基于平滑饱和函数改进的自适应超扭转空间系绳系统部署控制

Adaptive Super-Twisting Deployment Control for a Space Tethered System Enhanced by a Smooth Saturation Function

摘要: 针对空间系绳系统在未知边界扰动与模型不确定性下的稳定部署问题，本文提出一种改进的平滑自适应超扭转控制方法。为克服传统滑模及标准自适应超扭转算法中固有的控制抖振与不连续切换缺陷，所提方法在控制律中引入平滑饱和函数替代不连续的符号函数。在完整保留自适应增益机制以应对未知边界扰动的同时，实现了控制输入的连续化与抖振抑制。基于李雅普诺夫理论分析了闭环系统的稳定性，证明滑模变量可在有限时间内收敛至原点附近的小邻域，并在所引入的边界层内保证一致最终有界性。在无扰动与复合强扰动工况下的数值仿真对比表明，相较于标准自适应超扭转控制与带幂次趋近律的滑模控制，本文改进方法在保持收敛速度的前提下，张力控制输入更平滑、系绳长度跟踪的均方根误差更小、对面内角摆动的鲁棒抑制能力更强。仿真结果验证了该方法在降低执行机构磨损及提升部署稳定性方面的工程优势。

Abstract: To address the stable deployment of space tethered systems subject to unknown bounded disturbances and model uncertainties, an improved smooth adaptive super-twisting control method is proposed. To overcome the inherent control chattering and discontinuous switching of conventional sliding-mode control and standard adaptive super-twisting algorithms, a smooth saturation function is introduced into the control law to replace the discontinuous signum function. The adaptive gain mechanism is retained to compensate for unknown bounded disturbances while ensuring continuous control input and suppressing chattering. The stability of the closed-loop system is analyzed using Lyapunov theory. It is demonstrated that the sliding variable can reach a small neighborhood of the origin within finite time and remain uniformly ultimately bounded within the introduced boundary layer. Numerical simulations under disturbance-free and composite strong-disturbance conditions show that, compared with standard adaptive super-twisting control and sliding-mode control with a power reaching law, the proposed method provides a smoother tether-tension input, a smaller root-mean-square tether-length tracking error, and stronger robust suppression of in-plane libration while maintaining a comparable convergence rate. The results demonstrate the engineering advantages of the proposed method in reducing actuator wear and improving deployment stability.