基于四元数反馈线性化的飞行器姿态控制方法研究

Research on the Quaternion Feedback Linearization for Spacecraft Attitude Control

空间飞行器姿态控制系统是一个非线性多输入多输出系统,其姿控执行机构的布局及工作特性决定了姿态控制的难易程度。针对飞行器以姿控发动机作为姿控执行机构时的大角度姿态运动需求,本文采用单位四元数作为弹体姿态描述,考虑到姿控发动机布局对姿态控制的影响,直接以姿控发动机推力作为系统的控制输入,利用反馈线性化方法,将原非线性系统转化为一个六阶线性子系统和一个一阶内动态子系统。在对内动态分析的基础上,针对线性子系统设计了四元数PD反馈控制律。在转动惯量不确定性以及轨控大干扰力矩存在的情况下,对闭环控制系统进行了大角度姿态运动数字仿真。仿真结果表明,本文所设计的姿控方法能够有效地实现飞行器大角度姿态控制,并对系统参数摄动及外部干扰具有较强的鲁棒性。

Spacecraft attitude control system is a nonlinear MIMO system in which the layout and the working mechanism of the attitude control thrusters are important to the attitude control. Due to the demand of the large angle attitude control, the unit quaternion is used to describe the spacecraft attitude in this thesis. Considering the influence of the layout of the attitude control, thruster forces are taken as the control input directly. By the feedback linearization, the previous nonlinear system is turned into a six-degree linear subsystem and a one-degree internal dynamics subsystem. Based on the analysis of the internal dynamics, a quaternion PD feedback control law is designed for the linear subsystem. Finally, the correctness and the robustness of the control strategy are validated by the simulation of the closed loop control system in the presence of the inertial uncertainties and the big disturbing torques.