This paper investigates the issue of tracking control for a free-floating space manipulator with prescribed performance constraints, considering the inertia uncertainties, internal disturbances and input saturation. An inherently continuous adaptive controller is proposed by incorporating non-singular fixed-time sliding mode control, prescribed performance control (PPC), and auxiliary compensation. First, a modified non-singular fast fixed-time terminal sliding surface is constructed, which has a shorten convergence time than the conventional fixed-time sliding surface. Unlike the existing complicated PPCs, a simple structure controller is developed to satisfy prescribed performance constraints through a unique tangent-type PPC technique. The input saturation is then compensated adaptively by an auxiliary mechanism. The Lyapunov theory thoroughly validates the stability and fixed-time convergence of the closed-loop tracking system. With the suggested control scheme, the system states can converge quickly to a small neighbourhood around the origin within a preassigned time, while the position tracking error can be confined within a prescribed performance bounds even in the presence of input saturation. Compared to the existing tracking methods, the suggested control approach has the advantages of faster transient convergence, higher steady-state tracking precision, and stronger robustness. Simulation comparisons demonstrate the effectiveness and superiority of the proposed controller.

中文翻译：

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具有规定约束和输入饱和度的自由浮动空间操纵器的固定时间控制

本文研究了具有规定性能约束的自由浮动空间机械臂的跟踪控制问题，考虑了惯性不确定性、内部扰动和输入饱和。通过结合非奇异固定时间滑模控制、规定性能控制（PPC）和辅助补偿，提出了一种本质连续自适应控制器。首先，构造了一种改进的非奇异快速固定时间终端滑动面，其收敛时间比传统的固定时间滑动面更短。与现有复杂的PPC不同，通过独特的切线型PPC技术，开发了一种结构简单的控制器来满足规定的性能约束。然后通过辅助机制自适应地补偿输入饱和度。李亚普诺夫理论彻底验证了闭环跟踪系统的稳定性和定时收敛性。通过所提出的控制方案，系统状态可以在预先指定的时间内快速收敛到原点周围的小邻域，而即使在存在输入饱和的情况下，位置跟踪误差也可以限制在规定的性能范围内。与现有的跟踪方法相比，所提出的控制方法具有瞬态收敛速度更快、稳态跟踪精度更高、鲁棒性更强的优点。仿真比较证明了所提出的控制器的有效性和优越性。