what is an actuator
Electrical, hydraulic, or pneumatic device (such as a relay) that controls the flow of material or power. Also called actuation device. I liked to study machines and today I had a look at an interesting thing called an actuator, which I had never heard of.
Actuator: A power mechanism used to effect motion, or maintain position of the robot (for example, a motor which converts electrical energy to effect motion of the robot) (R15.07). The actuator responds to a signal received from the control system.