Flight-trim system for quadrotors with rotatable arms

A study develops a flight-trim system for a quadrotor with rotatable arms (QRA) to trim the bias torque in the quadrotor plane of the QRA, motivated by the trim systems for airplanes and helicopters. It is demonstrated that by rotating the arms of the QRA to proper positions, the flight-trim system can trim the bias torque of the QRA without generating different rotor thrusts and can maintain the same available range of authority on both sides of the trim control position. The full range of each rotor thrust can be entirely used for maneuvering control of the QRA, which may improve the maneuvering performance of the quadrotor in certain scenarios.