Prescribed‐Time Disturbance Observer‐Based Sliding Mode Control for Uncertain Manipulator Systems Under Dos Attack

ABSTRACT The predefined‐time nonsingular fast terminal sliding mode (NFTSM) control problem is studied based on a prescribed‐time disturbance observer (PTDO) for a robotic manipulator system with Denial‐of‐Service (DoS) attack. Firstly, a new predefined‐time NFTSM control strategy is constructed to enable fast‐tracking performance for the uncertain manipulator with DoS attack. Then, a well‐designed PTDO is developed to deal with the unknown lumped uncertainty, and the observation error variable is proved to converge within a prescribed time. Next, the entire prescribed‐time disturbance observer‐based NFTSM controller is devised, and the error system of the uncertain manipulator is proved to be tunable predefined‐time stability (PdTS) without DoS attack. Meanwhile, the DoS attack issue is addressed, and the quantitative relationship between the PdTS and the attack parameters is formalized utilizing a switched system framework. Finally, the developed prescribed‐time disturbance observer‐based NFTSM control method is demonstrated via a 2‐link robotic manipulator, which provides a higher quality control performance compared with existing control methods.