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What to consider when choosing
rotary encoders Rotary encoders play a critical role in robot design and production. They must be matched to the given space, cabling, sensors, precision, and tolerances. Installation should be efficient. Find out what to consider. The Robot Report Staff
Controlled servo drives are used in many areas of automation technology, including robotics. The selection of a rotary encoder, or encoder technology, for use within the system depends on the accuracy requirements of the application and whether the application will use position control, velocity control, or both. Before making an encoder decision, engineers should examine this and all the major encoder properties that have the largest influence on important motor performance. These include: • Positioning accuracy • Speed stability • Audible noise • Power loss • Bandwidth, which determines drive command-signal response Positioning accuracy Positioning accuracy depends solely on the application requirements. Resolvers, for example, mostly have one signal period per revolution. Therefore position resolution is extremely limited and accuracy is typically in the range of ±500 arcsec. Assuming interpolation in the drive electronics, this usually results in a total of 16,384 positions per revolution. On the other hand, an inductive scanning system — as found in many rotary encoders — will provide significantly higher resolution, typically in the range of 32 signal periods per revolution, resulting in an accuracy in the range of ±280 arcsec. The interpolation in this case is internal to the encoder, resulting in 131,072 positions per revolution.
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11/3/21 2:10 PM
