• Title/Summary/Keyword: servo systems

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A Dual-Stage Servo System for an NFR Disk Drive using Iterative Learning Control (반복 학습 제어를 이용한 NFR 디스크 드라이브의 2단 서보 시스템)

  • 문정호;도태용
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.4
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    • pp.277-283
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    • 2003
  • Recently, near-field recording (NFR) disk drive schemes have been proposed with a view to increasing recording densities of hard disk drives. Compared with hard disk drives. NFR disk drives have narrower track pitches and are exposed to more severe periodic disturbances resulting from eccentric rotation of the disk. It is difficult to meet servo system design specifications for NFR disk drives with conventional VCM actuators in that the servo system for an NFR disk drive generally requires a feater gain and higher bandwidth. To tackle the problem various dual-stage actuator systems composed of a microactuator mounted on top of a conventional VCM actuator have been proposed. This article deals with the problem of designing a tracking servo system far an NFR disk drive adopting a dual-stage actuator. We summarize design constraints pertaining to the dual-stage servo system and present a new servo scheme using iterative teaming control. We design feedback compensators and an iterative teaming controller for a target plant and verify the validity of the proposed control scheme through a computer simulation.

Nonlinear Friction Compensator Design for Mechatronics Servo Systems Using Neural Network

  • Chung, Dae-won;Nobuhiro Kyra;Hiromu Gotanda
    • Transactions on Control, Automation and Systems Engineering
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    • v.3 no.2
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    • pp.111-116
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    • 2001
  • A neural network compensator for stick-slip friction phenomena in meashartonics servo systems is practically proposed to supplement the traditionally available position and velocity control loops for precise motion control. The neural network compensa-tor plays the role of canceling the effect of nonlinear slipping friction force. It works robustly and effectively in a real control system. This enables the mechatronics servo systems to provide more precise control in the digital computer. It was confirmed that the con-trol accuracy is improved near zero velocity and points of changing the moving direction through numerical simulation. However, asymptotic property on the steady state error of the normal operation points is guaranteed by the integral term of traditional velocity loop controller.

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$H_{\infty}$ Position Controller Design for Servo Systems Containing Resonance Effects and Coulomb Friction (공진효과 및 클롱마찰이 있는 서보 시스템의 $H_{\infty}$ 위치 제어기 설계)

  • Hong, Kook-Nam;Lim, Dong-Jin
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.720-725
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    • 1995
  • The most important problems which should be considered in designing servo controllers are resonance effects and nonlinear friction. These problems exist in almost all the servo systems, especially for the robotic maniplators and numerical control systems and cause difficulties in designing controllers. In this paper, controller design procedure which employs $H_{\infty}$ control theory is proposed for the servo systems with these problems. Sometimes, for these systems, there is a possibility of limit cycles due to the interation between the nonlinear friction and integrator. To check the possibility of limit cycles, describing fuction method is used.

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Concurrent Relay-PID Control for Motor Position Servo Systems

  • Li, Guomin;Tsang, Kai Ming
    • International Journal of Control, Automation, and Systems
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    • v.5 no.3
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    • pp.234-242
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    • 2007
  • A Concurrent Relay-PID controller (CRPID) for motor position servo systems is proposed in this paper. The proposed controller is composed of a deadband-relay subcontroller and a parallel PID subcontroller. The deadband-relay subcontroller is capable of improving the transient system performance while the PID subcontroller is responsible for near steady state system regulation. Systematic design methods for various controller components are developed. Design procedures are illustrated by an example. The proposed hybrid scheme is applied to a DC motor position servo system. Both numerical and experimental results demonstrate that the proposed controller performs satisfactorily and is superior to PID control alone.

