• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.128-131
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• 2005

In this paper a robust controller using adaptive backstepping technique is proposed to control the speed of a wind turbine system. To make wind power generation truly cost effective and reliable, advanced and robust control algorithms are derived to on-line adjust the excitation winding voltage of the generator based on both mechanical and electrical dynamics. This method is shown to be able to achieve smooth and asymptotic rotor position tracking, as justified by analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1227-1229
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• 2007

In this paper a robust controller using adaptive backstepping technique is proposed to control the position of wind power generation system. To make wind power generation truly cost effective and reliable, advanced and robust control algorithms are derived to on-line adjust the excitation winding voltage of the generator based on both mechanical and electrical dynamics. This method is shown to be able to achieve smooth and asymptotic rotor speed tracking, as justified by analysis and computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.48.1-48
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• 2001

In this paper, we present a global adaptive output feedback control scheme for a class of uncertain nonlinear systems to which adaptive observer backstepping method may not be applicable directly. The allowed output feedback structure includes quadratic and multiplicative dependency of unmeasured states. Our novel design technique employs a change of coordinates and adaptive backstepping. With these proposed tools, we can remove linear and quadratic dependence on the unmeasured states in the state equation. Also, the multiplication of the two unmeasured states can be eliminated ...

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.405-413
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• 2006

본 논문에서는 비선형 동적 마찰 성분을 효과적으로 보상하고 적응적으로 제어함으로써 차세대 항만 자동화 이송시스템으로 주목받고 있는 LMTT(linear motor-based transfer technology)의 위치 정밀도를 향상시키는 것을 목적으로 하고 있다. 셔틀카(shuttle car)와 컨테이너들의 다양한 중량과, 이로 인해 발생하는 동적 마찰 특성 파라미터들을 정확하게 추정할 수 있는 관측기를 설계하였다. 적응 backstepping 제어 기법을 적용하여 시스템이 안정하게 제어될 수 있도록 하는 제어기를 설계하였다. 시스템은 변화하는 환경에 대하여 높은 적응성을 가질 수 있어 여러 종류의 부하는 물론 마찰 특성의 변화에도 양호한 제어 특성을 유지할 수 있었다. 제안한 제어시스템의 타당성을 보여주기 위해 축소된 형태의 LMTT 시뮬레이터를 제작하여, 이에 대해 시뮬레이션과 실험만을 수행하여 제안하는 방법의 타당성과 실현성을 입증하고자 하였다.

• 한국항해항만학회지
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• 제31권1호
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• pp.55-64
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• 2007

일반적으로 서보 제어 시스템에서 비선형 동적 특성을 갖는 마찰력은 제어기 성능에 악영향을 미친다. 특히, 선형으로 고려된 시스템에 제어기 이득을 잘 설계한다 하더라도 마찰 현상에 포함된 동적으로 변화하는 dead zone에 의한 정상상태 오차 및 리미트 사이클(limit Cycle) 등을 야기한다. 따라서, 본 논문에서는 비선형 동적 마찰 성분을 효과적으로 보상하고 적응적으로 제어함으로써 차세대 항만 자동화 이송시스템으로 주목받고 있는 LMTT(linear motor-based transfer technology) 시스템의 위치 정밀도를 향상시키는 것을 목적으로 하고 있다. 본 제어대상은 셔틀카(shuttle car)와 컨테이너들의 다양한 중량과, 이로 인해 발생하는 동적 마찰 특성 파라미터들의 변화가 발생하므로 마찰력 내부 파라미터들의 추정이 요구된다. 제안하는 방법은 적응 backstepping 제어 기법으로 시스템이 안정하게 제어될 수 있는 조건으로 내부 파라미터 추정기를 설계하여 비선형 동적 마찰력을 보상하도록 하였다.

