Correlation detector based on a FPGA for ultrasonic sensors

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