• Title/Summary/Keyword: Cartesian space control

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A Compliant Contact Control Strategy for Robot Manipulators with Unknown Environment

  • Kim, Byoung-Ho;Chong, Nak-Young;Oh, Sang-Rok;Suh, Il-Hong
    • 제어로봇시스템학회:학술대회논문집
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    • 1998.10a
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    • pp.20-25
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    • 1998
  • This paper proposes a new compliant contact control strategy for the robot manipulators accidentally interacting with an unknown environment. The main features of the proposed method are summarized as follows: First, each entry in the diagonal stiffness matrix corresponding to the task coordinate in Cartesian space is adaptively adjusted during con-tact along the corresponding axis based on the contact force with its environment. Second, it can be used for both unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end effector. Third, the adjusted stiffness gains are automatically recovered to initially specified stiffness gains when the task is changed from constrained motion to unconstrained motion. The simulation results show the effectiveness of the proposed method by employing a two-link direct drive manipulator interacting with an unknown environment.

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A study on Real-Time Implementation of Robust Control for Horizontal Articulated Arm with Eight Axis

  • Nguyen, Hoo-Cong;Kim, Jun-Hong;Lee, Hee-Seop
    • Journal of the Korean Society of Industry Convergence
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    • v.18 no.3
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    • pp.139-149
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    • 2015
  • In this paper, we describe a new approach to perform real-time implementation of an robust controller for robotic manipulator based on digital signal processors in this paper. The Texas Instruments DSPs chips are used in implementing real-time adaptive control algorithms to provide enhanced motion control performance for dual-arm robotic manipulators. In the proposed scheme, adaptation laws are derived from model reference adaptive control principle based on the improved direct Lyapunov method. The proposed adaptive controller consists of an adaptive feed-forward and feedback controller and time-varying auxiliary controller elements. The proposed control scheme is simple in structure, fast in computation, and suitable for real-time control. Moreover, this scheme does not require any accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the proposed adaptive controller is illustrated by simulation and experimental results for robot manipulator consisting of dual arm with eight degrees of freedom at the joint space and cartesian space.

A Study on Real Time Working Path Control of Vertical Type Robot System for the Forging and Casting Process Automation

  • Lim, O-Deuk;Kim, Min-Seong;Jung, Yang-Geun;Kang, Jung-Suk;Won, Jong-Bum;Han, Sung-Hyun
    • Journal of the Korean Society of Industry Convergence
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    • v.20 no.3
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    • pp.245-256
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    • 2017
  • In this study, we describe a new approach to real-time implementation of working path control for the forging and casting manufacturing process by vertical type articulated robot system. The proposed control scheme is simple in structure, fast in computation, and useful for real-time control of factory automation based on robot system. Moreover, this scheme does not require any accurate parameter information, nor values of the uncertain parameters and payload variations. Reliability of the proposed controller is proved by simulation and experimental results for robot manipulator consisting of arm with six degrees of freedom under the variation of payloads and tracking trajectories in Cartesian space and joint space. The vertical type articulated robot manipulator with six axes made in SMEC Co., Ltd. has been used for real-time implementation test to illustrate the enhanced working path control performance for unmanned automation of the forging and casting manufacturing process.

A Compliance Control Method for Robot Manipulators Using Nonlinear Stiffness Adaptation (비선형 강성 조절 방법을 이용한 로봇 매니퓰레이터의 컴플라이언스 제어 방법)

  • Kim, Byoyng-Ho;Oh, Sang-Rok;Suh, Il-Hong;Yi, Byung-Ju
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.8
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    • pp.703-709
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    • 2000
  • This paper proposes a compliance control strategy for the robot manipulators accidentally interact-ing with an unknown environment. In this proposed method each in the diagonal stiffness matrix corre-sponding to the task coordinate in a Cartesian space is adaptively adjusted during contact along the corresponding axis based on the contact force with its environment. This method can be used for both unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end-effector. The experimental results show the effectiveness of the proposed method by employing a two link direct drive manipulator interacting with an unknown environment.

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Teaching Method Without Work Space Limit for Industrial Robot (산업용 로봇의 작업공간 제한이 없는 교시 방법)

  • Choi, Taeyong;Do, Hyunmin;Park, Chanhun;Park, Dongil;Kim, Doohyeong;Kyung, Jinho
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.6
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    • pp.492-497
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    • 2016
  • Teaching an industrial robot is still a dangerous and time-consuming process. It is expected that a robot can track a trajectory that is repeatedly taught by a human operator. Teaching a robot in joint space is easier than that in Cartesian space or a work space because the robot will never lose its stability when it is taught and operated in a joint space. However, it is very easy for a robot to lose its stability when it is taught in a work space. This is because of the singular points problem in kinematics for manipulators. Thus, experts should teach a given task to a robot in a careful manner. A new algorithm that avoids the problem of singular points is proposed. Using this proposed method, a user can freely teach a robot without the chance of instability in an entire work space.

