Structured Control for Future European Launchers

Control of a flexible launcher during the atmospheric flight phase is a highly challenging control problem involving multiple and concurrent design requirements: stability (stabilization of unstable rigid dynamics, sloshing modes and flexible structural modes), performance (guidance tracking, structural load minimization) and robustness (physical parameter uncertainties and accommodation to multiple vehicle configurations) on a non-stationary system. This paper focuses on co-funded AG/CNES research activities on the development of an advanced modular control strategy using recent advances in structured control design. We demonstrate here that structured H_∞ synthesis could give a gain scheduling solution to full timevarying flexible launcher control problems during the non-stationary ascent phase, enabling load performance improvement between complex sets of requirements, and, design cost improvements through simplification of the tuning process. We also present a generic framework for rapid control design that is now applicable both for European launcher families already in activity (with existing S/W and fixed controller structure) and for future expendable and reusable launchers.