Many SMLAs can be outfitted to provide feedback by adding a rotary encoder. Rotary encoders, also known as shaft encoders, convert the angular position of a shaft to analog or digital output signals. Optical rotary encoders are the most common option for adding feedback functionality to SMLA assemblies. Figure 4 illustrates how adding an encoder to an SMLA can provide feedback to the controller and share important motion data such as position, speed or direction.