Multiple model adaptive evasion strategies from an incoming homing missile are presented. The problem is formulated in the context of an evading target aircraft having imperfect information on the relative state and on the employed guidance law and guidance parameters of the missile. The missile’s guidance strategy is assumed to belong in a finite set of linear guidance laws and to be fixed throughout the engagement. Arbitrary-order linear missile and target dynamics, bounded target control, and nonlinear kinematics are also assumed. The filter used to identify the missile’s guidance strategy is a nonlinear adaptation of the multiple model adaptive estimator, in which each model represents a possible guidance law and corresponding guidance parameters of the attacking missile. Specific limiting cases are carefully analyzed in which the attacking missile uses proportional navigation, augmented proportional navigation, or an optimal guidance law. Matched optimal evasions from these specific cases are also derived and fit into the framework of the multiple model adaptive control approach. For the limiting cases, an alternative reduced-order approach is proposed to save computational resources. Considering noisy bearing-only measurements, the performance of the proposed evasion concepts is compared through a Monte Carlo simulation campaign to the scenario when the target has full knowledge about the attacking missile and the relative state.

Cooperative estimation/guidance for a team of missiles is the topic of this paper. An example scenario is considered where an aircraft simultaneously launches several cooperative defending missiles as a countermeasure against an attacking homing missile. A new reduced-order estimation scheme based on information sharing to cooperatively estimate the relative states and the unknown parameters of the attacking missile is proposed. Each defending missile shares its own noise-corrupted line-of-sight angle measurement with the rest of the team. The observability of this multi-line-of-sight measuring environment is enhanced by cooperatively imposing nonnegative relative intercept angles between consecutive defenders. The ability of the proposed strategy to protect the targeted aircraft is studied for a two-defender case via extensive Monte Carlo simulations. The effect of different values of the commanded relative intercept angle on the pure estimation as well as on the intertwined guidance-estimation performance is carefully analyzed for various considerations of the defenders’ maneuverability.

A novel cooperative defensive guidance law is presented for a two-on-two engagement. Instead of classical strategies in which evasive maneuvers are performed or additional agents (e.g., defender missiles) are deployed, the target pair lures the pursuing missiles into collision. The optimal cooperative strategy is solved using state-dependent Riccati equation method. Linearized kinematics and arbitrary-order linear adversaries’ dynamics are assumed in the guidance law derivation. Imperfect information is assumed on the relative states and the guidance laws employed by the missile pair. Guidance strategies that the pursuing missiles may employ are assumed to belong to a finite set of linear guidance laws. In addition to the proposed cooperative defensive strategy, a decentralized estimation scheme based on the multiple-model adaptive estimation approach is also presented. Guidance law and estimation performance are demonstrated using nonlinear simulations. Simulation results show the viability of the proposed guidance law and highlight the sensitivity of the guidance law to range measurement accuracy.