Modeling and experimental study of a directly coil-actuatedswashplate-less rotorcraft

The coaxial rotorcraft typically achieves attitude adjustments through the swashplate’s cyclic pitch motion. However, the complex linkage system in the swashplate, along with the parasitic resistance it introduces, imposes limitations on the lightweight design and reliability of the current coaxial rotorcraft. To address these challenges, this paper introduces a simplified and compact swashplate-less approach: the directly coil-actuated rotorcraft. This rotorcraft employs coils to drive the magnet-embedded blades to deflect, thus changing the blade pitch angle. Leveraging its unique magnetic-driven characteristics, we propose a novel solution method for the blade pitch angle. This method utilizes Hall-effect sensors to sense the magnetic field intensity generated by the coil and magnet, and experimental results demonstrate that it enables high-precision real-time detection of the blade pitch angle. The core challenge of the swashplate-less rotor lies in replicating the cyclic pitch motion. This paper proposes a state feedback control method that successfully achieves the cyclic pitch motion at high rotational speed. Mechanical experiments are conducted to analyze the directly coil-actuated rotor’s characteristics of thrust-torque and tilting moment. Finally, the attitude control experiments demonstrate that the control accuracy of the roll and pitch motion can reach 0.215^∘.