Modeling and Control of a Co-Axial Helicopter
This thesis lays the foundations for the development of a small autonomous coaxialhelicopter. This is an helicopter with two propellers mounted on the same axis andrevolving in opposite directions. To steer the helicopter, this thesis proposes a mechanismthat moves the helicopter’s centre of mass. Although such a mechanism has already beeninvestigated experimentally in the literature, it has never been rigorously modeled, anda theoretical analysis has never been performed. This thesis, for the first time, presentsan accurate mathematical model of the coaxial helicopter which takes into account thegyroscopic effects of the rotors, the reaction forces and torques exerted by the movingmass actuator on the helicopter body, and the fact that the inertia of the helicopter istime-varying. A nonlinear controller is rigorously derived which makes the helicopterhover at desired positions in three-space. A number of physical prototypes are discussed.None of them is capable of autonomous flight yet, but the experimental and simulationresults provide reassurances that the proposed methodology is viable.