带攻击角度约束的非奇异终端滑模固定时间收敛制导律

Nonsingular terminal sliding mode based impact angle constraint guidance law with fixed-time convergence

针对拦截机动目标的末制导问题,设计一种带攻击角度约束的末制导律.该制导律构造一种新型的固定时间收敛非奇异终端滑模面,能够在解决终端滑模面奇异性问题的同时使得滑模面、弹目视线角和弹目视线角速率在固定时间内收敛,保证收敛时间的上界是独立于弹目初始条件,可以被预先设定的.与传统的固定时间收敛控制相比,该制导律通过调节滑膜面和弹目视线角误差的趋近律指数使得制导系统收敛速率更快.同时,针对目标机动引起的未知扰动,引入一种扩张状态观测器进行估计,能够增强制导系统的鲁棒性,避免震颤现象的发生.最后,通过仿真实验验证所提出制导律能够以不同的攻击角度对机动目标进行有效拦截,且与其他制导律相比,所提出的制导律使得制导系统收敛更快,导弹拦截时间更短,拦截精度更高.

A terfminal guidance law is developed for missiles intercepting maneuvering targets with impact angle constraints.A novel nonsingular terminal sliding mode with fixed-time convergence is constructed to avoid the singularity problem while ensuring the sliding surface,LOS angle and the LOS angular rate are fixed-time convergent.The upper-bound of convergence time is independent of the initial states of missiles and targets and can be set in advance.Compared with conventional fixed-time convergence control,the proposed guidance law has a faster convergence rate by regulating the index of the approaching laws of the sliding surface and the LOS angle error.Besides,an extended state observer is introduced to estimate the unknown disturbance caused by the target acceleration,which ensures that the guidance system has a good robustness and avoids the chattering problem.Finally,simulation results indicate that with the proposed guidance law,the missile can intercept the maneuvering targets effectively under different impact angles.Besides,comparisons with other guidance laws show that the proposed guidance law can improve the convergence rate of the guidance system and allow the missie to intercept the targets more accurately in less time.