Temperature Compensation in Ultrasonic Ranging Systems: An Empirical Model

Abstract

'Ultrasonic ranging systems have for many years been used to measure the distance between two points by emitting short bursts of high frequency signals and listening to the echo. It has been used as a means of acoustic location with applications in intelligent suspension systems, modem naval warfare and measurement of echo characteristics of targets in water. The measurement of distance by ultrasonic ranging systems is characterized by the problem of the errors that arise due to variation of the speed of sound with :change of temperature. In this thesis a design of an ultrasonic ranging system is made based on the temperature-distance characteristic correction technique to minimize the errors in the measurement of distance of the ultrasonic ranging system. The main objective of designing a unique temperature compensating ultrasonic ranging system to track resonant frequency drifts of ultrasonic transducer caused by variation in temperature is taken into consideration. The objective was achieved by measuring mean deviation in distances between two fixed points as the temperature changed. It is shown that the errors can be minimized by using a built-in compensator or an algorithm developed based on the deviationtemperature equations. The study is likely to significantly improve on accuracy of distance measurement using ultrasonic ranging systems whenever temperature changes occur. Applications which employ time-of-flight technique in ultrasonic auto ranging systems is best suited for this method which can be implemented by incorporating either a built in compensating system or using an algorithm for the error correction whenever there are temperature variations when measuring distance.