• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1157-1161
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• 2003

A novel actuator with built-in the displacement and the thrust control function is presented in this paper. This actuator is a kind of compact hydraulic cylinder system which consists of a hydraulic cylinder, a spool, a sleeve, a mechanical feedback mechanism and a stepping motor. The displacement and thrust is in proportion to the rotational angle of stepping motor by the mechanical feedback. In order to investigate characteristics of this actuator, simulation study and preliminary experiments are conducted. Through the preliminary experiment this actuator is very effective in the control for displacement and thrust. Also, it became obvious that the stability of system can be adjusted by using the restrictor with the effect of velocity feedback. Furthermore, this paper explained that a flexible compliance control could be realized by adjusting the feedback weighting in the actuator.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.242-249
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• 1995

In order to search more efficient structural control algorithm, several closed-loop algorithm are developed. Among those, feedback control algorithm using parameters as displacement velocity, and acceleration has been studied. In this paper, especially the characteristics of accleration feedback is studied as more efficient control algorithm than any others. Furthermore the fact that ATMD with acceleration feedback system further reduce the variance of structural displacement rather than with displacement or velocity feedback system will be examined and proved.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1317-1326
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• 2008

This paper presents a self.levelling system for a mass, which undergoes a severe acceleration, with integrated displacement feedback control. After a general description of such a system, theoretical analysis is investigated to design an active control device. The self-levelling system can be used to reduce the "quasi-static" deflection while isolating the "dynamic" vibration. A computer simulation model of 45 kg with two air spring mounts is considered to predict the performance of the control system. Important control parameters were acquired to meet the requirement of the system. The results showed the controller can reduce the displacement of the mass to the level of about 1/5 after control. Thus the self-levelling system can be applied usefully to reduce the displacement of a mass which experiences a high g dynamics.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.9
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• pp.520-525
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• 2003

A robust controller for large space structures(LSS) is studied from passivity point of view. While velocity sensors are commonly used for proportional-derivative (PD) control law to stabilize large space structures, if the structure can be controlled without velocity measurements, it is desirable against the failure of velocity sensors and for the cost reduction of the sensing system. In a recent result a dynamic output feedback control law has been provided using only displacement measurements. This paper presents a passivity-based controller design method and provides an alternative stability analysis tool for the previous displacement feedback robust control law. The closed-loop system can be viewed as a feedback interconnection of a passivated large space structure (LSS) and a strictly positive real (SPR) system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.7
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• pp.339-345
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• 2000

This paper deals with the displacement estimation of magnetically suspended simple 1 DOF(degree of freedom) system without the displacement sensor. Inherently electro-magnet for control has two natural feedback loops. One is the transfer function which represents the dependance of the amount of the magnetic flux on the gap displace-ments. The other is the transfer function expressing the properties that the back electromotive force is derived from the time derivative of the magnetic flux. Through these two feedback loops, information about the gap length can be represented by the magnetic flux and the coil current. This means that the gap length can be detected from these two states variables of the electromagnet without a displacements sensor(self-sensing). The displacement can be estimated with the magnetic flux subtracted by the coil current. In this paper we use a balance beam in order to deal with the displacement sensorless estimation of the magnetic bearing system. For the stable estimation of the gap displacements by using the method of self-sensing simple PD controller is used. We first show the mathematical model of the balance beam, and then we show the effectiveness of the current and flux feedback for making stable estimation of the gap displacements for the balance beam. Simulation results show the effectiveness of the current and flux feedback for good estimation of the displacement without using displacement sensor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.504-507
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• 2005

This paper presents a self-levelling system for a mass, which undergoes a severe acceleration, with integrated displacement feedback control. After a general description of such a system, theoretical analysis is investigated to design an active control device. That is, the self levelling system is used to reduce the 'static' deflections while isolating the 'dynamic' vibration. A computer simulation model of 45 kg with two air spring mounts is considered to predict the performance of the control system. The results showed the controller can reduce the mass's displacement to the level of 1/3-1/5. Thus the self-levelling system can be applied usefully to reduce the dispalcement of a mass which experiences a high g dynamics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.721-724
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• 2002

This study deals with a dynamic behavior analysis of pump control regulator varied the swash plate tilting angle with the positive and negative direction. To accomplish it's purpose, modeling and displacement response analysis about principal parts (spool, servo piston, feedback lever, sleeve) of pump control regulator was performed. We have been able to verifying the propriety of servo mechanism and design parameters of pump control regulator by research results. So, it respect to utilized with useful research data at variable displacement control valve development of variable displacement piston pump.

• Journal of KSNVE
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• v.7 no.6
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• pp.1007-1013
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• 1997

This paper presents active vibration control scheme of multi-mode forced vibration using piezocetamic sensors and actuators. The control scheme adopted is the Positive Position Feedback (PPF) control. Among various vibration control techniques. PPF control technique makes use of generalized displacement measurements to accomplish the 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 ratios and feedback gains of the PPF controllers are compared with respect to the contorl efficiency. The results indicate that steady state vibration under wide band excitation can be controlled effectively when multiple sets of PZT sensors and actuators were used with PPF control technique.

• 전기의세계
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• v.26 no.4
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• pp.54-60
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• 1977

The feedback sources of oculomotor control system consist of three types of feedback path originating from retinal image displacement, in the proprioceptive fibers of the extraocular muscles, in the efference copy within the C.N.S. From above feedback loops, the retinal image feedback path is a main subject in this experiment. The electrical output of eye ball motion detecting with a photo-electric matrix method is fed into galvanometer through the external feedback path, and the stability was also examined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.449-454
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• 1994

The Stewart Platform is one example of a motion simulator which generater 6DOF motion in space by six actuators in parallel. The presented control methrol of 6DOF motion simulator is generally classified into two types, one is SISO and the other is MIMO control type. The SISO control can't compensate for external load variation and different dynamic behavior of 6DOF motion, trerefore this type don's control motion precisely. On the other hand, the MIMO control compensates for a interference of 6DOF motion because MIMO controller is designed with 6DOF motion simulator synamics. But MIMO control of motion simulator has a complexity of 6DOF displacement feedback, because in oder to obtain feedback value we must solve the forward kinematics using measurement of cylinder length or design a state estimator, unless measurement of 6DOF displacement is possible. In this paper, a multivariable controller using H .inf. optimal control theory is designed to consider a interference of 6DOF motion and to obtain robust,precise control of system. Also in order to solve the mentioned problem of MIMO control, this paper presents a modified MIMO control model which control 6DOF motion by using feedback of measurement od cylinder length.