• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2046-2048
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• 2003

In this paper, a neural disturbance observer(NDO) is developed and its application to the control of a nonlinear system with the internal and/or external disturbances is presented. To construct the NDO, a parameter tuning method is proposed and shown to be useful in adjusting the parameters of the NDO. The tuning method employes the disturbance observation error to guarantee that the NDO monitors unknown disturbances. Each of the nodes of the hidden layer in the NDO network is a radial basis function(RBF). In addition, the relationships between the suggested NDO-based control and the conventional adaptive controls reported in the previous literatures are discussed. And it is shown in a rigorous manner that the disturbance observation error converges to a region of which size can be kept arbitrarily small. Finally, an example and some computer simulation results are presented to illustrate the effectiveness and the applicability of the NDO.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1740-1751
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• 2018

This paper proposes a novel fault tolerant tracking control (FTTC) scheme for a class of nonlinear systems with actuator failures based on the policy iteration (PI) algorithm and the adaptive fault observer. The estimated actuator failure from an adaptive fault observer is utilized to construct an improved performance index function that reflects the failure, regulation and control simultaneously. With the help of the proper performance index function, the FTTC problem can be transformed into an optimal control problem. The fault tolerant tracking controller is composed of the desired controller and the approximated optimal feedback one. The desired controller is developed to maintain the desired tracking performance at the steady-state, and the approximated optimal feedback controller is designed to stabilize the tracking error dynamics in an optimal manner. By establishing a critic neural network, the PI algorithm is utilized to solve the Hamilton-Jacobi-Bellman equation, and then the approximated optimal feedback controller can be derived. Based on Lyapunov technique, the uniform ultimate boundedness of the closed-loop system is proven. The proposed FTTC scheme is applied to reconfigurable manipulators with two degree of freedoms in order to test the effectiveness via numerical simulation.

• 한국지능시스템학회논문지
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• 제17권5호
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• pp.582-590
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• 2007

천정주행 크레인의 고속 권상작업 및 흔들림 억제 궤적추종을 위한 비선형 적응제어 방법을 제시한다. 천정주행 크레인의 흔들림 운동은 트롤리의 가속도. 권상로프의 길이 및 권상속도와 강하게 결합되어 있다. 이는 비간섭 제어 기반의 흔들림 억제 궤적추종 제어법칙을 설계하는데 있어 장애요인으로 작용한다. 이러한 문제를 해결하기 위해, 트롤리의 가속도와 권상속도의 영향을 최소화하는 방법으로 불확실성이 존재하는 경우에도 흔들림 운동의 궁극적 균일 유계성을 보장하는 퍼지 비선형 적응형 흔들림 억제 궤적추종제어법칙을 제안한다. 특히, 제안한 방법은 파라미터 변화. 외란 등을 포함한 시스템 불확실성을 퍼지 불확실성 관측기를 이용하여 보상한다. 따라서, 퍼지관측기의 근사화 오차가 영으로 수렴할 때 추종오차 및 흔들림 각도의 궁극적 한계치는 영으로 감소한다. 끝으로 제안한 방법의 성능검증을 위한 모의실험 견과를 제시한다.

• International Journal of Aeronautical and Space Sciences
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• 제12권2호
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• pp.179-189
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• 2011

In this paper, robust adaptive control design problem is addressed for a class of parametrically uncertain aeroelastic systems. A full-state robust adaptive controller was designed to suppress aeroelastic vibrations of a nonlinear wing section. The design used leading and trailing edge control actuations. The full state feedback (FSFB) control yielded a global uniformly ultimately bounded result for two-axis vibration suppression. The pitching and plunging displacements were measurable; however, the pitching and plunging rates were not measurable. Thus, a high gain observer was used to modify the FSFB control design to become an output feedback (OFB) design while the stability analysis for the OFB control law was presented. Simulation results demonstrate the efficacy of the multi-input multi-output control toward suppressing aeroelastic vibrations and limit cycle oscillations occurring in pre- and post-flutter velocity regimes.

