• Title/Summary/Keyword: Position/Velocity Control

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Orthogonalization principle for hybrid control of robot arms under geometric constraint

  • Arimoto, Suguru
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.1-6
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    • 1992
  • A principle of "orthogonalization" is proposed as an extended notion of hybrid (force and position) control for robot manipulators under geometric endpoint constraints. The principle realizes the hybrid control in a strict sense by letting position and velocity feedback signals be orthogonal in joint space to the contact force vector whose components are exerted at corresponding joints. This orthogonalization is executed via a projection matrix computed in real-time from a gradient of the equation of the surface in joint coordinates and hence both projected position and velocity feedback signals become perpendicular to the force vector that is normal to the surface at the contact point in joint space. To show the important role of the principle in control of robot manipulators, three basic problems are analyzed, the first is a hybrid trajectory tracking problem by means of a "modified hybrid computed torque method", the second is a model-based adaptive control problem for robot manipulators under geometric endpoint constraints, and the third is an iterative learning control problem. It is shown that the passivity of residual error dynamics of robots follows from the orthogonalization principle and it plays a crucial role in convergence properties of both positional and force error signals.force error signals.

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A Position Control for a Parallel Stage with 6 degrees of freedom Using Magnetic Actuators (전자기 구동장치를 이용한 병렬형 6자유도 스테이지의 위치제어)

  • Lee Se-Han
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.7 s.172
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    • pp.102-111
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    • 2005
  • In this paper, we address a position control for a parallel stage, which is levitated and driven by electric magnetic force. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal force. A dynamic equation of the stage system is derived based on Newton-Euler method and it's special Jacobian matrix describing a relation between the limited velocity and Cartesian velocity is done. There are proposed two control methods for positioning which are Cartesian space controller and Actuator space controller. The control performance of the Cartesian space controller is better than the Actuator space controller in task space trajectory while the Actuator space controller is simpler than the Cartesian space controller in controller realization.

A Motion-Control Chip to Generate Velocity Profiles of Desired Characteristics

  • Cho, Jung-Uk;Jeon, Jae-Wook
    • ETRI Journal
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    • v.27 no.5
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    • pp.563-568
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    • 2005
  • A motion-control chip contains major functions that are necessary to control the position of each motor, such as generating velocity command profiles, reading motor positions, producing control signals, driving several types of servo amplifiers, and interfacing host processors. Existing motion-control chips can only generate velocity profiles of fixed characteristics, typically linear and s-shape smooth symmetric curves. But velocity profiles of these two characteristics are not optimal for all tasks in industrial robots and automation systems. Velocity profiles of other characteristics are preferred for some tasks. This paper proposes a motion-control chip to generate velocity profiles of desired acceleration and deceleration characteristics. The proposed motion-control chip is implemented with a field-programmable gate array by using the Very High-Speed Integrated Circuit Hardware Description Language and Handel-C. Experiments using velocity profiles of four different characteristics will be performed.

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A Study on the Position and Speed Control of PM Step Motor Using Micro-Step Control Drive (미세스텝 제어 방식에 의한 PM 스텝 모터의 위치 및 속도 제어에 관한 연구)

  • 김동현;한권상
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.6
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    • pp.871-878
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    • 1990
  • The control method which electrically subdivides 1 step(1.8\ulcornerstep) of a PM step motor into 64 micro-step (0.028\ulcornerstep) is realized using micro-step algorithm on the basis of the look up table method and the position and velocity control using Z-80 microprocessor is also realized. With micro-stepping. The resolution of the system is improved, also by micro-step control of driving-current of the step motro, which is followed by the increase of micro-step subdivision-coefficient, the precise position and velocity control of step-motor can be realized and the stabilization of the system is improved.

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A New Variable-Structure Position Control for DC Motor Using Fuzzy Logic (퍼지논리를 이용한 직류전동기용 가변구조 위치제어시스템)

  • 이상래;이광원
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.6
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    • pp.625-632
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    • 1992
  • This paper presents a new dc-motor position control approached by Variable Structure System. In order to eliminate a steady-state position error, we propose a switching function composed of position error, velocity, and current ripple. The switching function has an advantage compared to other ones. To determine the control signal voltage, we use a fuzzy logic method. The simulation results show expected performances.

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PLL-type Position Control of Step Motors (스텝모터의 PLL 타입 위치제어)

  • Kim, Chang-Hwan
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.49 no.4
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    • pp.69-77
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    • 2012
  • We propose a PLL-type position control method for step motors. Our control method considerably improves the instability problem at rapid acceleration or deceleration, which is a major problem of conventional open loop control methods. Moreover, our controller reduces the steady state position error to zero and guarantees lower vibration and acoustic noise at high speed. Also, our controller can produce more torque at high speed, and hence it can extend the controllable velocity range. To demonstrate the practical significance of our control method, we present some simulation results for a commercially available step motor using Simulink.

Sway Control of c Container Crane (Part II): Regulation of the Pendulum Sway through Patternizing Trolley Moving Velocity (컨테이너 크레인의 흔들림 제어 (Part II): 트롤리 주행속도 조절을 통한 진자운동의 제어)

  • Hong, Keum-Shik;Sohn, Sung-Chull;Lee, Man-Hyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.3 no.2
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    • pp.132-138
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    • 1997
  • Six different types of velocity profiles of trolley movement of a container crane are investigated for the minimal sway angle at the target trolley position. Three velocity patterns which include trapezoidal, stepped and notched-type velocity patterns are obtained assuming constant rope length. The notched type velocity pattern is shown to be derived from the time-optimal bang-bang control. The stepped type velocity pattern can be shown to be derived as bang-off bang control as well. Considering the damping effect due to hoist motion a double stage acceleration pattern is also analyzed. The main objective of the paper is to show how much time-reduction can be obtained among several velocity patterns appearing in the literature.

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Weighted fuzzy controller composed of position type fuzzy controller and velocity type fuzzy controller (위치형퍼지제어기와 속도형퍼지제어기로 구성된 퍼지 가중치 제어기)

  • 김병수;박준열
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.181-183
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    • 1996
  • Generally, While position type fuzzy controller has good performance in transient period, it has uniform steady state error of response. While velocity type fuzzy controller is capable of reducing steady state error of response, it is hard to develop the performance in transient period. In order to have both good performance in transient period and ability to reduce the steady state error of response, weighting fuzzy controller, which is composed of these two fuzzy controllers, is proposed. For the decision of weight to each fuzzy controller, Weighting fuzzy set is established according to the system state variables and applied to each fuzzy controller. The proposed weighted fuzzy controller has the merits of both position type fuzzy controller and velocity type fuzzy controller simultaneously.

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A Study of High Precision Constant Velocity Control for Spiral Servo Writing in Hard Disk Drive (하드디스크 드라이브의 Spiral Servo Writing을 위한 초정밀 등속 제어 기법 연구)

  • Cho, K.N;Kang, H.J;Lee, C.W;Chung, C.J;Sim, J.S
    • Transactions of the Society of Information Storage Systems
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    • v.1 no.1
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    • pp.99-107
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    • 2005
  • According to recent trend, hard disk drive(HDD) has been smaller and less weight. Therefore, it needs new method of writing position information. In this thesis, a new controller that is suitable for SSW is proposed. The controller accepted SSW technology that is used to write position information in current HDD industry. The important condition to perform SSW is to reach constant velocity decided from the head velocity profile as fast as possible. The constant velocity decides the positional accuracy of spiral pattern and setup time decides the capacity of HDD. The head velocity profile as a reference signal must be designed not to cause resonance mode. The proposed controller was designed with consideration of these 3 elements, and it properly works for SSW. The velocity profile designed with SMART control not only minimizes the jerk, but also does not cause the resonance mode of a plant. After designing a conventional PID controller, it compared with electrical spring technique and ZPET technique.

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Fuzzy control of a robot manipulator in Cartesian space (Cartesian 공간에서 로봇 머니퓰레이터의 퍼지제어)

  • 곽희성;강철구
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1995.10b
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    • pp.165-173
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    • 1995
  • In order to eliminate position errors existing at the steady state in the motion control of robotic maniprlators, a new fuzzy control algorithm is proposed using three variables, position error, velocity error and integral of position errors as input variables of the fuzzy controller, This controller is applied to the tracking control of robotic manipulators in Cartesian space. Three dimensional look-up table is used to reduce the computational time in rel-time control. Simulation and experimental studies are conducted to evaluate the control performance for the two axis direct drive SCARA robot system.

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