• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.1
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• pp.41-47
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• 2000

A better tracking performance can be achieved, if visual sensors such as CCD cameras are used in controling a robot manipulator, than when only relative sensors such as encoders are used. However, for precise visual servoing of a robot manipulator, an expensive vision system which has fast sampling rate must be used. Moreover, even if a fast vision system is implemented for visual servoing, one cannot get a reliable performance without use of robust and stable inner joint servo-loop. In this paper, we propose a dynamic control scheme for robot manipulators with eye-in-hand camera configuration, where a dynamic learning controller is designed to improve the tracking performance of robotic system. The proposed control scheme is implemented for tasks of tracking moving objects and shown to be robust to parameter uncertainty, disturbances, low sampling rate, etc.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.702-712
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• 2008

This paper presents a novel approach for controlling electrically driven robot manipulators based on voltage control. The voltage-based control is preferred comparing to torque-based control. This approach is robust in the presence of manipulator uncertainties since it is free of the manipulator model. The control law is very simple, fast response, efficient, robust, and can be used for high-speed tracking purposes. The feedback linearization is applied on the electrical equations of the dc motors to cancel the current terms which transfer all manipulator dynamics to the electrical circuit of motor. The control system is simulated for position control of the PUMA 560 robot driven by permanent magnet dc motors.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1960-1961
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• 2006

In this paper, The trajectory control of robot manipulator is proposed. It divides by trajectory planning and tracking control. A trajectory planning and tracking control of robot manipulator is used to the neural network and evolutionary algorithm. The trajectory planning provides not only the optimal trajectory for a given cost function through evolutionary algorithm but also the configurations of the robot manipulator along the trajectory by considering the robot dynamics. The computed torque method (C.T.M) using the model of the robot manipulators is an effective means for trajectory tracking control. However, the tracking performance of this method is severely affected by the uncertainties of robot manipulators. The Radial Basis Function Networks(RBFN) is used not to learn the inverse dynamic model but to compensate the uncertainties of robot manipulator. The computer simulations show the effectiveness of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1075-1086
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• 2004

In this paper, Time Delay Control(TDC) for robot manipulators is analyzed and its problems are founded. In order to remedy the problems, the enhanced controller is proposed and analyzed. The effect of friction associated with TDC is reported and its cause is presented. Through the analysis, simulation and experiment, it is shown that the friction effect causes serious degradation in control performance and that it is a result of the error of Time Delay Estimation(TDE) in TDC. In order to remedy the problems, TDC combined with Internal Model Control(IMC) concept is proposed. The proposed compensator is effective enough to handle the bad effect of friction, and is so simple and efficient as to match positive attribute of TDC. The simulation and experimental results show the effectiveness of proposed controller against the friction of the robot manipulators.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1609-1612
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• 1997

Kinematically redundantant manipulators have a nimber of potential advantages over nonredundant ones. Questions associated with manipulability measures for (non)redundant manipulators derived by minimum 2-norm solution and minimum infinity-norm solution in unit joint velocity are examined in detail.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.44.2-44
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• 2001

This paper presents a new concept for controlling of under actuated robot manipulators with avoiding obstacles using switching computed torque method (SCTM). One fundamental approach of this algorithm is to use the partly stable controllers (PSCs) in order to fulfill the ultimate control objective. Here, we use genetic algorithms (GA)in order to employ the optimum control action for a given time frame with the available set of elemental controllers, depending on which links/variables are controlled, i.e. the selection of optimum switching sequence of the control actions. The proposed approach models links of the robot using evolving ellipses and then introduces a penalty scheme for the objective function of GA when it detects collisions. An under actuated robot manipulator, which has three detrees-of-freedom is taken into consideration so as to illustrate the design procedure. Simulation results show the e.ectiveness of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3253-3269
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• 1994

In this paper a new concept, named the Extended Operational Space Formulation, has been proposed for the effective analysis and real-time control of the robot manipulators with kinematic redundancy. The extended operational space consists of operational space and optimal null space. The operational space is used to describe robot end-effector motion; whereas the optimal null space, defined as the target space of the self motion manifold, is used to express the self motion for the secondary tasks. Based upon the proposed formulation, the kinematics, statics, and dynamics of redundant robots have been analyzed, and an efficient control algorithm has been proposed. Using this algorithm, one can optimize a performance measure while tracking a desired end-effector trajectory with a better computational efficiency than the conventional methods. The effective ness of the proposed method has been demonstrated with simulations.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.5
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• pp.259-267
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• 2019

This paper proposes a structure of a variable impedance control system based on sensor-less external force estimator of industrial manipulators for cyber physical production systems (CPPS). To implement CPPS, a feedback system is constructed by using the robot operating system (ROS) and an external force estimator which is designed to measure the external force applied to the manipulator without a force sensor. Based on the robot dynamics, the robot-human cooperating system for the cyber physics production system is implemented through a controller that changes the impedance characteristics of the manipulator according to the situation using the external force estimator. Simulation and experimental results verify the effectiveness of the proposed control system.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.927-932
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• 2007

This paper proposes a robust back-stepping control with polynomial-type PD input for flexible joint robot manipulators to overcome parameter uncertainty. In the first step, a fictitious control is designed with polynomial-type PD input for the rigid link dynamic by the H-infinity control method. In second and third steps, the other fictitious control and real control are designed using saturation control and polynomial-type PD input based on the Lyapunov's second method. In each step, the designed robust inputs satisfy the L2-gain, which is equal to or less than gamma in the closed loop system. In contrast with the previous researches, the proposed method proves performance relations with PD gain from the robust gain. The performance robustness of the proposed control is verified through a 2-DOF robot manipulator with joint flexibility.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.426-426
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• 2000

When real robot manipulators arc mathematically modeled, uncertainties are not avoidable. The uncertainties are often nonlinear and time varying, The uncertain factors come from imperfect knowledge of system parameters, payload change, friction, external disturbance and etc. We proposed a class of robust hybrid position/force control of manipulators and provided the stability analysis in the previous work. In the work, we propose a class of adaptive robust hybrid position/force control of manipulators with bound estimation and the stability based on Lyapunov function is presented. Especially, this controller does not need the information of uncertainty bound. The simulation results are provided to show the effectiveness of the algorithm.