Abstract
The nonlinear and open-loop unstable dynamics of a quadrotor helicopter makes a control system design non-trivial. However, even more difficulty lies in adapting to an uncertain dynamic model and unknown payloads while remaining robust to significant buffeting wind disturbances. Fuzzy-adaptive or neural-adaptive control offer possible solutions, exhibiting computational efficiency and adaptation to arbitrary nonlinearities. A common method for making these adaptive controls robust to disturbances, e-modification, is found to be unsuitable when applied to the quadrotor in simulation. The adaptive parameters tend to drift to large values in the presence of a sinusoidal disturbance. In this work, we propose a method that uses alternate adaptive parameters in the adaptation scheme. The proposed method successfully controls the quadrotor in simulation, with realistic control signals and computational effort. The adaptive parameter drift and control chatter present with e-modification both vanish. Moreover, performance improves dramatically in the presence of disturbances.