• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.523-530
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• 2007

Crane systems are very important in industrial fields to carry heavy objects such that many investigations about control of the systems are actively conducted for enhancing its control performance. This paper presents an adaptive control approach using the model matching for a complex 3-DOF nonlinear crane system. First, the system model is linearized through feedback linearization method and then PD control is applied in the approximated model. This linear model is considered as nominal to derive corrective control law for a perturbed crane model using Lyapunov theory. This corrective control is primitively aimed to compensate real-time control deviation due to partially known perturbation. We additionally study stability analysis of the crane control system using Lyapunov perturbation theory. Evaluation of our control approach is numerically carried out through computer simulation and its superiority is demonstrated comparing with the classical control.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.379-380
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• 2011

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2248-2250
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• 2004

본 논문에서는 유연한 단일링크 매니퓰레이터의 끝단 위치 추적제어를 위해 웨이블렛 신경망을 이용한 강인 적응제어기를 제안한다. 전체 제어기는 웨이블렛 신경망에 의해 추정된 피드백 선형화 제어기와 그 추정오차를 보상하기 위한 보상제어기로 구성된다. 시스템의 출력값은 최소위상을 보장하기 위하여 재정의하여 사용된다. 구성된 웨이블렛 신경망의 연결 가중치는 Lyapunov 안정도 이론에 기초해서 조절된다. 제안된 제어기의 성능 향상은 PD 제어기와 비교함으로써 입증된다.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.936-938
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• 1999

In this Paper, the design of a feedback linearization controller using multilayer neural network is proposed. The Proposed feedback linearization control scheme is designed by finding Lie derivatives from an identified neural networks. Lie derivatives are expressed as a combination of weights and neuron outputs. The proposed method is applied to an antenna arm problem and the simulation results show performance comparisons between the ordinary feedback linearization and the Proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.261-266
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• 1995

본 연구에서는 자기부상시스템에 대해 흡인식 자기부상방식을 채택하고 쇠구슬에 대한 운동을 상하 1자유도로 가정하여 운동방정식을 세운다. 이때 전자석이 자기 부상력은 전자석에 흐르는 전류와 인덕턴스의 함수라 가정하고, 모델의 불확실성은 자기부상계의 운동 방정식으로부터 선형화 할 때 발생하는 오차 및 파라미터 변동으로 생각한다. 또한 모델의 불확실성이 존재하더라도 정상편차 없이 부상하는 서보제어계를 설계한다. 그런데 저자등은 강인성 문제 및 정상편차 없는 것에 역점을 두어 H$_{\infty}$ 제어이론에 기초한 1형 로바스트 서보 제어기를 구하여 자기부상 시스템의 안정화 제어계로써 적용한 적이 있다. 이때 중심해 이외의 해를 이용하여 설계한 서보 제어계는 자기부상계의 과도상태시에 일어나는 오버슈트를 줄일 수 없었다. 따라서 시스템 내부 안정화를 위하여 H$_{\infty}$ 제어이론에 의해 설계된 피드백(feedback) 제어기와 물체가 부상할 때 오버슈트를 줄이고 제어량이 목표치에 잘 추종하기 위해 설계된 피드 포워드(feed forward) 제어기로써 2자유도를 갖는 제어계를 설계한다. 이렇게 설계한 2자유도 제어계를 가지고 모의 응답실험과 본 연구자들이 만든 자기부상 시스템의 실험결과를 비교함으로써 설계된 제어기의 타당성을 조사한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.352-360
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• 2010

This paper proposes a precise position control of an automatic door using a disturbance observer. Although the conventional PID controller is usually used for an automatic door system, the demand of the robust controller considering the parameter deviations and disturbances is increasing due to the various size and weight of a door. The linear model for an automatic door system is presented. Based on this model, the LQR controller using a state feedback controller and an observer are suggested. A disturbance observer to compensate the undesirable factors is also proposed. Simulation and Experimental results are presented to illustrate the feasibility of the proposed control strategy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.534-537
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• 1995

An open loop vibrational control of underactuated mechanical system with amplitude and frequency modulations is investigated. The underactuated systems sonsidered in the paper are assumed to have free joints with no brake. The active joints are positioned first by a linearizing control, and then periodic oscillatory input are applied to them to move the remaining free joints to their desired states. A systematic way of obtaining averaged systems for the underactuated systems with oscillatory vibration is developed. A complete solution to the open loop control strateegy in terms of determining amplitudes and frequencies for general system is still under investigation. However, a specific control design for 2R manipulator which is obtained through the averaged system is demonstrated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.305-316
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• 2014

As avionics and mechanical devices have been developed, the size of unmanned aerial vehicle (UAV) is getting smaller. However, the complicated and accurate missions are provided to the UAV. Among various types of UAVs, quadrotors are widely used for their availability by virtue of simple structure and hovering function. However, the control of quadrotor is highly constrained, because the quadrotor is an under-actuated system which has only 4 actuator inputs. To deal with this under-actuated problem, a new quadrotor model with two more actuators in addition to the 4 propeller inputs is provided to make the system fully-actuated. For the proposed model, a controller is designed using feedback linearization methods. To validate the model and to verify the performance of the proposed controller, numerical simulation is performed.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.384-394
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• 2002

In this paper, a new control strategy is proposed to improve the quality of the welding products. The conventional nonlinear power control system of spot welders is linearized using nonlinear feedback linearization technique based on differential geometry theory. An evolution strategy(ES) geometry is used to find optimal gain of PI controllers. It tries to find out the optimal control parameters by imitating the natural evolution. Some Simulation and experimental results show that the proposed variable power control system using ES algorithm has better dynamic performances than the conventional one.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.5
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• pp.299-307
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• 2003

The local structure of CMAC neural networks (NN) results in better and faster controllers for nonlinear dynamical systems. In this paper, we propose a CMAC NN-based disturbance observer and its corresponding controller for a flexible joint robot. The CMAC NN-based disturbance observer compensates for the parametric uncertainties and the external disturbances throughout the entire mechanical system. Finally, a simulation result is given to demonstrate the effectiveness of proposed design method's robust tracking performance.