Spark

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 reversing. The distance and location of the object is determined by 4 object sensors located in the rear bumper. The parking assist system will notify the driver using an audible beep signal through the radio.

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

The object alarm module provides an 8V reference and a low reference to the four object alarm sensors. The object alarm module receives individual signals from each of the four sensors and determines the location and distance of an object based on these inputs. When an object is detected, the object alarm module will send a data message via CAN-Bus to the radio requesting an audible alert.

The object alarm sensors are located in the rear bumper 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 any object located in front of or behind the vehicle. These reflections are received by the sensors. The time difference between the emission of the frequency and when the reflection is received is known as sensor ring time, it is used to determine the distance to the object. The sensors report this information to the object alarm module.

When an object is within the measuring range of the sensor, the ultrasonic pulse is reflected and is received by the sending or a neighbouring sensor. The sensor converts this signal into a voltage signal and sends this signal to the object alarm module. The object alarm module evaluates the received sensor signals. As soon as an object is within the measuring range, the object alarm module sends a message via CAN-Bus to the radio in order to give out the acoustic distance signal. The measuring range is between 40-120 cm (15.74-47.24 in). From a distance of 120 cm (15.74 in), the acoustic signal is active. The frequency of the beep sound increases with decreasing distance. From a distance less than 40 cm (15.74 in), the sound becomes continuous.

The parking assist can be activated and deactivated by engaging the reverse gear.

The object alarm module carries out a self test and monitors the sensors for electrical and mechanical faults. Monitored is the power supply of each sensor and the sensor signals, which need to alter when the vehicle moves. If this is not the case, the sensor is acoustically blocked or faulty. Mud, ice and snow may cause obstruction of the function of the sensors. Besides that the object alarm module checks whether the correct type of sensor is installed.