A rigid and accurate piezo-stepper based on smooth learning hybrid force-position controlled clamping

Two new processes, ELID-grinding and high speed chipping, can combine high removal rates with high surface quality through a mechanism of sub-micron chip removal. For the successful application of these processes, ultra-precision positioning systems are needed. Classical solutions, based on traditional guideway technology, cannot meet the requirements of these new machining processes. The piezostepper solution presented in this paper can provide accurate motion, combined with high stiffness, through the use of piezoelectric actuators with high resolution. High passive stiffness is provided by integrating the driving, bearing and transmission functions. The same actuators can provide infinite active stiffness by referring the position of the positioning stage with respect to an absolute reference frame. In contrast with existing (position-controlled) piezo-steppers, this paper presents a way to provide smooth stepping by avoiding hammering through hybrid force-position controlled clamping and by rolling traction.