Abstract
In this study, a fault-tolerant control (FTC) tactic using a sliding mode controller–observer method for uncertain and faulty robotic manipulators is proposed. First, a finite-time disturbance observer (DO) is proposed based on the sliding mode observer to approximate the lumped uncertainties and faults (LUaF). The observer offers high precision, quick convergence, low chattering, and finite-time convergence estimating information. Then, the estimated signal is employed to construct an adaptive non-singular fast terminal sliding mode control law, in which an adaptive law is employed to approximate the switching gain. This estimation helps the controller automatically adapt to the LUaF. Consequently, the combination of the proposed controller–observer approach delivers better qualities such as increased position tracking accuracy, reducing chattering effect, providing finite-time convergence, and robustness against the effect of the LUaF. The Lyapunov theory is employed to illustrate the robotic system’s stability and finite-time convergence. Finally, simulations using a 2-DOF serial robotic manipulator verify the efficacy of the proposed method.
Highlights
In industry, robotic manipulators are very popular
Faults are regarded as extra uncertainties, and the overall impacts of the system’s lumped uncertainties and faults (LUaF) are evaluated
This study proposed a disturbance observer (DO) to approximate the LUaF of robotic manipulator system with high accuracy and fast convergence
Summary
Robotic manipulators are very popular. They have been employed in many applications such as material handling, milling, painting welding, and roughing. In order to get rid of them simultaneously, the non-singular fast TSMC (NFTSMC) is proposed [34,35,36,37,38] This controller has outstanding control features such as singularity removal, high tracking precision, finite-time convergence, and durability to LUaF effects. This study proposed a disturbance observer (DO) to approximate the LUaF of robotic manipulator system with high accuracy and fast convergence. The Actuators 2021, 10, 332 combination of proposed controller–observer technique provides high tracking precision, fast convergence, less chattering effect, and finite-time convergence.
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