YAWING ANGLE MEASURING INSTRUMENT AND POSITION MEASURING INSTRUMENT FOR UNDERGROUND EXCAVATING MACHINE

摘要

PROBLEM TO BE SOLVED: To provide an optical yawing angle measuring instrument which can prevent the deterioration of its measurement accuracy caused by the fluctuation of the received light quantities of position detecting elements which respectively receive diffused light rays emitted from light sources. SOLUTION: An optical yawing angle measuring instrument is provided with a lens 411 which condenses diffused light rays emitted from light sources 41 and 42, in order to measure the yawing angle between two segments respectively connecting a base point to points which are set up on both sides of the base point at distances; position detecting elements 412-1 and 412-2 which respectively receive the diffused light rays emitted from the light sources 41 and 42 and detect the receiving positions of the light rays; and reflecting prisms 413-1 and 413-2 which respectively transmit the diffused light rays emitted from the light source 42 and 41 before the light rays are made incident to the lens 411, and lead the light rays condensed through the lens 411 to the elements 412-1 and 412-2, so that the instrument may measure the yawing angle by calculation from the detected results of the elements 412-1 and 412-2. The measuring instrument is also provided with a controller 43 which detects the receivable light quantities of the elements 412-1 and 412-2 and makes the light receiving positions of the element 412-1 and 412-2 to be detected appropriately, by adjusting the light receiving quantities of the elements 412-1 and 412-2 based on the detected results.