Rotary Actuator

Rotary actuators are used in almost all electromechanical systems, they are the motors that move your electric car, move its wiper blades, your handheld drill, in your food processor and blender. In many use cases a human provides some kind of feedback mechanism to close a control loop, you release your foot pressure on the accelerator pedal when the car has moved far enough, when the rain starts or stops you turn the wipers on and off, when you feel the drill bit punch through the material you are making a hole in you release the trigger on the drill, when the food looks chopped or mixed enough you turn the blender off.

When used in automated systems, the control isn’t a feedback loop closed by a human somewhere in the system. Instead somewhere a computer or logic circuit is deciding whether the motor should speed up or slow down, and what direction it should run.

Even though computer vision systems have leaped forwards in capability recently, for most automation use cases the control systems aren’t using cameras in a generalized way to decide whether a mechanism has moved far enough or fast enough or pressed hard enough. Generally automated actuation systems rely either on precise motion delivered in discreet packets by the actuator, such as where stepper motors are used in an open loop configuration, or they utilize sensors to feed back the position or speed or force being applied by a motor in the system.

The rotary actuators that makers most commonly use fall into one of these categories: