Encoders
Our design objectives of controlling the position and velocity of the motor will require feedback (i.e., the measurement of the angular position or velocity of the motor shaft). This section reviews the primary methods of making such a measurement.
The most common and useful class of sensor is the rotary encoderEncoders!rotary: a digital and usually optical device that is mounted on the end of a shaft, often at the rear of a motor. There are three common types of optical rotary encoder: single channel, quadrature, and absolute. The rotors of these three types are shown in fig:encoders.
As shown in fig:encoder-tachometer, the rotor, which turns with the shaft, has evenly spaced slits on its periphery. The encoder housing that encloses the rotor is often affixed to the motor frame. As shown in fig:encoder-high-low, an …
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