Aiming at the trajectory tracking of a free-flying flexible-joint space robot (FFSR) with unknown time-varying disturbances and input saturation, we develop a robust control law with prescribed performance constraints via backstepping technique. A disturbance observer is employed to estimate the unknown time-varying disturbances and two auxiliary systems are introduced to handle input saturation. Moreover, we use the dynamic surface control (DSC) technique to deal with the complexity explosion caused by multiple derivatives of the virtual control signals. The performance function and transformation function are utilized to improve the tracking performance. It is proved that the designed control law can maintain the tracking error of the FFSR within a predefined region, while guaranteeing the uniform ultimate boundedness of all signals in the FFSR closed-loop control system. Finally, simulations are carried out to demonstrate the effectiveness of the developed prescribed performance tracking control.

针对具有未知时变扰动和输入饱和度的自由飞行柔性关节空间机器人 (FFSR) 的轨迹跟踪，我们通过反步技术开发了具有规定性能约束的鲁棒控制律。采用扰动观测器来估计未知的时变扰动，并引入两个辅助系统来处理输入饱和。此外，我们使用动态表面控制（DSC）技术来处理由虚拟控制信号的多重导数引起的复杂性爆炸。利用性能函数和变换函数来提高跟踪性能。证明设计的控制律可以将 FFSR 的跟踪误差保持在预定区域内，同时保证FFSR闭环控制系统中所有信号的最终有界一致。最后，进行仿真以证明所开发的规定性能跟踪控制的有效性。