Developers of robotic devices sometimes need to actuate rotational elements between two positions over a range of several tens of degrees. Such motion control is particularly useful for opening doors, actuating valves, or controlling the movement of small robotic arms or legs. Two altenatives to produce this type of actuation are a solenoid and a motor attached to a gear train. This article introduces an alternative to these two approaches.
EDN The Design magazine for the Electronics Industry (1999).