This article proposes a control method for space manipulators rendezvousing with and capturing a target, involving concurrent operation of an optimal and a coordinated controller. The optimal controller drives the whole system to rendezvous with the target, which saves onboard fuel and satisfies obstacle avoidance constraint and base spacecraft thrust limits. The optimal control problem is solved using calculus of variations method, with state inequality constraints transformed into extended dynamical subsystems and thrust limits formulated as saturation functions. The coordinated controller is designed based on the dynamic equations of the space manipulator on a noninertial frame attached to the system center of mass, which drives the end-effector to approach the target along a desired trajectory while making the base attitude follow a desired profile. It also generates proper reaction moments on base through manipulator motions to ensure controlling the base attitude when base attitude actuators reach their torque limits. The solution optimality of the optimal controller and the stability of the coordinated controller are demonstrated. Numerical simulations verify the performance of the proposed concurrent control method.

中文翻译：

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致动器饱和下空间机械臂交会和捕获目标的最优并发控制

本文提出了一种空间机械手与目标交会和捕获的控制方法，涉及最优控制器和协调控制器的并发操作。最优控制器驱动整个系统与目标交会，节省机载燃料，满足避障约束和基地航天器推力限制。最优控制问题使用变分法求解，状态不等式约束转化为扩展的动态子系统，推力限制公式化为饱和函数。协调控制器是基于空间机械手在与系统质心相连的非惯性框架上的动力学方程设计的，它驱动末端执行器沿着所需的轨迹接近目标，同时使基础姿态遵循所需的轮廓。它还通过机械手运动在底座上产生适当的反作用力矩，以确保在底座姿态执行器达到其扭矩限制时控制底座姿态。证明了最优控制器的解最优性和协调控制器的稳定性。数值模拟验证了所提出的并发控制方法的性能。