• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.595-598
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• 2000

This paper presents new cutting force measuring system for milling process. Usually, tool dynamometer is the most appropriate measuring tool in an analysis of cutting mechanism. High price and limited space, however, make it difficult to be in-situ system for controllable milling process. Although an alternative using AC current of servomotor has been suggested, it is unsuitable for cutting force control because of low bandwidth and noise. We suggest new cutting force measuring system, using two load cell placed between moving table and nut of ballscrew, and modelled on the system statically and dynamically. And to verify the accuracy of the proposed system, a series of carefully conducted experiments were carried out. Experiment results show that models are in reasonably good agreement with the experiment data.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.4
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• pp.79-91
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• 1995

Recently, the AC motor which has a simple structure and needs less maintenance has become to be used frequently as a servomotor for position control in the automatic control field. This paper concerns with a method to improve the current and power waveforms of an AC motor, and the current waveforms and 3$\phi$ power waveforms are analyzed by FFT under verious running conditions. The system is composed of a digital bridge inverter, low pass LC filter, and 3$\phi$ AC motor. Through the computer simulations and experiments, it is confirmed that current waveforms and $\phi$ power waveforms con by improved by utilizing the high order low pass LC filter than that of lower order.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.2
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• pp.21-27
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• 2007

This paper deals with the issue of trajectory tracking control of a clamping cylinder for injection moulding machine, which is directly driven by speed controlled hydraulic pump in combination with AC servomotor. As a fundamental step prior to tracking controller design, feedback control system is developed by implementing a position control loop parallel with a system pressure control loop. A sliding mode controller combining velocity feedforward scheme is developed for enhancing the tracking performance. Consequently a significant reduction in tracking error is achieved for both position and pressure control applications.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.209-217
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• 2003

In this paper, the dynamic system modeling and the state sensitivity analysis of the spin-coater system are proposed for the reduction of the vibration. In the respect of modeling, the spin-coater system is considered to be composed of servomotor, spindle, supporting base and so on. Each component of model is combined and derived to 3 dimensional equations. The combined model is verified by experimental values of actual system in the frequency domain. By direct differentiation of the constraint equations with respect to kinematic design variables, such as eccentricity of spindle, moment of inertia, rotational stiffness and damping of supported base, sensitivity equations are derived to the verified state equations. Sensitivity of design variables could be used for vibration reduction and natural frequency shift in the frequency domain. Finally, dominant design variables are selected from the sensitivity analysis.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.136-146
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• 1992

This paper provides the end-point positioning of a single-link flexible robot arm by inverse dynamics. The system is composed of a flexible arm, the mobile ballscrew stage as an arm base, a DC servomotor as an actuator, and a computer. Actuator voltages required for the model of a flexible arm to follow a given tip trajectory are formulated on the basis of the Bermoullie-Euler beam theory and solved by applying the Laplace transform method, and computed by the numerical inversion method proposed by Weeks. The mobile stage as the arm base is shifted so that the end-point follows the desired trajectories. Then the trajectory of end-point is measured by the laser displacement sensor. Here, two kinds of functions are chosen for the given tip trajectories. One is what is called the bang-bang acceleration profile and the other is the Gaussian velocity profile.

• Journal of Welding and Joining
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• v.31 no.1
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• pp.26-32
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• 2013

Recently, welding technology of nonferrous metals which were difficult to implement by arc welder has become available through digitalization of arc welding machine. Among them, the welding quality improvement of aluminum welding is very noticeable. These results increase the arc stability by controlling arc current and voltage waveform precisely, and control wire feed speed by synchronizing with arc current which the feed rate of filler wire is controlled by a precise motor control of servomotor and not by a simple constant speed feeding. Not only through the hardware digitalization of arc welding machine but also through advance of software of arc welding, it became possible to implement a certain level of welding quality by a simple operation. These led to CMT welding process implementation which requires low heat input than current arc welding and highly increased the applicability of the aluminum welding.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.199-208
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• 1994

The inverted pendulum is one of the control mechanism that has been frequently used to verify the control theory in the laboratory. In this paper, the author made an inverted pendulum driven by DC servomotor with a simple DC motor drive circuit, and constituted a control system. The control mechanism is modeled, and identified parameters of inverted pendulum system by experimental method. The author used the LQ regulator as control algorithm and the minimum order observer algorithm to observe states that can not be measured. And the validity of parameter identification and the excellent performance of the control system designed by LQR are confirmed.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2111-2113
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• 2002

This paper proposes the design of PI controller using real-coding genetic algorithm showing a good performance on convergence velocity and diversity of population among evolutionary computations. To evaluate the proposed method's effectiveness, we apply the proposed GA-PI controller to the speed control of an actual DC servomotor system. The experimental results show that GA-PI controller has the better control performance than PI controller in terms of settling time rising time and overshoot.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2158-2160
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• 2002

In this paper, we designed the adaptive fuzzy controller(AFLC) using neural network and tabu search. We tuned the weights of neural network changing adaptively input/output gain of fuzzy logic controller and the gain of fuzzy logic controller using tabu search. To evaluate the proposed method's effectiveness, we apply the proposed AFLC to the speed control of an actual AC servomotor system. The experimental results show that AFLC has the better control performance than PI controller in terms of settling time, rising time and overshoot.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.72-75
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• 2018

An initial rotor position estimation method is proposed in this study for an interior permanent-magnet synchronous motor without a resolver or an absolute encoder. This method uses least squares approximation to estimate the initial rotor position. The magnetic polarity is identified by injection of short pulses. The proposed estimation process is robust because it does not require complex signal processing that depends on the performance of a digital filter. In addition, it can be applied to various servo systems because it does not require additional hardware. Experimental results validate the effectiveness of the proposed method using a standard industrial servomotor with interior-permanent magnets.