Abstract
An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a receiver and several transmitters. The transmitters are immobilized at a fixed point, whereas the receiver set-up is separately arranged on the opposite side. In order to improve measurement accuracy, a correction method that utilizes polynomial approximation is introduced. A good responsiveness is demonstrated by conducting a dynamic response experiment. When five transmitters are arranged, their measurement range is easily extended up to ±60 mm with an accuracy of 0.7 mm. The fluctuations to the measurement ranges show less than 1%. These results indicate that the developed sensor system is useful for measuring relative lateral displacement of a seismically isolated building in the field of structural health monitoring.
