Design of Digital Tracking Controller based on Disturbance Observer for Micro Electrostatic Actuator with Nonlinearity

비 선형 요소를 갖는 정전 마이크로 구동기의 외란 관측기에 기초한 디지털 추종 제어기 설계

  • 최현택 (한양대 전자 및 컴퓨터 공학부) ;
  • 서일홍 (한양대 전자 및 컴퓨터 공학부)
  • Published : 1999.06.01

Abstract

A digital tracking controller is proposed for micro electrostatic actuator with input nonlinearity, where disturbance observer is utilized in cooperation with inverse function. Generally the disturbance observer is announced to be robust to modeling uncertainty, and external disturbance. But, when the nonlinearity exists in the systems, the disturbance observer may not directly be applied to that system, because the nonlinearity may destabilize the overall system. Therefore, first, we linearize the nonlinear input characteristics of micro electrostatic actuator by the use of inverse function. Secondly, we apply disturbance observer to approximately linearized system for eliminating the residuals of nonlinearity and the modeling uncertainty. Then, we get the good properties of the disturbance rejection as well as the robustness due to the own nature of disturbance observer. In this case, we propose a sufficient condition for the robust stability of overall systems. Furthermore, we discuss the problem that may be exposed when disturbance observer is applied to the internally stable system with saturation, and analyze two methods to overcome input saturation problem in the sense of internal stability. Simulations have been carried out to show the effectiveness of the proposed controller.

Keywords

References

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