Relative Displacement Generated in Three-Dimensional Coordinate Measuring Machine (1st Report)

Abstract

Takashi YAMAGIWA and Masatake SHIRAISHI This paper deals with a control structure and a method for reducing relative displacement in a three-dimensional coordinate measuring machine. In general, this system consists of a numerical controller, a servo motor, an elastic feed mechanism and a scanning mechanism. In a scanning mechanism, a tip position attached to the tool or the probe and the controlled position are usually arranged at the other positions each other, so that the relative displacement between both positions causes measuring errors. We clarify the control structure that can provide a relative displacement based on a three-inertia system and then propose a control method for reducing relative displacement. In the proposed method, current, velocity and position control loops with a damping compensator are applied to the control object modeled by the three-inertia system. The result of the control structure analysis is validated by simulation and experiments.