• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2602-2604
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• 2000

In this paper, we study robust linear optimal model following servo system in the presence of disturbances and parameter perturbations. A technique to directly design the generalized differential operator based unified control system that covers both differential operator based continuous time and delta operator based discrete time case is presented. The quadratic criterion function for a linear system is used to design the robust unified servo control system. This servo control system is designed by applying a simple genetic algorithm to follow the output of the reference model optimally. The characteristics of the proposed servo system are analysed and simulated to verify the robustness.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.276-281
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• 1989

Comparison 3-port servo system with 4-port is made to obtain optimal design for heavy and unidirectional hydraulic system, It is concluded that 3-port servo system it more adequate than 4-port for the heavy load system which is usually operated at lower frequencies. High performance electro-hydraulic position controller is designed using 3-port servo valve. It includes dynamic pressure feedback as a inner loop and position feedback as a outer loop.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.215-215
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• 2000

In this paper, depth and course controllers of autonomous underwater vehicles using H$_{\infty}$ servo control are proposed. An H$_{\infty}$ servo problem is formulated to design the controllers satisfying a robust tracking property with modeling errors and disturbances. The solution of the H$_{\infty}$ servo problem is as follows: first, this problem is modified as an H$_{\infty}$ control problem for the generalized plant that includes a reference input mode, and then a sub-optimal solution that satisfies a given performance criteria is calculated by LMI(Linear Matrix Inequality) approach. The H$_{\infty}$ depth and course controllers ate designed to satisfy with the robust stability about the modeling error generated from the perturbation of the hydrodynamic coefficients and the robust tracking property under disturbances(wave force, wave moment, tide). The performances(the robustness to the uncertainties, depth and course tracking properties) of the designed controllers are evaluated with computer simulations, and finally these simulation results show the usefulness and application of the proposed H$_{\infty}$ depth and course control systems.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.420-422
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• 1998

In this paper, we propose a position-speed control of servo system with a state estimator. And also we utilized two mass modelling in order to deals with real system accurately. The overall control system consists of two parts: the position-speed controller and state estimator. The Kalman filter applied as state - feedback controller is an optimal state estimator applied to a dynamic system that involves random perturbations and gives a linear,unbiased and minimun error variance recursive algorithm to estimate the unknown state optimally. Therefore we consider the error problem about the servo system modelling, the measurement noise at low-speed ranges a stochastic system, and implement a optimal state observer. Performance of the proposed state estimator are demonstrated by computer simulations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.1
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• pp.39-44
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• 1992

Analog PID controllers have been designed to make good use of position control in industries. Recently, the importance of digital position control is emphasized for the requirements of controller which are not only to control the objects but to include various aspects such as easiness of design and implementation, simple exchange of control program and convenient communications of data between various controllers and a host computer. This study proposes a combined control method which is mixed the vaiable structure control (VSC) with the PI control for minimum time position control of DC servo motor by microcomputer. The results of test by this method show offset-free and minimum time optimal position control which is not affected by the disturbance and the system parameter variations. The validity of the proposed method comparing with the conventional PID control is proved by the response experiments.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.7
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• pp.22-28
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• 1998

This paper includes AC servo motor speed control usig the predictive control strategy. Generally, AC servo motor control should have the fast response characteristics. For the issue, sliding mode control and PID control have been applied. However, the former has the speed ripple response due to the chattering and the latter requires the many trial efforts. Originally, the predictive control which has been used in process control area does not need the priori knowledge for the application system and it is easy to compute the optimal gain with the prediction. In this paper, the TMS320C31 DSP pocessor is used for AC motor control with fst dynamics and the tuning guid-line for the parameters of the predictive control algorithm is given in order to reduce the computation load. Also, the actuator saturationis implemented uisngthe QP(Quadratic Programming) method and the transient response is improved by the identified intertia coefficient when AC motor is drived at forward/reverse rotation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.153-156
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• 2004

This Paper deals with speed control of DC servo motor using a Fuzzy-Sliding observer. Speed sensor detect a speed of rotor continuously. But It have a limit as a driving speed to detect speed precisely. So it is problem to improve the performance of the driving system To solve the problem, it is studied to detect a speed of DC motor without sensor In particular, study on the method to estimate the speed using the observer is performed a lot. In this parer, the gain of the observer is properly set up using the fuzzy control and sliding observer that have a superior transient characteristic and is easy to implement compared the exist ing method is designed. It estimate the derivative of the armature current directly using the armature current measured in the DC motor. It estimate the speed of the rotor using the differentiation. It is Proposed speed sensor less control method using the estimated speed. Optimal gain of Luenberger observer is set up using the fuzzy control and adapted speed control of DC servo motor. It is proved excellence and feasibility of the presented observer from the comparison tested a case with a speed sensor and a case without a speed sensor which used a highly efficient drive and 200W DC servo motor start ing system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.679-682
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• 2002

Resistance spot welding using air gun has been used for joining the sheet metal in automotive manufacturing process. Although air gun has many advantages, it also has the limitation to control the pressure as a factor to improve weld quality. In this study, we apply servo gun using servo motor to resistance spot welding and find the relationship between welding pressure and welding quality. Trough the experiment to change welding pressure during the welding cycle, we can make it clear that the change of welding pressure is greatly influence on the welding quality. To get in a. using response surface methodology, drew out the optimal welding pressure profile for welding quality progresses. We made an optimal profile of welding pressure which improves welding quality using response surface methodology.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.803-812
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• 2006

In order to reduce the negative effects of dynamic coupling among vehicle subsystems and improve the handling performance of vehicle under severe driving conditions, a vehicle chassis control integration approach based on a main-loop and servo-loop structure is proposed. In the main-loop, in order to achieve satisfactory longitudinal, lateral and yaw response, a sliding mode controller is used to calculate the desired longitudinal, lateral forces and yaw moment of the vehicle; and in the servo-loop, a nonlinear optimizing method is adopted to compute the optimal control inputs, i.e. wheel control torques and active steering angles, and thus distributes the forces and moment to four tire/road contact patches. Simulation results indicate that significant improvement in vehicle handling and stability can be expected from the proposed chassis control integration.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.377-384
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• 2007

This paper studies on the relation between linearization methods and controller gains in the looper ILQ(lnverse Linear Quadratic optimal control) system for hot strip finishing mills. Firstly, two linear models arc respectively derived by a linearization method using Taylor's series expansion and a static state feedback linearization method, respectively, and the linear models are compared with the nonlinear model. Secondly, the looper servo controllers are respectively designed on the basis of two linearization models. Finally, the relation between the performances of two ILQ servo controllers and the linearization methods, and the structures and control gains of two controllers are evaluated by a computer simulation.