Finite-Time Fault-Tolerant Control for a Stewart Platform Using Sliding Mode Control With Improved Reaching Law

In this paper, a fault-tolerant control (FTC) is proposed for a nonlinear system as a Stewart platform (SP). To reject the singularity issue of a traditional fast terminal sliding mode control (FTSMC) and to have a fast finite-time convergence, a nonsingular fast terminal sliding mode control (NFTSMC) is used. In addition, an extended state observer (ESO) is applied for the control scheme to estimate uncertainties, disturbances, and faults. To increase the convergence speed and alleviate the chattering phenomenon, a novel reaching law is proposed which gives the system a quick reaching speed. Finally, a novel FTC that ensures robustness to disturbances and faults is developed based on the NFTSMC, the ESO, and the proposed reaching law. Consequently, the proposed FTC has outstanding features such as high tracking performance, a decrease in the effects of disturbances and faults, a fast convergence speed in finite time, and less chattering. The simulation and experiment results demonstrate the efficiency of the proposed FTC compared to other control schemes.