We have developed a spatial dimension measurement device (orientator) using airborne ultrasonic waves. We achieved spatial measurement by using 3 ultrasonic transducers and 3 ultrasonic microphones. The measurement principle is based on 3 sets of 3-side measurements. We acquire plane equations of microphones and transducers, and calculate the orientation angle and direction based on the surface normal vector. Using 40kHz ultrasonic wave, by transmitting through a plate with a 1mm diameter hole on the transmitting side and a plate with a 0.5mm diameter hole on the receiving side, it is possible to transmit it hemispherically and to receive it from any direction on the hemisphere. It is expected that this device can instantly measure the positional relationship of pipes, etc. at plant construction work with displaying the 3D data on PC. Test results show that the measurable distance range is about 1000 mm, the accuracy is about ±1 mm. Furthermore, the 3D image is updated at approximately 13 frames per second (FPS). In the era of CPS (Cyber-Physical System), with cheaper and easier spatial dimension measurement devices and motion capture, it is expected that they will become more widespread in many fields, including plant construction and maintenance.
Inada et al. (Wed,) studied this question.