Improvement of Self-shape Measurement Accuracy in a Self-sensing Flexible Array Probe

Abstract

Nowadays, flexible array probes are actively studied for ultrasonic non-destructive inspection of various shapes. However, in order to perform imaging with ultrasound, it is necessary to know the shape of the probe at the time of imaging. Conventionally, a method such as attaching a surface shape measurement device to a flexible array probe has been used, but there are problems such as the cost and labor involved in using a separate device. Therefore, in this research, we developed a self-sensing flexible array probe that can measure its own shape using the piezoelectric effect of the array sensor. The principle of self-sensing is the piezoelectric effect of the ultrasonic element, and the voltage output when the element is deformed is measured by time integration. In addition, we devised a shape estimation method at an inflection point where the curvature changes in shape measurement, and tried to improve the shape measurement accuracy. As a result, the positional coordinates of the element could be estimated with an error of 0.5 mm from the true value, and the response speed was about 200 ms or less.