Robust adaptive control of a quadrotor helicopter

This work presents a direct approximate-adaptive control, using CMAC nonlinear approximators, for an experimental prototype quadrotor helicopter. The method updates adaptive parameters, the CMAC weights, as to achieve both adaptation to unknown payloads and robustness to disturbances. Previously proposed weight-update methods, such as e-modification, provide robustness by simply limiting weight growth. In order to let the weights grow large enough to compensate unknown payloads, the proposed method relies on a set of alternate weights to guide the training. The alternate weights produce nearly the same output, but with values clustered closer to the average weight so that the output remains relatively smooth. This paper describes the design of a prototype helicopter suitable for testing the control method. In the experiment the new method stops weight drift during a shake test and adapts on-line to a significant added payload, whereas e-modification cannot do both.