Study on Guidance Laws of Varying-Velocity Missiles

Abstract

The midcourse and terminal homing guidance algorithms for varying-velocity missiles are studied in this dissertation. An application study is performed for those algorithms with an example missile system, anti-ballistic missile. The midcourse guidance algorithm is designed for anti-air and anti-ballistic missiles with high operating altitudes. This algorithm consists of two parts

the midcourse guidance law and the terminal constraint update algorithm. The midcourse guidance law is designed with an optimal control theory to satisfy the constraints on flight path angle and lead angle constraints at missile burn-out against a stationary virtual target. Those constraints and the position of the virtual target are required to be defined to construct designated engagement geometry with the real target at missile burn-out. The terminal constraint update algorithm calculates those values at each update cycle. This algorithm is based on the assumption that the target trajectory information is estimated and provided by the external sources, such as ground radar. Numerical simulations are conducted to show the features of the designed midcourse guidance algorithm. The terminal impact angle control guidance (IACG) law design methodology is proposed to be applicable to the various combinations of missile and target motions. This methodology extends the capturability-proven guidance laws to their IACG versions. The IACG laws designed with this methodology consist of two terms. The first term guarantees the capturability of the IACG law. It also maintains the terminal flight path angle to be that achieved with the original capturability-proven guidance law. The second term is introduced to make the terminal flight path angle to converge to the desired value. The sample IACG laws are devised with the proposed methodology. The performances and characteristics of those sample IACG laws are studied with mathematical analysis as well as numerical simulations. 2-stage anti-ballistic missile is considered in the application study. This missile system is modeled to perform midcourse guidance with the first stage and terminal homing guidance with the second stage. The midcourse guidance algorithm proposed in this dissertation is utilized during the midcourse guidance phase. The IACG law for accelerating anti-ballistic missiles is derived with the terminal IACG law design methodology, which is modified for the missile system in consideration. This IACG law is applied during the terminal homing guidance phase. The applicability of the proposed algorithms is examined with the numerical simulations.