Analysis and improvement of positioning accuracy in ball screw-driven table system with variations of mechanical parameters

Abstract

The paper presents analysis and improvement of the control accuracy for a positioning device with a ball screwdriven table system. In the analytical studies, effects of variations of mechanical parameters on the positioning accuracy are examined, where a precise simulator with static and dynamic friction models are provided to simulate actual responses in the positioning. The analyses clarify that the mechanical variations behave as equivalent disturbances with components in low frequency range and deteriorate the positioning accuracy. A robust disturbance observer, therefore, is designed in the frame work of 2-degrees-of-freedom positioning controller, in order to improve the disturbance suppression characteristics. The effectiveness of the proposed design has been verified by experiments with a ball screw-driven table system on machine stand. © 2008 The Institute of Electrical Engineers of Japan.