To address the challenging problem of fixed-time anti-sway and positioning control for tower cranes with uncertain disturbances and input saturation, a novel fixed-time anti-saturation robust algorithm is proposed. First, on the basis of a newly designed fixed-time convergence system, a fixed-time disturbance observer (FTDO) is developed to estimate the matched and unmatched disturbances. Then, an anti-saturation compensator is employed to deal with the input saturation and make the control input leave the saturated region rapidly. Upon which, a novel non-singular fast terminal sliding mode surface is presented. Furthermore, in order to ensure the stability of each subsystem, a hierarchical sliding mode surface taking into account unmatched disturbances and input saturation is designed. Finally, the FTDO based hierarchical sliding mode control law is introduced to improve the transient control performance and robustness of tower cranes. The fixed-time convergence of the closed-loop system is proved by Lyapunov technique. Numerical simulations for four scenarios demonstrate the validity of the presented control scheme and fastest convergence speed in comparison to the recently proposed fixed-time control methods.

中文翻译：

---

具有不匹配扰动和输入饱和的塔式起重机定时鲁棒控制

针对具有不确定扰动和输入饱和的塔吊定时防摇定位控制的挑战性问题，提出了一种新颖的定时抗饱和鲁棒算法。首先，在新设计的固定时间收敛系统的基础上，开发了固定时间干扰观测器（FTDO）来估计匹配和不匹配的干扰。然后，采用抗饱和补偿器对输入饱和进行处理，使控制输入迅速离开饱和区。在此基础上，提出了一种新的非奇异快速终端滑模面。此外，为了保证各子系统的稳定性，设计了考虑不匹配扰动和输入饱和的分层滑模面。最后，引入基于FTDO的分层滑模控制律以提高塔式起重机的暂态控制性能和鲁棒性。Lyapunov技术证明了闭环系统的固定时间收敛性。四种情况的数值模拟证明了所提出的控制方案的有效性和与最近提出的固定时间控制方法相比最快的收敛速度。