Ultrasonic Distance Measurement Technique in Chair of Cripple Application

Abstract

The present paper illustrates a type of distance measurement by use an ultrasonic sensor for distance from the foundation of selected points to a frontal object. The sensor was based on the measurement time of travel to an ultrasonic pulse-echo, that was reflected by the object. A controlled technique was use to obtain reflected pulses that were able to detectable by means of a threshold comparator. Such a technique, which takes the frequency response of the ultrasonic transducers into account, allows received pulse detection to be obtained. Experiments performed with a 40 kHz piezoelectric-transducer based sensor, showed a standard stability in laboratory experiment and the sensor still works at motion state by bond the sensor with chair of cripple system. The experimental standard deviation of the linearity with respect to the distance has been found 0.005%. The sensor is composed of only low cost components, thus being equipment in many cases, and is able to adapt to different conditions in order to give the best results.