An adaptive H∞ control for robotic manipulator with compensation of input torque uncertainty (original) (raw)
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The H∞ regulation problem for robot manipulators using gravitational force compensation or precompensation has been solved locally while global asymptotical stability (or global stability) has been demonstrated using other methodologies. A solution to the global nonlinear H∞ regulation problem for l-degrees-of-freedom (l-DOF) robot manipulators, affected by external disturbances, is presented. We showed that the Hamilton-Jacobi-Isaacs (HJI) inequality, inherited in the solution of the H∞ control problem, is satisfied by defining a strict Lyapunov function. The performance issues of the nonlinear H∞ regulator are illustrated in experimental and simulation studies made for a 3-DOF rigid links robot manipulator.
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Al-Nahrain Journal for Engineering Sciences, 2017
The robot manipulator output feedback problem points out to the controlled system in which the measurements of the joint position are available. In this study, all kinematic and dynamic parameters of robot manipulator are supposed unknown and the manipulator have to follow the desired trajectory. Therefore, the adaptive control problem for robot manipulators based on velocity estimation is investigated. According to the practical robot actuator power limitation, the bounded torque input is also considered in this study. The control algorithm is applied for 2-link manipulator to evaluate controller effectiveness. The design parameters that guaranteed the control performance of closed loop system are chosen by using optimization output constrained method. The proposed controller performances are provided by numerical simulations.
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In this work, a hybrid control strategy integrating proportional derivative and H-infinity control method is proposed for a serial two-link robotic manipulator. The aim of this research is to achieve an improved trajectory tracking performance of the robot arm. The H-infinity controller achieves high performance and robustness in the presence of disturbances and uncertainties, such as unwanted overreaction caused by the derivative control's quick response times, while the proportional derivative controller stabilizes the nonlinear manipulator system. Simulation results using matlab shows that, the proposed hybrid controller, which integrates the advantages of both proportional derivative and H-infinity controllers, has the lowest rise time for the second link, the lowest settling time for the two links, the lowest peak time for both links and the fastest decay of the error response. In addition, the hybrid control scheme also has the lowest mean square error value, with 53.3% im...
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In this paper, previous works on nonlinear H ϱ control for robot manipulators are extended. In particular, integral terms are considered to cope with persistent disturbances, such as constant load at the end-effector. The extended controller may be understood as a computed-torque control with an external PID, whose gain matrices vary with the position and velocity of the robot joints. In addition, in order to increase the controller robustness, an extension of the algorithms with saturation functions has been carried out. This extension deals with the resulting nonlinear equation of the closed-loop error. A modified expression for the required increment in the control signal is provided, and the local closed-loop stability of this approach is discussed. Finally, simulation results for a two-link robot and experimental results for an industrial robot are presented. The results obtained with this technique have been compared with those attained with the original controllers to show the improvements achieved by means of the proposed method.
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Adaptive nonlinear ℋ;/sub ∞/ techniques applied to a robot manipulator
Proceedings of 2003 IEEE Conference on Control Applications, 2003. CCA 2003.
In this paper, three nonlinear H, control techniques used to control a robot manipulator are compared. The first technique consists in an explicit solution of the robotic H, control problem. It is found considering that the dynamic parameter matrices are exactly known. In the second, a linear parameterization is used to generate an adaptive control law in the presence of uncertain parameters. Finally, a neural network is considered when there is unmodeled dynamics. Results obtained from the experimental robot manipulator UArm 11, using the three methodologies, are presented.
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2009 17th Mediterranean Conference on Control and Automation, 2009
The development of an adaptive controller for a flexible link manipulator is the subject of this article. The system's measurements are assumed to be corrupted with noise of a priori known bounds. A Set Membership Identifier computes the feasible set (orthotope) within which the parameter vector resides. The orthotope's vertices provide the parameter-vector's bounds, which are used to compute the predicted system-output uncertainty. The controller tunes its gains through an on-line minimization of a cost that penalizes the control effort, the induced uncertainty on the system output, and the tracking error. The scheme is applied in simulation studies on a planar single flexible-link manipulator.