Robust-Control-Based Design and Comparison of an Adaptive Controller for the VEGA Launcher

This article presents the design and evaluation of an adaptive controller for the atmospheric phase VEGA launcher. This design uses an Adaptive Augmenting Control (AAC) architecture to further extend the performance and capabilities of a robust-control structured H∞ controller, which was designed based on the current VEGA control architecture. The main goal of this paper is first, to explore adaptive features for the VEGA control system and second, to evaluate its performance and robustness properties. To that end, the adaptive controller is compared with the structured H∞ baseline controller and a linear parameter varying (LPV) design (both without adaptive augmentation). The three controllers are analysed for several extreme off-nominal condition tests using a high-fidelity, nonlinear simulator of the VEGA launcher. And the main performance indicators for the atmospheric phase are evaluated through a Monte-Carlo campaign. The results show that the adaptive and LPV controllers successfully provide stability under extreme adverse flight conditions over the non-adaptive robust controller. It is also shown that the LPV approach provides a more formal and methodological way to achieve these improvements.