The ingenious folks over at University of Pennsylvania have created a method of providing pitch, roll and yaw control on a small vehicle using only 2 counter-rotating and axial motors, no swashplate. This is ground-breaking in the field of small radio controlled vehicles. To achieve this they’ve created a special hinge:
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.
Still trying to process all this? No worries, check out the video above for an illustrated explanation of this method.