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External disturbances, internal uncertainties and actuator faults with an unknown range have detrimental effects on controller performance of industrial robots. In this paper, to deal with such challenges, a new fault-tolerant control (FTC) strategy using a combination of nonsingular integral-type terminal sliding mode (NITSM) and adaptive high-order super-twisting (AST) control is proposed for a delta-type parallel robot. To eliminate the chattering of sliding mode controller as a key ingredient of excessive energy consumption and convergence rate reduction, high-order algorithm is applied. Stability analysis of the closed-loop system is performed using Lyapunov theory. Moreover, to achieve optimal performance, controller parameters are obtained using harmony search algorithm (HSA) by minimizing an objective function consisting of integral time absolute error (ITAE) and control signal rate. The proposed controller performance is compared with conventional sliding mode and feedback linearization control methods. The obtained results reveal the superiority of the proposed AST-NITSM.

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In this paper, a new hybrid fault-tolerant control (FTC) strategy based on nonsingular fast integral-type terminal sliding mode (NFITSM) and time delay estimation (TDE) is proposed for a Schönflies parallel manipulator. In order to detect, isolate, and accommodate actuator faults, TDE is used as an online fault estimation algorithm. Stability analysis of the closed-loop system is performed using Lyapunov theory. The proposed controller performance is compared with conventional sliding mode and feedback linearization control methods. The obtained results reveal the superiority of the proposed FTC based on TDE and NFITSM.

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