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Model-free discrete control for robot manipulators using a fuzzy estimator

Mohammad Mehdi Fateh (Department of Electrical and Robotic Engineering, Shahrood University of Technology, Shahrood, Iran)
Siamak Azargoshasb (Department of Electrical and Robotic Engineering, Shahrood University of Technology, Shahrood, Iran)
Saeed Khorashadizadeh (Department of Electrical and Robotic Engineering, Shahrood University of Technology, Shahrood, Iran)
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Abstract

Purpose

Discrete control of robot manipulators with uncertain model is the purpose of this paper.

Design/methodology/approach

The proposed control design is model-free by employing an adaptive fuzzy estimator in the controller for the estimation of uncertainty as unknown function. An adaptive mechanism is proposed in order to overcome uncertainties. Parameters of the fuzzy estimator are adapted to minimize the estimation error using a gradient descent algorithm.

Findings

The proposed model-free discrete control is robust against all uncertainties associated with the model of robotic system including the robot manipulator and actuators, and external disturbances. Stability analysis verifies the proposed control approach. Simulation results show its efficiency in the tracking control.

Originality/value

A novel model-free discrete control approach for electrically driven robot manipulators is proposed. An adaptive fuzzy estimator is used in the controller to overcome uncertainties. The parameters of the estimator are regulated by a gradient descent algorithm. The most gradient descent algorithms have used a known cost function based on the tracking error for adaptation whereas the proposed gradient descent algorithm uses a cost function based on the uncertainty estimation error. Then, the uncertainty estimation error is calculated from the joint position error and its derivative using the closed-loop system.

Keywords

Citation

Mehdi Fateh, M., Azargoshasb, S. and Khorashadizadeh, S. (2014), "Model-free discrete control for robot manipulators using a fuzzy estimator", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 33 No. 3, pp. 1051-1067. https://doi.org/10.1108/COMPEL-05-2013-0185

Publisher

:

Emerald Group Publishing Limited

Copyright © 2014, Emerald Group Publishing Limited

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