• 한국정밀공학회지
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• 제18권4호
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• pp.203-208
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• 2001

In this paper, a novel dual-type positioning mechanism using a voice coil motor(VCM) and a piezoelectric actuator is proposed for optical disk drive or near-field recording type drive. The VCM is used for a coarse motion actuator and the piezoelectric actuator, "S" configuration deflection motion when voltage applied, is used for a fine motion actuator with self-sensing technique, which allows it to sense and actuate simultaneously in a closed loop frame work. When the VCM rotates and stops, a position feedback control algorithm is adopted to further control residu vibration. The performance of the control scheme is confirmed through simulations and experiments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1866-1870
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• 2005

Typical small desktop robots have limied application due to their intrinsic feaures like friction, backlash, etc. However, a newly developed small gantry desktop robot needs smaller footprint and shows better performance in position accuracy, velocity, and acceleration. In order to achieve such results, synchronization control of two axes, position compensation methods in plane are suggested.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.424-427
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• 2002

Pneumatic control systems have the potential to provide high output power to weight and size ratios at a relatively low cost. However, they are mainly employed in open-loop control applications where positioning repeatability is not of great importance. This paper presents precision positioning control of pneumatic servo cylinder with on-off valve, Pneumatic low-friction cylinder with servo valve and DC servo motor under parameter variations. Basically positioning control uses PID controller, where needs a linearized model. A neural network is added to a PID controller to compensator nonlinearity of the system and an influence of friction force is consider as disturbance. The performances of the proposed algorithms were compared by experiments with them of PID controller. From those experiments is was shown that the proposed algorithms are more efficient about settling time, steady 7tate error and overshoot than PID control algorithm.

• 한국정밀공학회지
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• 제15권10호
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• pp.73-80
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• 1998

Recently, we have developed a linear brushless DC motor(LBLDCM) with high speed and precise position control performance to apply it to the semiconductor assembly and inspection machinery. It is composed of double side alignment by two armature-stator pairs and each pair is consist of a moving armature with 8 poles by 3 phase coils and a stator with rare earth permanent magnet (Nd-Fe-B) arrays. Through the thrust force analysis on a simplified and whole model of the suggested LBLDCM by an Electromagnetic FEM solver, skew angle of magnet arrays to reduce the thrust force ripple and the winding conditions of the armature is designed. From experimental results, the user's requirements was satisfied and we confirmed distinctly that the repeatable accuracy less than a micron of the linear motion can be obtained at high speed by the developed LBLDCM. This is owing to directly drive the work without the gear train.

• 전력전자학회논문지
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• 제4권2호
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• pp.138-143
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• 1999

본 논문에서는 직접 구동용 브러쉬 없는 직류 전동기(BLDD)에 있어서 외란에 강인한 위치 제어를 하기 위한 새로운 제어 방법으로 적응 제어형 외란 관측기를 제시하였다. 정밀 위치 제어를 위해서 Field-orientation 방법을 통해 선형화 하였다. BLDC 전동기는 뒤틈(backlash)이 없는 반면에 높은 가격과 비선형 특성에 의한 복잡한 제어기가 필요하다는 단점이 있다. 또한 외부 외란은 전동기의 축에 직접 영향을 미치고 있다. 이 외란은 영향을 줄이기 위해서 Lyapunov 안정성 이론을 이용하였다. 이 이론을 바탕으로 제안된 시스템의 안정성을 증명하였으며, 관측기에서 취한 값을 순간적으로 등가 전류로 계산하여 정궤환(feedforward)하여 보상하였다.

• 한국정밀공학회지
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• 제14권3호
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• pp.98-106
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• 1997

In this paper, a new method of position synchronizing control is proposed for multi-axes driving system. The proposed position synchronizing control system is constituted with speed and synchronizing controller. The speed controller is aimed at the following to speed reference. Furthermore, it is designed to guarantee low sensitivity under some disturbance as well as robustness against model uncertainties using $H_{\infty}$technique. The synchronizing controller is designed to keep minimizing the position error using PID control law which is considered to reduce the dimension of transfer function in the control system. Especially, the proposed method can be easily conducted by controlling only slave axis speed, because it, has variable structure which is decided to master and slave axis by the sign of synchronizing error. Therfore, the master axis which is smaller influenced than another axes by disturbance can be controlled without reducing or increasing its speed for precise position synchronization. The effectiveness of the proposed method is sucessfully confirmed through many experiments.s.

• 한국정밀공학회지
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• 제20권10호
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• pp.22-30
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• 2003

• 제어로봇시스템학회논문지
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• 제22권4호
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• pp.271-275
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• 2016

For machining systems like the motor driven linear stage which have high precision positioning with a long stroke, it is necessary to examine the repeatability of the reference position decision. Though piezo (PZT) actuator driven linear stages have high precision feed drivers and a short stroke, they have some limitations for reference position decisions if they have not been equipped with an accurate home sensor. This study was performed to examine the repeatability for home position decision of a EE-SX671 photo sensor as a home switch by using piezo actuator driven linear stages and capacitance probe.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.389-391
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• 1999

Recently, the application of the linear machine for industrial field is remarkable increased, especially for the gantry machine. machine tool system and CNC. In these application fields. high precise position control performance is essentially required in both the steady and transient state. And linear machine is necessary for high-precision processing and manipulation when relatively high forces are involved. This paper presents the new unified PID position control algorithm which have rare sensitivity to disturbance, which the gain adjusting process is simple. Also this paper investigates the use of the New Unified PID control to design for high stiffness. Through the experimental results, it is shown that the proposed algorithm has high dynamic characteristic for the linear machine application field nevertheless of its simple structure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.383-388
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• 2004

A piezoelectric actuator yields hysteresis effect due to its composed ferroelectric. Hysteresis nonlinearty is neglected when a piezoelectric actuator moves with short stroke. However when it moves with long stroke and high frequency, the hysteresis nonlinearty can not be neglected. The hysteresis nonlinearty of piezoelectric actuator degrades the control performance in precision position control. In this paper, in order to improve the control performance of piezoelectric actuator, an inverse modeling scheme is proposed to compensate the hysteresis nonlinearty problem. And feedforward - feedback controller is proposed to give a good tracking performance. The Feedforward controller is inverse hysteresis model, Nueral network and PID control is used as a feedback controller. To show the feasibility of the proposed controller and hysteresis modeling, some experiments have been carried out. It is concluded that the proposed control scheme gives good tracking performance