Improving Multirotor Landing Performance on Inclined Surfaces Using Reverse Thrust

Conventional multirotors are unable to land on inclined surfaces without specialized suspensions and adhesion devices. With the development of a bidirectional rotor, landing maneuvers could benefit from rapid thrust reversal, which would increase the landing envelope without involving the addition of heavy and complex landing gears or reduction of payload capacity. This letter presents a model designed to accurately simulate quadrotor landings, the behavior of their stiff landing gear, and the limitations of bidirectional rotors. The model was validated using experimental results on both low-friction and high-friction surfaces, and was then used to test multiple landing algorithms over a wide range of touchdown velocities and slope inclinations to explore the benefits of reverse thrust. It is shown that thrust reversal can nearly double the maximum inclination on which a quadrotor can land and can also allow high vertical velocity landings.