An apparatus and method is disclosed for ultra-precision positioning. A slide base provides a foundational support. A slide plate moves with respect to the slide base along a first geometric axis. Either a ball-screw or a piezoelectric actuator working separate or in conjunction displaces the slide plate with respect to the slide base along the first geometric axis. A linking device directs a primary force vector into a center-line of the ball-screw. The linking device consists of a first link which directs a first portion of the primary force vector to an apex point, located along the center-line of the ball-screw, and a second link for directing a second portion of the primary force vector to the apex point. A set of rails, oriented substantially parallel to the center-line of the ball-screw, direct movement of the slide plate with respect to the slide base along the first geometric axis and are positioned such that the apex point falls within a geometric plane formed by the rails. The slide base, the slide plate, the ball-screw, and the linking device together form a slide assembly. Multiple slide assemblies can be distributed about a platform. In such a configuration, the platform may be raised and lowered, or tipped and tilted by jointly or independently displacing the slide plates.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of application Ser. No. 09/289,761 filed on Apr. 12, 1999, now U.S. Pat. No. 6,408,526, entitled "Ultra-Precision Positioning Assembly".
A microscopic positioning device having machine rigidity and being capable of achieving nano-order positioning accuracy and a method of compensating tool position and orientation. A driving unit comprises two piezoelectric elements P1 and P2 arranged into alignment along an expanding/shrinking direction. Both ends of the piezoelectric element P1, facing in the expanding/shrinking direction, are fixed to a base member and a movable member, respectively. The other piezoelectric element P2 is fixed to the base member only at one end. A gap L is formed between the piezoelectric element P2 and the movable member. Where expanding displacement amounts of the piezoelectric elements P1 and P2 are a1 and a2, respectively, voltage applied to the piezoelectric elements P1 and P2 is so controlled to satisfy an equation, a1+a2=a.gtoreq.L. It is possible to position the movable member at a position within a maximum stroke a in the nano-order. The driving units may be arranged in the orthogonal directions, thereby providing the positioning device with two degrees of freedom, and further providing six degrees of freedom including rotation axes.
A positioning apparatus has a stage, guide elements provided on both ends of the stage, and drive elements which are provided at one of both ends of the stage and move the stage along the guide elements. Like linear guide rails 61A, 61B and linear guide bearings 23A, 23B, two guide elements are provided in an area where a ball screw shaft 52 serving as a drive element is placed. One guide element is provided in an area where a non-drive element is provided.
