Robust safety margin assessment and constrained worst-case analysis of a launcher vehicle

The robustness of an industrial standard, closed-loop launcher model during an atmospheric flight phase is assessed in terms of robust safety margins in a multi-dimensional parameter space made up of various rigid and bending mode uncertainties. A single-axis launcher model with time-varying aerodynamic and thruster efficiency parameters, along with an H∞ controller and bending mode filter is considered. A constrained hybrid optimisation approach is adopted to determine the safety margins for different wind perturbations acting at different time instances of the flight. In addition, optimisation-based analysis is performed to determine the worst-case uncertain parameter combination for the launcher during the atmospheric flight phase. Probability constraints on the uncertain parameter combination satisfying the dispersion requirements are considered during the analysis.