• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1663-1674
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• 2017

This paper deals with the robust speed regulation of a surface-mounted permanent magnet synchronous motor (SPMSM) that is subject to parametric uncertainties and external disturbances. The proposed approach retains a conventional cascade control configuration composed of an outer-loop speed control module and inner-loop current control modules. Baseline proportional-integral (PI) controllers are designed for nominal modular systems without accounting for the uncertainties to set a desired control performance of the closed-loop system. After studied in both frequency and time domains, a reduced-order proportional-integral observer (PIO), as a modular disturbance observer, is incorporated with each control module to maintain the ideal performance of the modules. Theoretical analysis confirms the desired performance recovery of the augmented system with modular PIOs to the nominal system. Comparative computer simulations and experimental results validate the proposed cascade control method for SPMSM speed regulation.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.513-518
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• 1998

In this paper, a robust fault-tolerant control scheme for robot manipulators overcoming actuator failures is presented. The joint(or actuator) fault considered in this paper is the free-swinging joint failure and causes the loss of torque on a joint. The presented fault-tolerant control framework includes a normal control with normal(non-failed) operation, a fault detection and a fault-tolerant control to achieve task completion. For both no uncertainty case and uncertainty case, a stable normal con-troller and an on-line fault detection scheme are presented. After the detection and identification of joint failures, the robot manipulator becomes the underactuated robot system with failed actuators. A robust adaptive control scheme of robot manipulators with the detected failed-actuators using the brakes equipped at the failed(passive) joints is proposed in the presence of parametric uncertainty and external disturbances. To illustrate the feasibility and validity of the proposed fault-tolerant control scheme, simulation results for a three-link planar robot arm with a failed joint are presented.

• 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 Industry Convergence
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• v.18 no.2
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• pp.119-128
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• 2015

In this paper, we propose a new motion control technology to design robust control system of industrial robot. The system modeling of robotic manipulation tasks with constraints is presented, and the control architecture for unconstrained and constrained motion system with parametric uncertainties is synthesized. The optimal reference of robot manipulator is generated by the reference controller as a discrete state system and the control behavior of constrained system which has poor modeling information and time-invariant constraint function is improved motion control system is successfully evaluated by experiment to the desired tasks.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.3
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• pp.294-299
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• 2006

This paper studies a visual feedback control scheme for robot manipulators with camera-in-hand configurations. We design a robust controller that compensates for bounded parametric uncertainties of robot mechanical dynamics. In order to reduce steady state tracking error of the robot arms due to uncertain dynamics, integral action is included in the control input. Using the Lyapunov stability criterion, the uniform ultimate boundedness of the tracking error is proved. Simulation and experimental results with a 2-1ink robot manipulator illustrate the robustness and effectiveness of the proposed control algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.731-737
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• 2013

In this paper, we propose an image-based output feedback robust controller of robot manipulators which have bounded parametric uncertainty. The proposed controller contains an integral action and high-gain observer in order to improve steady state error of joint position and performance deterioration due to measurement errors of joint velocity. The stability of the closed-loop system is proved by Lyapunov approach. The performance of the proposed method is demonstrated by simulations on a 5-link robot manipulators with two degrees of freedom.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1249-1253
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• 2004

A robust input modification approach to the control of flexible joint robot is presented. In our previous study, we developed an observer based state feedback control for the suppression of residual vibration of a robot. The control was very effective in suppressing the inherent vibration of a flexible joint robot. However it did not meet high performance requirements under high speed motion and model uncertainties. As a solution of the problem, we present an input modification method with robustness against parametric uncertainties. The main idea of the proposed input modification method is to generate a modified reference position command for fast and accurate motion of the robot. Using this proposed method we can reduce the servo delay and settling time by about 60% and substantially improve the path accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1533-1538
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• 1991

A parameter space approach for robust control system design is developed by reducing several design specifications to sign definite conditions. It is shown that the gain and phase margin constraints for the parametric perturbed plant hold if and only if the four Kharitonov systems satisfy the margins. On pole location, it is shown that D-stability of convex combinations (1-t)p(s)+tq(s) can be determined by the coefficients corresponding to p(s) and q(s) based on the sign definite condition. We show a method of PI-type robust control system design as a useful example.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.32-38
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• 1998

In this paper, we design a robust controller for trajectory control of n-link robot manipulators with bounded parametric uncertainties. The proposed control scheme with integral control improves tracking error due to limit of the robust feedback gains and use of continuous control input for chattering rejection. The integral of the tracking error is augmented to the error system equation and the stability of the closed-loop system is achieved. The performance of the proposed method is demonstrated by simulation on a 2-link manipulator.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.217-227
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• 2000

Although inverter-driven hydraulic elevators(HEL's) have advantages over traditional valve-controlled HEL's energy efficiency and performance they need robustness in performance and stability to accomodate nonlinearities big parametric variations and resonances in mechanical-hydraulic inner system. In this paper a robust controller based on DGKF/$\mu$ mixed approach is applied to a HEL system with carring capacity of 24 persons for Incheon International Airport. The results of a test tower(T/T) has shown good ro-bustness in performance and stability of the proposed controller thereby proving a feasibility of this robust controller-based approach for other HEL problems.