International Journal of Control, Automation, and Systems 2025; 23(2): 479-488
https://doi.org/10.1007/s12555-024-0624-7
© The International Journal of Control, Automation, and Systems
This paper deals with a robust trajectory tracking controller for articulated manipulators that are subject to model uncertainties and external disturbances. The proposed controller employs the disturbance observer based controller which can effectively estimate and compensate for the effect of model uncertainties and the disturbances. It is assumed that the model uncertainty is bounded with known bounds, and that the disturbance is composed of two parts; the one, called modeled disturbance, is a summation of sinusoids with known frequencies, and the other, called unmodeled disturbance, is unknown time-varying with known bounds. To deal with the modeled disturbance, we embed its internal model into the proposed controller so that the controller can reject this modeled disturbance without using the magnitude or phase. The unmodeled disturbance is approximately rejected by tuning the controller parameter using the bounds. The stability of the closed-loop system is rigorously analyzed and it turns out that all the signals are bounded and the tracking error can be made arbitrarily small by choosing the controller parameters appropriately. Simulation results on a 2-DOF manipulator are included to validate the proposed controller.
Keywords Articulated manipulators, disturbance rejection, internal model, nonlinear system, robust control.
International Journal of Control, Automation, and Systems 2025; 23(2): 479-488
Published online February 1, 2025 https://doi.org/10.1007/s12555-024-0624-7
Copyright © The International Journal of Control, Automation, and Systems.
Wonseok Ha, Jae-Han Park, and Juhoon Back*
Kwangwoon University
This paper deals with a robust trajectory tracking controller for articulated manipulators that are subject to model uncertainties and external disturbances. The proposed controller employs the disturbance observer based controller which can effectively estimate and compensate for the effect of model uncertainties and the disturbances. It is assumed that the model uncertainty is bounded with known bounds, and that the disturbance is composed of two parts; the one, called modeled disturbance, is a summation of sinusoids with known frequencies, and the other, called unmodeled disturbance, is unknown time-varying with known bounds. To deal with the modeled disturbance, we embed its internal model into the proposed controller so that the controller can reject this modeled disturbance without using the magnitude or phase. The unmodeled disturbance is approximately rejected by tuning the controller parameter using the bounds. The stability of the closed-loop system is rigorously analyzed and it turns out that all the signals are bounded and the tracking error can be made arbitrarily small by choosing the controller parameters appropriately. Simulation results on a 2-DOF manipulator are included to validate the proposed controller.
Keywords: Articulated manipulators, disturbance rejection, internal model, nonlinear system, robust control.
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