Robust transition control of a Martian coaxial tiltrotor aerobot

Abstract

Hyperion is an autonomous solar-electric powered coaxial tiltrotor aerobot proposed to investigate the Isidis Planitia region on Mars. The objective of this paper is to propose a robust control strategy for transition flight between hover and cruise based on the supervisory control method and the linear robust control method. The proposed transition controller has two levels. The lower level is a series of candidate controllers for the subproblems, which are obtained by the operation of divide and conquer. The higher level uses the state variables to determine which lower level candidate controller should be used. The candidate controllers are solved using the μ synthesis and the conventional longitudinal and lateral control loops. The robustness of the candidate controllers is guaranteed by the robust control theory. The stability and robustness of the transition controller is determined by the switch logic in the higher level. The stability of the proposed control strategy is analyzed. A 6 Degree of Freedom simulation with uncertain aerodynamic model is used to show the robustness and the performance of the proposed controller.