Chevrolet Trax: Object detection description and operation (rear cross traffic alert, UFG)

Rear Cross Traffic Alert Block Diagram

Fig. 21: Rear Cross Traffic Alert Block Diagram

The rear cross traffic alert system is a feature that utilized two side object sensor modules to provide enhanced customer convenience while backing up by sensing and providing warnings to the driver on impending rear cross traffic. The rear cross traffic alert system is designed to detect and track moving objects as small as a 125cc motorcycle with rider within a specified coverage zone behind the vehicle. The system is designed to alert the driver, with a visual display and either an audible sound or a haptic warning, if equipped and enabled, to the presence of moving objects of interest that may cause a collision with the host vehicle. Although the system is intended to assist drivers in backing up, it does not replace driver's vision. The driver is responsible to check carefully for objects outside of the coverage zone (e.g., a fast approaching vehicle) for a safe backing maneuver.

Rear Cross Traffic Alert System Components

The side blind zone alert system is made up of the following components:

• Left side object sensor module
• Right side object sensor module
• Visual Display Icons located on the infotainment display screen
• Audio system chime
• Haptic safety seat (if equipped)

Side Object Sensor Modules

The side object sensor modules are located on each side of the vehicle behind the rear fascia and are not directly visible from outside the vehicle. The sensors use radar to determine the presence of moving objects nearby. The left side object sensor is the master that communicates on serial data. There is a private communication network between the left and right sensors. The scan tool is able to communicate only with the left sensor.

When a moving object is detected in the left rear cross traffic zone while the engine is running and the transmission in reverse, the side object sensor module sends a serial data message to the human interface module and memory seat module to provide alerts. Each sensor is supplied B+ and ground.

Display Icons

The rear cross traffic alert system visual alert display consists of two visual icons, one on each side of the display screen of the rearview camera display, that are used to alert the driver on rear cross traffic from each side of the host vehicle respectively. In addition to visual indicators, the audio system will beep (if enabled) and the haptic safety seat will vibrate (if equipped and enabled). Refer to owner's manual for vehicle customization

Audio or Haptic Notification

The alert output type can be driver selected to either audio or haptic. The chime location will be left rear for left rear cross traffic alert and right rear for right rear cross traffic alert. The haptic seat system response will be to generate 3 repetitions of haptic vibration in the left rear area of the seat for left cross traffic alert and right rear area of the seat for right cross traffic alert. If there is a problem with the haptic seats, the audio chime will be substituted.

Rear Cross Traffic Alert Operation

The rear cross traffic alert system is designed to detect moving objects of interest as small as a 125cc motorcycle with rider. The detection zone extends approximately 30m (99 ft) from the rear corner of the car and covers an area from behind the vehicle to 125 degrees towards the front at a height of 0.45m (1.5 ft) to 2m (6.5 ft) above ground. The system operates when vehicle speed is 10 kph (6 mph) or less and is designed to detect objects moving at speeds up to 36 kph (22 mph).

When the vehicle is backing up, the side object sensors receive energy that is reflected from external objects and determine if the objects are objects of interest or not. The system may at times detect pedestrians, shopping carts, or similar moving objects. This is normal and should not be considered as a false alert or problem with the system. The rear cross traffic alert system will estimate vehicle travel trajectory and use the information in conjunction with object travel trajectory information to determine if there is a potential collision between the vehicle and the object of interest. The rear cross traffic alert function will only alert on objects of interest that pose a potential collision with the host vehicle. The system is not designed to provide an alert to objects that have no potential collision with vehicle. In addition, the system will not alert to stationary objects such as signs, parked cars, etc.

If the vehicle is towing a trailer or has an object such as a bicycle rack attached to the rear of the vehicle, the rear cross traffic alert system may not function properly.

Foul weather may affect the operation of the rear cross traffic alert system. Occasional missed alerts can occur under normal circumstances and will increase in wet conditions. The number of missed alerts will increase with increased rainfall or road spray. Heavy rainfall, as well as mud, dirt, snow, ice, or slush build-up on the rear fascia, can completely disable the system.

Rear Cross Traffic Alert Driver Information Center Messages

REAR CROSS TRAFFIC ALERT OFF

This message indicates that the system has been disabled through the driver information center. Refer to the vehicle owners manual for instructions on how to set personalization options on the driver information center

SERVICE SIDE DETECTION SYSTEM

This message indicates that the system requires service. Since the side object sensors are also used for side blind zone alert and/or lane change alert, these feature will also be inoperative. Check vehicle for DTCs to determine the cause of this notification.

SIDE DETECTION SYSTEM TEMPORARILY UNAVAILABLE

This message indicates that the system has been temporarily disabled because the sensors are blocked or can otherwise not accurately detect vehicles or objects. Verify there is no damage to rear fascia or there are any bumper stickers that may interfere with the radar signals. Ask the customer if any of the following circumstances that present when the system became unavailable: mud, dirt, snow, ice, or slush build-up on the rear fascia, heavy rainfall, or excessive road spray.

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