基于平面内目标-导弹相对运动方程的离散形式,给出了离散滑模变结构导引律设计方法。推导出了一种与连续时间自适应滑模制导律的离散化形式相同的离散变结构导引律。在不需要知道目标法向加速度界限,而只需要知道其在两个采样周期之间可能变化范围的条件下,设计了一种能显著降低系统抖动的离散滑模导引律,设计的同时给出了一种近似估计目标法向加速度的方法。从理论上证明了上述两种离散滑模导引律具有有限时间收敛的特性。讨论了离散滑模导引律的准滑动模态的切换带范围,给出了离散滑模导引律的终端脱靶量计算方法,最后以某空间拦截问题为实例验证了本文结果的正确性。
In this article a method of designing discrete sliding-mode guidance laws is proposed based on the discrete form of the target-missile relative motion equation in plane. A discrete sliding-mode guidance law is presented which is similar to the discrete form of the continuous time adaptive sliding-mode guidance law. Furthermore,another discrete sliding-mode law is designed which requires just knowing the possible variation range of target normal acceleration between two adjacent sampling instants rather than the target normal acceleration bound. This design significantly reduces system chattering and also suggests a method to estimate target normal acceleration. It is theoretically proved that the two preceding discrete sliding-mode guidance laws are finite time convergent. The quasi sliding-mode switching scope of the discrete sliding-mode guidance laws is discussed;mean while a method to calculate the terminal miss distance of discrete sliding-mode guidance laws is presented. The effectiveness of the above results is verified by simulating a space interception process.