Collision Avoidance and Parking Assist Systems: Description and Operation

Object Detection Description and Operation

The ultrasonic parking assist system is designed to identify and notify the driver of an object in the vehicle's path when moving forward or reversing at speeds of less than 8 km/h (5 mph). The distance and location of the object is determined by eight object sensors: four located in the rear bumper and four located in the front bumper. The parking assist system will notify the driver using the parking assist indicators and an audible signal through the radio.

The parking assist system is made up of the following components:

* Object alarm module
* Rear parking assist sensors
* Front parking assist sensors
* Rear parking assist indicator
* Front parking assist indicator

Object Alarm Module

The object alarm module provides an 8-volt reference and a low reference to the eight parking assist sensors. The object alarm module receives individual signals from each of the eight sensors and determines the location and distance of an object based on these inputs. When an object is detected, the object alarm module will illuminate the appropriate LED on the appropriate parking assist indicator and send a serial data message to the radio requesting an audible alert.

Parking Assist Sensors

The parking assist sensors are located the in front and rear bumpers of the vehicle. The sensors are used to determine the distance between an object and the bumper. Each sensor emits an ultrasonic frequency which is reflected off object located behind the vehicle. These reflections are received by the sensors. The time difference between when the frequency was emitted and when the reflection is received, known as sensor ring time, is used to determine the distance to the object. The sensors report this information to the object alarm module.

Parking Assist Indicators

The rear parking assist indicator is located in the interior rear of the vehicle and is visible through the inside rearview mirror. The front parking assist indicator is located on the instrument panel. Each indicator contains three LEDs: two amber and one red. The object alarm module controls these three LEDs as a visual indicator of how close the vehicle bumper is to an object. The object alarm module supplies voltage to each of the LEDs and commands each LED on by supplying an individual ground.

Parking Assist Operation

When the vehicle is first placed into reverse or drive, the parking assist system performs a bulb check. During the bulb check, the all three LED located in the parking assist indicator will illuminate for approximately 2 seconds to indicate that the system is working.

When backing up or pulling forwards at speeds of less than 8 km/h (5 mph), the system is constantly monitoring for object of interest. The parking assist system can detect objects greater than 7.6 cm (3 in) wide and 25.4 cm (10 in) tall. The system cannot detect objects below the bumper, underneath the vehicle,. If an object is detected, one of the following will occur:

* If the object is 1-2.5 m (40-96 in) away from the vehicle, the amber outside indicator will illuminate and a single chime will sound when the object is first detected.
* If the object is 0.6-1.0 m (23-40 in) away from the vehicle, the amber outside and the amber middle indicators will illuminate.
* If the object is 0.3-0.6 m (11-23 in) away from the vehicle, the amber outside, amber middle, and red outside indicators will illuminate.
* If the object is less than 0.3 m (12 in) away from the vehicle, the amber outside, amber middle, and red outside indicators will flash and the chime sounds continuously.

If the parking assist system detects a malfunction, a DTC will be stored and the object alarm module will send a serial data message to the instrument panel cluster (IPC) to display the SERVICE PARK ASSIST message on the driver information center (DIC). A chime will sound and the red LED on the parking assist indicator will be illuminated. as a notification to the driver that a malfunction exists and the system is disabled.

Parking Assist System DIC Messages

SERVICE PARK ASSIST

The driver information center (DIC) displays SERVICE PARK ASSIST when the object alarm module detects a malfunction in the parking assist system and the system is disabled. The DIC also displays SERVICE PARK ASSIST when a loss of communication occurs with the object alarm module.

PARK ASSIST OFF

The PARK ASSIST OFF message is displayed in the DIC when the object alarm system is disabled due to conditions that disable or inhibit the system. The red LED in the park assist indicator will be illuminated to indicate that the system has been disabled. The object alarm module requests the DIC display PARK ASSIST OFF when it detects that one of the following conditions:

* The parking assist system is manually disabled using the driver information center (DIC).
* The park brake is applied or not fully released.
* An object is attached to the rear of the vehicle, such as a trailer, bicycle rack, trailer hitch receiver, or tow bar.
* The parking assist sensors are covered by snow, mud, dirt, slush, or ice.
* The vehicle bumper is damaged.
* Excessive paint thickness on a replacement parking assist sensor.
* The parking assist sensors are disrupted by vibrations, like those caused by a large nearby vehicle or from heavy equipment such as a jackhammer.