• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.703-705
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• 2000

In this paper, we design a robust adaptive controller for a nonlinear systems with uncertainties to be rejected via disturbance adaptation law. The nonlinear system considered in this paper has unknown nonlinear functions being influenced by external disturbance. The upper bounds of unknown nonlinear functions at each time is estimated by using disturbance adaptation law. The estimated nonlinear functions are used to design stabilizing function and control of input. Tuning function is used to estimate unknown system parameter without overparametrization. A set-point regulation error converges to a residual set close to zero asymptotically fast.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.912-915
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• 1996

The computed-torque method (CTM) shows good trajectory tracking performance in controlling robot manipulator if there is no disturbance or modelling errors. But with the increase of a payload or the disturbance of a manipulator, the tracking errors become large. So there have been many researches to reduce the tracking error. In this paper, we propose a new control algorithm based on the CTM that decreases a tracking error by generating new reference trajectory to the controller. In this algorithm we used the concept of sliding mode theory and fuzzy system to reduce chattering in control input. For the numerical simulation, we used a 2-link robot manipulator. To simulate the disturbance due to a modelling uncertainty, we added errors to each elements of the inertia matrix and the nonlinear terms and assumed a payload to the end-effector. In this simulation, proposed method showed better trajectory tracking performance compared with the CTM.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.754-758
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• 1996

In this paper, a new method of position synchronizing control is proposed for multi-axes driving system. The proposed synchronizing control system is constituted with speed and synchronizing controller. The structure of synchronizing control system is varied by sign of synchronizing error. When a disturbance input becomes added to one axis, this axis becomes slave axis. The other axis is master axis. Therefore, master axis is not influenced by the disturbance. The speed controller of the first axis is designed by $H_{\infty}$ control theory. The speed controller of the second axis is designed by inverse dynamics of speed control system of the first axis. The speed control system designed with $H_{\infty}$ controller guarantees low sensitivity for the disturbance as well as robustness against model uncertainties. Especially, the synchronizing controller is designed to keep position error to minimize by controlling speed of slave axis. The effectiveness of the proposed method is successfully confirmed through several experiments.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.243-250
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• 2003

In this paper, the speed controller of permanent-magnet synchronous motor (PMSM) using the RBF neural (NN) disturbance observer is proposed. The suggested controller is designed using the input-output feedback linearization technique for the nominal model of PMSM and incorporates the RBF NN disturbance observer to compensate for the system uncertainties. Because the RBF NN disturbance observer which estimates the variation of a system parameter and a load torque is employed, the proposed algorithm is robust against the uncertainties of the system. Finally, the computer simulation is carried out to verify the effectiveness of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.586-588
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• 2011

Adaptive feedforward control(AFC) is largely aimed for improving control performance of dynamic systems particularly involving periodic disturbance signals in engineering fields. This paper presents a novel hybrid AFC approach for specific systems with multiple disturbances in control input and state variables. The proposed AFC mechanism is hierarchically composed of the conventional AFC and a PID typed auxiliary control law in parallel. The former is generic to decrease periodic disturbance in control actuators and the latter is additionally constructed to overcome control deterioration due to time-varying uncertainty of given systems. We carry out numerical simulation to test reliability of the hybrid AFC system and compare its control performance with a well-known conventional AFC method in terms of time and frequency domains for proving of its superiority.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.426-429
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• 1989

The robust self-tuning controller is designed which is guaranteed the asymptotic regulation and tracking in the presence of a bounded parameter perturbation. The global stability in the presence of a finite noise and disturbance is ensured. The controller has a error driven structure, and involves the common model of a disturbance and reference input in the internal model. The adaptive system tunes the controller parameters such that the quadratic performance index which involves a weighting factor is optimized.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.441-444
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• 1992

In this paper, for tracking and filtering seaway information which act as a control disturbance the adaptive notch filter which removes disturbance with fast convergence and stability without changing the value of gain parameter $\mu$ when statistical property of input signal varies rapidly is designed by improving conventional RMXMS(Recursive Maximum Mean Square) algorithm. Besides, in consideration of measurement noise of sensors in underwater vehicle, the system which removes the noise and the disturbance is suggested.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1-6
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• 1991

This paper is concerned with the design of a robust tracking controller using a state observer on a robotic manipulator under the disturbance. The controller is designed to follow a step or ramp reference input without steady state error in the presence of a disturbance and a system parameter variation. In most cases, since all the state vectors are not measured, unmeasurable state vectors must be estimated or reconstructed. A reduced order observer is proposed to estimate unmeasurable state vectors of the non-linear system. Some problems are caused by the Coulomb friction, the disturbance, and the spring effect of a link between the drive motor and the manipulator arm. The state variables, directly measured and estimated by the reduced order observer, are fed back to the controller. When the robot system exhibits the 'limit cycle, the feedback gains initially obtained by optimal control theory are changed. As a result, the limit cycle is eliminated by the new controller gains,

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1188-1193
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• 2011

A nonlinear version of disturbance observer is presented. The system under consideration is an uncertain single input single output nonlinear system and the nominal plant is also a nonlinear system. Compared to the previous implementation given in [8], the proposed scheme does not require an auxiliary variable anymore, thus it has a simpler and more intuitive structure. A robust stability condition for the overall closed-loop system is also provided.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1058-1062
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• 2003

This paper proposes a self-organizing fuzzy controller (SOFC) design technique applied to the vibration control of a dynamic system under irregular disturbance. In this controller, the fuzzy rules generate control signal continuously using the array of input and output pairs without using any special controller model. The generated rules are saved in the fuzzy rule matrix in real-time by self-organizing methods. This fuzzy logic control is demonstrated by simulation and shows the efficiency of the real-time self-organizing fuzzy controller in this system.