pneumatic actuator

A pneumatic actuator is a muscle that runs on compressed air. Air is pushed into a sealed cylinder, and its pressure drives a piston back and forth; let the air out, and a spring or the opposite air port returns it. It is the same idea as a hydraulic actuator, but with air instead of oil — and that one swap changes its whole personality.

Because air squashes like a cushion, a pneumatic actuator is naturally springy and forgiving. It can move fast and light, it does not mind being bumped or held against a stop, and it gives a gentle, compliant push rather than a rigid shove — handy when a robot must touch delicate things or work near people. The flip side is that this same sponginess makes it hard to stop at an exact position in the middle of its stroke; pneumatics shine at snapping cleanly between two endpoints, like open and closed.

Control is done with valves that switch or throttle the airflow. The whole approach is cheap, clean, and lightweight — no oil to leak, just air — which is why pneumatics fill factory grippers, sorting machines, and many soft, muscle-like actuators. They do need a compressor and air lines, and they waste some energy whenever the used air is simply vented away.