• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.72-78
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• 2021

This paper presents a robust impedance control of high-DOF robot based on disturbance observer(DOB). A novel DOB is derived by considering the residual disturbance caused by the difference between actual disturbance and disturbance decoupling input which utilizes the estimated disturbance. It focuses on the elimination of the residual disturbance and improvement of the control performance as well as the good estimation of disturbances. In the control of high-DOF robot, numerical dynamic model, which is conducted by a software based on dynamics, is utilized because the analytical model of high-DOF robot is difficult to be obtained. The simulation of high-DOF robot with numerical dynamic model is provided to verify the performance of the proposed controller.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.6
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• pp.78-82
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• 1995

It is needed to robust control for D.C. servo motor according to industrial automation. However, when a motor has an effect of disturbance and variable load, it is very difficult to guarantee the robustness of the system. as a compensation way of solving this problem, in this paper, a expert supervisory control method for motor control system is presented. Expert supervisory controller is designed by error and error change, and nth control input is decided by the addition of (n-1)th control input and inference amount of increase or decrease. Control input of expert supervisory control is transmitted to input, and the disturbance effect decrease remarkable by control input. The robustness of D.C. servo motor using expert supervisory control is demonstrated by the computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.101.5-101
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• 2001

A linear input/output data-based predictive control with integral action is developed. The control input is obtained directly from the input/output data in a single step. However, the state estimation in subspace identification gives a biased estimate and there is model mismatch when the controller is applied to a nonlinear process. To overcome such difficulties, we add integral action to a linear input/output data-based predictive controller by augmenting the integrated white noise disturbance model and use each of best linear unbiased estimation(BLUE) filter and Kalman filter as a stochastic observer for the unmeasured disturbance. When applied to a continuous styrene polymerization reactor the proposed controller demonstrates.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.382-382
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• 2000

The external force disturbance is the one of the main causes that deteriorate the performance of the magnetic suspension. Thus, this paper develops a fuzzy estimator for gain scheduling control of magnetic suspension systems suffering from the unknown disturbance. The proposed fuzzy estimator computes the disturbance injected to the plant and the gain scheduled controller generates the corresponding stabilizing control input associated with the estimated disturbance. In the simulation results we confirm the novelty of the proposed control scheme comparing with the other method using a feedback linearization.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.283-290
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.411-413
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• 1992

This paper proposes a simple and high performance hybrid position/force control of robots based on disturbance compensation by using the disturbance observer in task coordinate space. The disturbance observer linealizes system of robot manipulators in task coordinate space and realizes acceleration control. To realize the strict acceleration control, the disturbance observer whose input is a position signal by simple computation, works as if it were a disturbance detector. The inverse kinematics can be simplified, because the disturbance observer in task coordinate space compensates not only the disturbance but also the error due to the simplification of the inverse kinematics. The new strategy is applied to a three-degrees-of freedom direct drive robot. The robust and simple hybrid position/force control is realized experimentally.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.417-423
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• 2016

Using a sliding mode controller and observer techniques, this paper presents a robust current controller for a DC motor in the presence of parametric uncertainties. One of the most important issues in the practical application of sliding mode schemes is the chattering phenomenon caused by switching actions. This paper presents a novel sliding mode controller that incorporates an integral control with a sliding mode disturbance observer to attenuate the chattering by reducing the controller/observer switching gains. The proposed sliding mode disturbance observer is designed to estimate a relatively slow varying signal in the equivalent lumped disturbance owing to system uncertainties. Combining the estimated uncertainty with the sliding mode control input, the proposed controller can achieve the control objective by using the relatively low gain of the controller. The proposed disturbance observer does not include the switching control input of the baseline sliding mode controller to reduce the observer switching gain. In the proposed approach, the integral sliding mode control is used to improve the steady state control performance. Comparative computer simulations are carried out to demonstrate the performance of the proposed method. Through the simulation results, the proposed controller realizes the robust performance with reduced current ripples.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.169-175
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• 2003

In this paper, and estimation method for estimating the states of underwater vehicle systems with external unknown disturbance is proposed. First, the dynamics of underwater vehicle are induced by Taylor series expansion in the vertical plane and horizontal plane, respectively. For constructing the system model, the external efforts, i.e., the sea surface disturbances, the current, wave and etc., are regarded as external unknown disturbances. Thus the disturbance is added as external input into state-space form of underwater vehicle system. To estimate the state of systems with unknown disturbance, a disturbance observer which does not effected the external unknown input is proposed, and the existence condition for the observer is given. Finally, the effectiveness of the proposed disturbance observer for robust control of underwater vehicle systems is verified by using numerical simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.615-620
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• 2015

DOB (Disturbance Observer) is an useful control method for estimating the disturbance applied to dynamic systems. Disturbance observer can be used to implement a robust control system to generate a control input for rejecting the disturbance, and it can be also used to estimate the disturbance to obtain information. The system that uses disturbance estimation is investigated for high performance control such as automatic door systems, walking robot and electric power steering system in vehicles. In this paper, a novel disturbance observer which is called disturbance and current observer for estimating load torque in the motor system is proposed. The difference between the DOB for disturbance rejection and DCOB is mathematically verified. Current and angular velocity are required for estimating the load torque of the motor in DOB. However, the DCOB can estimate load torque and current without current sensor. DCOB is designed based on modeling of the motor system. Appropriate Q-filter is selected and the applicability of DCOB is verified by simulation. The estimated disturbance and current of the electric motor can be verified without current sensor, as experiments of the actual motor system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.470-473
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• 1995

There exist two critical in application of the magnetic bearing system. One is the control axis interference caused by gyroscopic effect and the other is the vibration caused by the unbalance on the rotor. To solve both problems at the same time, first, a centralized full-state feedback controller based on the LQR control theory was designed to compensate for the gyroscopic effect. Second, disturbance rejection control input based on the observer was designed to avoid the vibration causer by the unbalanced rotor. Balancing input computer accroding to LQR and output of the observer were derived in term of rotational speed. Effectiveness of the on-line balancing was verified through numerical simulation. The developed observer-based controller was also applied to the linear and nonlinear magnetic bearing systems.