抄録
Curved micro-tunneling using small conduit pipes with diameters of 1m or less is recently applied in many construction sites. A new position sensing system to pinpoint the head of the first pipe has been come up with 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 the diode laser with a large divergence is used as a point source of light and 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 polarized beam splitter can suppress error led by rotating the sensing unit. (2) Through the simulation and some field tests, 20 seconds or less detection accuracy of direction angle was achieved.
