIC display unit. The initial search screen to pop up will be for the parallel parking feature, but text at the bottom of the EVIC display advises, Press OK for Perpendicular Park . The vehicle operator can then press the OK push button in the EVIC switch pod on the left horizontal spoke of the steering wheel to toggle back and forth between the parallel parking space and perpendicular parking space search screens. From this point through completion of the selected parking maneuver, the system will automatically coach the vehicle operator through the location of an appropriate parking space and the parking maneuver using both graphical representations and text that pops up within the EVIC display unit.
During parallel and perpendicular parking maneuvers the PPPA system assists the vehicle operator by measuring and identifying an appropriate parking space while driving slowly past the potential space. Then the system calculates the appropriate trajectory and controls the steering wheel to steer the vehicle into the selected space. Depending upon the parking maneuver selected, the PPPA system is capable of steering a vehicle into a parallel or a perpendicular parking space on either the driver side or the passenger side of the vehicle. The PAM controls the measuring and maneuvering of the vehicle by monitoring the ultrasonic sensor inputs and sending the appropriate electronic messages to the EPS module over the CAN data bus.
When the PAM monitors a problem in any of the park assist system circuits or components, it stores a fault code or DTC in its memory circuit, sends an electronic message to the EVIC and the EVIC displays a graphic with a SERVICE PARK ASSIST SYSTEM textual message. If the PAM detects that the park assist sensors are inoperative due to an accumulation of road film, mud, ice or snow on the front or rear fascia, the EVIC will display a WIPE OFF FRONT PARK ASSIST SENSORS or WIPE OFF REAR PARK ASSIST SENSORS graphic and textual message. When the system is disabled by the PAM due to a detected external error or influence, a PARK ASSIST SYSTEM DISABLED graphic and textual message will appear in the EVIC display of the IPC whenever a new ignition cycle begins and each time the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) position or the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions.