空間姿勢計測用超音波近接センサ

二重位相差による測定範囲の改善

抄録

This paper deals with the method for measuring the 3D orientation of an objective surface using the ultrasonic proximity sensor.
Two orientation angles of a surface normal can be measured by two phase differences of three received echoes. The method using the phase difference has many advantages as stability, high resolution and so on. However, the phase information cannot be distinguished over one period of reflected echoes. Then, the measuring range is restricted in a relatively small orientation.
The paper discusses a method to correct the phase difference over one period of received echoes by referring the dual phase difference of two different frequencies. The correction algorithm is based on relations between the individual phase difference and the dual phase difference. The proper threshold levels among the relations can separate regions of the phase difference regardless of considerable errors of the dual phase difference. This correction method enable the 3D orientation measurement over a wide range without decreasing the accuracy.
The experiment using the transducers having 23kHz center frequency shows that the sensing system can measure the 3D orientation over an angle of 30° or more.