A Hoverability Analysis Method for Multirotor UAVs with a Case Study on Fault Tolerance

This paper presents a method for analyzing hov-erability of multirotor unmanned aerial vehicles (UAVs), These vehicles need to be able to remain at a constant position in the air and should keep safe flight even after rotor failure. However, there has been no systematic method so far to analyze such an ability of multirotor UAVs. This is due to the difficulty in finding equilibria of a multirotor UAV system whose rotors can exert force only in one direction. The present method only requires mechanical properties of the vehicles: the center of mass; rotor positions; and directions of rotor rotation. First, dynamics of a generalized multirotor UAV model is introduced. Second, the hoverability analysis method is proposed. Third, an example of multirotor UAV structure is presented, and the present hoverability analysis method is conducted. Finally, the method is applied to investigation of multirotor UAVs' hoverability in the case of rotor failure, and some kinds of vehicles which can tolerate the failure are introduced.