Uncertainty analysis of flight dynamic characteristics for hypersonic vehicles

Knowledge of the dynamic characteristics bounds of hypersonic vehicles is necessary during the process of control law design and clearance due to the multi-sources and large magnitude of uncertainties arising from the inaccuracy of mathematical dynamic models. A coupled longitudinal dynamical model is developed in this paper for a typical hypersonic waverider with parametric uncertainties depicted as intervals. A comparative study is made of the open-loop/closed-loop eigenvalue bounds estimation by the three methods of Taylor expansion based interval analysis method (TIAM), collocation interval analysis method (CIAM), and direct Monte Carlo (DMC) simulation method. For complex eigenvalues, the problems are transformed into two sub-problems of the intervals of the frequency and damping ratio, which are both real numbers. The results indicate that CIAM can give comparatively more accurate and safe bounds estimation while keeping the computation cost low, which demonstrates its potential for application in robust controller design and assessment.