• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
• /
• pp.448-451
• /
• 2004

MSC (Multi-Spectral Camera) system is an electro-optical camera system which is being developed to be installed on KOMPSAT-2 satellite. High resolution image data from MSC system will be transmitted to the ground-station through x-band antenna called APS (Antenna Pointing System). APS is a directional antenna which will point to the receiving antenna at ground station while the satellite is passing over it. The APS needs to be controlled accurately to provide the reliable communication with big RF link margin. The APS is controlled by ATS (Antenna Tracking Software) which is included in the MSC software. ATS uses the closed loop control algorithm which will use TPF (Tracking Parameter File) as an input for antenna position, and will use two resolve readings from APS as a feedback. ATS has been developed and verified using APS QM (Qualification Model) and all the control parameters for ATS have been tested and verified. Various kinds of maximum, nominal and realistic dynamics for the APS movement have been simulated and verified. In this paper, closed loop servo control algorithm and obtained APS position error from the verification test with APS QM will be presented in detail

• 제어로봇시스템학회논문지
• /
• 제14권4호
• /
• pp.385-391
• /
• 2008

To effectively cope with a complexity of kinematic metrology due to workspace enlargement of the planar stage, the linear induction motor is suggested as its new driving source. Especially, the linear induction motor under uniform plate type of secondary doesn't inherently have a periodical force ripple which is generally shown in the brushless DC motor. But, it presents a poor transient characteristic at zero or low speed zone owing to time delay of flux settling, resulting in slow response. To improve the servo property of linear induction motor and apply successfully it to the precision stage, this paper discusses a modified vector control methodology. The controller has a novel input form, fixed d-axis current, q-axis current and forward-fed DC current, to control thrust force and normal force of the linear induction motor independently. Influence of the newly introduced input and the feasibility of controller are validated experimentally.

• 대한기계학회논문집
• /
• 제8권2호
• /
• pp.104-110
• /
• 1984

본 연구에서는 유압식 방법보다 절삭 정밀도가 높고 전기신호를 사용함으로 인한 조작과 증폭이 간단하고 특성 개선을 위한 조작과 증폭이 간단하고 특성 개선을 위한 계의 보상(sysyem compensation)을 할 수 있는 전기 유압식 모방장치를 설계, 제 작하여 그 성능을 실험적으로 해석하였다.

• 대한기계학회논문집A
• /
• 제24권3호
• /
• pp.728-734
• /
• 2000

An asymmetric actuator can be used to reduce the distance between the reflective mirror and objective lens of a small optical disk drive for use in the notebook-sized personal computer data storage devices. However, this asymmetric actuator is very sensitive to the subsidiary resonance which is caused by its rigid body motion. In this paper, an analytical approach using a simple lumped parameter system model is presented with a physical insight to investigate why the subsidiary resonance occurs. The finite element method is used to figure out the force and torque characteristics of the asymmetric actuator which are essential to understand the subsidiary vibration characteristics. The frequency responses are presented to examine how the subsidiary resonance is altered for various situations of having different thickness of a yoke and permanent magnet and of having a different magnet circuit. Finally, the design guidelines to avoid the subsidiary resonance will be presented.

• 한국정밀공학회지
• /
• 제7권4호
• /
• pp.85-102
• /
• 1990

Up to now, most robot control systems are very naive. They consist of a number of independent position-servo loops to control each joint angle separately. Those control systems have constant predefined gains and do not cover the complex dynamic interactions between manipulator joints. As a result, the manipulator is severely limited in range of application, speed of operation and variation of payload. This study proposed a new method to design a robot manipulator controller capable of tracking the reference trajectories of joint angles in a reasonable accuracy to cope with actual situations of varying payload, uncertain parameters. The adaptive model following control method has been used to improve existing robot manipulator controllers. The proposed controller is operated by adjusting its gains based on the response of the manipulator in such a way that the manipulator closely matches the reference model trajectories defined by the designer. The stability of adaptive controller is based on the Second Method of Lyapunov. The coupling among joints and the nonlinearity in the dynamic equation are explicitly considered. The designed manipulator controller shows good tracking performance under various load varia- tion and parameter uncertainties.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 추계학술대회 논문집
• /
• pp.375-381
• /
• 2004

