Motion Control: Rotary Encoders

Explore encoders as feedback devices in motion control systems, understand closed-loop motion control, and review encoder classifications, including linear and rotary encoders.

Incremental encoders use optical disc with opaque and transparent sectors, a photoelectric sensor, and a converter to generate square pulses that measure travel distance, speed, and resolution from disc slots.

Learn how incremental encoders generate square wave pulses for position data. Interface them with controllers using pulse counter and driver types such as open collector, push-pull, and differential driver.

Explore gray code, a one-bit change representation used in rotary encoders to minimize errors. Compare gray code disks with binary coded disks, using a mask wheel to sense shaft position.

Explore how Gray code relates to encoder signaling, learn how an absolute encoder works, compare incremental and absolute encoders, and understand the concept of a multi-turn absolute encoder.

Learned how parallel output interface works and gained an overview of popular absolute encoders output interfaces, including SSI and BIS.

Explore accuracy, precision, and resolution in rotary encoders. Learn how deviations, repeatability, and units such as degrees, arc minutes, and arc seconds impact CNC and robotics.

Identify how optical encoders use a light source and a coded disc to convert light transitions into position and speed signals, outlining transmissive and reflective types and material trade-offs.

Explore magnetic encoders as alternatives to optical encoders, using a hall sensor and permanent magnet on a magnetic disk with alternating poles to set resolution and reliability in harsh environments.

Explore the forms and types of rotary encoders, and learn to understand and describe their physical construction, fieldbus interfaces, and datasheets.

Discover the physical forms of rotary encoders—solid shaft, hollow shaft, and ring encoders—and how secure installation, precise alignment, and the right housing and working distance impact accuracy.

Identify encoder options through selection criteria, sizing parameters, and non-technical factors. Match application type and class, shaft, housing, and interfaces, including absolute versus incremental, resolution, and IP and safety certifications.

Identify common applications and systems for encoders and outline the key factors in encoder sizing and selection.