红外寻的制导空空导弹变结构比例导引律研究

A Variable Structure PN Law Suitable for HighPerformance IR Homing AirtoAir Missile

经典的比例导引律不能满足近距格斗导弹大离轴发射和攻击高机动目标的要求。前人提出了多种解决此问题的制导规律，除需要目标视线角速度信息外，还需相对速度、目标加速度和剩余时间等信息，这在被动红外制导导弹上实现是十分困难的。本文以变结构控制理论为基础，给出一种只需目标视线角速度信息的新型制导律，实现了在目标机动的条件下、有限时间内目标视线角速度的零化，大幅度地改善了制导性能。仿真结果证实了设计方法的正确性。

PN(proportional navigation) law is in wide use. After a great deal of careful research, we decided to make PN law a variable structure one in order to make it less difficult to implement while satisfying two stringent requirements: (1) the IR(infrared) homing airtoair missile should be effective against highly maneuverable targets; (2) even large offboresight angle launching can be effective. When implementing ordinary PN law, the assumption of small offboresight angle launching is usually made. The implementation of our variable structure PN law has no need of such assumption. In our research we considered target normal acceleration, related to target maneuverability, to be bounded disturbance. We utilized variable structure control to overcome such disturbance by making dq/dt, lineofsight rate, approach zero in a limited time. We derived eq.(10) as the model of our variable structure PN law. Simulation results are presented in Fig.2(a). Fullline curve shows the variation of dq/dt with time for PN law; dottedline curve shows the variation of dq/dt with time for variable structure PN law(dq/dt indistinguishable from zero after only about one second for our numerical xample). The comparison shows that highperformance of IR homing missile appears to be attainable with variable structure PN law. Our method is simple and requires no signals additional to dq/dt; thus it is less difficult to implement.