Design of an electromechanical actuation system for optional autopilot integration on an ultralight aircraft

Abstract

This paper presents the design of an electromechanical actuator system developed to enable autonomous flight control of an ultralight aircraft. The system allows the aircraft to fly autonomously when the pilot releases the controls, while preserving full manual authority at all times. Actuators are installed on all three primary control surfaces — aileron, elevator, and rudder. The core design concept is an overlaid architecture, where the actuator is added to the existing mechanical command chain without replacing it. In manual mode, the pilot operates the controls normally with no added resistance. When the autopilot is activated, a solenoid engages a mechanical coupling that transfers control of the surface to a brushless motor. If power is lost at any point, a return spring automatically disengages the coupling, giving the pilot back full control without any action required. Motor control uses Field-Oriented Control with an absolute position encoder, providing smooth and precise surface movement at the low speeds required for flight control.