POSITION MEASUREMENT METHOD OF SMALL-DIAMETER PROPULSION TECHNIQUE CAPABLE OF SHARP CURVE CONSTRUCTION, AND DEVICE THEREFOR

PROBLEM TO BE SOLVED: To provide a position measurement method of a sharp curve propulsion technique for a small internal diameter of, for example, 150 mm, which easily detects respective positions of a pilot body, a propulsion tube behind it, etc., and takes measurements with high precision.SOLUTION: In a small-diameter propulsion technique that connects a plurality of propulsion tubes behind a pilot body in order through joints 4 and drives the pilot body and the plurality of propulsion tubes forward into the ground, each of the joints 4 has one joint member 4a and another joint member 4b connected rotatably in a horizontal direction with a perpendicular pin 7, a rotation of the perpendicular pin 7 united with the one joint member 4a relative to the other joint member 4b is detected by a rotary encoder 15 provided at the other joint member 4b through rotation amplification. Horizontal rotational angles of the plurality of joints 4 are detected, and those rotational angles and distances between successive joints are totalled and computed, thereby measuring positions of the respective propulsion tubes from a base point to the pilot body.