Gain-scheduling Hinfinity control of the launcher in atmospheric flight via linear-parameter varying techniques

This paper is concerned with the design of a gain-scheduled controller for the attitude control of a launcher in atmospheric flight. The design problem is characterized by classical requirements such as satisfactory phase/gain margin constraints and flexible modes attenuation as well as time-domain constraints in the form of an upper bound on the angle of attack in the presence of wind disturbance. Moreover, these requirements must be fulfilled over the full atmospheric flight. In order to achieve this goal, we exploit a recently available Linear Parameter-Varying (LPV) technique suitably extended to discrete-time systems. The advantage of this technique is that both time-invariant constraints and the gain-scheduling phase are incorporated into a single design procedure and neither interpolation nor extensive simulations are required to accomplish the overall design task. An important ingredient in the proposed technique is the Cross Standard Form formulation which allows to incorporate the various specifications of the launcher problem in a streamlined manner. It leads to a specific control standard form which can be immediately handled by the LPV design technique under consideration