Abstract
Ultrasonic range finders have already been used successfully for indoor mobile robots. However, in outdoor environment, the sensor should be robust against noise from vehicle engines and other sound sources. We already proposed the a simple, low-cost, and robust ultrasonic range finder that is based on the use of correlation technique. The aim of this paper is to describe the fast calculating method to get the correlation value for the this robust sonar. In this method, a calculation quantity is drastically a little compared with conventional method. This method is to calculate difference of correlation using the characteristic of the shape of the transmitted signal, then to calculate the correlation using the difference. The experimental results using the ultrasonic range finder that equips 8 sets sensors and one controller without DSP show the ultrasonic range finder with the conventional method need plenty of time for the mobile robot until it shows measurement results, but that with the fast calculating method needs little time.
