• 전자공학회논문지SC
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• 제37권5호
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• pp.22-33
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• 2000

고감속비의 관절을 갖는 고하중 조작기를 원격조작 힘반영 제어시스템의 슬레이브 조작기로 사용할 경우에는 마스터 조작기에 비하여 느린 동특성으로 인해 슬레이브 조작기의 제어입력에 포화가 빈번히 발생한다. 슬레이브 조작기가 유연성을 갖도록 설계한 경우에도 제어입력이 포화되면 위치제어루프가 끊어지기 때문에 시스템이 불안정해지고 슬레이브 조작기가 물체에 강하게 접촉하는 경우가 발생하며, 유연한 힘제어 성능을 얻는데 어려움이 있다. 본 논문에서는 고하중 원격조작기에 대해 제어입력의 포화를 고려한 힘반영 유연성 제어기법을 제안한다. 제안하는 힘반영 유연성 제어기법은 제어입력의 포화를 가지는 원격조작기에 대하여 안정한 힘반영 성능과 함께 정밀한 위치제어와 유연성제어 성능을 얻을 수 있다는 장점이 있다. 제안한 제어기법의 안정도를 해석하였고 실험을 통하여 성능을 검증하였다.

• 한국멀티미디어학회논문지
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• 제9권11호
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• pp.1455-1464
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• 2006

본 논문에서는 컬러 이미지에 적합한 화질 향상 알고리듬을 제안 하였다. 제안된 알고리듬은 입력 이미지의 명도 향상을 위한 MIE기법과 채도 향상을 위한 MSE기법으로 구분된다. MIE기법은 휘도 신호 처리 시 발생하는 색 재현 문제 및 과도한 밝기 변화를 제어하기 위한 알고리듬이고, MSE기법은 색차 신호 처리 시 발생하는 De-Saturation 혹은 Over-Saturation의 발생을 제어하기 위한 알고리듬이다. 제안된 알고리듬은 인간의 시각선호색을 중심으로 연산하며, 전체 이미지에 균등하게 적용하는 것 보다 고품질의 이미지를 얻을 수 있다. 제안한 알고리듬은 고화질을 위한 모니터나 TV등의 디스플레이 장치에 적용 가능하다.

• 한국정밀공학회지
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• 제23권6호
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• pp.81-87
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• 2006

A new gain-scheduled control design is proposed to improve disturbance attenuation for systems with bounded control input. The state feedback controller is scheduled according to the proximity to the origin of the state of the plant. The controllers is derived in the framework of linear matrix inequality(LMI) optimization. This procedure yields a linear time varying control structure that allows higher gain and hence higher performance controllers as the state move closer to the origin. The main results give sufficient conditions for the satisfaction of a parameter-dependent performance measure, without violating the bounded control input condition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.305-306
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• 2006

• KIEE International Transaction on Systems and Control
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• 제2D권2호
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• pp.108-114
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• 2002

This paper describes the design of a robust adaptive controller for a nonlinear dynamical system with unknown nonlinearities. These unknown nonlinearities are approximated by multilayered neural networks (MNNs) whose parameters are adjusted on-line, according to some adaptive laws far controlling the output of the nonlinear system, to track a given trajectory. The main contribution of this paper is a method for considering input constraint with a rigorous stability proof. The Lyapunov synthesis approach is used to develop a state-feedback adaptive control algorithm based on the adaptive MNN model. An overall control system guarantees that the tracking error converges at about zero and that all signals involved are uniformly bounded even in the presence of input saturation. Theoretical results are illustrated through a simulation example.

• 제어로봇시스템학회논문지
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• 제5권2호
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• pp.166-173
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• 1999

Reference models are used in many control algorithms for improvement of transient response characteristics. They provide desired trajectories that the plant should follow Most control systems have bounded control inputs to avoid saturation of the plant. If we design the reference models that do not account for limits of the control inputs, control performance of the system may be deteriorated. In this paper a new approach of avoiding saturation by varying the reference model for TDC(time delay control) based systems subject to step changes in the reference input. In this scheme, the variable reference model is determined based on the information on control inputs and the size of the step changes in the reference inputs. This scheme was verified by application to the BLDC motor position control system in simulations and experiments. The responses of the TDC with the variable reference model showed better tracking performance than that with the fixed reference model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.325-328
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• 2002

In this paper, we proposed that the problem of controlling induction motor with magnetic saturation is studied from an input-output feedback linearization with adaptive algorithm. The $\pi$-model of induction motor is considered. An adaptive input-output feedback linearizing controller is considered under the assumption of known motor parameters and unknown load torque. Simulation results are provided for illustration.

• 한국정밀공학회지
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• 제24권12호
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• pp.65-73
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• 2007

In this paper, the gain scheduled state feedback and disturbance feedforward control design proposed in the previous paper has been applied to a simple matching system and a turret stabilization system. In such systems, it is needed to attenuate disturbance response effectively as long as control input satisfies the given constraint on its magnitude. The scheduled control gains are derived in the framework of linear matrix inequality(LMI) optimization by means of the MatLab toolbox. Its effectiveness is verified along with the simulation results compared with the conventional optimum constant gain control and the scheduled state feedback control cases.

• International Journal of Automotive Technology
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• 제5권2호
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• pp.89-94
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• 2004

In this paper, a safe control strategy is considered in the situation when a platoon of vehicles need to decelerate rapidly. When the vehicles ate spaced closely, it is known that the reference information should be transmitted to the whole platoon to minimize the undesirable effects of small leader disturbances. However, the vehicle control should also depend on the preceding vehicle position to maintain the desired distance. Tracking the preceding vehicle position can lead to amplification of the control input along the following vehicles, therefore the vehicles in the rearward generally exert larger maximum control input than the vehicles in the front. The theoretical bounds for the $i^{th}$ vehicle control input are calculated using a linear vehicle and controller model. In the simple illustrative example, the designed controller maintains string stability, and the control inputs of the following vehicles stay within bounds.

• 대한전기학회논문지:전력기술부문A
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• 제48권6호
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• pp.773-780
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• 1999

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.