Correlation detector based on a FPGA for ultrasonic sensors

In the field of mobile robots ever more frequent use is being made of ultra sonic sensors composed of several transducers carrying out readings simulta neously and in a coordinated way. These sensors can read not only the dista nces but also listening angles, and they can also determine the reflector t ype (i.e. edge, plane or corner). To this end it is especially important th at, after each emission of a pulse of ultrasound, each transducer can accur ately detect the arrival of the echoes (providing accurate time-of-flight ( TOF) readings). Another desirable feature is that the transducers be capabl e of discriminating between the echoes of simultaneous emissions (avoiding problems of crosstalk). This article describes the design and development o f a correlation detector (implemented on a low-cost electronic system) allo wing for both functions. (C) 1999 Elsevier Science B.V. All rights reserved .