• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.166-172
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• 2003

The dynamics of the DDWMR depends on the velocity difference of the two driving wheels. And which is known as a type of non-holonomic equation. By this reason, the treatment of DDWMR had become difficult and conservative. In this paper, the differential-driving wheeled mobile robot is considered. The Takaki-Surgeno fuzzy model and a control method for DDWMR is presented. The suggested controller has three control elements. The first element is fuzzy state feedback designed for eliminating the dependence of time-varying parameter. The second element is weighting controller which is designed for good frequency response. The third controller is PI-controller which is designed for good command following and robustness with un-modeled dynamics. In order for achieving the performance objective, the design of controller is based on the loop-shaping algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.959-965
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• 2011

This paper presents the dynamic modeling and vibration suppression methods for axially deploying beams subjected to gravity. A modal modeling method is employed to develop the lateral vibration model for axially deploying beams. Simulation is made to validate the proposed model as well as to investigate the dynamics of axially deploying beams. This paper rigorously investigates the gravity effect as a source of vibration for axially deploying beams. In order to suppress lateral vibration for deploying beams, the moving speed command is modified by using the input shaping method, Experiments are also performed to prove the proposed vibration suppression method. The simulations and experiments show that the proposed modeling and input shaping methods are effective for the dynamic analysis and vibration suppression of axially deploying beams subjected to gravity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1854-1862
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• 2000

Input shaping method is to convolute input shaper, which is sequence of impulses, with reference input command not to excite the natural frequency of system. To reduce residual vibration for the ch ange of frequency, the number of impulses should be increased. Until now, amplitudes and time interval of those has been searched from the derivative of residual vibration. However, if time interval of impulses is fixed as the half of vibration period of system, input shaper H(z) in z-domain becomes (I-pz-1)n/K in which increasing n is the mean that robustness for change of parameter is improved. Also, design of many types of input shapers in z-domain is very easy because sensitivity curve is displayed with $\mid$H(z)zn$\mid$$\times$100. In the z-domain, EI(Extra-Insensitive) input shaper could be designed without solving nonlinear simultaneous equations as design in continuous time domain. In addition to, the design possibility of input shaper for a damped system was shown.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.9-16
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• 1996

LQ-servo is a robustness guaranteed multivariable controller design method based on the LQR structure to improve command following with output feedback. in this paper we introduce a weighting factor on the low frequency part of the state weighting matrix in the performance index in order to increase the low frequency gain of loop transfer function matrix T(s) in the loop shaping design method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.3
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• pp.48-57
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• 1995

The feasibility of generating controller surface topographies in single-point conventional turning operations is investigated. First, a mathematical model of the surface generation process was developed. Second, in order to control the texture of the machined surface, a micro-positioning stage and the associated command generation software were designed and built. Experimental examples have shown that surface texture can be precisely controlled and is in good agrement with the theoretical predictions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.24-33
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• 1995

The feasibility of generating controlled surface topographies in single-point conventional turning operations is investigated. First a mathematical model of the surface generation process was developed. Second in order to control the texture of the machined surface a micro-positioning stage and the associated command generation software were designed and built. Experimental examples have shown that surface texture can be precisely controlled and is in good agreement with the theoretical predictions.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.109-115
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• 2004

Polishing process has been applied to get extremely fine surfaces, e.g., mirror surfaces such as optical mirrors, lens, molds and etc. Nowadays not only fine surface quality but also submicron order of dimensional accuracy is required for many applications. To meet the requirements polishing process should be provided with an active control of polishing pressure especially for automation of polishing process. In this paper a study on development of an active polishing pressure control system has been presented. A new type of tool assembly has been developed to facilitate the control. The tool is attached to an axis of a polishing machine with a coil spring and control of the polishing pressure is done by the position control of the axis, which needs no additional actuator. The polishing pressure is successfully measured by the measurement of the spring deformation. Control specifications were quantitatively considered by weighting functions and a controller was designed by using loop-shaping technique based on the no synthesis. Some experiments have been executed on a polishing machine with a PC-NC controller. It is shown that the results were coincident well with the theoretical analyses and satisfied the design specifications.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.67-76
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• 2008

In this research, a simple technique for designing PID controller, which guarantees robust stability for two-mass systems with parameter uncertainties as well as rigid-body behavior and zero steady-state error,is described. As well, such a PID controller is designed to mate two important frequencies, at which the given system is excited, very close so that an appropriate reference profile generated by using command shaping techniques can cover those two frequencies. Root-locus analysis. which shows traces of closed-loop poles for the given system, is used to design this PID controller. Finally, feedforward controller is added to improve tracking performance of the closed-loop system. Simulation for a system with a flexible mode and parameter uncertainties is executed to prove the feasibility of this technique.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.157-163
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• 2001

This paper presents the new linear notion device so called \"inch-werm\" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Finite element method and experimental approach are used to analyse the static and dynamic motion of the designed inch-worm. Command reference input is shaped to reduce the residual vibration of inch-worm. The practical feasibility of inch-worm is also examined by running tests.ing tests.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.5
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• pp.443-449
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• 1997

LQ-servo design procedure introduced by Athans is a method using a partial states feedback and an output feedback in order to improve the poor performance robustness of the LQR as well as to maintain its stability robustness. Although the method guarantees good stability robustness, it is not effective in performance robustness as it does not match the singular value at low or high frequencies of the transfer matrix obtained by breaking at the plant output. This paper intends propose of a new method, using the limited behaviour of the control gain introduced by Kwakernaak and Sivan, in order to improve it does it refer to controlga introduced by kwakernaak or the new metho Anblguouls.