Walking of a Planar Biped with an Intuitive Method (직관적인 방법에 의한 평면형 2족 로봇의 보행)

  • Chung, Goo-Bong
    • The Journal of Korea Robotics Society
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    • v.4 no.1
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    • pp.17-24
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    • 2009
  • This work deals with an intuitive method for a planar biped to walk, which is named Relative Trajectory Control (RTC) method. A key feature of the proposed RTC method is that feet of the robot are controlled to track a given trajectory, which is specially designed relative to the base body of the robot. The trajectory of feet is presumed from analysis of the walking motion of a human being. A simple method to maintain a stable posture while the robot is walking is also introduced in RTC method. In this work, the biped is modeled as a free-floating robot, of which dynamic model is obtained in the Cartesian space. Using the obtained dynamic model, the robot is controlled by a model-based feedback control scheme. The author shows a preliminary experimental result to verify that the biped robot with RTC method can walk on the even or uneven surfaces.

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A Pointwise PD-optimal Control of Robotic Manipulators for Continuous Path with Bounded Inputs (제한된 입력하에서 로보트 매니플레이터의 Pointwise PD 최적 연속경로 제어방)

  • 현웅근;서일홍;서병설;임준홍;김경기
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.37 no.3
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    • pp.186-193
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    • 1988
  • A pointwise PD-optimal control method is proposed for the continuous path control of robot manipulators with bounded inputs. The controller employs the desired acceleration plus PD (proportional and derivative) actions in the Cartesian space. The gain parameters of the controller are adjusted so that the Euclidean norm of the deviation between the actual and desired accelerations is minimized subject to the constraints of bounded input torques and the system guarantees negative feedback. To show the Validities of the proposed mithods, computer simulations are performed for a SCARA type robot.

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Design of Torque Compensatory Controller for Robot Manipulator using Chaotic Neural Networks (카오틱 신경망을 이용한 로봇 매니퓰레이터용 토크보상제어기의 설계)

  • Moon, Chan;Kim, Sang-Hee;Park, Won-Woo
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.530-532
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    • 1998
  • In this paper, We Designed the torque compensatory controller for robot manipulator using modified chaotic neural networks with self feedback loop. The proposed torque compensatory controller compensate torque of the PD controller. In order to estimate the proposed controller, we implemented to the Cartesian space control of three-axis PUMA robot and compared the simulation results with recurrent neural networks(RNNs) controller. Simulation results show that the learning error drastically decrease at on-line learning. The proposed CNNs controller shows much better control performance and shorter processing time compared to the recurrent neural network controller in the robot trajectory control.

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Robot motion planning for time-varying obstacle avoidance using view-time concept ('관측 시간'개념을 이용한 로보트의 시변 장애물 회피 동작 계획)

  • 고낙용;이범희;고명삼;남윤석
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.1040-1045
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    • 1991
  • An approach to time-varying obstacle avoidance problem is pursued. The mathematical formulation of the problem is given in Cartesian space and in joint space. To deal with the time-varying obstacles, view-time is introduced. A view-time is the time interval viewing the time-varying obstacles to model equivalent stationary obstacles. For the analysis of the properties of the view-time, avoidability measure is defined as a measure of easiness for a robot to avoid obstacles. Based on the properties, a motion planning strategy to avoid time-varying obstacles is derived. An application of the strategy to the collision-free motion planning of two SCARA robots and the simulation on the application are given.

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Design of Incoming Ballistic Missile Tracking Systems Using Extended Robust Kalman Filter (확장 강인 칼만 필터를 이용한 접근 탄도 미사일 추적 시스템 설계)

  • 이현석;나원상;진승희;윤태성;박진배
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.188-188
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    • 2000
  • The most important problem in target tracking can be said to be modeling the tracking system correctly. Although the simple linear dynamic equation for this model has used until now, the satisfactory performance could not be obtained owing to uncertainties of the real systems in the case of designing the filters baged on the dynamic equations. In this paper, we propose the extended robust Kalman filter (ERKF) which can be applied to the real target tracking system with the parameter uncertainties. A nonlinear dynamic equation with parameter uncertainties is used to express the uncertain system model mathematically, and a measurement equation is represented by a nonlinear equation to show data from the radar in a Cartesian coordinate frame. To solve the robust nonlinear filtering problem, we derive the extended robust Kalman filter equation using the Krein space approach and sum quadratic constraint. We show the proposed filter has better performance than the existing extended Kalman filter (EKF) via 3-dimensional target tracking example.

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