Standard quadrotor UAVs are inherently underactuated as they posses only four independent control inputs - their four propeller spinning velocities. Therefore they only possess a limited mobility in space for the six dofs parameterizing the quadrotor position/orientation. This implies that for standard quadrotors it is impossible to follow an arbitrarily designed trajectory.
A standard quadrotor for example cannot translate position while remaining horizontal. The common use of UAVs and quadrotors in particular is changing from common observer tasks to more applied flying service robot tasks including interaction with the environment. Here the loss of mobility on the basis of the inherent underactuation can constitute a limiting factor. In this thesis we will present a novel quadrotor UAV design that surmounts these limitations by additional four control inputs actuating the four propeller tilting angles.
First, we will show that our novel quadrotor UAV with tilting propellers offers behavior as a fully-actuated flying vehicle with full actuation of the quadrotor position and orientation in space. Second, a comprehensive modeling and control framework for the proposed quadrotor is presented, and the hardware/software specifications of an experimental prototype will be introduced. Finally, the results of several simulations and real experiments are reported to illustrate the capabilities of the proposed novel UAV design.
A MatLAB simulation can be donwloaded here: