• Title/Summary/Keyword: Torque Feedback

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Dynamic Control of Robot Manipulators Using Multilayer Neural Networks and Error Backpropagation (다층 신경회로 및 역전달 학습방법에 의한 로보트 팔의 다이나믹 제어)

  • 오세영;류연식
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.12
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    • pp.1306-1316
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    • 1990
  • A controller using a multilayer neural network is proposed to the dynamic control of a PUMA 560 robot arm. This controller is developed based on an error back-propagation (BP) neural network. Since the neural network can model an arbitrary nonlinear mapping, it is used as a commanded feedforward torque generator. A Proportional Derivative (PD) feedback controller is used in parallel with the feedforward neural network to train the system. The neural network was trained by the current state of the manipulator as well as the PD feedback error torque. No a priori knowledge on system dynamics is needed and this information is rather implicitly stored in the interconnection weights of the neural network. In another experiment, the neural network was trained with the current, past and future positions only without any use of velocity sensors. Form this thim window of position values, BP network implicitly filters out the velocity and acceleration components for each joint. Computer simulation demonstrates such powerful characteristics of the neurocontroller as adaptation to changing environments, robustness to sensor noise, and continuous performance improvement with self-learning.

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A Research on the Adaptive Control by the Modification of Control Structure and Neural Network Compensation (제어구조 변경과 신경망 보정에 의한 적응제어에 관한 연구)

  • Kim, Yun-Sang;Lee, Jong-Soo;Choi, Kyung-Sam
    • Proceedings of the KIEE Conference
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    • 1999.11c
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    • pp.812-814
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    • 1999
  • In this paper, we propose a new control algorithm based on the neural network(NN) feedback compensation with a desired trajectory modification. The proposed algorithm decreases trajectory errors by a feed-forward desired torque combined with a neural network feedback torque component. And, to robustly control the tracking error, we modified the desired trajectory by variable structure concept smoothed by a fuzzy logic. For the numerical simulation, a 2-link robot manipulator model was assumed. To simulate the disturbance due to the modelling uncertainty. As a result of this simulation, the proposed method shows better trajectory tracking performance compared with the CTM and decreases the chattering in control inputs.

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Robot manipulator's contact tasks on uncertain flexible objects

  • Wu, Jianqing;Luo, Zhiwei;Yamakita Masaki;Ito, Koji
    • 제어로봇시스템학회:학술대회논문집
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    • 1995.10a
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    • pp.460-463
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    • 1995
  • The present paper studies a robot manipulator's contact tasks on the uncertain flexible objects. The flexible object's distributed parameter model is approximated into a lumped "position state-varying" model. By using the well-known nonlinear feedback compensation, the robot's control space is decomposed into the position control subspace and the object's torque control subspace. The optimal state feedback is designed for the position loop, and the robot's contact force is controlled through controlling the resultant torque on the object using model-reference simple adaptive control. Experiments of a PUMA robot interacting with an aluminum plate show the effectiveness of this control approach. approach.

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Off-line parameter Estimation of Induction Motors for Vector Control in Industrial Field (산업현장에서 벡터제어용 유도전동기의 오프라인 파라미터 추정)

  • 권병기;박가우;신원창;조응상;이진섭;최창호
    • Proceedings of the KIPE Conference
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    • 1998.07a
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    • pp.234-238
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    • 1998
  • Parameter estimation of induction motor for vector control presented in this paper can be easily implemented and applied to inverters in the industrial field, because it needs no additional hardware such as voltage sensor and measuring equipment. At first, the stator resistance including switching loss of inverter is measured by simple voltage-current equation. Next, in pre-magnetization of machine by imposing the d-axis constant field-current, q-axis torque current is forced to the machine until its speed feedback reachs to pre-defined level of speed limit. At this time, we can measure the rotor time-constant by decreasing the distorted output-voltage of inverter. At last, stator inductance, transient inductance, and moment of inertia can be measured by the relationship of output voltage, output torque and speed feedback. The validity and usufulness of this method is verified by experimental results.

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Modeling of a 5-Bar Linkage Robot Manipulator with Joint Flexibility Using Neural Network (신경 회로망을 이용한 유연한 축을 갖는 5절 링크 로봇 메니퓰레이터의 모델링)

  • 이성범;김상우;오세영;이상훈
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.431-431
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    • 2000
  • The modeling of 5-bar linkage robot manipulator dynamics by means of a mathematical and neural architecture is presented. Such a model is applicable to the design of a feedforward controller or adjustment of controller parameters. The inverse model consists of two parts: a mathematical part and a compensation part. In the mathematical part, the subsystems of a 5-bar linkage robot manipulator are constructed by applying Kawato's Feedback-Error-Learning method, and trained by given training data. In the compensation part, MLP backpropagation algorithm is used to compensate the unmodeled dynamics. The forward model is realized from the inverse model using the inverse of inertia matrix and the compensation torque is decoupled in the input torque of the forward model. This scheme can use tile mathematical knowledge of the robot manipulator and analogize the robot characteristics. It is shown that the model is reasonable to be used for design and initial gain tuning of a controller.

