• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.175-178
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• 2002

In a conventional speed sensorless Stator Flux Oriented(SFO) induction machine drive system, the estimated speed is delayed in transients by the use of a low pass filter(LPF). To prevent extreme overshoot caused by this delay, PI controller gains should be small, which consequently is greatly affected by disturbance torque. In this paper, by taking advantage of disturbance torque observer and feedforward control, robust speed controller is designed for speed sensorless SFO system. The proposed method is verified by the simulation results.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.362-368
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• 2001

We study on the velocity matching algorithm for transfer alignment of inertial navigation system(INS) using a robust H$_2$ filter. We suggest an uncertainty model and a discrete robust H$_2$filter for INS and apply the suggested robust H$_2$ filter to the uncertainty model. The discrete robust H$_2$filter is shown by simulation to have better performance time and accuracy than Kalman filter.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.3
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• pp.114-119
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• 2001

An automatic train operation(ATO) system executes the operation of constant speed travelling and fixed point parking by using microprocessors instead of driver's manual operation. This paper describes the mathematical model for the train considering unknown disturbances which consist of start resistance, travelling resistance, slope resistance, curve resistance, and so on. The speed controller of ATO system is designed by considering the disturbances. The simulation is executed to verify the speed control and fixed point parking performance and to compare its performance with that of a PID-type ATO control system under disturbances. Simulation results show that the control performance of gain scheduled control scheme for ATO system is better than that of the conventional PID controller.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.271-273
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• 2001

This paper presents a adaptive speed controller for field oriented controlled (FOC) permanent magnet synchronous motor (PMSM) drives. However, achieving FOC requires machine specific knowledge, and tracking of drifting motor parameters in order to maintain control. The proposed controller based on Minimum Controller Syntheses (MCS) algorithm does not require exact knowledge of motor parameters. This controller structure simplifies the design and implementation of the adaptive controller requiring less effort to synthesis than a standard MRAC system. Simulation results using Matlab/Simulink show that the proposed controller has good dynamic performances and it is insensitive to parameter variations.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.2
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• pp.80-88
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• 2005

In this paper, an robust adaptive backstepping controller is proposed for the speed control of separately excited DC motor with uncertainties and disturbances. Armature and field resistance, damping coefficient and load torque are considered as uncertainties and noise generated at applying load torque to motor is also considered. It shows that the backstepping algorithm can be used to solve the problems of nonlinear system very well and robust controller can be designed without the variation of adaptive law. Simulation and experiment results are provided to demonstrate the effectiveness of the proposed controller.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.241-250
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• 2022

This paper describes the design of H-infinity controller for robust control of a DC motor system. The suggested controller can ensure robustness against disturbance and model uncertainty by minimizing H-infinity norm of the transfer function from exogenous input to performance output and applying the small gain theorem. In particular, the controller was designed to reduce the effects of disturbance and model uncertainty simultaneously by formalizing these problems as a mixed sensitivity problem. The validity of the proposed controller was demonstrated by computer simulations and real experiments. Moreover, the effectiveness of the proposed controller was confirmed by comparing its performance with PI controller, which was tested under the same experimental condition as the H-infinity controller.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2092-2099
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• 2013

Through the data transfer race in industry since 1990s, the operational speed of optical disk drive(ODD) becomes commonly over 10,000 rpm. Such high speed operation inevitably causes the vibration, which is also the disturbances in the read-write process of pick-up servo-controller. Generally the vibration disturbance problem can be solved by the vibration isolation using the rubber mount and the increase of robustness of the pick-up servo-controller. Optical disk itself has not been targeted for the vibration reduction, because it is manufactured under the standardized format. In this paper we focused on the increase of critical speed of optical disk, that is, the improvement of dynamic characteristics, with the control of residual stresses which are come from the injection molding process. To do this, first, the residual stresses induced from the injection molding process are calculated using finite element method. The major design parameters of the process conditions are flow rate and melt temperature, which control the residual stresses in optical disk. Second, the critical speed of optical disk is calculated with modal analysis considering residual stress distributions. It was found out that the critical speed can be improved by the control of operational parameters in the injection molding process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1899-1909
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• 2000

This paper proposes a new $H_{\infty}$ yaw moment control scheme using brake torque switching for improving vehicle performance and stability especially in high speed driving. In the scheme, one wheel is selected, depending on the vehicle states, at which a brake torque for control is applied. Steering angles are modeled as a disturbance to the system and the $H_{\infty}$ controller is designed to minimize the difference between the performance of the vehicle and that of the desired model. Its performance robustness as well as stability robustness to system parameter variations is assured through ${\mu}$-analysis. Various simulations with a nonlinear 8-DOF vehicle model show that proposed controller enhances the vehicle performance and stability under disturbances and parameter variations as well as under the normal driving condition.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.192-198
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers and one synchronous controller. The speed controllers based on PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order that speed response of the second axis corresponds with one of first axis. Especially, considering to model uncertainties of each axis, the synchronous controller has been designed using H$\infty$ control theory. The controller eliminates the synchronous error by controlling speed of the second axis. The effectiveness of the proposed method has been verified through simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.249-255
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• 2010

The paper proposes a new type of robust speed control strategy for permanent magnet synchronous motor by using PD-sliding mode hybrid control. The PD control has a good performance in the transient region while the sliding mode controller provides the robustness against system uncertainties. Taking advantages of the two control strategies, the proposed control method utilizes the PD control in the approaching region to the sliding surface and the sliding mode control near at the sliding surfaces. The chattering problem of the sliding mode controller is eliminated by applying the saturation function for the switching function of the sliding mode control. The stability of the sliding mode control is verified by using Lyapunov function with the proper selection of variable gains. It is shown that with this simple switching algorithm, stability of the overall hybrid control system is ensured. Through the simulations, the PD-sliding mode algorithm is shown to have a good performance in the transient response as well as being robust against disturbances. The robustness of the PD-sliding mode algorithm is further demonstrated against various external disturbances in the real experiments of SPMSM motor control.