Swing door operator - AbsoluteAstronomy.com

A swing-door operator is a device that operates a swing door for pedestrian use. It opens or helps open the door automatically, waits, then closes it.
There are 3 basic types of swing door operators:

Full Energy – It opens and closes the door at full speed.
Low Energy – It opens and closes the door at reduced speed to limit the kinetic energy of the moving door to levels deemed safe for disabled users.
Power Assist – This is a version of the low-energy operator.