• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.128-133
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• 2001

This paper presents a new approach to the design of adaptive control system using DSPs(TMS320C50) for robotic manipulators to achieve trajectory tracking angles. Digital signal processors are used in implementing real time adaptive control algorithms to provide motion for robotic manipulators. In the proposed scheme, adaptation laws are derived from the improved second stability analysis based on the indirect adaptive control theory. The proposed control scheme is simple in structure, fast in computation, an suitable for implementation of real-time control. Moreover, this scheme does not require an accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the adaptive controller is illustrated by experimental results for a SCARA robot.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.898-904
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• 1987

A new control algorithm using the VSS theory is developed for accurate trajectory control of robot manipulators. This paper focuses on the implementation of VSS controller with smoothing laws in the design of effective tracking control for robotic arms. The VSS controller for multi-linkage robot arm is realized using balance condition and its simplification which possesses powerful smoothing capability to reduce or even remove undesirable chattering and meanwhile keep the robust characteristic to reject system uncertainties. The design principle of selecting different smoothing methods, which aims at achieving trade-off between smoothing and robust behaviors while considering the actual system constraints, is also given and further confirmed through experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1012-1016
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• 1991

An effective visual servo control system for robotic manipulators based on neural networks is proposed. For this control system, firstly, one neural network is used to learn the mapping relationship between the robot's joint space and the video image space. However, in the proposed control scheme, this network is not used in itself, but its first and second derivatives are used to generate servo commands for the robot. Secondly, an adaptive Adaline network is used to identify the dynamics of the robot and also to generate the proper torque commands. Computer simulation has been performed indicating its superior performance. As far as the authors know, this is the first time attempt of the use of neural networks for a visual servo control of robots that compensates for their changing dynamics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1908-1913
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• 2010

In this paper, a robust variable structure tracking controller is designed for the mixed tracking control of highly nonlinear rigid robot manipulators for the first time. The mixed control problem under consideration is extended from the basic tracking problem, with the different initial condition of both the planned trajectory and link of robots. This control problem in robotics is not addressed to until now. The tracking accuracy to the sliding trajectory after reaching is analyzed. The stability of the closed loop system is investigated in detail in Theorem 2. The results of Theorem 2 provide the stable condition for control gains. Combing the results of Theorem 1 and Theorem 2 gives rise to possibility of designing the improved variable structure tracking controller to guarantee the tracking error from the determined sliding trajectory within the prescribed accuracy after reaching. The usefulness of the algorithm has been demonstrated through simulation studies on the mixed tracking control of a two.link robot under parameter uncertainties and payload variations.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.113-118
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• 1999

This paper presents a new approach to the design of neural control system using digital signal processors in order to improve the precision and robustness. Robotic manipulators have become increasingly important n the field of flexible automation. High speed and high-precision trajectory tracking are indispensable capabilities for their versatile application. The need to meet demanding control requirement in increasingly complex dynamical control systems under significant uncertainties, leads toward design of intelligent manipulation robots. The TMS320C31 is used in implementing real time neural control to provide an enhanced motion control for robotic manipulators. In this control scheme, the networks introduced are neural nets with dynamic neurons, whose dynamics are distributed over all the network nodes. The nets are trained by the distributed dynamic back propagation algorithm. The proposed neural network control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Performance of the neural controller is illustrated by simulation and experimental results for a SCARA robot.

• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1081-1088
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• 2000

In this paper, a compliance control strategy for robot manipulators that employs a self-adjusting stiffiness function is proposed. Based on the contact force, each entry of the diagonal stiffness matrix corresponding to a task coordinate in the operational space is adaptively adjusted during contact along the corresponding axis. The proposed method can be used for both the unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end-effector. The experimental results involving a two-link direct drive manipulator interacting with an unknown environment demonstrates the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.12
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• pp.980-984
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• 2001

When robot manipulatros as mathematically modeled. uncetainties may not be avoided. The uncertain factors come from imperfect knowledge of system parameters, payload change. friction, external disturbance and etc. In this work, we proposed a class of robust hybrid control of manipulatosrs. We propose a class of expanded robust hybrid control with the separated bound function and the simulation results are provided to show the effectiveness of the algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.89-96
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• 2002

A new chattering free PD-sliding mode hybrid control scheme is proposed for robot manipulators. This hybrid controller is composed of a PD controller and a semi-continuous sliding mode controller. It has a good robust performance in reaching mode which does not possess invariance property of sliding mode, and has chattering free characteristics in sliding mode. Thus, the PD-sliding mode hybrid controller has a good robust performance in the whole region. It is shown that the proposed control has a good transient response and trajectory tracking performance for a 2-link SCARA robot manipulator.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.12
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• pp.1601-1609
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• 1988

In the control of the robotic manipulators, the variable structure control method for the set point Regualation has an advantage of the insensitivity about parameter variations and disturbances. When the robotic manipulatores are controlled by a point-to-point scheme, no path constraint is considered. Thus, the variable structure control method will be effectively applied only if the trajectory of the robot hand is estimated precisely. In this paper, the joint trajectories in the joint space and the hand trajectory in the cartesian space are calculated by the variable structure control method, and an algorithm is suggested to elaborate the deviation error of the robot hand from a straight line path. The result of this study will become a base of the effective path planning about robotic manipulators with the variable structure control concept.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.380-382
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• 1993

In this paper, we derive a simple robust nonlinear control scheme for n-link robot manipulators subject to parameter uncertainty. By using the theory of variable structure system(VSS) and taking advantage of the important property of the robot dynamics, the stability of the derived control scheme is proved. This scheme utilizes the desired trajectory outputs, which can be calculated a priori, instead of the actual joint outputs in the nonlinear compensation controller. So the amount of on-line calculations is largely reduced, and as a result, this scheme can be implemented much more efficiently.