• Proceedings of the KIEE Conference
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.133-135
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• 2006

This paper considers a speed control problem of DC motor under load variations. In order to reduce the effect of load variation, a disturbance observer has been designed for the given system. With a cheap encoder there exists considerable measurement noise in the velocity feedback and it should be reflected in designing the disturbance observer. The authors have obtained the nominal transfer function of a DC motor and designed a disturbance observer for the control purpose. With the disturbance observer a digital controller has been implemented using a DSP(TMS320F2812). Some experiments show the enhanced performance of the control system with the proposed method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제7권4호
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• pp.130-135
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• 1998

This paper deals with a position control problem of a hydraulic proportional position control system using a friction compensation control. There are many nonlinearities in hydraulic systems. With only proportional controller, response is slow and steady-state error cannot be compensated properly. Controller designed in this paper achieves fast transient response through the velocity and acceleration feedback and good steady-state response through the friction compensator. A/D and D/A board is employed for data acquisition and manipulation. The experimental results are compared with computer simulation results using Matlab.

• Journal of the Korean Society for Precision Engineering
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• 제14권6호
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• pp.90-98
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• 1997

A time-optimal control law for quick, strongly nonlinear systems has been developed and demonstrated. This procedure involves the utilzation of neural networks as state feedback controllers that learn the time-optimal control actions by means of an iterative minimization of both the final time and the final state error for the systems with constrained inputs and/or states. A neural identifier or a genetic algorithm identifier could be utilized for modeling the partially known systems and the unknown systems. The nature of neural networks as a parallel processor would circumvent the problem of "curwe of dimensionality". The control law has been demonstrated for both a torque input motor and a velocity input motor identified by a genetic algorithm called GENOCOPed GENOCOP.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.950-957
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• 2003

This paper deals with adaptive fuzzy logic controller design to achieve proper dynamic response of a composite thin-walled beam with a tip mass. In order to check the effectiveness of this controller, three different types of control logic are selected and applied. The adaptive control capabilities provided by a system of piezoactuators bonded or embedded into the structure are also implemented in the system. Results show that the fuzzy logic controller is more effective than the proportional or velocity feedback controller for the vibration control of composit thin-walled beam with a tip mass.

• Proceedings of the KIEE Conference
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.105-108
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• 1988

In this paper, a control system design method is proposed for DC motor drive. A state space model is used to control sysytem and for closed loop system the technique of pole assignment is applied. The control system is designed with state feedback theory and to improve the response further more feedforward theory is applied to control system. The microprocessor as a controller and the interfaces in the system are proposed. Digital simulation results for step changes in reference velocity and load torque are shown.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.424-428
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• 2004

A wind turbine system converts wind energy into electric energy, the system operated under normal environmental conditions. In case of particular turbulent wind flow such as typhoon, hurricane etc, the control of a blade used to a yaw control and a pitch control method. A small wind turbine has not a speed control system to only a manual tail safety brake. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The controller composed of wired motor, relay system, steel wired motor him down a perpendicular to wind flow and then the blade speed reduced high to zero. The operation of automatic tail safety controller verified by manual test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제11권6호
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• pp.193-199
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• 2001

Active control of forced vibration of the cantilevered laminated composite plates using collocated piezoceramic sensor/actuator is analyzed numerically and verified experimentally for various fiber orientations. Impact on the stiffness and the damping properties is studied by varying stacking sequence of [$\theta$$_{4}$O$_{2}$90$_{2}$]s for the laminated composite plate. For the forced vibration control, the plate is excited by one pair of collocated PZT exciters in resonance and its vibrational response is suppressed by the other collocated PZT sensor/actuator using direct negative velocity feedback. It is shown that the active control of forced vibration is more effective for the smart laminated plate with higher modal damped stiffness(2ζ$\omega$/aup 2/) .

• Journal of the Korean Society of Physical Medicine
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• 제12권3호
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• pp.67-71
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• 2017

PURPOSE: Muscle fatigue is a cause to change proprioception. The purpose of this study was to investigate the effects of calf muscle fatigue and visual control on postural balance during single-legged standing in healthy adults. METHODS: Nineteen healthy adults (male) were participated in this study (mean age: 24.36 years; mean height: 171.32 cm; mean weight: 64.58 kg). The postural balance (sway length, sway area, sway velocity of COG displacement) was measured by Balance Trainer System (BT4) in before and after calf muscle fatigue feeling in single legged stance. In this study, repetitive single-legged heel rise test was used to induce fatigue of the calf muscle. Paired t- test was used to compare the postural balance between before and after calf muscle fatigue. Data of subjects were analyzed using SPSS 22.0 (SPSS Inc., Chicago, IL, USA). Level of significance was set to .05. RESULTS: The sway length, sway area, sway velocity of COG (center of gravity) displacement after calf muscle fatigue feeling was significantly increased compared to before calf muscle fatigue feeling during single leg standing both eye open and close conditions (p<.05). CONCLUSION: This study suggested that calf muscle fatigue feeling has affected on postural balance when standing one leg both eye open and close conditions and postural control was disturbed by muscle fatigue and visual feedback in single leg standing.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제5권3호
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• pp.266-272
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• 2004

In this paper, an observer-based adaptive controller is proposed to control the longitudinal motion of vehicles. The standard gradient method will be used to estimate the vehicle parameters such as mass, time constant, etc. The nonlinear model between the driving force and the vehicle acceleration will be chosen to design the state observer for the vehicle velocity and acceleration. It will be shown that the proposed observer is exponentially stable, and that the adaptive controller proposed in this paper is stable by the Lyapunov function candidate. It will be proved that the errors of the relative distance, velocity and acceleration converge to zero asymptotically fast, and that the overall system is also asymptotically stable. The simulation results are presented to investigate the effectiveness of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.701-704
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• 2005

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But They are difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose a nonlinear adaptive PID controller based on a cell-mediated immune response and a gradient descent learning. This algorithm has a simple structure and robustness to system parameters variation. To verify performances of the proposed nonlinear adaptive PID controller, the speed control of nonlinear DC motor is performed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation.