Target Speed Sensing Technique using Dilation Correlation of Ultrasonic Signal for Vehicle

Abstract

Direct measurement of the target speed ahead of the vehicle helps control the vehicle in many ways. Ultrasonic sensing is mostly used for distance measurement and differentiation is used for obtaining speed information. In most cases, the distance value differential is accompanied by a large speed error. This paper proposes direct target speed measurement in time domain, using the dilation correlation and the Doppler effect. Using the binarized ultrasonic signal in the correlation, it is possible to calculate the target speed even at a low sampling rate of 100 kHz, and the memory and computational load required for signal processing is low. Experimental results using two vehicles show acceptable RMS errors of 1.81 km/h that can be used for vehicle control, and have a better RMS error than the method of calculating the speed by differentiating the distance values obtained by the ultrasonic time-of-flight method.