The controller parameters of a quadrotor helicopter have to be properly adjusted for the helicopter to fly stably, while considering the helicopter’s dynamics. Typically, there exists uncertainty in helicopter dynamics such as parametric uncertainty and unmodeled dynamics including external disturbances. To cope with uncertainty in the dynamics, it is effective to update controller parameters according to the performance during the flight. This paper proposes the introduction of a simple adaptive control (SAC), which is an adaptive control technique to augment the conventional attitude controller based on the PD controller to attenuate the effect of uncertainty. The introduction of a constraint to the adaptive gain is also proposed to suppress overshoot in the transient response. In this study, it was demonstrated through numerical simulations and experiments that the proposed controller was effective and that its performance was better in comparison to the original PD controller.

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