利用受限张力的拖曳变轨欠驱动姿态稳定策略

Underactuated attitude stabilization for space tethered towing using constrained tension

在空间绳系拖曳变轨中,目标和平台形成一种哑铃型绳系系统,且仅依靠有限的平台推力和系绳张力来抑制系绳的摆动。针对此类输入受限的欠驱动控制问题,提出了一种利用受限张力的姿态稳定策略。首先,推导了组合体姿态动力学模型。然后通过数值求解姿态平衡方程得出理论面内姿态指令,再采用高斯伪谱法对其优化获得实际指令。最后,基于分层滑模理论设计欠驱动张力控制律,并嵌入抗饱和模块以缓解张力饱和。仿真表明空间平台能在正向有限的张力控制下,平滑地收放系绳使面内角和绳长跟踪实际姿态指令。此外,所提策略对目标体摆动和传感器误差也具有良好的鲁棒性。

During space tethered towing,the target and the space platform constitute a dumbbell-like tethered system,which only relies on the limited platform thrusts and tether tension to suppress the tether libration.An effective attitude stabilization strategy using bounded tension is proposed for such an underactuated system subject to input constraints.The dynamic model governing the attitude of the system is established.By solving the in-plane equilibrium equation numerically,the theoretical in-plane attitude commands are obtained,which are then optimized using Gauss pseudospectral method.The actual in-plane commands are thus yielded.An underactuated tension controller is designed based on hierarchical sliding mode theory,and an anti-windup auxiliary module is embedded to mitigate the tension saturation.Simulation results show that under the positive and constrained tension control,the tether can be deployed and retrieved smoothly by the platform,making the in-plane angle and tether length track the actual commands appreciably.The proposed strategy is also robust to the target swing and sensor errors.