Center Compensation Servo Control for High Speed CD-RW System (고배속 CD-RW 시스템을 위한 중점 서보 제어)

  • Seo, Sam-Jun;Kim, Dong-Sik
    • Proceedings of the KIEE Conference
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    • 2003.07d
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    • pp.2438-2440
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    • 2003
  • This thesis presents a design methodology of a Digital Servo Signal Processor for high speed CD-ROM drive systems. The proposed Digital Servo Signal Processor enables us to develop CD-related systems for the very high speed applications and is one of the key components of the CD-ROM systems. The proposed center compensation servo control is newly built for a actuator shaking due to the fast response of a step motor when it jumps to a long distance. From experimental results, we can see that the performance of the control system is improved greatly. The proposed servo algorithm shows a shorter setting time including a pull-in time and a faster access time.

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Implement of Fuzzy Inference Hardware for Servo Control Using $\alpha$ -level Set Decomposition ($\alpha$-레벨집합 분해에 의한 서보제어용 퍼지추론 하드웨어의 구현)

  • Hong Soon-ill;Lee Yo-seob;Choi Jae-yong
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.662-665
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    • 2001
  • As the fuzzy control is applied to servo system the hardware implementation of the fuzzy information systems requires the high speed operations, short real time control and the small size systems. The aims of this study is to develop hardware of the fuzzy information systems to be apply to servo system. In this paper, we propose a calculation method of approximate reasoning for fuzzy control based on $\alpha$-level set decomposition of fuzzy sets by quantize $\alpha$-cuts. This method can be easily implemented with analog hardware. The influence of quantization levels of $\alpha$-cuts on output from fuzzy inference engine is investigated. It is concluded that 4 quantization levels give sufficient result for fuzzy control performance of do servo system. It examined useful with experiment for dc servo system.

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The Comparison Experiment of Rotation Range of RC Servo Motors According to change of a Periods (주기변화에 따른 RC 서보모터 회전범위 비교실험)

  • Cha, Young-Youp
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.11
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    • pp.1179-1182
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    • 2011
  • RC servos are electro-mechanical devices that respond to a control signal, which instructs them to move their output shaft to a certain position. A servo is normally plugged into a radio receiver with a three pin connector. The three wires are a power (usually 4.8V to 6.0V), a ground, and a signal wire. The signal wire carries a PWM (Pulse-Width Modulation) signal consisting of a 1-2msec pulse repeated 50 times a second. A 1.5msec pulse will tell the servo to move to its output shaft to the center position, 0 degrees. For a servo with a 180 degree of motion, a 1msec pulse will move the servo to -90 degrees, and a 2msec pulse will move the servo to +90 degrees. In order to development a humanoid robot, mechanical design, fixtures design, analysis of kinematics, implementation moving program, selection of RC servo motor and controller are required. This study was performed to experimentally compare the rotation range of RC servo motors according to change of a periods.

Trajectory generation for contour control of mechatronics servo systems subjected to torque constraints

  • Goto, Satoru;Nakamura, Masatoshi;Kyura, Nobuhiro
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.66-70
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    • 1994
  • The actuator saturation defects the countour control performance of mechatronics servo systems. In this paper, trajectory generation of contour control of the mechatronics servo system is developed taking into account of the constraints of the torque in the system. By using the generated trajectory, the torque constraint and assigned working accuracy are satisfied and the accurate contour control performance is achieved.

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An Optimal Approach to Auto-tuning of Multiple Parameters for High-Precision Servo Control Systems (고정밀 서보 제어를 위한 다매개변수 자동 조정 방법)

  • Kim, Nam Guk
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.7
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    • pp.43-52
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    • 2022
  • Design of a controller for a high-precision servo control system has been a popular topic while finding optimal parameters for multiple controllers is still a challenging subject. In this paper, we propose a practical scheme to optimize multi-parameters for the robust servo controller design by introducing a new cost function and optimization scheme. The proposed design method provides a simple and practical tool for the systematic servo design to reduce the control error with guaranteeing robust stability of the overall system. The reduction of the position error by 24% along with a faster convergence rate is demonstrated using a typical hard disk drive servo controller with 41 parameters.