• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1036-1055
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• 1992

In this paper the feedback linearization of the valve-controlled nonlinear hydraulic velocity control system and the implementation of the digital state feedback controller is studied. The $C^{\infty}$ nonlinear transfomation to the electro-hydraulic velocity control system, which transforms nonlinear system to linear equivalent one, is obtained. It is shown that this transformation is global one. The digital controller to this linearized model is obtained by using the one-step ahead state estimator and implemented to real plant. The proposed implementation method is easier than the other proposed methods and it is possible to control in real time. The experiment and simulation study show that the implementation of the digital state feedback controller based on the feedback linearized model is successful..

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.228-235
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• 2010

This paper deals with an autonomous flight controller design problem for a tilt-rotor aircraft in rotary-wing mode. The inner-loop algorithm is designed using the output-based approximate feedback linearization. The model error originated from the feedback linearization is cancelled within allowable tolerance by using single-hidden-layer neural network. According to Lyapunov direct stability theory, the adaptive update law is derived to run the neural network on-line, which is based on the linear observer dynamics. Moreover, the outer-loop algorithm is designed to track the trajectory generated from way-point guidance. Especially, heading and flight-path angle line-of-sight guidance are applied to the outer-loop to improve accuracy of the landing tracking performance. The 6-DOF nonlinear simulation shows that the overall performance of the flight control algorithm is satisfactory even though the collective input response shows instantaneous actuator saturation for a short time due to the lack of the neural network and the saturation protection logic in that loop.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.342-349
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• 1991

In this paper, a method is presented for designing a tracking and disturbance rejecting controller for a nonlinear control system in which approximate linearization is not applicable due to a s stiff nonlinearity. Only the measurable variables are used for the controller synthesis. The system is augmented by a compensator at the output side for the tracking and disturbance rejection. An output delayed feedback controller is designed for the augmented system without nonlinearity. Then the feedback parameters are adjusted by describing function method to overcome the limit cycle due to the nonlinearity.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.5
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• pp.56-64
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• 1994

본 논문은 직류초퍼구동 전동기 제어시스템을 해석 대상으로 하여 전류 연속모드와 전류 불연속모드의 양 모드 동작시에 있어서의 해석을 상태변수법과 상태평균화법을 적용하여 해석하였으며 두 해석 방법의 결과를 비교 검토함과 동시에 상태평균화법에 의하여 시스템의 해석이 근사적이지만 해석이 용이하다는 것을 나타내고 있다. 또한, 본 시스템의 궤환루프 제어시스템에 있어서 상태평균화법을 이용한 평형점 근방의 근사 선형화 방법을 적용함으로써 전달 매트릭스의 형태로 동특성을 표현할 수 있으며, 이것을 이용한 선형 제어법을 적용하여 궤환루프 제어계의 설계기법을 제시하고 있다.