Servomechanism
also: servo · servo mechanism · servo system
A system that measures where it is, compares that to where it should be, and drives the difference to zero, continuously. A closed loop with a motor or actuator at the end of it.
A servomechanism, or servo, has three parts: a command (the setpoint), a sensor that measures the actual position, speed, or force, and a controller that drives an actuator to close the gap between the two. Because it keeps measuring, it corrects itself when the load changes or something pushes it off course. That is the difference between a servo and an open-loop drive, which just applies an output and hopes.
The hobby servo in a model aircraft (a small motor, a gearbox, and a potentiometer feeding a position loop) is the simplest example. The same idea runs industrial axes, robot joints, camera gimbals, valve positioners, and the autopilot in a plane. Three properties describe a good servo: stability (it settles on the target without overshooting and ringing), tracking (it follows a moving target closely), and disturbance rejection (it holds position when something knocks it).
Where it bites: a servo is only as good as its sensor, its tuning, and its actuator limits. Too much gain and it oscillates; too little and it lags. Backlash, friction, and saturation all show up as errors the loop cannot fully remove.
Founder takeaway
If your product moves, holds, or regulates something, it almost certainly contains a servo loop. Ask what is measured, how fast the loop runs, and how it was tuned across the loads and temperatures it will see in the field. Our name comes from this idea: measure, compare, correct.
engineer review pending