Position sensing system using laser for curved tunneling

摘要

Curved micro-tunneling using small conduit pipes with diameters of lm or less is recently applied in many construction sites. We have come up with a new position sensing system to pinpoint the head of the first pipe even when it cannot be seen directly from the base position. It differs from the traditional method of using the collimated laser beam, in that a diode laser with a large divergence is used as the point source of light. The direction of the point source of light is detected by using an objective lens and CCD camera. To apply this method to the position detection of the first pipe, the structure of the sensing unit and its detection accuracy were examined and the following results were obtained. (1) The structure using a polarized beam splitter can suppress error led by rotating the sensing unit. (2) Through simulation and some field tests, 20 seconds or less detection accuracy of direction angle was achieved.