Estimating evasive acceleration for ballistic targets using an extended state observer

This paper presents the development of an estimation algorithm for ballistic-target evasive acceleration during the terminal phase of interception. The proposed design is based on an application of the extended state observer, using target information acquired from a seeker to estimate target evasive acceleration. It is applicable to multiple-input multiple-output plants with variable observer gains applied in nonlinear coupled line-of-sight pitch and yaw dynamics. Design and stability analysis are evolved based on the theory of Lyapunov, with noncontinuous, piecewise, smoothly Lyapunov function candidates.