• 제어로봇시스템학회논문지
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• 제9권4호
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• pp.329-339
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• 2003

A neural network based adaptive controller design method is proposed for reconfigurable flight control systems in the presence of variations in aerodynamic coefficients or control effectiveness decrease caused by control surface damage. The neural network based adaptive nonlinear controller is developed by making use of the backstepping technique for command following of the angle of attack, sideslip angle, and bank angle. On-line teaming neural networks are implemented to guarantee reconfigurability and robustness to the uncertainties caused by aerodynamic coefficients variations. The main feature of the proposed controller is that the adaptive controller is designed with assumption that not any of the nonlinear functions of the system is known accurately, whereas most of the previous works assume that only some of the nonlinear functions are unknown. Neural networks loam through the weight update rules that are derived from the Lyapunov control theory. The closed-loop stability of the error states is also investigated according to the Lyapunov theory. A nonlinear dynamic model of an F-16 aircraft is used to demonstrate the effectiveness of the proposed control law.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.278-294
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• 2015

Considering the guidance and control problem of the near space interceptor (NSI) during the terminal course, this paper proposes a three-channel independent integrated guidance and control (IGC) scheme based on the backstepping sliding mode and finite time disturbance observer (FTDO). Initially, the three-channel independent IGC model is constructed based on the interceptor-target relative motion and nonlinear dynamic model of the interceptor, in which the channel coupling term and external disturbance are regarded as the total disturbances of the corresponding channel. Then, the FTDO is introduced to estimate the target acceleration and control system loop disturbances, and the feed-forward compensation term based on the estimated values is employed to effectively remove the effect of disturbances in finite time. Subsequently, the IGC algorithm based on the backstepping sliding mode is also given to obtain the virtual control moment. Furthermore, a robust least-squares weighted control allocation (RLSWCA) algorithm is employed to distribute the previous virtual control moment among the corresponding aerodynamic fins and reaction jets, which also takes into account the uncertainty in the control effectiveness matrix. Finally, simulation results show that the proposed IGC method can obtain the small miss distance and smooth interceptor trajectories.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.15-23
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• 2007

In surveillance, monitoring, and target tracking operations, high-resolution images should be obtained even if the target is in a far distance. Frequent movements of vehicles such as boats degrade the image quality of onboard camera systems. Therefore, stabilizer mechanisms are required to stabilize the line of sight of boatboard camera systems against boat movements. This paper addresses design and implementation of a strapdown boatboard camera stabilizer. A two degree of freedom(DOF)(pan/tilt) robot performs the stabilization task. The main problem is divided into two subproblems dealing with attitude estimation and attitude control. It is assumed that exact estimate of the boat movement is available from an attitude estimation system. Estimates obtained in this way are carefully transformed to robot coordinate frame to provide desired trajectories, which should be tracked by the robot to compensate for the boat movements. Such a practical robotic system includes actuators with fast dynamics(electrical dynamics) and has more degrees of freedom than control inputs. Backstepping method is employed to deal with this problem by extending the control effectiveness.

• International Journal of Control, Automation, and Systems
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• 제6권3호
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• pp.364-377
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• 2008

Due to the difficulty in solving the Hamilton-Jacobi-Isaacs equation, the nonlinear optimal control approach is not very practical in general. To overcome this problem, Ezal et al. (2000) first solved a linear optimal control problem for the linearized model of a nonlinear system given in the strict-feedback form. Then, using the backstepping procedure, a nonlinear feedback controller was designed where the linear part is same as the linear feedback obtained from the linear optimal control design. However, their construction is based on the cancellation of the high order nonlinearity, which limits the application to the smooth ($C^{\infty}$) vector fields. In this paper, we develop an alternative method for backstepping procedure, so that the vector field can be just $C^1$, which allows this approach to be applicable to much larger class of nonlinear systems.

• 전자공학회논문지SC
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• 제46권2호
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• pp.7-14
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• 2009

본 논문에서는 불확실성을 가지는 비선형 시스템에 대한 강인 유한 시간 안정화 문제를 고려한다. 불확실성은 시변 외란 혹은 이미 알고 있는 옹골 집합에 포함된 파라미터들이다. 제안된 설계기법은 역진기법(backstepping)과 추가된 다이나믹스를 이용한 다이나믹 지수 보정법(dynamic exponent scaling)에 기반을 두고 있으며, 이로부터 다이나믹 스무스 궤환 제어기(dynamic smooth feedback controller)가 유도된다. 페루프 시스템의 유한 시간 안정과 제어기의 유한함은 각각 유한 시간 안정에 관한 리아푸노프 안정 이론과 새로운 개념인 '차수 지표자(degree indicator)'를 이용하여 증명된다.