Unstationnary Control of a Launcher Using Observer-Based Structures

This paper deals with the design of a gain-scheduled controller for the attitude control of a launcher during atmospheric flight. The design is characterized by classical requirements such as phase/gain margins and flexible mode attenuations as well as time-domain constraints on the response of angle of attack to a worst-case wind profile. Moreover, these requirements must be fulfilled over the full atmospheric flight envelope and must be robust against parametric uncertainties. In order to achieve this goal, we propose a method based on minimal observer-based realizations of arbitrary stabilizing compensators. An original technique to assign the closed-loop dynamics between the state-feedback dynamics and the state-estimation dynamics is presented for the H_∞, compensators case. The structure is used to mix various specifications through the Cross Standard Form (CSF) and to perform a smooth gain scheduling interpolation through an Euler-Newton algorithm of continuation.