• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.126-135
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• 1992

Up to now, there has been a lot of researches on the sliding mode control which has the insensitive characteristics to the variations of plant parameters, nonlinearities and external disturbances. One difficulty in applying the sliding mode control is the need for the knowledge of the full-state vector. The use of state observer is a natural step towards the relaxation of this condition. However, the exact plant-modeling is assumed to be known. Recently, there has been a remarkable advance in the microprocessor and one can construct the controller which could not realize due to hardware restriction in the past. Therefore in this paper, the PID sliding mode controller which has only one output feedback signal is suggested by means of microprocessor and the performance of electro-hydraulic servosystem compensated with this controller is proved.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1081-1087
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• 2006

Generally, biped walking is difficult to control because a biped robot is a nonlinear system with various uncertainties. In this paper, we propose a hybrid sliding-mode control method using a WNN uncertainty observer for stable walking of the 5-link biped robot with model uncertainties and the external disturbance. In our control system, the sliding mode control is used as main controller for the stable walking and a wavelet neural network(WNN) is used as an uncertainty observe. to estimate uncertainties of a biped robot model, and the error compensator is designed to compensate the reconstruction error of the WNN. The weights of WNN are trained by adaptation laws that are induced from the Lyapunov stability theorem. Finally, the effectiveness of the proposed control system is verified through computer simulations.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2174-2176
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• 1997

The purpose of this paper is to improve tracking performance for an EMS system using variable structure control. To improve current control of characteristics and to reduce chattering, a reaching law is applied. A disturbance observer using sliding observer is designed to compensate the influence of disturbances. This observer compensates modelling uncertainty and steady state error as well as external disturbance. The effectiveness of the proposed control scheme is demonstrated by experiments

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.186-189
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• 2001

In a precise control system, the Lu-Gre friction model has often been used to describe the nonlinear friction. For the XY table system with this friction model, we identified the friction parameters and designed nonlinear observer. The nonlinear friction effects could be removed within appropriate position tracking errors and control inputs through experiments. Also, we designed the nonmodel-based SMC system to compensate the nonlinear friction. Through experiments, it is shown that this method has the similar performance compared with the nonlinear observer system and is useful when friction parameters are hard to identify except the problem of input chattering.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1509-1510
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• 2008

In this paper, we propose a robust adaptive controller for induction motors with uncertainties using nonlinear disturbance observer(NDO). The proposed NDO is applied to estimate the time varying lumped uncertainty which are derived from unknown motor parameters and load torque, but NDO error does not converge to zero since the derivate of lumped uncertainty is not zero. Then the high order neural networks(HONN) is presented to estimate the NDO error such that the rotor speed to converge to a small neighborhood of the desired trajectory. Rotor flux and inverse time constant are estimated by the sliding mode adaptive flux observer. Simulation results are provided to verify the effectiveness of the proposed approach.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.736-741
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• 1998

It is well known that an encoder or a resolver is necessary to obtain the position data for speed or position control Generally utilized speed sensors are mal-affected by the EMI, dusty, and high temperature surroundings. Therefore, the speed and position sensorless controls using observers have been studied widely. In this paper, the binary observer which is composed of two feedback regulation loops to control the speed of SRM(Switched Reluctance Motor) is applied. One loop compensates the control input directly like the sliding mode control, and the other one compensates the system parameters indirectly. This observer is constructed on the foundation of variable structure control on the foundation of variable structure control theory and has the inertial term for the varying parameter. The validities of this proposed method is proved by experiments.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.391-393
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• 2007

The rotor speed and flux information is most important in the vector control. The accuracy of flux observers for induction machine inherently depends on parameter sensitivity. The control strategy is using online flux observer for flux estimation. In the proposed system, the speed control characteristics using a online flux observer control isn't affected by a load torque parameter disturbance. Simulation results are presented to prove the effectiveness of the adaptive sliding mode controller for the drive variable load of induction motor.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.280-285
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• 2007

This paper presents a robustly adaptive flux observer for speed-sensorless induction motor control. The proposed approach employs additional robustifying signals to cope with the parametric uncertainties instead of designing an estimator, which has been normally used in power electronic drives. For that, the sliding-mode like adaptive controls are designed and their gain parameters are determined so that the observer dynamics are stable in the sense of Lyapunov, and furthermore they can guarantee the robustness against parametric uncertainties in induction motor systems. Estimated rotor speed is to be used to generate feedback control signal for the speed sensorless vector control system. To show the validity and efficiency of the proposed system, simulation results are presented.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.15 no.3
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• pp.200-207
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• 2015

This paper proposes an active damping control method for a grid-side converter that has an LCL grid filter in the back-to-back converter. To remove the resonant frequency components produced by the LCL filter, it is necessary to measure the grid current. To do this, sensors must be added. However, it is not necessary to add sensors because the grid current is estimated by designing a suboptimal observer. In order to remove the nonlinearity and to gain fast response of control, both feedback linearization and sliding mode control are applied. The proposed method is verified through a simulation.

• The Journal of Korea Robotics Society
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• v.18 no.2
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• pp.155-163
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• 2023

Auto Guided Vehicle (AGV) equipped with mecanum wheels can move in all directions, unlike ordinary wheeled AGVs. In this paper, we propose a robust trejectory tracking control method for the mecanum wheeled AGVs in the presence of disturbances. It is constructed by combining impedance control with Integral Sliding Mode Control (ISMC), which shows robust performance against disturbances, and adding a disturbance observer (DOB) that estimates and removes disturbances. Simulation result using MATLAB/SIMULINK shows that the proposed control method has robust performance in tracking the reference trajectory under the circumstance with disturbance. The control performance is further improved when the disturbance observer is additionally used. In addition, the performance of the proposed control method was verified through experiment. It shows the result of tracking the set trajectory well.