• Journal of Drive and Control
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• v.18 no.4
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• pp.52-58
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• 2021

The variable structure controller is designed such that in sliding mode, the system moves along the switching plane in the vicinity of the switching plane, thus it is robust because it is not affected by the parameter fluctuations of the plant. However, a controller based on a variable structure may not meet the desired performance when it is commanded to track any input or is exposed to disturbances. This study proposes a sliding mode controller that follows the IVSC (Integral Variable Structure Control) approach with ELO (Extended Luenberger observer) to solve this problem. The proposed sliding mode control is applied to the velocity control of the hydraulic motor. The sliding plane was determined by the pole placement, and the control input was designed to ensure the existence of the sliding mode. The feasibility of modeling and controller are reviewed by comparing with conventional proportional-integral control through computer simulation using MATLAB software and experimenting on the cases of significant plant parameter fluctuations and disturbances.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.157-164
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• 2007

In this paper, a novel sensorless drive for brushless DC (BLDC) motor using the fuzzy back-EMF observer is proposed to improve the performance of conventional sensorless drive methods. Existing sensorless drive methods of the BLDC motor have low performance at transients or low speed range and occasionally require additional circuits. To cope with these problems, the back-EMF of the BLDC motor must be precisely estimated by a fuzzy logic, which is suitable to estimate the back-EMF which has a trapezoidal shape. The proposed algorithm using fuzzy back-EMF observer can achieve robust control for the change of an external condition and continuously estimate position of the rotor at transients as well as at steady state. The superiority of the proposed algorithm is proved through the simulation compared with other sensorless drive methods.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.11
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• pp.1145-1153
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• 2011

EMB (Electro-Mechanical Brake) systems can provide improved braking and stability functions such as ABS, EBD, TCS, ESC, BA, ACC, etc. For the implementation of the EMB systems, reliable and robust fault detection algorithm is required. In this study, a model-based fault detection algorithm is designed based on the analytical redundancy method in order to monitor current and force sensor faults in EMB systems. A state-space model for the EMB is derived including faulty signals. The fault diagnosis algorithm is constructed using the analytical redundancy method. Observer is designed for the EMB and the fault detectability condition is examined based on the residual analysis. The performance of the proposed model-based fault detection algorithm is verified in simulations. The effectiveness of the proposed algorithm is demonstrated in various faulty cases.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.439-442
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• 2000

An adaptive nonlinear control of a brushless direct drive motor(BLDDM) is proposed. Comparing to the traditional PMSM the direct drive motor has smaller number of per pole and per phase slots to provide higher torque in low speed. This generic construction generates flux harmonics and finally results in unwanted torque harmonics. To control the speed a feedback linearization method is applied by choosing the $i_{ds}$ and $\omega_{m}$ as the output variables. The control of the flux harmonics is provided by using a flux observer with MRAC technique. As shown in the simula-tion results the proposed nonlinear speed controller has a good speed response in the steady state and robust to the flux variation

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1775-1776
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• 2008

This paper presents a adaptive fuzzy control suitable for motion control of multi-link robot manipulators with uncertainties. When joint velocities are available, full state adaptive fuzzy feedback control is designed to ensure the stability of the closed loop dynamic. If the joint velocities are not measurable, an observer is introduced and an adaptive output feedback control is designed based on the estimated velocities. To reduce the number of fuzzy rules of the fuzzy controller, we consider the properties of robot dynamics and the decomposition of the unknown input gain matrix. The proposed controller is robust against uncertainties and external disturbances. The validity of the control scheme is demonstrated by computer simulations on a two-link robot manipulator.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.70-78
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• 2005

In this paper, a novel rotor flux estimation method of an induction motor using support vector regression(SVR) is presented. Two well-known different flux models with respect to voltage and current are necessary to estimate the rotor flux of an induction motor. Training of SVR which the theory of the SVR algorithm leads to a quadratic programming(QP) problem. The proposed SVR rotor flux estimator guarantees the improvement of performance in the transient and steady state in spite of parameter variation circumstance. The validity and the usefulness of proposed algorithm are throughly verified through numerical simulation.

• Journal of Power Electronics
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• v.11 no.5
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• pp.713-718
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• 2011

This paper presents an online voltage disturbance estimator to achieve precise torque control of IPMSMs over a high speed operating region. The proposed design has a type of state-filter based on a Luenburger-style closed loop stator current vector observer. Utilizing the frequency response plot (FRF) approach, the estimation accuracy and the parameter sensitivities are analyzed. Accurate torque control and improved efficiency are provided with the decoupling of the effect of the parameter variations. The feasibility of the presented idea is verified by laboratory experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1094-1102
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• 2008

Through the motion control experiment using Industrial Emulator(Model 220 by ECP), the performance comparison of three kinds of controllers such as PID, RIC and LQR was carried out. It was shown that RIC has the best performance in the presence of disturbances such as step one, sinusoidal one and Coulomb friction for the rigid body. LQR using feedback state variables has the best tracking performance far the flexible body. The performance of PID controller is low compared to other controllers, but the design process is simple. The most advanced controller is LQR. In order to attenuate disturbance, an additional state observer should be used to estimate it, making more complex control system. RIC lies between PID and LQR in view of complexity of design. Even though RIC is not complicated, it has good disturbance rejection ability and less tracking error. By considering these aspects, the RIC is suggested as high precision controller to be used in motion control system.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.956-962
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• 2008

This paper is devoted to yarn tension control problem in winding machines. The passive take-up unit is replaced by active one with ADRC(Active Disturbance Rejection Control) and it was compared with the method using conventional PD(Proportional-Derivative) controller. The main part of ADRC is ESO(Extended State Observer) which continuously estimates nonlinearities of the system, such as intrinsic nonlinearity, external disturbance and sensor noise. Then the estimated nonlinearity is used to compensate the real one, thus making controlled system linear. A number of experiments have been conducted in order to verify the performance of the original winding system to the modified one. Experiments have shown improved efficiency of the system with adopting active yarn tension control. Experimental results show that the ADRC achieves a better tension response than PD controller and is robust to parameters variation.