Body Electrical System > Rear Parking Assist System > Parking Assist Sensor

Operation

The sensor emits ultrasonic wave to the objects, and it measures the time until reflected wave returns, and calculates the distance to the object.

Distance detection type

Direct detection type and indirect detection type are used together for improving effectiveness of the detection.

1.	Direct detection type: One sensor transmits and receives signals to measure the distance.

2.	Indirect detection type: One sensor transmits signals and the other sensor receives the signals to measure the distance.

Measurement principle

Back warning system (BWS) is a complementary device for reversing. BWS detects objects behind vehicle and provides the driver with buzzer alarm finding objects in a certain area, using ultrasonic wave propagation speed and time.

The propagation speed formula of ultrasonic wave in air is following :

v=331.5 + 0.6t (m/s)

v=ultrasonic wave propagation speed

t=ambient temperature

The basic principle of distance measurement using ultrasonic wave is :

Sensor detection range

1.	14cm (Diameter) plastic rod is used for the test target.

2.	The test result may differ by a different target object.

3.	Detection range may be reduced by dirt accumulated on sensor, and extremely hot or cold weather.

4.	The following object may not be detected.

-	Sharp object or thin object like rope.

-	Cotton, sponge, snow or other materials absorbing sonic wave.

-	Smaller objects than 14cm (Diameter), 1m length.