Abstract: In a linear movement/rotation mechanism, inside a tube-like housing, a ball screw/ball spline mechanism and a hollow planetary reduction gear are coaxially disposed, a drive shaft extends therethrough, and a ball screw nut, a ball spline nut, a hollow planetary reduction gear, and a driven pulley are disposed in that order along a center axis of the drive shaft. A rotational force inputted to the driven pulley is inputted to a hollow rotational shaft of the hollow planetary reduction gear, and a reduced rotation output is outputted from a rear stage internal gear. The reduced rotation output is transmitted to the ball spline nut that is connected and fixed to the rear stage internal gear. When the rotation of the ball screw nut is restricted, a feeding operation of the drive shaft is realized.

Abstract: The present invention relates to a positioning device capable of positioning a member in any direction with a high degree of resolution by using a hollow type harmonic drive mechanism, and to a drilling-direction control device for a drilling system utilizing the positioning device. The device of the present invention is mainly constituted by a double eccentric mechanism section (10). A first annular member (12) is rotatably supported by a circular inner circumferential surface (11a) of the cylindrical member (11) of this mechanism section, and a second annular member (13) is rotatably supported by a circular inner circumferential surface (11b) of the first annular member.