Ultrasonic ranging gets thermal correction

Abstract

This paper presents some aspects of the research activities on sensors for robots, developed in the Instituto de Automatica Industrial (IAI) during the last years. The demand for greater precision in the measurement of distances using US techniques, makes it necessary to compensate for alterations in the sound‐speed in the interposed medium due to temperature. In this paper we will describe a method for calculating this correction in order that no other external sensor be necessary. The method is based on the resonance‐frequency variation of the piezoelectric elements with temperature. The accuracy reached with this correction is higher than normally would be needed in robotics applications.