Structured Singular-Value Analysis of the Vega Launcher in Atmospheric Flight

Abstract

Using the structured singular value , an independent control law assessment is presented for the Vega launcher thrust vector control system. A systematic uncertainty modeling and analysis process is illustrated to retrieve and structure driving perturbation combinations affecting competing control system design requirements. It is demonstrated how analysis not only complements and generalizes classical frequency-domain stability assessments but also how it applies naturally as a performance indicator to manage the requirements tradeoff 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, analysis effectively complements and enhances the verification and validation tasks by guiding the analyst toward 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 postflight assessments.