Control
H. Chenarani; M.M. Fateh
Abstract
Background and Objectives: This paper presents a robust passivity-based voltage controller (PBVC) for robot manipulators with n degree of freedom in the presence of model uncertainties and external disturbance.Methods: The controller design procedure is divided into two steps. First, a model-based controller ...
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Background and Objectives: This paper presents a robust passivity-based voltage controller (PBVC) for robot manipulators with n degree of freedom in the presence of model uncertainties and external disturbance.Methods: The controller design procedure is divided into two steps. First, a model-based controller is designed based on the PBC scheme. An output feedback law is suggested to ensure the asymptotic stability of the closed-loop error dynamics. Second, a regressor-free adaptation law is obtained to estimate the variations of the model uncertainties and external disturbance. The proposed control law is provided in two different orders.Results: The suggested controller inherits both advantages of the passivitybased control (PBC) scheme and voltage control strategy (VCS). Since the proposed control approach only uses the electrical model of the actuators, the obtained control law is simple and also has an independent-joint structure. Moreover, the proposed PBVC overcomes the drawbacks of torque control strategy such as the complexity of manipulator dynamics, practical problems and ignoring the role of actuators. Moreover, computer simulations are carried out for both tracking and regulation purposes. In addition, the proposed controller is compared with a passivity-based torque controller where the simulation results show the appropriate efficiency of the proposed approach.Conclusion: The robust PBVC is proposed for EDRM in presence of external disturbance. To the best of our knowledge, it is the first time that a regressorfree adaptation law is obtained to approximate the lumped uncertainties according to the passivity-based VCS. Moreover, the electrical model of the actuators is utilized in a decentralized form to control each joint separately.
H. Chenarani; T. Binazadeh
Abstract
This paper presents some analyses about the robust practical stability of a class of nonlinear affine systems in the presence of non-vanishing perturbations based on the passivity concept. The given analyses confirm the robust passivity property of the perturbed nonlinear systems in a certain region. ...
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This paper presents some analyses about the robust practical stability of a class of nonlinear affine systems in the presence of non-vanishing perturbations based on the passivity concept. The given analyses confirm the robust passivity property of the perturbed nonlinear systems in a certain region. Moreover, robust control laws are designed to guarantee the practical stability of the perturbed systems. For this purpose, the control laws are designed in two cases. In the first case, it is assumed that the designer has freedom in choosing the outputs. In the second case, it is assumed that the outputs are predefined. In this case, first it is considered that the nominal system is passive between its inputs and outputs and then the control law is designed as static output feedback law for the perturbed system. Moreover, in the case that the nominal system is not passive, first, a law is designed such that the new nominal system is passive between the virtual inputs and the outputs. Then, the virtual input is designed as a static output feedback law such that the proposed controllers guarantee the practical stability of the perturbed system. Finally, the computer simulations are performed to show the efficacy and applicability of the designed controllers.
