Enhanced extended state observer based control for missile acceleration autopilot

In disturbance rejection based control methodologies, the term disturbance generally refers to internal uncertainties, external disturbances, and/or a combination of both. This paper argues that this concept can be further extended to the difference between what a controlled system is actually and what it should be, and an enhanced extended state observer is proposed to estimate this generalized disturbance. Combining the novel observer with state feedback strategy, a method is developed to force the controlled output to track the reference signal, rather than just stabilizing it around zero. Moreover, for the first time, this paper gives a rigorous proof of equivalent input disturbance (EID) for single-input-single-output systems. Introducing the concept of EID further enables the proposed method to handle multiple disturbances. Both numerical simulation studies and an application example of missile acceleration autopilot design demonstrate the feasibility and efficacy of the proposed method.