• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2519-2526
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• 2002

A disturbance observer-based vehicle stability controller is proposed in this paper. The lumped disturbance to the vehicle yaw rate dynamics caused by the uncertain factors such as uncertain tire forces and parameters is estimated by the disturbance observer, which is utilized by the robust controller to stabilize the lateral dynamics of the vehicle. The dynamics of the hydraulic actuator is incorporated in the vehicle stability controller design using the model reduction technique. Modular control design methodology is adopted to effectively deal with the mismatched uncertainty. Simulation results indicate that the proposed disturbance observer-based vehicle stability controller can achieve the desired reference tracking performance as well as sufficient level of robustness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1217-1223
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• 2015

In this paper, we study the problem of torque ripple minimization in Brushless DC Motors (BLDC) and proposes a disturbance observer (DOB) based controller in order to efficiently reduce the torque ripple. In the DOB based control system, an equivalent disturbance (plant disturbance and effect of modelling error) is cancelled by its estimate. When the DOB controller is applied to BLDC motors, the effect of inverter switching is considered as an equivalent disturbance and to be cancelled by the DOB controller. Through computer simulations, it is shown that the performance of the proposed DOB controller is superior to that of the conventional PI controller. In the case where the numerical values of resistance and inductance are not known exactly, it is shown that the proposed DOB controller achieves better performance than the PI controller.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1561-1575
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• 2002

A reduced-order linear feedback controller, which is used to control the linear disturbance in two-dimensional plane Poiseuille flow, is applied to a boundary layer flow for stability control. Using model reduction and linear-quadratic-Gaussian/loop-transfer-recovery control synthesis, a distributed controller is designed from the linearized two-dimensional Navier-Stokes equations. This reduced-order controller, requiring only the wall-shear information, is shown to effectively suppress the linear disturbance in boundary layer flow under the uncertainty of Reynolds number. The controller also suppresses the nonlinear disturbance in the boundary layer flow, which would lead to unstable flow regime without control. The flow is relaminarized in the long run. Other effects of the controller on the flow are also discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.338-341
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• 2015

From the past, maglev technique study(mainly for transportation like maglev) has been done. In the domestic, urban maglev train is practical steps now. High-speed maglev train(550km/h) development comes complete, followed by Japan. This year, system of High-speed maglev train(550km/h) is expected to be verified. This paper simulate FEM model for EMS(Electro-Magnetic Suspension) maglev system and verify tendency of reducing disturbance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.395-396
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.131-132
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• 2011

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.8-12
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• 2003

To protect digital communications and broadcasting that are expected to be increasingly used at frequencies above 1GHz, there is a need to determine permissible disturbance limits for frequency bands above 1GHz according to indicates that better correlates with interference level in digital systems. The quality of digital communications is expressed in terms of bit error rate(BER) or throughput. In this regard, it has been reported that degradation of BER or throughput can be estimated from the amplitude probability distribution (APD) of disturbance amplitude. Therefore, if the APD can simply be measured with a high accuracy, APD will be an optimal index for the assessment of interference in digital communications. In this paper, we show that a measurement method using statistic model of APD has compatibility about performance reduction estimation of WLAN. And through approach of this inspection, we propose numeral models about interference effects of peak value and time rate of spurious.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.348-356
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• 2019

The backdrivable servovalve is a desirable component for force and interaction control of hydraulic actuation systems because it provides direct force generation mechanical impedance reduction by its own inherent backdrivability. However, high parametric uncertainty and friction effects inside the hydraulic actuation system significantly degrade its advantage. To solve this problem, this letter presents a disturbance-adaptive robust internal-loop compensator (DA-RIC) to generate ideal interactive control performance from the backdrivable-servovalve-based system. The proposed control combines a robust internal-loop compensator structure (RIC) with an explicit disturbance estimator designed for asymptotic disturbance tracking, such that the controlled system provide stable and ideal dynamic behavior for impedance control, while completely compensating the disturbance effects. With the aid of a backdrivable servovalve, we show that the proposed control structure can be implemented based on a simplified nominal model, and the controller enables implementation without accurate knowledge of the target system parameters and disturbances. The performance and properties of the proposed controller are verified by simulation and experiments.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.60-67
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• 2000

An improved disturbance rejection control scheme is presented for minimizing the position error due to the repeatable runout disturbances in high density disk drive systems The proposed control algorithm is capable of attenuating repeatable disturbances which is one of the major detractors to hard disk drive quality and performance. This is achieved by a sys-tematic combination of an optimal feedback component and a feedforward preview component. The feedback component is designed where the emphasis is placed on robustness. The feedforward component is on the basis of a preview control comprised of a measured disturbance signals which leads to better disturbance rejection capabilites. The designed con-troller is applied as a plug-in module to a high density hard disk drive with a pre-existing conventional servo controller. Simulations have been carried out to demonstrate the effectiveness of this control scheme in the reduction of the periodic disturbances.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.27-34
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• 2018

In this study, the generating of torque regarding the Control Moment Gyro (CMG) is proportional to the angular velocity of gimbal. This is the case because gimbal affects the attitude control of the satellite directly, and it is necessary to reduce the incidence of torque ripple of gimbal. In this paper, the cause of the torque ripple of gimbal is reviewed and mathematically modeled by assuming the friction imbalance of bearing, the magnetic field and the phase current imbalance of the motor. We are able to confidently estimate the modeling parameters of gimbal disturbance using a constant speed test, and then analyze the influence of applying feedforward control to our modeling. Additionally, the simulation results show that the torque ripple and angular velocity fluctuations are reduced when apply this modeling to the identified study parameters. Finally, we present the disturbance reduction technique using our disturbance modeling.