• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.55-58
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• 2003

A LQ-servo PI controller is proposed to deal with the uncertainty caused variations of load inertia of direct drive do motor by using loop shaping technique.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.390-395
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• 2009

In this paper, we present practical issues in a Mobile Haptic Interface (MHI) and their improvements. The improvements can be categorized in three parts: 1) high-accuracy estimation of the world position of the haptic interface point, 2) motion planning algorithm to move the mobile base while avoiding collisions with the user and other objects, and 3) closed-loop force control to compensate the undesired effect of mobile base dynamics on the final rendering force perceived by the user.

• 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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• 1993.10b
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• pp.179-184
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• 1993

In this paper, an optimal motion control scheme is proposed for robot manipulators. A simple explicit solution to the Hamilton-Jacobi equation is presented. The optimization of motion control is based on the mininization of the torque term affecting the kinetic energy and the augmented error which has the first-order stable dynamics for the position and velocity tracking error. In the presence of parametric uncertainty, an adaptive control scheme using the optimal principle is proposed. The global stability of the closed-loop system is guaranteed by the Lyapunov stability approach, The effectiveness and feasibility of the proposed control schemes are shown by simulation results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.922-930
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• 1999

This paper describes a new 14-CPU real-time distributed automatic gauge control (AGC) system for POSCO's No. 2 Hot Strip Mill at Pohang Works. The new AGC system has adopted gaugemeter AGC, Monitor AGC, and roll gap disturbance compensators. The computer system for the new AGC system has been developed based on VMEbus computer systems and a commercial real-time operating system. A VMEbus computer system is also used for the position servo control of hydraulic cylinders. All the application programs and input/output signals have been reasonably distributed over the control computer systems for the maximum reliability and effectiveness of the system. The new AGC system has been successfully used for the No. 2 Hot Strip Mill.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.331-336
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• 1995

In this past decade, industrial robot have substituted human workers successfully in certain areas, however, the applications are limited due to the shortcoming in their mechanism and control strategies. Many researchers, therefore, have focused on improving the mechanical and sensory capabilities. Developing mult-degree-of-freedom end effectors, in other words robot hands, is one of the topics that researchers have begun to improve the limitation. A set of direct drive type servo-pneumatic finger joint has been developed for a dexterous robot hand. To control the pneumatic finger joints, a prototype 4/3-way proportional control valve has been designed and tested as a preliminary, research for the control of the pneumatic finger joints. A series of experiments have been conducted to verify the performance characteristics of the valve and the conventional proportional error contral with minor-loop compensation has been used to control the anguar position of the finger joints.

• Journal of KSNVE
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• v.6 no.5
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• pp.567-574
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• 1996

This paper concerns an articulated space robot with flexible links. The equations of its motion are derived by means of the Lagrangian mechanics. Assuming that magnitude of elastic motions are relatively small, the perturbation approach is taken to separate the original equations of motion into linear and nonlinear equations. Th effect the desired payload motion, open loop control inputs are first determined based on the nonlinear equations. One the other hand, in order to reduce the positional errors during the maneuver, vibration suppression is actively done with a feedforward control for disturbance cancellation to some extent. Additionally, for performance robustness against residual disturbance, an LQ control modified to have a prescribed degree of stability is applied based on the linear equations. Measurement equations are formulated to be used for the maximum likelihood estimator to reconstruct states from the original robot equations of motion. Finally, numerical simulations show effectiveness of the proposed control design scheme.

• Journal of Mechanical Science and Technology
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• v.17 no.7
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• pp.978-985
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• 2003

In this paper, a new proportional solenoid invented for pneumatic directional control valves is introduced. The new proportional solenoid has two-dimensional structure and a pivoting armature on which the friction force is inherently negligible. Another advantageous feature of this solenoid is that its mechanical parts can be easily manufactured and assembled. The working principle and design example of the now proportional solenoid, its application to the activation of a 4/3-way directional control valve, and the evaluation of its control performance in a position control loop are reported.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.936-941
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• 2011

This paper deals with the issue of motion control of a single rod cylinder-load system using simple adaptive control (SAC) method. Prior to controller design, the experiment of open-loop response has been performed. Based on it, design parameters of transfer function are obtained and used for controller design. The effect of parallel feedforward compensator has been investigated by computer simulation, suppressing the oscillatory motion. Through experiments it is conformed that the SAC method gives good tracking performance compared to the PD control method.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.102-109
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• 2000

In this industrial induction motor speed and torque controlled drive system, the closed loop control usually requires the measurement of speed or position of amotor. However a sensorless drive of an induction motor has several advantages ; low cost and mechanical simplicity. Thus this paper investigates a field oriented control method without speed and flux sensors. The proposed control strategy is based on the Model Reference Adaptive System(MRAS) using a new flux estimator which replaces integrators with two lag circuits as the reference model. This algorithm may overcome several shortages of conventional MRAS such as integrator problems, small EMF at low speed. The simulation and experimental results indicate good speed responses.