In this article an application of LFT/LPV modeling and data-based validation techniques to a re-entry vehicle is shown. This work is part of a European Space Agency project tasked with examining the use of LPV technologies for the control design process of space systems. The application presented serves as an assessment on the technological readiness level of LPV/LFT modeling approaches and data-based validation algorithms, as well as a review of their features, shortcomings and needs. The selected vehicle is the longitudinal nonlinear motion of NASA HL-20 during an approach trajectory from Mach 4.5 down to 1.5.

In this paper the application of linear parameter varying (LPV) modeling, design and analysis methods to a re-entry vehicle is presented. The selected atmospheric re-entry benchmark includes full nonlinear motion, a detailed aerodynamic database (from hypersonic to subsonic), relevant actuator and sensor models and physically-meaningful aerodynamic and parametric uncertainty profiles. The results show that: (i) LPV controller design methods can solve gain-scheduling problems in a very effective manner, (ii) integral quadratic constraint (IQC) analysis methods can be used very efficiently to accurately interpret the nonlinear time domain simulation results, and, (iii) the use of linear fractional transformation (LFT) and LPV modeling representations are key to a successful analysis.

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