Force Control of Linear Motor Stages for Microassembly

Dynamic Systems and Control, Volumes 1 and 2 ◽

10.1115/imece2003-42079 ◽

2003 ◽

Cited By ~ 8

Author(s):

Jason J. Gorman ◽

Nicholas G. Dagalakis

Keyword(s):

Force Control ◽

Microelectromechanical Systems ◽

Linear Motor ◽

Dynamic Friction ◽

Nonlinear Friction ◽

Ripple Effects ◽

Micro Scale ◽

Working Volume ◽

Nonlinear Force ◽

Force Ripple

The microassembly of microelectromechanical systems from various micro-components requires the development of many new robotic capabilities. One of these capabilities is force control for handling micro-scale components with force control resolution on the order of micronewtons. In this paper, the force control of linear motor stages is discussed with application to the microassembly of MEMS. Linear motor stages provide an attractive solution for microassembly robots because they have a large working volume and can achieve high-precision positioning. However, the nonlinear friction and force ripple effects inherent in linear stages provide an obstacle to the required level of force control. A model of a single motor stage has been developed including dynamic friction effects. Based on this model, a robust nonlinear force controller has been designed to meet the microassembly requirements. The controller has been tested in simulation to demonstrate its effectiveness.

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On-Line Force Ripple Identification and Compensation in Precision Positioning of Wafer Stages

Volume 9: Mechanical Systems and Control, Parts A, B, and C ◽

10.1115/imece2007-42563 ◽

2007 ◽

Cited By ~ 1

Author(s):

Shu-Wen Yu ◽

Sandipan Mishra ◽

Masayoshi Tomizuka

Keyword(s):

Adaptive Estimation ◽

Tracking Error ◽

Linear Motor ◽

Feedback Controller ◽

Precision Positioning ◽

Positioning Systems ◽

Line Force ◽

Nonlinear Force ◽

On Line ◽

Force Ripple

This paper presents the design and implementation of a composite controller to reduce the effect of force ripple in a linear motor wafer stage system. The composite controller consists of two components: 1) a PID feedback controller and 2) an adaptive feedforward compensator. The feedback controller is tuned to achieve good transient response and enhanced robustness of the system. Force ripples are a major source of tracking error in linear motor precision positioning systems. An approximation of the nonlinear force ripple model can be obtained by expressing the ripple as the sum of a sequence of sinusoidal harmonics, multiplied by the motor current. The force ripple is first approximated by on-line adaptive estimation of the unknown coefficients associated with each harmonic, and then compensated with a feedforward term. Experimental results on a prototype single degree of freedom wafer stage are presented to show the performance improvement obtained by the proposed control scheme.

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Research on Dynamic Friction Compensation of High-Speed Precision Slider

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.2742 ◽

2011 ◽

Vol 130-134 ◽

pp. 2742-2745

Author(s):

Sun Hua ◽

Yue Hong Dai ◽

Chuan Sheng Tang

Keyword(s):

Mathematical Model ◽

High Speed ◽

Linear Motor ◽

Experimental Results ◽

Friction Compensation ◽

Dynamic Friction ◽

Nonlinear Friction ◽

Feed Forward ◽

Liapunov Functions

. The tracing precision is greatly influenced because of the friction when high-precise linear motor moved in a low speed.Explore the ways of nonlinear friction compensation in a practical angle. A tribology mathematical model has been found based on the viscoplasticity theory and Stribeck friction mathematical model.This paper aims at applying the Stribeck friction mathematical model to linear motor slider system and designing the controller.The controller can be designed by the feed-forward Integral to conduct identification and compensation online, according to the characters of tribology model.the stability of systems has also been analyzed by using Liapunov functions and LaSalle Invariance Principle.As has been demonstrated by the experimental results, the friction compensation of this model has improved the tracing performance of linear motor slider system.

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