• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.75-81
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• 2001

Fuzzy supervisory control method is studied for the active control of earthquake excited structures. The proposed algorithm supervises and tunes previously designed control gains by evaluating the state of a structure through the fuzzy inference mechanism, which uses the information of relative displacements and velocities. Example designs and numerical simulations of earthquake exited three degrees of freedom structures are performed to prove the validity of the proposed control algorithm. Comparative results with conventional LQR method show that the proposed method is effective for the vibration suppression of earthquake excited structures.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.413-418
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• 1992

This paper presents a tree search technique to solve the dynamic control problems. To illustrate the proposed procedure, the swinging control of a pendulum carried by a motor-driven cast is discussed as an example. Since the control system is of two degrees and the control problem is a nonlinear one, it is difficult to determine a swinging control rule analytically. However, by means of the proposed tree search approach, the problem can be solved in a relatively easy way. Some numerical calculations axe performed to verify the methodology. The result of the study shows that the proposed tree search technique is suitable for the dynamic control problems, in particular, for the complicated nonlinear dynamic control problem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.407-412
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• 1997

There has been a recent surge of research interest on the smart structure. This paper presents active vibration control scheme of multi-mode forced vibration using piezoceramic sensors/actuators. The control scheme adopted is the Positive Position Feedback control. Among various vibration control techniques, PPF control technique makes use of generalized displacement measurements to accomplish vibration suppression. Two independent controllers are implemented to control the first and the second modes of the beam under external excitation. Experimental results for various damping ratio and feedback gains of the PPF controllers are compared with respect to the control efficiency. The results indicate that steady state vibration under wideband excitation can be controlled effectively when multiple sets of PZT sensors/actuators were used with PPF control technique.

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.535-549
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• 2011

Control chart is most widely used in SPC(Statistical Process Control), Recently it is a critical issue that the standard control chart is not suitable to non-normal process with very small percent defective. Especially, this problem causes serious errors in the reliability procurement, such as semiconductor, high-precision machining and chemical process etc. Procuring process control technique for non-normal process with very small percent defective and perturbation is becoming urgent. Control chart technique in non-normal distribution become very important issue. In this paper, we investigate on research trend of control charts under non-normal distribution with very small percent defective and perturbation, and propose some variable-transformation methods applicable to CUSUM control charts in non-normal process.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.786-795
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• 2000

In this paper, a new impedance force control method for deburring and polishing process is proposed. The proposed method is robust to deal with unknown environment stiffness as unknown well as environment location. An adaptive technique is used to minimize the force error occurred due to unknown environment surface profile. A robust position control algorithm based on time-delayed information is used to cancel out uncertainties in robot dynamics. A three link robot manipulator is used to demonstrate performances of the proposed control on deburring and polishing tasks. Stability analysis for the adaptive control is presented and its results are confirmed by simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.244-249
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• 1998

In this paper, the hybrid state space self-tuning control technique Is studied within the framework of fuzzy systems and dual-rate sampling control theory. We show that fuzzy modeling techniques can be used to formulate chaotic dynamical systems. Then, we develop the hybrid state space self-tuning fuzzy control techniques with dual-rate sampling for digital control of chaotic systems. An equivalent fast-rate discrete-time state-space model of the continuous-time system is constructed by using fuzzy inference systems. To obtain the continuous-time optimal state feedback gains, the constructed discrete-time fuzzy system is converted into a continuous-time system. The developed optimal continuous-time control law is then convened into an equivalent slow-rate digital control law using the proposed digital redesign method. The proposed technique enables us to systematically and effective]y carry out framework for modeling and control of chaotic systems. The proposed method has been successfully applied for controlling the chaotic trajectories of Chua's circuit.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.701-708
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• 1999

The PWM rectifiers are capable of supplying sinusoidal current control and unity power factor control on the input side and dc output voltage control on the output side. By applying nonlinear control to the PWM rectifiers, the responses of input current and output voltage can be improved and due to fast voltage control the output electrolytic capacitor can be reduced remarkably. In addition, it is checked whether or not the current capacity of the reduced-size capacitor allows the ripple current of the rectifier. The nonlinear control technique gives a good performance for supply voltage disturbances. The validity of the proposed scheme has been verified by the experiment using DSP.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.401-408
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• 2006

An optimum design method for hybrid control systems is proposed in this study. By considering both active and passive control systems as a combined or a hybrid system, the optimization of the hybrid system can be achieved simultaneously. In the proposed approach, we consider design parameters of active control devices and the elements of the feedback gain matrix as design variables for the active control system. Required quantity of the added dampers are also treated as design variables for the passive control system. In the proposed method, the cost of both active and passive control devices, the required control efforts and dynamic responses of a target structure are selected as objective functions to be minimized. To effectively address the multi-objective optimization problem, we adopt a preference-based optimization model and apply a genetic algorithm as a numerical searching technique. As an example to verify the validity of the proposed optimization technique, a wind-excited 20-storey building with hybrid control systems is used and the results are presented.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.3
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• pp.132-138
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• 2011

This paper presents an intelligent control approach for lateral position control of an autonomous four wheel steered snowplowing robotic vehicle. The vehicle is built for removing snow on the highway. Dynamics of the vehicle is derived and linearized for LQR control. Lateral position is controlled by the LQR method first, then the neural network control technique is introduced to improve tracking performances under the presence of load. The feasibility of using four wheel steering control is investigated by simulation studies of lateral position tracking of the Ford F-250 truck model. Performances of a LQR control method and a neural network control method under virtual snowplowing situation are compared.

• ETRI Journal
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• v.20 no.2
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• pp.115-132
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• 1998

This paper proposes an extended service filtering technique to prevent overload in service control point (SCP) due to televoting (VOT) or mass calling (MAS) services with the heavy traffic characteristics. Also, this paper compares this extended technique with the existing overload control techniques, and calculates steady state call blocking probabilities in intelligent network (IN) under overload conditions. The proposed technique considers SCP overload and IN Capability Set (CS)-1 services (such as VOT or MAS service) that have to use the specialized resources of intelligent peripheral (IP). This technique uses first an activating step in which SCP requests service filtering to service switching point (SSP). Then, in the filtering step, SSP sends filtering results to SCP periodically or each N-calls. Also, when filtering time-out expires, SSP stops service filtering, and sends service filtering response to SCP in the deactivating step. This paper applies this technique to VOT/MAS service, and calculates SCP and SSP-IP (circuit) call blocking probabilities by using an analytical VOT/MAS service model. With the modeling and analyzing of this new technique, it shows that this technique reduces the traffic flow into SCP from SSP and IP prominently.