挠性欠驱动航天器的姿态镇定方法

Attitude Stabilization of a Flexible Spacecraft under Actuator Failure

针对挠性欠驱动航天器的姿态系统的镇定问题,提出了一种基于自适应观测器的容错控制方法,使得航天器的角速度和姿态收敛到有界的区域.所考虑的挠性航天器几乎是轴对称的,其中小参数ε给出了航天器关于欠驱动轴的非对称性的度量程度.首先,利用齐次系统的思想简化系统的模型,消除部分难以处理的耦合项;其次,设计自适应观测器实现对挠性非线性项的未知信息进行估计,并给出观测值与真值的范数界限;进而设计容错控制器使得系统的输出对于耦合项的估计是输入状态稳定的.最后,仿真结果验证了所提方法的有效性.

We consider the problem of attitude stabilization of a flexible spacecraft under complete failure of a single actuator. A novel adaptive observer-based fault-tolerant control scheme is proposed to guarantee the convergence of the angular velocity and attitude of the spacescraft to a bounded region. The spacecraft model under consideration is a flexible body that is almost axisymmetric. A small parameter gives a measure of the nonsymmetry of the spacecraft about its axis. Firstly,the system model is simplified by eliminating the coupling term using a homogeneous system approach. Secondly,an adaptive observer is designed to estimate the nonlinear coupling,and the norm boundary of error between the estimated and true values is determined. Based on this,a fault-tolerant control law is further designed to ensure that the system output is input-to-state stable with respect to the estimation of the coupling term. Finally,the simulation results illustrate the efficiency of the theoretical results.