针对终端角度约束制导问题,提出了一种采用部分状态反馈的固定时间收敛角度约束制导律。首先,基于一致精确鲁棒微分器(uniform robust exact differentiator, URED)算法,设计了固定时间状态观测器来估计不可测的系统状态。然后,基于固定时间稳定理论,设计了固定时间收敛的积分滑模面,并设计了固定时间制导律保证滑模面及制导误差的固定时间收敛。相比于传统有限时间制导律,文中所设计的固定时间制导律的收敛时间上界不受初始制导误差影响,因此可以在各类初始条件下都能保证快速收敛性能。同时,所设计的方法只需部分状态进行反馈,可以有效简化制导系统的硬件组成。最后,仿真结果表明,在各类初始制导误差及部分状态反馈条件下,所提出的方法都能取得良好的收敛速度与制导精度。

For the terminal angle constraint guidance problem, a fixed-time angle constraint guidance law based on partial states feedback was developed. Firstly, based on the uniform robust exact differentiator algorithm, a fixed time state observer was developed to estimate the unmeasured system state. Then, based on fixed-time stability, an integral sliding-mode surface was developed, and a fixed-time guidance law was developed to guarantee the fixed-time convergences of sliding-mode surface and guidance error. Compared with the conventional finite-time guidance law, the proposed guidance law not only can guarantee that the upper bound of convergence time is bounded by the constant which is not relate to the initial system states but also only need partial states to feedback to simplify the guidance system. Finally, the simulation results illustrate that the proposed guidance law can achieve the fixed-time stability by using the partial states to feedback.