L1 Adaptive Control for Autonomous Rotorcraft

In this paper, the L1 adaptive control theory is used to design a high bandwidth inner loop controller to provide attitude and velocity stabilization of an autonomous small-scale rotorcraft in the presence of wind disturbances. The nonlinear model of the vehicle is expressed as a linear time-varying system for a predefined region of operation, for which an L1 adaptive controller is designed. The L1 adaptive controller ensures that an uncertain linear time-varying system has uniformly bounded transient response for system’s input and output signals, in addition to stable tracking. The performance bounds of L1 adaptive controller can be systematically improved by increasing the adaptation rate without hurting the robustness of the system. The performance achieved with the L1 controller is compared with that obtained via a linear state feedback controller for demanding reference signals in the presence of wind disturbances. Simulation results show that the performance of the L1 surpasses that of the linear controller illustrating the advantages of fast adaptation.