一种有攻击角约束的三维有限时间导引律

为解决目标加速度信息未知且存在攻击角约束的三维末端制导问题,提出一种基于非线性观测器的有限时间导引律,使得弹目视线角可在有限时间内收敛至期望攻击角.首先,提出一类非线性观测器,利用导引系统中易测量的位置和速度等信息来估计目标加速度,理论分析给出了观测器稳定的充分条件;然后,利用目标加速度估计值,基于有限时间稳定理论和滑模变结构控制理论设计一种有限时间导引控制律,使三维末端导引系统的弹目视线角可以在有限时间内收敛到期望攻击角.通过分析观测误差对导引系统有限时间特性的影响,表明该方法满足工程实践需求;最后,分别对加速度为匀变速和变加速的两类变速目标进行了数值仿真,并与传统比例导引法进行了对比,仿真结果验证了所提方法的可行性与有效性.研究表明,利用非线性观测器可以稳定地估计目标加速度信息,进而利用该观测器给出的目标加速度信息设计滑模变结构有限时间三维导引律,利用该方法可以有效地解决三维末端制导过程中存在目标加速度信息未知且存在攻击角约束的难题.

A finite-time guidance law for three-dimensional terminal interception with impact angle constraints

A finite-time stable guidance law is proposed to deal with the three-dimensional terminal interception impact angle constraints problem where the accelerations of target are not available. A kind of non-linear observer is designed to estimate target''s accelerations with the positions and velocities information given by missile. Further theoretical analysis is introduced to prove this observer''s accuracy. Then the finite-time guidance law is deduced by sliding-mode control laws and finite-time stability theory using the observer estimated values, by which the convergence of line of sight (LOS) angles in three-dimensional space to expected impact angles in finite time is guaranteed. Through analyzing the effect of observer''s errors on the guidance system, it is shown that the finite-time convergence can be achieved for the engineering practice by the proposed composite guidance law. Simulation results for uniformly/non-uniformly accelerated targets and the comparison with Proportion Navigation (PN) are provided to demonstrate the effectiveness of the proposed approach. The results suggest that difficulties of finite-time three-dimensional terminal interception problem with impact angle constraints can be solved by the proposed method combining the non-linear observer of target''s accelerations with the finite-time sliding-mode control laws.