Robust Control of a Hypersonic Gliding Vehicle with Significant Model Uncertainties
| Hypersonic gliding vehicles (HGVs) operate in flight regimes characterized by nonlinear dynamics, significant aerodynamic uncertainties, and strong coupling between vehicle motions. These characteristics pose challenges for flight control design, particularly when tracking performance must be maintained despite model inaccuracies, changing flight conditions, and practical implementation limitations. This work addresses robust flight control of an HGV, with emphasis on acceleration tracking under aerodynamic model uncertainty. A nonlinear six-degree-of-freedom model serves as the basis for simulation and controller evaluation. Control-oriented linear models are derived around selected operating conditions, while uncertain aerodynamic parameters are represented explicitly in an affine form within a structured uncertainty framework. This formulation enables the application of H-infinity and structured singular value (μ-synthesis) methods for controller synthesis and robustness analysis. The control design incorporates actuator and sensor dynamics, together with frequency-dependent weighting functions that shape tracking performance, improve transient response, and limit control effort. The weights also address elastic modes through frequency shaping, without explicitly including aeroelastic dynamics in the synthesis model, thereby simplifying the model and controller design. Practical implementation aspects are examined through discrete-time synthesis and controller-order reduction. Closed-loop performance is evaluated through frequency-domain analysis, linear time responses, and nonlinear Monte Carlo simulations with uncertain aerodynamic parameters. Aeroelastic modes are incorporated into the nonlinear simulations to assess their influence on closed-loop behavior. The results demonstrate stable responses and effective reference tracking across the tested cases, supporting the applicability of the linear-model-based controllers to the nonlinear vehicle despite aerodynamic uncertainties and aeroelastic effects. This work is towards an M.Sc. degree under the supervision of Prof. Moshe Idan and Dr. Oded Golan, The Stephen B. Klein Faculty of Aerospace Engineering, Technion. |
