• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.977-981
• /
• 2000

Direct drive linear motors have large potential for use as high speed machine tool feed units since they can increase machining rates and improve servo accuracy by eliminating gear related machining problems. So, in this paper, characteristic of 2-axis linear motor feed unit are studied and control gain are adjusted considering positioning, velocity, acceleration and static stiffness. We confirm linear motor feed unit are affected value of control gain sensitively, because drive directly. From the experiment, this feed unit has l${\mu}{\textrm}{m}$ micro step resolution, 5.7${\mu}{\textrm}{m}$ positioning accuracy and under 60${\mu}{\textrm}{m}$ circularity.

• 한국정밀공학회지
• /
• 제34권4호
• /
• pp.265-272
• /
• 2017

Velocity ripple in manufacturing processes reduces productivity and limits the precision of the product. In practice, the frequency and phase of velocity ripples always change minutely, which makes it impossible to compensate for the ripple by simply inserting an opposite feed-forward signal in the system. In this study, an active-phase compensation algorithm was developed to enable the velocity-ripple controller to track the phase change of the ripples in real time. The proposed controller can compensate for the velocity ripple whatever its cause, including disturbance by the torque ripple. The algorithm consists of three functional modules: the velocity-ripple extractor, the synchronized integrator, and the phase shifter. Experimental results showed that the proposed controller clearly reduces velocity ripples with phase variation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.314-316
• /
• 2001

This paper present the position control method for the application of permanent magnet linear synchronous motor. Controller is designed as a conventional P-PI controller, but the extra information is used such as velocity and acceleration from motion profiles. The profiles comes from S-Curve which is an optimized point-to-point motion profiles to achieve fast motions with minimum vibration[2]. In this application, the targets of the position control are maximum 10um position error within 10msec after respective ending point of position profiles. The implementation of the controller has been done in full digital way. All the controller is designed on the DSP TMS320VC33 control board. To prove performance of the controller, the experiment was performed with a servo linear motor.

• Journal of Power Electronics
• /
• 제19권5호
• /
• pp.1216-1223
• /
• 2019

The Double-sided Linear Switched Reluctance Machine (DLSRM) suffers from complex eccentricities in practical operations. A novel sensorless control method for a DLSRM with eccentricities is developed in this paper. The influences of eccentricities on the machine inductance characteristics and the estimated positions in sensorless control systems are discussed. A new position index, which is independent of eccentricities, is proposed according to an analysis of a DLSRM equivalent magnetic circuit. On the basis of this position index, the starting and low-velocity operation of eccentric DLSRMs are achieved. Experimental results obtained in the laboratory validate the proposed method.

• 한국정밀공학회지
• /
• 제22권12호
• /
• pp.51-60
• /
• 2005

This paper describes a robust control scheme for high-speed and long stroke scanning motion of high precision linear motor system consisting of linear motor, air bearing guide and position measurement system using heterodyne interferometer. Nowadays, semiconductor process and inspection of wafer or LCD need high speed and long travel length for their high throughput and extremely small velocity fluctuations or tracking errors. In order to satisfy these conditions, linear motor system are widely used because they have large thrust force and do not need motion conversion mechanisms such as ball screw, rack & pinion or capstan with which the system are burdened. However linear motors have a problem called force ripple. Force ripple deteriorates the tracking performances and makes periodic position errors. So, force ripple must be compensated. To maximize the tracking performance of linear motor system, we propose the control scheme which is composed of a robust control method, Time Delay Controller (TDC) and a feedforward control method, Zero Phase Error Tracking Control (ZPETC) for accurate tracking a given trajectory and an adaptive force ripple compensation (AFC) algorithm fur estimating and compensating force ripple. The adaptive ripple compensation is continuously refined on the basis of tracking error. Computer simulation results based on modeled parameters verify the effectiveness of the proposed control scheme for high-speed, long stroke and high precision scanning motion and show that the proposed control scheme can achieve a sup error tracking performance in comparison to conventional TDC control.

• 대한기계학회논문집B
• /
• 제28권10호
• /
• pp.1238-1246
• /
• 2004

Momentum exchange theory has been generally used for an analysis of the regenerative turbomachines due to its direct description of the complicate circulatory flow. However, because its application is limited only to linear region and its model equations are incomplete on three variables, it needs further refinements. In the present study it is improved by introducing a central pivot of circulatory flow. Also, by assuming linear circulatory velocity distribution, mean radii of inlet and outlet flows through the impeller are newly suggested. By applying control volume analysis to both linear region and the acceleration region, the governing equation on the circulatory velocity is derived. As a result, systematic performance analysis on the entire region of the incompressible regenerative turbomachines can be carried out based on the proposed model equations.

• 한국전산유체공학회지
• /
• 제4권3호
• /
• pp.28-34
• /
• 1999

The objective of this study is to present a numerical treatment of the pressure gradient when control volumes are sharing the interface between a homogeneous fluid and a porous medium. Two possible approaches, e.g. linear interpolation and extrapolation, are considered, and they are applied to the case of a steady and two-dimensional curved channel flow which is partially filled with a porous medium. It was found that the linear extrapolation produces a continuous velocity-field at the interface and thus is recommended. On the contrary, the linear interpolation entails a discontinuous velocity field at the interface, thereby warning its use in connection with the Brinkman-Forchheimer-extended Darcy flow model.

• 한국산학기술학회논문지
• /
• 제12권8호
• /
• pp.3360-3365
• /
• 2011

본 논문은 힘 보조형 휠체어에 있어 힘 센서 없이 사용자의 구동 의지를 측정하는 방법과 이를 통한 차량제어 방법을 제시한다. 이를 위해 먼저 모터의 수학적 모델을 이용하여 사용자의 구동 의지력을 추정하는 알고리즘을 도출한다. 이후 도출된 외력을 기반으로 사용자가 원하는 차량 속도 및 방향을 추정한다. 이를 토대로 차량의 이동량을 결정하고 차량이 이에 따라 구동되도록 알고리즘을 구성하였으며 이를 시뮬레이션을 통해 검증하였다.

• 제어로봇시스템학회논문지
• /
• 제21권5호
• /
• pp.434-441
• /
• 2015

In this paper, we propose an inverse optimal distributed protocol for the formation and velocity consensus of nonholonomic mobile robots. The communication among mobile robots is described by a simple undirected graph, and the mobile robots' kinematics are considered. The group of mobile robots driven by the proposed protocols asymptotically achieves the desired formation and group velocity in an inverse optimal fashion. The design of the protocols is based on dynamic feedback linearization and the proposed linear quadratic (LQ) inverse optimal second-order consensus protocol. A numerical simulation is given to verify the effectiveness of the proposed scheme.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 B
• /
• pp.679-681
• /
• 1995

In this paper, a friction compensation scheme using a fuzzy logic is presented. For the precision positioning and tracking control, the proper friction compensation is essential. Friction compensation schemes based on velocity and controlling input or desired velocity, have limitations because the compensation values are fixed. In this paper, a fuzzy friction compensation scheme adjusts the compensation value depending on the velocity and the position error. The proposed fuzzy friction compensator is implemented in a linear positioning system. The performance is illustrated by simulations and experiments.