A temperature Compensated Ultrasonic Sensor Operating in Air for Distance and Proximity Measurements

An ultrasonic sensor operating in air was developed to measure distance (up to 100 cm) or to operate as a proximity sensor in a presettable distance range. The error in the measured distance is about ± 1 mm while the accuracy is maintained within ±1% of the reading in the whole temperature range from -20 °C to +110 °C, being the temperature dependence of the sound velocity electronically compensated. As a proximity sensor it can overcome most of the drawbacks and limitations of inductive, capacitive, optical, and Hall-effect commercial proximity sensors.