• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.31-35
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• 2005

Higher productivity requires high-speed motion of machine tool axes. The iron core linear DC motor (LDM) is widely accepted as a viable candidate for high-speed machine tool feed unit. LDM, however, has two inherent disturbance force components, namely cogging and thrust force ripple. These disturbance forces directly affect the tracking accuracy of the feeding system and must be eliminated or reduced. In order to reduce motor ripple, this research adapted the feedforward compensation method and neural network control. Experiments carried out with the linear motor test setup show that these control methods are effective in reducing motor ripple.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.48-58
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• 2010

In this study, position tracking and force reflection control of a master-slave manipulator which will be used for handling objects contaminated by radioactivity has been addressed. Since available measurements concerning on dynamic motion of the master-slave manipulator are restricted, a simple constrained control structure was suggested. In the consideration of the uncertain dynamic behaviors of the slave manipulator which is dependent upon mass and shape of work pieces grasped and dynamic properties of the environment contacted, a simple structured sliding mode control was suggested to guarantee robustness with respect to parameter uncertainties and external disturbances. The proposed control was applied to a 1-DOF master-slave link system. The control performances were verified along with some computer simulation results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.577-580
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• 2005

This paper reports the high sensitivity actuator for flexible disk. The air stabilized flexible optical disk has very small axial runout. Therefore, It is proper to develop an actuator which has high sensitivity in tracking direction rather than in focusing direction. In order to maximize driving force in radial direction, we present an efficient design of magnetic circuit with simple multi-polarized magnets and auxiliary magnets. Designed magnetic circuit has big force in tracking direction. And we shift 2$^{nd}$ resonance frequency of moving parts Into high frequency band, not causing increase of mass and discord between force and mass centers to secure high sensitivities and sufficient control bandwidth. Finally, experimental results show that designed actuator has superior sensitivity in tracking direction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.213-216
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• 2005

This paper presents force feedback control performance of a 3DOF haptic device that can be used for minimally invasive surgery (MIS). As a first step, a 3DOF electrorheological (ER) joint is designed using a spherical mechanism. And it is optimized based on the mathematical torque modeling. Subsequently, the master haptic device is manufactured by the spherical joint. In order to achieve desired force trajectories, model based compensation strategy is adopted for the ER master. Therefore, Preisach model fur the PMA-based ER fluid is identified using experimental first order descending (FOD) curves. A compensation strategy is then formulated through the model inversion to achieve desired force at the ER master. Tracking control performances for sinusoidal force trajectory are presented, and their tracking errors are evaluated.

• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.47-61
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• 2000

To study the characteristic of the weight center control of humans, the tracking control capability of circular and wave motion by weight center movement was conducted by using the force platform. The control performance(the integrated value of the $|Object\;value(X)-Control\;Value(Y)|^{2}$) and control trace record was used to evaluate the individual performance characteristics. The size of the population for this study was 73, which consisted of engineering students, students majoring in taekwondo, students majoring in dance, all of which were in their twenties, and also people in their sixties. The results of this study indicate that the weight center control characteristics of humans can be represented by the evaluation method and values. People who were capable of tracking the object did not stop nor overshot the objective. In addition, habits or training characteristics and aging seemed to influence the performance of the subjects. In the future, development of different objectives for weight center control could be used to determine the severity of the disease of the subject and the effects of the treatment.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.338-344
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• 2002

In this paper, neural network force tracking control is proposed. The conventional impedance function is reformulated to have direct farce tracking capability. Neural network is used to compensate for all the uncertainties such as unknown robot dynamics, unknown environment stiffness, and unknown environment position. On line training signal of farce error for neural network is formulated. A large x-y table is built as a test-bed and neural network loaming algorithm is implemented on a DSP board mounted in a PC. Experimental studies of farce tracking on unknown environment for x-y table robot are presented to confirm the performance of the proposed technique.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.87-96
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• 2018

A trajectory control system plays an important role in controlling motions of marine vehicle when a series of way points or a path is given. In this paper, a sliding mode control (SMC)-based trajectory tracking controller for marine vehicles is presented. A small-sized unmanned ship is considered as a control object. Both speed and heading angle of a ship should be controlled for tracking control. The common point of related researches was to separate ship's speed and heading angle in control methods. In this research, a new control law from a general sliding mode theory that can be applied to MIMO (multi input multi output) system is derived and both speed and heading angle of a ship can be controlled simultaneously. The propulsion force and rudder force are also applied in modeling stage to achieve accurate simulation. Disturbance induced by wind is also tackled in the dynamics considering robustness of the proposed control scheme. In the simulation, we employed a way-point method to generate ship's trajectory and applied the proposed control scheme to ship's trajectory tracking control. Our results confirmed that the tracking error was converged to zero, thus demonstrating the effectiveness of the proposed method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.43-51
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• 2021

A robust tracking controller design was developed for a rotary motion control system. The friction force versus the angular velocity was measured and modeled as a combination of linear and nonlinear components. By adding a model-based friction compensator to a nominal proportional-integral-derivative controller, it was possible to build a simulated control system model that agreed well with the experimental results. A zero-phase error tracking controller was selected as the feedforward tracking controller and implemented based on the estimated closed-loop transfer function. To provide robustness against external disturbances and modeling uncertainties, a disturbance observer was added in the position feedback loop. The performance improvement of the overall tracking controller structure was verified through simulations and experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.548-551
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• 1997

Performance of force tracking impedance control of robot manipulators is degraded by the uncertainties in the robot and environment dynamic model. The purpose of this paper is to improve the controller robustness by applying neural network. Neural networks are designed to learn the uncertainties in robot and environment model for compensating the uncertainties. The proposed scheme is verified through the simulation of 20DOF robot manipulator.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.157-160
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• 2002

When the teleoperation system has a signal transmission time delay between slave system and control system, the position tracking performance of the slave system and system stability are likely to be deteriorated. This paper proposes a force reflecting position control scheme for teleoperation system with signal transmission time delay. The proposed scheme not only satisfy the system internal stability but also improves the position tracking performance with disturbance rejection capability. The simulation results show that the proposed control method provides excellent performances.