• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.10
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• pp.439-445
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• 2002

In this paper force feedback control system is investigated for improving the quality of the haptic feedback in virtual reality applications. We suggested the method of controlling the haptic device and modelling the virtual environment. Haptic device is composed of five bar link structure, voice coil motor, control board, and virtual environment modeling program. We applied voice coil motor in the actuating system for simple structure and easy control. Virtual environment modelling is constructed in PC, and the control signals of the actuators and the encoder data are transferred to the control system through USB. Experiment is performed to evaluate the characteristics of the haptic device.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.438-443
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• 2003

In this paper, we propose a control algorithm for two-wheel mobile robot that can move the rider to his or her command and autonomously keep its balance. The control algorithm is based on a mixed $H_2/H_{\infty}$ control scheme. In this control problem the main issue is to move the rider while keeping its balance in the presence of disturbances and parameter uncertainties. The disturbance force caused by uneven road surfaces and the uncertainty due to different rider's heights are considered. To this end we first consider a state feedback controller as a basic framework. Secondly, we obtain the state feedback gain $K_2$ minimizing the $H_2$ norm and the state feedback gain $K_{\infty}$ minimizing the $H_{\infty}$ norm over the whole range of parameter uncertainty. Finally, we select mixed $H_2$/$H_{\infty}$ state feedback controller K as the geometric mean of $K_2$ and $K_{\infty}$. Simulation results show that the mixed $H_2/H_{\infty}$ state feedback controller combines the effects of the optimal $H_2$ state feedback controller and robust $H_{\infty}$ controller state feedback controller efficiently in the presence of disturbance and parameter uncertainty.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.653-660
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• 2000

The automatization by industrial robot of today is merely rely on to the simple position repeating works, but requirements of research and development to the force control which would adapt positively to various restriction or contacting works to environment. In this paper, a learning control algorithm using, neural networks is proposed for the position and force control by a direct-drive robot. The proposed controller is the feedback controller to which the learning function of neural network is added on to and has a character of improving controller's efficiency by learning. The effectiveness of the proposed algorithm is demonstrated by the experiment on the hybrid position and force control of a parallelogram link robot with a force sensor.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.840-843
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• 1996

This paper presents an adaptive cutting force controller for milling process, which can be attached to most commercial CNC machining centers in a practical way. The cutting forces of X,Y and Z axes measured indirectly from the use of currents drawn by AC feed-drive servo motors. A typical model for the feed-drive control system of a horizontal machining center is developed to analyze cutting force measurement from the drive motor. The pulsating milling forces can be measured indirectly within the bandwidth of the current feedback control loop of the feed-drive system. It is shown that indirectly measured cutting force signals can be used in the adaptive controller for cutting force regulation. The robust controller structure is adopted in the whole adaptive control scheme. The conditions under which the whole scheme is globally convergent and stable are presented. The suggested control scheme has been implemented into a commercial machining center, and a series of cutting experiments on end milling and face milling processes are performed. The adaptive controller reveals reliable cutting force regulating capability under various cutting conditions.

• Physical Therapy Korea
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• v.8 no.3
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• pp.27-34
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• 2001

Physical therapists have been using biofeedback training to induce improvements in various circumstances. The purpose of this study was to compare the effects of visual and tactile feedback using electrical stimulation on quadriceps strength. Nineteen women without known impairment of the neuromusculoskeletal system volunteered for this study. Subjects were randomly allocated into three groups: visual feedback, tactile feedback, and control group. The torque of isometric knee extension force was measured. Subjects were asked to exert the maximal isometric contraction force of quadriceps over a 30 second period. The resting period of 10 minutes was given after the maximal isometric contraction to avoid the muscle fatigue. In between groups comparison, significant differences of the peak torque and the torque area were found on the performance of the maximal isometric contraction of quadriceps (p<.05). The values peak of torque and torque area were significantly higher during visual feedback than tactile feedback. The results of this study suggest that visual feedback is more powerful than tactile feedback (p<.01).

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1513-1518
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• 1996

A force reflecting hand controller can be used to provide more realistic information to the operator of a teleoperation system such as kinesthetic feedback from a slave robot. In this paper, a new design concept of a force reflecting 6-DOF hand controller utilizing the kinematic structure of a Stewart Platform is presented. Based on the optimal design technique of a Stewart Platform, a force reflecting hand controller has been designed and constructed to verify the technical feasibility of proposed design concept. In order to provide an operator with kinesthetic feedback information, a force mapping algorithm based on a reciprocal product of screws has been introduced. Finally, the technical feasibility of the design concept has been demonstrated through some of experimental results of the device under virtual environment on a real-time graphic system.

• Smart Structures and Systems
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• v.18 no.1
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• pp.31-52
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• 2016

The paper first reviews the theory of active tendon control with decentralized Integral Force Feedback (IFF) and collocated displacement actuator and force sensor; a formal proof of the formula giving the maximum achievable damping is provided for the first time. Next, the potential of the control strategy for the control of suspension bridges with active stay cables is evaluated on a numerical model of an existing footbridge; several configurations are investigated where the active cables connect the pylon to the deck or the deck to the catenary. The analysis confirms that it is possible to provide a set of targeted modes with a considerable amount of damping, reaching ${\xi}=15%$. Finally, the control strategy is demonstrated experimentally on a laboratory mock-up equipped with four control stay cables equipped with piezoelectric actuators. The experimental results confirm the excellent performance and robustness of the control system and the very good agreement with the predictions.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.3
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• pp.150-156
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• 2015

In this paper, it was proposed a new technology to improve the performance of the remote control in virtual reality applications. The operator must know the information of surroundings of the robot, collision possibility of the equipment, and force feedback of the manipulator. The time delay problem occurs in the tele-operating and it causes vibration and expressive power of the manipulator owing to bidirectional force feedback. We presented a new control method to control of the teleoperating system based on serial bus. The reliability is evaluated by simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.35-40
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• 1997

The present study considers the analysis and control of the bonding process for a LOC DIe Bonder. A mathematical model for describing the bonding process is developed and proved by experiments. A feedback scheme is also applied for system in order to ensure the robustness of the bonding force control. The theoretical and experimental results are proved useful for the design and control of the LOC Die Bonder.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1684-1687
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• 1997

A dynamic load simulator which can reproduce on-ground the hinge moment of aircraft control surface is and essential rig for the loaded performance test of aircraft test of aircraft acutation system. The hinge moment varies wide in the aricraft flight enveloped depending on specific flight condition and maneuvering status. To replicate the wide spectrum of this hinge moment variation within some accuracy bounds, a force controller is designed based on the Quantiative Feedback Theory (AFT). Through the analysis on hinge moment dynamics, a design specification for the force controller is suggested. The efficacy of QFT force controller is verivied by simulation, in which combined aricraft dynamics/flight control law and hydraulic actuation system dynamics of aircraft control surface are considered.