Research on Fixed-Time Convergence of Multi-Missile Cooperative Terminal Guidance Law

This paper investigates the problem of cooperative guidance strategies for multiple missiles attacking a maneuvering target. Based on the consistency theory and algebraic graph, a fixed-time cooperative guidance law with a terminal line-of-sight (LOS) angle constraint is proposed. Initially, the maneuvers of target in the LOS direction and normal to the LOS are considered as disturbances affecting the missiles. A two-dimensional guidance encompassing three degrees of freedom model is formulated based on the missile-target kinematics. Next, the guidance law design is divided into two parts. Along the LOS, a disturbance observer estimates the disturbances, and a fixed-time convergent, time-coordinated guidance law is formulated, integrating a consensus protocol to handle these disturbances. In the LOS normal direction, an adaptive estimation method is utilized to estimate the upper bound of disturbance. A non-singular fast terminal sliding mode control method is employed to generate LOS normal acceleration commands while ensuring convergence to the sliding surface within a fixed time. Lastly, a scenario with three missiles engaging a maneuvering target is designed, and saturation limits are applied on the acceleration commands in both directions. The simulations validate the proposed cooperative guidance law's accuracy and efficacy for multiple missiles with a LOS angle constraint.