• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.684-686
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• 1998

This paper consider fuzzy control of a single-inverted pendulum attached to the tip end of a rotating arm driven by a direct driven motor. Control objectives stabilization of the pendulum at the upright position and regulation of the arm at an arbitrary specified position. Fuzzy control is an effective method to achieve multiple control objectives in control of nonlinear systems. In this paper, fuzzy logic control is proposed to obtain increased control performance and stability.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.6-11
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• 1988

Alight-weight robot arm carrying a payload is modelled as a cantilever beam with a tip mass subjected to a high speed rotation. Equations of Motion, for modal control, are represented as discrete state variable form. Digital optimal control law with observer is developed to suppress the arm vibration and control the position of the joint angle. The effects of the number of controlled modes, weighting factors of the performance index, reference rotation time, and sampling time on the control performance are analyzed by computer simulation and experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.8
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• pp.682-688
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• 2000

To improve the performance of a flexible robot arm one of the important things is the vibration displacement measurement of a flexible arm. Many types of sensors have been used to measure it, The most popular has been strain gauges which measures the deflection of the beam,. Photo sensors have also been for detecting beam displacement and accelerometers are often used to measure the beam vibration. But the vibration displacement can be obtained indirectly from these sensors. In this article a vision sensor is used as a displacement sensor to measure the vibration displacement of a flexible robot arm. Several schemes are proposed to reduce the image processing time and increase its accuracy. From the experimental results it is seen that the vision sensor can be an alternative sensor for measuring the vibration displacement and has a potential for on-line tip position control of flexible robot systems.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.68-75
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• 2000

The flexibility of a manipulator inevitably yields vibration at the end effector. In this work, position and vibration control for a flexible robot arm was studied using a separate voice coil type actuator to raise the accuracy and speed of end tip. A flexible robot arm with a tip mass is modeled as an Euler-Bernoulli beam. An $H_$\infty$$ controller is adapted to get a robust control against unmodeled higher-order mode vibration, output sensor noise, and etc. Simulations and experiments show that the modeling of the system is acceptable and robust vibration control is also achieved.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.3
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• pp.81-88
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• 1997

This paper dealt with the position control of a flexible miniature finger driven by piezoelectric bimorph cells, cemented on both side of the finger. Bending moments generated by cells drives the finger, and end-point of the finger is controlled, so as to move in synchrony with fluctation of target and maintain a constant distance between target surface and inger's tip. The voltage applied for the cell is controlled by tip displacement error and error rate. We proposed a PD-Fuzzy controller under conception of PD control strategy. It brought and advantage which reduce number of rules than that of same type conventional fuzzy system and more correct redponse than PID control results.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.842-848
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• 2005

The decoupling control using state feedback was once intensively studied during 1960's by many researchers. However, this control scheme was sensitive to the disturbance and Parameter variations. SMC(sliding mode control) is known as a robust control methodology to overcome such a disturbance. In this paper. the decoupling control by means of SM(sliding mode) for a trajectory control of a two-degrees-of- freedom manipulator was discussed. The position and velocity of manipulator tip were adopted to compose a nonlinear error functions. The reference inputs of the controller can be decided by switching function combined with the desired position and velocity. Simulation result is provided to verify the effectiveness of the proposed control scheme.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.223-231
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• 1999

The one of basic functional conditions of suspended overhead sprayer, which is openly made use of irrigating on bedding plants in greenhouse, is to be kept the growing uniformity of bedding plants by making uniformly the spraying irrigation depending on the distribution of sprayed water. This study was performed to find out the optimum position of sector formed injection nozzle which is placed from the top of plant 0 the tip of the nozzle to keep spraying uniformity. The test of spraying distribution using a overhead sprayer, which was installed in a row of sector formed injection nozzles, was performed The measuring factor to represent spraying distribution was the water weight filled in each cup when the overhead sprayer was moving across the upside of the cups which were placed directly under the nozzles on keeping the distance from nozzle tip. The test results were as following , The standard mr of weights of each cup filled with spraying water was lower values at Position far from more than 60cm under nozzle tip. The driving speed variation of sprayer was not effected on spraying uniformity but the spraying water weight was inversely proportioned to the speed. To make best spraying uniformity, it was represented that the tip of the nozzle is positioned to keep the distance which the top of plants is placed at the second cross point of each injection sector of nozzles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.342-345
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• 1995

This paper describes the design process and the experimental results of a fuzzy logic controller to control the tip position of a fixible-link manipulator, directly driven by a AC motor, with a large payload. The joint angle fuzzy logic controller is designed without a costly nonlinear system analysis of the flexible manipulator and the AC motor drive system. The state variables for the fuzzy logic controller are joint angle, joint velocity, link deflection, and link deflection velocity. The simulation and experimental results show that the joint position control is not satisfactory when the controller is designed under the assumption of no link flexibility and that stable joint position control and link vibration suppression can be cahieved with the fuzzy logic controller suggested in this paper.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.177-185
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• 2006

Cavitation is the dominant noise source of the marine vehicle. Of the various types of cavitation , tip vortex cavitation is the first appearance type of marine propeller cavitation and it generates high frequency noise. In this study, tip vortex cavitation behavior and noise are numerically investigated. A numerical scheme using Eulerian flow field computation and Lagrangian particle trace approach is applied to simulate the tip vortex cavitation on the hydrofoil. Vortex flow field is simulated by combined Moore and Saffman's vortex core radius equation and Sculley vortex model. Tip vortex cavitation behavior is analyzed by coupled Rayleigh-Plesset equation and trajectory equation. The cavitation nuclei are distributed and released in the vortex flow result. Vortex cavitation trajectories and radius variations are computed according to nuclei initial size. Noise is analyzed using time dependent cavitation bubble position and radius data. This study may lay the foundation for future work on vortex cavitation study and it will provide a basis for proper underwater propeller noise control strategies.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.1
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• pp.92-106
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• 1990

Active compliance is often used in the control of robot manipulators for the implementation of complex tasks such as assembly, multi-finger fine motion, legged-vehicle adaptive control,etc. This technique balances the interactive force between the manipulator tip and its working environment with its position and velocity errors to achieve the operation of a damped spring. This paper investigates the effecft of passive compliance on system stability with regard to force feedback implementation for actively compliant motion. Usually it is understood that accurate position control require a stiff system. However, theoretical examination of control experiments on a legged suspension vehicle suggests that, if the control includes discrete-time force feedback, some passive compliance is necessssary at the legs of the vehicle for system stability. This can be an important factor to bl considered in manipulator design and control. A theoretical analysis, numerical simulation, and experimental result, confirming the above conclusion, are introduced in this paper.