Patent ID: 6480289
Filing Date: 2002-11-12
Classification: E21D,G01B,G01C

Abstract:
A position measuring apparatus for an underground excavator, said apparatus being useful in measuring a position of excavation by said underground excavator advancing in the ground while excavating a tunnel and being adapted to measure a position of a measured point, which is arranged at a front in an excavating direction and serves as an indication for said position of excavation, on a basis of its positional relationship with a measuring cardinal point arranged at a rear in said excavating direction and serving as a cardinal point for said measurement, comprising:a cardinal-point measuring unit for setting said measuring cardinal point, said cardinal-point measuring unit having a light source capable of emitting a light forward, converging means capable of converging a diffuse light from a forward light source, and light-receiving means arranged such that said light-receiving means can receive a light converged by said converging means and can detect a direction of said forward light source on a basis of a position of said light so received, said position being located in a two-dimensional plane; a measured-point measuring unit for setting said measured point, said measured-point measuring unit being arranged on said underground excavator and having a light source capable of emitting a diffuse light rearward, converging means capable of converging a diffuse light from a rear light source, and light-receiving means arranged such that said light-receiving means can receive a light converged by said converging means and can detect a direction of said rear light source on a basis of a position of said light so received, said position being located in a two-dimensional plane; at least one intermediate measuring unit arranged between said cardinal-point measuring unit and said measured-point measuring unit in said tunnel and having a light source capable of emitting diffuse lights forward and rearward, converging means capable of converging diffuse lights from forward and rearward light sources, respectively, and light-receiving means arranged such that said light-receiving means can receive respective lights converged by said converging means and can detect directions of said forward and rearward light sources on a basis of said positions of said respective lights so received, said positions being located in their corresponding two-dimensional plane; and computing means for computing and measuring a position of said measured point relative to said measuring cardinal point on a basis of data, which are concerned with said two-dimensional directions of said respective light sources as determined based on detection results at said respective measuring units consisting of said cardinal-point measuring unit, said measured-point measuring unit and said intermediate measuring unit, and data on distances between said individual measuring units and their adjacent measuring units.