For those interested in details, the papers are linked from the project page: http://www.modlabupenn.org/2014/10/23/underactuated-rotor/ http://www.modlabupenn.

For those interested in details, the papers are linked from the project page: http://www.modlabupenn.org/2014/10/23/underactuated-rotor/ http://www.modlabupenn.org/2014/10/23/underactuated-rotor/. > The main motor directly drives the propeller hub, which is itself connected to the propeller blades by two inclined hinges. The hinge geometry couples blade lead-and-lag oscillations to a change in blade pitch. Instead of only driving the motor with a steady torque, we add a sinusoidal component in phase with the rotation of the rotor to induce a cyclic pitch variation. The amplitude and phase of this control signal determines the magnitude and direction of the vehicle response.