Noise-tolerant ultrasonic distance sensor based on a multiple driving approach

Ultrasonic sensors are a cost-effective solution to the problem of distance measurement when contactless operation is required. They are robust, intrinsically safe, and capable of noticeable accuracy when used in quiet environments, but suffer from acoustic noise that can greatly reduce their performance. In this paper an ultrasonic distance sensor that is able to provide good performance in different conditions is presented. The good performance is obtained by automatically changing the signal that drives the transmitter according to the environmental noise level. Such an approach allows accuracies of up to 1 mm to be obtained in distance measurements up to a few meters, even in the presence of acoustic noise levels which would otherwise impair the sensor performance. The proposed sensor is cheap and easy to be implemented, therefore enabling the design of low-cost, high-performance devices