Recently, the evolution in production techniques (e.g. high-speed milling) and the complex shapes involved in modem production design has been increasingly popular. The key to the achievement is a drastic improvement of the dynamic behavior of the machine tool axes used in production machinery. The more complex these tool paths the higher the speed and acceleration requirements. But it is very difficult to reach the target for high speed machine tool because of the limitations of servo system and motion control system. However the direct drive design of machine tool axes, which is based on linear motors and which recently appeared on the market, is a viable candidate to meet the ever increasing demands, because of these advantages such as no backlash, less friction, more mechanical simplicity and very higher acceleration and velocity comparing to the traditional system. This paper focused on the performance tests of the high speed horizontal machine tool based on linear motor. Especially, dynamic characteristics were investigated through circular test and circular form machining test is carried out considering many important parameter. Therefore these several experiments is used to be evaluated the model for prediction of circular motion error and circular machined error.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권3호
• /
• pp.412-420
• /
• 2003

This study describes the merits of PWM control of hydraulic system using high speed on-off valves. Generally, Electro-hydraulic valves can be classified into two classification: valves which are controlled by analog signal and which are controlled by digital. The former includes hydraulic servo valves and proportional valves which require A/D converters as interface to digital computer and too costly and sensitive to oil contamination because of complexity in structures. The latter includes high speed on-off valves which do not require A/D converters because they are normally operated in a pulse width modulation(PWM) method, and are low in price and robust to oil contamination because of their simple structures. The objectives of this study is to analyze the limit cycle which regularly appear in the position control system using 2/2way high speed on-off valves and to give a criterion for the stability of this system. The nonlinear characteristics of PWM and cylinder friction of this system are described by harmonic linearization and the effects of parameter variations to the system stability are simulated.

• 한국정밀공학회지
• /
• 제28권10호
• /
• pp.1159-1165
• /
• 2011

The recording density of HDD is increasing in ratio of 100% each year. Because the increasing of recording density requires the feature of high rotation, fixation and low-noise, fluid hydrodynamic bearing(FDB) has been paid attention to overcome a limitation in ball bearing. Most of researches related to improving performance of FDB have been studied in Japan which has 80% more market share of HDD spindle motor assembly. Main subject of studies are about for the design of the groove shape, manufacturing process of fluid dynamic bearing, performance evaluation and measurement. In HDD, non-repeatable runout(NRRO) is most important parameter which determines the performance of HDD spindle system because NRRO is unpredictable that cannot be compensated in head/slider servo system. In this study, performance evaluation system can measure dynamic behaviors were designed and methodology for calculating imbalance, RRO, and NRRO were proposed.

• 한국정보통신학회논문지
• /
• 제2권3호
• /
• pp.295-302
• /
• 1998

본 논문에서는 한계계단 응답특성을 이용하여 영구자석헝 동기전동기의 속도 제어계에 대한 새로운 자동동조 PI(Proportional Integral) 제어기를 설계하였다. 과도응답 기간동안 소위 한계입력이라고 하는 계단입력을 인가하여 Pㅑ 제어기의 자동동조를 위한 정보를 얻기 위한 기법을 제안한다. 시스템 파라메터 추정과 동시에 속도제어가 온라인으로 이루어지는데, 이것은 시스템의 불확실성에도 불구하고 한계입력에 의해서 얻어진 시스템 파라메터 정보가 연속적으로 PI 제어기에 적용될 수 있다는 것이다. 제안된 자동동조 알고리즘은 단조증가 계단응답 특성을 갖는 영구 자석형 동기전동기의 속도제어에 대한 시뮬레이션과 실험결과를 통하여 그 유효함을 확인하였다.

• 정보저장시스템학회논문집
• /
• 제3권4호
• /
• pp.191-195
• /
• 2007

The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to be equipped with 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added a tilt mechanism to the 2-axis moving magnet actuator which is designed in previous research. Addition of the tilt mechanism cuts down the focus sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.