Adaptive super-twisting nonsingular fast terminal sliding mode fault tolerant control of a 2-DOF helicopter with input quantization

Abstract

To address system uncertainties and external disturbances in a 2-DOF helicopter system, this paper proposes a novel adaptive super-twisting non-singular fast terminal sliding mode (NFTSM) fault-tolerant control (FTC) strategy. First, a hysteresis quantizer is utilized to mitigate chattering during the signal quantization process, and reduce energy loss. Second, a novel finite-time convergent NFTSM manifold is proposed, enabling the tracking trajectories to quickly reach the sliding mode surface, thereby endowing the controller with strong robustness. Additionally, neural networks (NNs) are employed to approximate the system’s nonlinear uncertainty functions. Furthermore, to overcome the dependency of the super-twisting algorithm on boundary information regarding disturbances during the design process, an adaptive super-twisting algorithm is introduced to compensate for the effects of quantization errors and external disturbances, ensuring FTC performance. Finally, simulation and experiment results effectively validate the superiority of the proposed control strategy.