Decoupling control by the center of rotation and gravity hybrid-driven method for high-precision scan stage with multiple actuators

Abstract

In a multi-input multi-output control system, coupling force between multiple axes can deteriorate control performance and stability. In this paper, a decoupling method utilizing a high-precision stage with multiple actuators is proposed. According to a model considering the misalignment between the center of gravity (CoG), the center of rotation (CoR), the actuation point, and the measurement point, the coupling characteristics from the translational force to the angle can be changed by varying the height of the actuation point. The model indicates that a CoR-driven method can suppress the coupling in the low frequency range and a CoG-driven method can suppress the coupling in the high frequency range. This paper proposes a CoR and CoG hybrid-driven method using complementary filters to place the actuation point at the CoR and the CoG in low and high frequency ranges, respectively. The effectiveness of the proposed method is verified by experiments.