Flight Control of Hypersonic Scramjet Vehicles Using a Differential Algebraic Approach

Abstract

[Abstract] Trajectory Linearization Control (TLC) is applied to a longitudinal hypersonic scramjet vehicle (HSV) model. The TLC algorithm is based on Differential Algebraic Spectral Theory (DAST) which features a time-varying eigenvalue concept and avoids the use of so-called frozen-time eigenvalues that can lead to unreliable results when applied to time-varying dynamical systems. A TLC controller was first designed for a nonlinear, affine, rigid-body model using an allocation strategy based on trim-condition lookup tables. The tables were populated by trimming the model at multiple operating points while varying velocity and altitude. The trim data was then fitted to a cubic polynomial function, and the lookup tables were replaced by analytical expressions for the effector settings. The TLC design was then verified on a first-principles based, longitudinal, rigid-body hypersonic vehicle model, and initial simulation testing results are presented.