• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.957-961
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• 1991

The parameters of electro-hydraulic servo system are closely dependent on the variation of system characteristics. Especially the parameter sensitivity is incleased in the servo system with heavy load and wide operating range. This paper shows the effect of parameter variation and the experimental parameter values of high power servo system.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.3
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• pp.41-45
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• 1984

Servo 기구의 특성을 해석하고, 또는 원하는 특성을 갖도록 설계하려면 먼저 Servo 기구를 수학적으로 취급하는 방법을 체득하여야 한다. 여기에 사용되는 수법으로 전달함수(transfer function)와 block 선도가 있다. 전달함수는 servo 기구를 구성하는 요소(모우터와 증폭기등)에 대해서 그 입력과 출력 과의 관계를 나타내는 것이며 block 선도는 servo 기구의 구성요소에 의한 시스템적인 구성과 각 부 신호간의 관계를 표시한 것이다.

• Journal of Welding and Joining
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• v.24 no.6
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• pp.13-20
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• 2006

Resistance spot welding is widely used for joining sheet metals in the automotive manufacturing process. Recently, servo-gun is used to increase the productivity and precise control the acting force. However, force control mechanisms have not been investigated with servo-guns until now. In this paper, it is proved that servo-motor current is proportional to torque and by experiment, experimental equation between servo-motor current and electrode force was derived. Algorithm for feedback control of electrode force was suggested using current measurement. In addition, applying soft touch method to this system the impact between electrode and specimen, which is the problem of air gun, could be reduced. Indentation made the force decrease in holding time of resistance spot welding. In order to overcome this problem, force compensation using the servo gun was used and it improved weld strength in good welding current range.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.497-506
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• 1991

In this paper, a new construction for training simulator of R/C helicopter based on two types of servo controller is proposed. Two modified algorithms (algorithm I and II) for servo controller design are presented. Algorithm I is developed by adopting Davison's method in the case that the expressions for the homogeneous differential equations of reference input and disturbance are different types, and algorithm II is done by considering error weighting function for the servo controller of algorithm I . The linear fractional transformation method is incorporated in both design methods in order to assign the closed loop poles of the servo system in a specified region. The helicopter simulator is composed by the gimbals with two freedom of rolling and pitching. The reliability and validity for the design methods of the proposed servo controller are investigated through the practical experiment for the simulator by using 16bits micro-computer with A/D and D/A converters. It can be observered from the experimental results that the proposed servo controller is applicable to practical plants since the simulator is robust for the arbitrary disturbance and it follows to the given reference input without significant steady state error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.453-456
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• 2005

In this paper, design of speed observer and controller for AC servo system by rapid design system(RG-01D) using DSP of Realgain company is introduced. 'AC Servo-Designer' system, including CEMTool/SIMTool S/W, RG-DSOPIO board, AC servo driver and AUTOTool program, is used in this research. Because 'AC Servo-Designer' system can use SIMTool blocks to design and implement various controller in short time, speed observer and controller for AC servo system is easily designed and implemented according to control objectives.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.393-400
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• 1992

The DC(Direct-Current) servo motor has widely used for many application areas, FA(Factory Automation), OA(Office Automation) and home applications. But DC servo motor needs periodical inspection because it has brush and commutator. Recently, AC servo motor has expanded it's application areas due to for the development of the power semi-conductor and control technology. But it has large torque ripple for it's small number of commutation. And it also has cogging torque due to permanent magenet rotor. Therefore it can't run balence rotarion. Many torque ripple reduction methods are published. In this paper, phase advanced method adopted for torque ripple reduction of AC servo motor. In this research, AC servo motor torque characteristic variation surveied under the phase advance control through the computer simulation. Under the simulation, the load inertia varied from 0.0001[Kg.m$^{2}$] to 0.0314[Kg.m$^{2}$]. The result os nonlinear simulation, torque and speed ripple of AC servo motor under the phase advance control reduced approximately 50[%] and 10[%]. And maximum torque of AC servo motor under phase advance control condition increased about 5[%] as compare with fixed switching time.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.95-98
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• 2002

This paper presents a study on DSP(TMS320F240) controller design for multi-axes transportation system using BLDC servo motor. This BLDC servo motor controller was realized with DSP(Digital Signal Processor) and IPM (Intelligent Power Module). The multi-axes transportation system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector modulation technique. As CPU of controller DSP(TMS320F240) is adopted because, it has PWM(Pulse Width Modulation) waveform generator, A/D(Analog to Digital) converter, SPI(Serial Peripheral Interface) port and input/output port etc. The controller of multi-axes transportation system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downword command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC servo motor using DSP and IPM Between host system and middle digital signal processor communicate with RS-422, between main processor and controller communicate with SPI port.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.25-34
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• 2000

In this paper, we design a H^\infty servo controller for gauge control of tandem cold mill. To improve the performance of the AGC(Aotomatic Gauge Control) system based on the Taylor linearized model of tandem cold mill, the H^\infty servo controller is designed to satisfy robust stability, disturbance attenuation and robust tracking properties. The H^\infty servo controller problem is modified as an usual H^\infty control problem, and the solvability condition of the H^\infty servo problem depends on the solvability of the modified H^\infty control problem. Since this modified problem does not satisfied standard assumptions for the H^\infty control problem, it is solved by an LMI(Linear Matrix Inequality) technique. Consequently, the comparison between the H^\infty servo controller and the existing PID/FF(FeedForward) controller shows the usefulness of this study.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1211-1214
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• 1992

AC servo motor drives, Fara DS series, proposed in this paper can be effectively used in robots, CNC machine tools, and FA system with AC servo motors as actuators. The inverter of the AC servo drive consists of IGBT (Insulated Gate Bipolar Transistor) which have high switching frequency. Noises and vibrations generated in variable speed control of AC servo motors can be greatly reduced due to their high switching frequencies. In the developed servo drive, maximum torque is always generated in the whole speed range by compensating phase shift, which results from the nonlinearies of the AC servo motor during abrupt acceleration and deceleration. Abundant protection functions are provided to prevent abnormal state of the servo motor, and furthermore diverse user options are considered provided for the effective application. The proposed AC servo motor drive is designed to minimize velocity variation with respect to external load, supply voltage, environmental temperature, and humidity, so can be widely used in the fields of factory automation including robots and CNC msachine tools.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1664-1672
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• 2002

Gantry mechanisms have been widely used for precision manufacturing and material handling in electronics, nuclear, and automotive industries. Dual-drive servo mechanism is a way to increase control bandwidth, in which two primary axes aligned in parallel are synchronously driven by identical servo motors. With this mechanism, a flexible coupling (compliance mechanism) is often introduced in order to avoid the damage by the servo mismatch between the primary drives located at each side of gantry. This paper describes the design guidelines of the dual-drive servo mechanism with focus on its dynamic characteristics and control ramifications. That is, the effect on the system bandwidth which is critical on the system performance, the errors and torques exerted on guide ways in case of servo mismatch, the vibration characteristics concerned with dynamic error and settling time, and the driving force required at each axis for control are thoroughly investigated.