L₁ adaptive augmentation of a helicopter baseline controller

In this paper we present L₁ adaptive control laws for augmenting an existing helicopter baseline controller. The adaptive augmentation is designed to maintain handling and flying qualities in situations the baseline controller was not designed for or performs poorly. Considering the peculiarities of helicopter dynamics, we propose a state-feedback L₁ flight control law with piecewise-constant estimation loops for attitude control. This control law augments an existing angular-rate baseline controller and receives commands from an outer-loop attitude control law. In addition, we also develop a standalone L₁ controller for vertical speed control in hover and low-speed regimes. The proposed controllers are tailored to comply with current philosophies for safety-critical systems in aerospace applications. The paper also presents simulation results obtained with a high-fidelity helicopter model.