An H_∞ control design approach for space vehicles application to Ariane 5 E/CB

Astrium has applied the 4-block H_∞ scheme to synthesize robust control laws for its satellites. For more than six years, flight experience has given the necessary maturity in the development, the implementation and the testing of such complex control laws. Considering the commonality in applications, this knowledge is applied to the Ariane launcher in order to assess its embarkability. The thorough analyses of the launcher specificities lead to the design of a dedicated H_∞ scheme and its application to an Ariane 5 E/CB benchmark. Worst case analysis techniques assess the performances of the resulting controller over the whole range of variation of the launcher uncertain characteristics. Application of this technique to the benchmark uses numerical identification of a pseudo-analytical model of the launcher dynamics prior to the construction of the LFT object. Meaningful destabilizing combinations of uncertain parameters validate the approach. This work was conducted under CNES contract. The contribution of Ariane architect EADS-LV is acknowledged in providing models of the nominal and perturbed dynamics.