What is the term for an electro-mechanical device used to move a control surface?

The term for an electro-mechanical device used to move a control surface is a servo. Servos are essential components in a variety of applications, particularly in unmanned aerial vehicles (UAVs), where they are responsible for adjusting control surfaces such as ailerons, elevators, and rudders.

Servos operate by receiving signals from the control system of the UAV and then executing precise movements to control the position of these surfaces. This is crucial for maneuvering and stabilizing the aircraft during flight. The ability to position control surfaces accurately allows for improved handling, responsiveness, and overall flight performance.

While actuators may also refer to devices that produce motion or control mechanical systems, the term "servo" specifically denotes a device used for precise control in such applications, making it the correct and more precise answer in this context. Transmitters and receivers, meanwhile, are elements of communication systems within UAVs, responsible for sending and receiving signals rather than directly controlling surfaces.