Servo (Smart Serial Bus Servo)

A small position-control actuator with a motor, gears, position sensor, and control board built into one unit.

A servo originally referred to the small actuator used in model aircraft to move control surfaces: a small box packing a motor, reduction gears, a position sensor (a potentiometer or magnetic encoder), and a control board — give it a target angle, and it drives itself there. Traditional servos take commands over PWM (pulse-width modulation); bus servos (smart servos) instead use a serial bus, so multiple servos can be chained on one line, each with its own ID, and can also report back position, current, and temperature. They're cheap and easy to use, but have limited torque and precision, so they're mostly used in education, desktop robot arms, small humanoids, and teleoperation leader arms. Newcomers doing real-robot experiments often start with a servo-based arm.

ExampleLeRobot's SO-100 / SO-101 arm uses Feetech STS3215 bus servos, and a full arm costs only a few hundred dollars.

Also called

Bus Servo, Smart Servo

Related

ROBOTIS Dynamixel Servo · Feetech STS3215 Servo · SO-100 / SO-101 Arm · Servo Motor · Pulse Width Modulation (PWM) · Desktop Robot Arm

Sources

Servo (radio control) - Wikipedia
SO-ARM100 (TheRobotStudio) GitHub