Black-box and grey-box identification of the attitude dynamics for a variable-pitch quadrotor

System identification is now a well established approach for the development of control-oriented models in the rotorcraft field (see, e.g., the survey paper Hamel and Kaletka (1997), the recent books Tischler and Remple (2006), Jategaonkar (2006) and the references therein). Though the application to full scale rotorcraft is by now fairly mature, less experience has been gathered on small-scale vehicles, such as, e.g., quadrotors. This paper deals with the problem of characterizing the attitude dynamics of a variable-pitch quadrotor from data and presents the results obtained in an experimental identification campaign. More precisely, on-line and off-line methods have been considered and the performance of black-box versus grey-box models has been compared.