• Journal of Institute of Control, Robotics and Systems
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• v.15 no.1
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• pp.37-43
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• 2009

This paper deals with designing a ground-based longitudinal landing controller which is robust to datalink time delays. Time delays occur because forward velocity measurements are downlinked and the controller output commands are uplinked. An $H_{\infty}$ controller was designed by using the input/output decomposition where time delay is modeled as a first-order system with Pade approximation. Linear simulations show that the system tracks well the predefined path and is robust to the variation of time delay.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.861-867
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• 2006

This paper presents the robust mobile robot localization method exploiting redundant motion information acquired from three optical mice that are installed at the bottom of a mobile robot in a regular triangular form. First, we briefly introduce a low-cost optical motion sensor, HDNS-2000, and a commercial device driver development tools, WinDriver, to be used in this research. Second, we explain the basic principle of the mobile robot localization using the motion information from three optical mice, and propose the least squares based localization algorithm which is robust to the noisy measurement and partial malfunctioning of optical mice. Third, we describe the development of the experimental optical odometer using three PC optical mice and the user-friendly graphic monitoring program. Fourth, simulations and experiments are performed to demonstrate the validity of the proposed localization method and the operation of the developed optical odometer. Finally, along with the conclusion, we suggest some future work including the installation parameter calibration, the optical mouse remodelling, and the high-performance motion sensor adoption.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.30-33
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• 1991

The natural frequency of an one-link flexible robot manipulator may be varied due to many kinds of causes and this natural frequency is regarded as the uncertain element. Utilizing measured state the robust controller is designed for bounding every system response within a certain neighborhood of the zero state.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.32-36
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• 1988

Generally, for nonlinear control of robotic system, the method of computed torque or inverse dynamics is frequently used. In this case, exact knowledge of the system parameters is required, however. This paper addresses the problem of nonlinear control when the parameter of system is varied. The approach is based upon decoupled model following. As an example, control of a three degree of freedom manipulator arm under mass variation is simulated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.177-178
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• 2012

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.448-454
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• 2008

This paper deals with a behavior based decentralized control strategy for UAV swarming utilizing the artificial potential functions and the sliding mode control technique. Individual interactions for swarming behavior are modeled using the artificial potential functions. The motion of individual UAV is directed toward the negative gradient of the combined potential. For tracking the reference trajectory of UAV swarming, a swarming center is considered as the object of control. The sliding-mode control technique is adopted to make the proposed swarm control strategy robust with respect to the system uncertainties and the varying mission environment. Numerical simulation is performed to verify the performance of the proposed controller.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.1999-2001
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• 2003

본 논문에서는 시간지연 관측기를 위치제어 시스템 적용하여 설계한 내용을 기술하였다. 시간지연제어기의 상태추정 기법을 이용한 시간지연 관측기는 플랜트 모델이 필요하지 않아 설계가 용이하고, 파라미터 변동 및 외란에 강건하다. 또한 계산이 간단하여 디지털 제어 시스템에 충분히 적용이 가능하다. 본 논문에서는 시간지연제어기가 위치제어기로 적용된 전기식 구동시스템에서 속도센서를 사용하지 않고 시간지연 관측기를 적용하여 제어기를 설계하였다. 시간지연 관측기를 적용한 구동시스템에 대해 비선형 시뮬레이션을 수행하였으며. 속도센서를 사용한 경우와 상태관측기를 적용한 경우 및 PID 제어기를 적용한 경우에 대해 비교하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1371-1381
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• 1995

A novel hybrid control scheme to actively control the endpoint position of a very flexible single-link manipulator is proposed. The control scheme consists of a motor mounted at the beam hub and a piezofilm actuator bonded to the surface of the flexible link. The control torque of the motor to produce a desired motion is firstly determined by employing the sliding mode control theory on the equation of motion of the rigid link having the same mass as that of the proposed flexible link. The torque is then applied to the flexible manipulator in order to activate the commanded motion. During the motion, undesirable oscillation is actively suppressed by applying a feedback control voltage to the piezofilm actuator. Consequently, the imposed desired position is accomplished. In order to demonstrate high control performances accrued from the proposed method, computer simulations are undertaken by treating both regulating and tracking control problems.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.40-46
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• 2004

Magnetic bearing has been adopted to support a rotor by electromagnetic force without mechanical contact and lubrication process. The recent growth of magnetic bearing applications in many industrial fields requires more accurate design of bearing-rotor system. Due to external forces and uncertainties of magnetic bearing system the actual performance and stability my be worse than it is designed. This paper describes the governing equations of rotor magnetic bearing systems and/or the designing of robust controller via standard $H_{\infty}$ control problem. The system stability and response characteristics are studied by simulations and verified with experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.612-618
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• 2004

This paper presents a robust vibration control methodology for smart structural systems. The governing equation and associated boundary conditions of the smart structural system are derived by using Hamilton's principle. The assumed mode method is used to discretize the governing equation into a set of ordinary differential equation. A robust controller is designed using a linear matrix inequality (LMI) approach for the multiobjective synthesis. The design objectives are to achieve a mix of H$_{\infty}$ performance and H$_2$ performance satisfying constraints on the closed-loop pole locations in the presence of model uncertainties. Numerical examples are presented to demonstrate the effectiveness of LMI approach in damping out the multiple vibration modes of the piezo/beam system.