深空探测柔性太阳帆航天器动力学建模与姿态控制

Dynamic modeling and attitude control of flexible solar sail spacecraft for deep space exploration

中文关键词  太阳帆航天器  动力学建模  姿态控制  柔性  仿真

英文关键词  Solar sail spacecraft  dynamic modeling  control  flexible  simulation

中文摘要

      柔性太阳帆完整的仿真模型包括多体动力学、刚柔耦合、以及太阳辐射光压模型，导致控制设计十分复杂。针对带有控制杆的太阳帆，本文采用拉格朗日方程和有限元方法，给出了解析形式的面向控制的模型。所推导的刚柔耦合动力学模型便于理解双框架控制杆的短周期运动，姿态与柔性太阳帆的耦合特性，以及在太阳光压恢复力矩下的静稳定姿态长周期运动。基于带控制杆的太阳帆的多时间尺度特性，给出了双回路控制结构，用于实现航天器俯仰轴和偏航轴的姿态控制。内回路设计为比例-微分（PD）控制器，用于实现质心位置的调整。外回路设计为比例-积分-微分（PID）控制器，用于阻尼姿态运动，并保持在平衡太阳光压力矩下的期望姿态。因此，将控制问题分解为低阶子问题，实现了在不同频带上的设计。仿真结果验证了动力学和姿态控制设计方法的有效性。

英文摘要

      Full simulation models for flexible solar sail spacecraft include multi-body dynamics, complex interplay between flexible and rigid modes, along with solar radiation pressure model, resulting in intractable systems for control design. In this paper, for a solar sail spacecraft with a control boom, a control-oriented model in closed form is obtained by Lagrange equation and finite element method. The deduced rigid-flexible coupling dynamic model allows a well understanding of the short-term motion of a two-axis gimbaled control boom, the coupling properties between attitude and flexible spars, and the long-term motion of statically stable attitude under solar-pressure restoring torque. Based on the multi-time-scale property of the solar sail spacecraft with a control boom, a dual-loop control structure is proposed to change the pitch axis and yaw axis attitude of the spacecraft, employing a gimbaled control boom. The inner-loop is designed as a proportional-derivative (PD) controller to realize the regulation of the center of mass. The outer-loop is designed as a proportional-integral-derivative (PID) controller to damping the oscillate motion and maintain the desired attitude under balanced solar-pressure torque. As a result, the full control problem is decomposed into lowerorder subproblems, which are solved at different frequency band. Simulation results are presented that validate the dynamic modeling and attitude control design approach.