• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.291-298
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• 2000

This paper describes a theoretical and experimental investigation into an active vibration isolation system in which four electromagnetic actuators are installed in parallel with each of four passive mounts placed between a piece of equipment and a vibrating base structure. Decentralised velocity feedback control is employed, where each actuator is operated independently by feeding back the absolute equipment velocity at the same location. Although one end of each actuator acts at the sensor positions on the equipment, the control system is not collocated because of the reactive forces acting on the flexible base structure, whose dynamics are strongly coupled with the mounted equipment. Isolation of low frequency vibration is considered where the equipment can be modelled as a rigid body and the mounts as lumped parameter springs and dampers. Control mechanisms are discussed, and some experimental and simulation results are reported.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.482-488
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• 2009

Dancer system is typically used equipment for attenuation of tension disturbances. In industrial converting machines, a composite type of dancer system is applied which is mixture of active and passive dancer. It includes feedback position control loop of roll with pendulum dancer and its characteristics is different from passive and active one. In this paper, a mathematical model of the pendulum dancer was derived including PI position feedback controller and it was analyzed by using a pole-zero map and bode plot under various conditions. It was found out that velocity, length of span and inertia were associated with the performance of regulation. It was suggested that the length of upstream span should be greater than that of the downstream and the inertia should be smaller for improvement of the performance. The results can be used for design guidelines of the industrial dancer system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.384-388
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• 1996

The closed-loop system modeling of an Active/semiactive suspension system has been accomplished through an artificial neural Networks. The 7DOF full model as the system equation of motion has been derived and the output feedback linear quadratic regulator has been designed for the control purpose. For the neural networks training set of a sample data has been obtained through the computer simulation. A 7DOF full model with LQR controller simulated under the several road conditions such as sinusoidal bumps and the rectangular bumps. A general multilayer perceptron neural network is used for the dynamic modeling and the target outputs are feedback to the input layer. The Backpropagation method is used as the training algorithm. The modeling of system and the model validation have been shown through computer simulations.

• Journal of KSNVE
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• v.7 no.5
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• pp.811-817
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• 1997

This paper is concerned with the active vibration controller design for the grid structure based on the positive position feedback (PPF) and the strain rate feedback (SRF) control. A new control methodology by the combination of the PPF and SRF control can suppress all the modes of the structure theoretically and can be easily implemented with analog circuits. The underlying concept for the design of the new controller is that the SRF controller stabilizes the modes higher than the second mode and the PPF controller stabilizes the fundamental mode which is destabilized by the SRF controller. In order for the new controller to be implemented succesfully, the collocated control is necessary. To this end, the piezoceramic sensor and actuator are located as close as possible, thus realizing the nearly collocated control. The combined PPF and ARF controller proves its effectiveness by experiments.

• 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.

• Journal of KSNVE
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• v.2 no.2
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• pp.107-116
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• 1992

An adaptive signal processing technique is implemented for the active noise cancellation of the plane acoustic wave propagating in a duct. To avoid the instability caused by the acoustic feedback from the control speaker to the detect microphone, an off-line modeling of the acoustic feedback plant is done using the FIR filter. Auxiliary path required for the filtered-x LMS algorithm is modeled as well. Before going into the experiments, a simulation is carried out under the same conditions with experiments. The simulation shows that the longer the length of the adaptive filter is, the better the results are achieved. Experiments have been carried out at lower audio frequency range (50 - 400Hz), and the results are in good agreements with those of simulation study. As a results of this adaptive noise control, around 50dB is reduced for a pure tone noise, and for a bandlimited noise with the bandwidth of 316Hz, a maximum of 30dB noise reduction is attained.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.3
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• pp.24-32
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• 2007

In this research, using Terfenol-D actuator composed of magnetostrictive material as shaker and controller, active vibration control theory was applied and verified by experiments. PPF(positive Position Feedback) algorithm which is effective for the control of low frequency vibration was used for the control of a structure. Responses of inputs due to various design variable used for the PPF filter were observed. To investigate the characteristics of magnetostrictive materials, actuator responses were measured for known inputs and satisfactory results were obtained to reduce the vibration level after applying the control input for the actuator.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.260-265
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• 2014

Recently, many active noise control (ANC) systems, which employ the adaptive filter controlling method, have been reported for eliminating unwanted noise. ANC systems based on the filtered-X least mean square (FXLMS) algorithm have a problem with compensating the acoustic feedback of secondary route. It is difficult to apply the real time, because transfer function of secondary route must be measured by off-line method to solve this problem. In this paper, we propose the ANC system that applies a correlation LMS(CLMS) algorithm for improving a problem of transfer function measurement. The proposed algorithm is based on input of road noise. The proposed ANC systems have an advantage of real-time process without degradation of performance, although there are many calculation compared with FXLMS algorithm.

• 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.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1307-1309
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• 1996

This paper presents hybrid active noise control (HANC) systems which is based on the combination of feedforward and feedback ANC controllers. HANC systems use FIR filters and is based on primary noise regeneration principle and filtered-X LMS algorithms. HANC systems show better attenuation characteristics and residual spectrum. The order of adaptive filters used in HANC systems is lower than that of conventional feedforward and feedback ANC systems. A proposed HANC algorithm was implemented using a Taxas Instruments TMS320C31 digital signal processor for experimental verification.