Structured singular-value analysis of the Vega launcher in atmospheric flight

Using the Structured Singular Value (SSV) µ, an independent control law assessment is present for the VEGA launcher Thrust Vector Control (TVC) system. A systematic uncertainty modeling and analysis is illustrated in order to retrieve and structure driving perturbation combinations affecting competing control system design requirements. It is demonstrated how µ analysis not only complements and generalises classical frequency domain stability assessments, but also how it applies naturally as a performance indicator to manage the requirements trade-off space. The proposed methodology is shown to be reliable and computationally more efficient than widespread verification and validation techniques that rely on random sampling via Monte Carlo analysis. Although not meant as a replacement of these traditional approaches, µ analysis effectively complements and enhances the veritification and validation tasks by guiding the analyst towards worst-case convergence over the uncertain parameter search space. The attitude dynamics in atmospheric flight of Europe's lightweight VEGA launcher is assumed throughout the paper. Comparative robustness analysis results are shown between pre and post-flight assessments.