• Steel and Composite Structures
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• 제46권1호
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• pp.107-114
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• 2023

A new intelligent adaptive control scheme was proposed that combines observer disturbance-based adaptive control and fuzzy adaptive control for a composite structure with a mass-adjustable damper. The most important advantage is that the control structures do not need to know the uncertainty limits and the interference effect is eliminated. Three adjustable parameters in LMI are used to control the gain of the 2D fuzzy control. Binary performance indices with weighted matrices are constructed to separately evaluate validation and training performance using the revalidation learning function. Determining the appropriate weight matrix balances control and learning efficiency and prevents large gains in control. It is proved that the stability of the control system can be ensured by a linear matrix theory of equality based on Lyapunov's theory. Simulation results show that the multilevel simulation approach combines accuracy with high computational efficiency. The M-TMD system, by slightly reducing critical joint load amplitudes, can significantly improve the overall response of an uncontrolled structure.

• 전자공학회논문지
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• 제51권1호
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• pp.202-208
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• 2014

로봇 시스템에 작용하는 마찰력은 비선형 형태이며 특히 저속에서의 정밀 제어를 어렵게 만든다. 본 논문에서는 로봇 연구에서 자주 활용되고 있는 벤치마크 로봇 시스템의 단축 모델에 대한 동적 마찰 보상 문제를 다룬다. 마찰 모델은 동적 특성 및 다양한 효과를 나타낼 수 있도록 비선형 동적 모델인 LuGre 모델을 고려한다. 본 논문에서 제안하는 제어기는 두 부분으로 구성된다. 동적 마찰의 추정 및 보상을 위해 Dual 관측기 기반의 적응 제어기를 사용한다. 마찰 추정 오차 및 나머지 외란을 보상하기 위해 PI 관측기를 추가로 설계한다. 모의실험을 통해 비선형 동적 마찰이 벤치마크 로봇 시스템의 제어 성능에 미치는 영향을 확인하고 제안된 제어기를 사용함으로써 동적 마찰에 대한 제어 성능이 향상됨을 보인다.

• Journal of Information Processing Systems
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• 제18권4호
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• pp.510-523
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• 2022

Considering the problems of poor control effect, weak disturbance rejection ability and adaptive ability of two-wheeled self-balanced robot (TWSBR) systems on undulating roads, this paper proposes a fuzzy neural network active disturbance rejection controller (FNNADRC), that is based on fuzzy neural network (FNN) for online correction of active disturbance rejection controller (ADRC)'s nonlinear control rate. Firstly, the dynamic model of the TWSBR is established and decoupled, the extended state observer (ESO) is used to compensate dynamically and linearize the upright and displacement subsystems. Then, the nonlinear PD control rate and FNN are designed, and the FNN is used to modify the control parameters of the nonlinear PD control rate in real time. Finally, the proposed control strategy is simulated and compared with the traditional ADRC and fuzzy active disturbance rejection controller (FADRC). The simulation results show that the control effect of the proposed control strategy is slightly better than ADRC and FADRC.

• Journal of Power Electronics
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• 제15권3호
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• pp.753-762
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• 2015

This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.

• 한국지능시스템학회논문지
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• 제22권2호
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• pp.174-180
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• 2012

본 논문은 미지의 시간 지연을 갖는 비선형 상호 연결 시스템을 위한 분산 적응 출력 궤환 제어기를 제안한다. 미지의 시간 지연을 갖는 상호 연결 부분은 부시스템들의 모든 상태 변수를 포함한다. 적당한 르아브노브-크라소브스키 함수와 함수 예측 기법을 사용하여 시간 지연 함수들을 보상한다. 각각의 부시스템을 위한 시간에 독립적인 지역 제어기를 설계하기 위해 관측 동적 표면 제어 기법을 이용한다. 제어된 페루프 시스템의 모든 신호들이 준 전역적이고 균일하게 유계됨과 제어 오차가 원점 주위의 조절 가능한 주변으로 수렴함을 증명한다.

• 제어로봇시스템학회논문지
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• 제15권1호
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• pp.72-81
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• 2009

This paper presents a robust adaptive control method using model reference control strategy against autonomous robot systems with random friction nature. We approximate a nonlinear robot system model by means of a feedback linearization approach to derive nominal control law. We construct a Least Square (LS) based observer to estimate friction dynamics online and then represent a perturbed system model with respect to approximation error between an actual friction and its estimation. Model reference based control design is achieved to implement an auxiliary control in order for reducing control error in practice due to system perturbation. Additionally, we conduct theoretical study to demonstrate stability of the perturbed system model through Lyapunov theory. Numerical simulation is carried out for evaluating the proposed control methodology and demonstrating its superiority by comparing it to a traditional nominal control method.