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Control Strategy to Reduce Tracking Error by Impulsive Torques at the Joint

  • Yang Chulho
    • International Journal of Precision Engineering and Manufacturing
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    • v.6 no.2
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    • pp.61-71
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    • 2005
  • The study reported deals with investigating the feasibility of control strategy for a serial rigid link manipulator that applies impulsive torques at the joints. The strategy is illustrated for a planar three rigid link manipulator. An impulse-based concept which uses successive torque impulses on rigid link as the controller for motion correction was introduced. This control strategy was tested over the entire trajectory to demonstrate that the tracking error could be reduced effectively. The best condition for minimizing the tracking error with the least impulse input at each joint is investigated by considering one design and one operating parameter. The first was the damping in the system, and the second was the sampling time during operation. The results show that this approach can provide useful guidance for the design and control of robot manipulators that require minimum impulse feedback for accurate tracking.

Hybrid Control of Position/Tension for a Stringing Troy Wire (가설 트롤리선의 위치 / 장력 혼합제어)

  • Hong, Jeng-Pyo
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.6
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    • pp.932-938
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    • 2009
  • As a stringing troy wire is installed by manual operation, it is necessary to scheme the automatic system for stringing troy wire. To accomplish a task of this kind, in this paper an approach to designing controllers for the hybrid Position/Tension control of a stringing troy wire is presented. Position control system is designed based on equation of dc motor and motion equation of robot, it is controlled by feedback with a detected speed dc motor. Tension control system is designed based on equation of ac servomotor for generating torque and dynamic equation of a troy wire, it is controled by feedback with a detected tension. The control parameters is determined by simulation in independence operation of each system. To suppress a mutual interference that the disturbance occur in operating of two task at same time. Dynamic hybrid control is proposed by feed forward compensator with a disturbance accelerator and a step torque at start. The operation of proposed system is simulated and experimented, results is verified the utilities.

Partial State Feedback $H_{\infty}$ Control of Two-Mass System (2관성계의 부분적인 상태궤환을 갖는 $H_{\infty}$제어)

  • Han, Yoon-Seok;Kim, Young-Seok
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.48 no.10
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    • pp.562-570
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    • 1999
  • In the industrial motor drive system which is composed of a motor and load connected with a flexible shaft, a torsional vibration is often generated because of the elastic elements in torque transmission. This vibration, which is generated in a two-mass mechanical system. To solve this problem, recently there has been a lot of researches for the robust control relevant to the $H_{\infty}$ control suppressing the torsional vibration and rejecting the torque disturbance. In the case of the $H_{\infty}$controller, however, the command tracking property becomes worse because of overshoot during transient response. For this reason the $H_{\infty}$ controller, which includes the two-degrees-of-freedom(TDOF) controller, is designed in order to improve command tracking property. However, it also includes complexity realizing this controller. In this paper, a new $H_{\infty}$ controller with partial state feedback is proposed. Proposed $H_{\infty}$controller has simple structure but satisfies with the fast command tracking property and the attenuation of disturbances and vibrations simultaneously, just like the complicated TDOF $H_{\infty}$ controller.

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Stabilization Control of line of sight of OTM(On-The-Move) Antenna (OTM 단말기 안테나 시선 안정화 제어)

  • Kang, Min-Sig;Cho, Yong-Wan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.11
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    • pp.2073-2082
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    • 2010
  • The 4-th generation of mobile communication aims to realize global, fast and mobile communication service. The satellite communication charges a key role in this field. In this study, an OTM(On-The-Move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite was addressed. Since vehicles move during communication, active antenna line-of-sight stabilization is a core technology to guarantee high satellite communication quality. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. Various disturbance torques such as static and dynamic mass imbalance torques, variation of moment of inertia according to elevation angle, friction torque related to vehicle motion, equivalent disturbance torque due to antenna roll motion, etc. were analyzed. As a robust stabilization control, rate feedback with sliding mode control and position feedback with proportional+integral control was suggested. To compensate antenna roll motion, a supplementary roll rate feed forward control was included beside of the feedback control loop. The feasibility of the analysis and the proposed control design were verified along with some simulation results.

Development of Joint Controller and Collision Detection Methods for Series Elastic Manipulator of Relief Robot (구호로봇용 연성 매니퓰레이터를 위한 조인트 제어 및 충돌감지 알고리즘)

  • Jung, Byung-jin;Kim, Tae-Keun;Won, Geon;Kim, Dong Sup;Hwang, Junghun
    • The Journal of Korea Robotics Society
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    • v.13 no.3
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    • pp.157-163
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    • 2018
  • This paper deals with the development and application of control algorithms for series elastic relief robots for rescue operations in harsh environment like disasters or battlefield. The joint controller applied in this paper has a cascade structure combining inner loop for torque control and outer loop for position control. The torque loop contains feedforward and feedback controller and disturbance observer for independent, decentralized joint control. The effect of the elastic component and motor dynamics are treated as the nonlinear disturbance and compensated with the disturbance observer of torque controller. For the collision detection, Band Designed Disturbance Observer is configured to recognize/respond to external disturbance robustly in the continuously changing environment. The controller is applied to a 7-dof series elastic manipulator to evaluate the torque tracking and collision detection/response performance.