Performance Capabilities and Detection Efficiency of Vehicle Backup Proximity Sensors for Narrow Objects

This paper investigates performance capabilities and potential safety effectiveness of ultrasonic backup proximity sensors with special attention on cylindrical and cubical shaped narrow obstacles with the dimensions varies from 2.6 cm to 11.0 cm. The experiment was performed using a commercially available parking aid system consisting of two ultrasonic sensors, and a rear bumper model constructed in a laboratory environment together with a test surface divided into grids having cells of 6 cm x 6 cm. It can be observed that there are considerable differences in detection zone patterns when comparing observations for cylinders and cubes even for same dimensions. Using detection zone maps, it can be seen that, when the size of the test objects become smaller, there are large blind spot areas in the space between the sensors and also near the right and left edges of the rear bumper. In average, when reducing the obstacle dimensions from 11.0 cm to 2.6 cm, the detection efficiency changes from 62.6% to 33.1% for cylindrical objects and for cubical shaped objects it was 39.3% to 21.6%. Average detection efficiency is lower than 50% for objects less than 5 cm in dimension irrespective of the object geometry.