Thanks to their compact size and low cost, incremental encoders often get the nod as motor feedback devices in motion systems. But U.S. Digital Corp. has come up with an absolute encoder that can compete with incremental encoders on both a cost and size basis.
Called the MAE3, this motor-mount encoder, which is based on magnetic encoder circuitry from austriamicrosystems, provides up to 12-bit resolution with an accuracy of ±1 bit. “Absolute systems are nice because they always know exactly where the motor shaft is without any homing or zeroing operations,” says Jim Stevens, U.S. Digital's chief engineer. That ability is particularly useful in applications subject to power interruptions. “But in the past, the benefits often didn't justify the cost of an absolute system,” Stevens says.
With the MAE3, cost isn't much of a problem. It sells for $49 in single-unit pricing, only a few bucks more than U.S. Digital's most common incremental encoders. And Stevens says the MAE3 costs about 90 percent less than a typical optical absolute encoders.
As for size, the MAE3 fits in a package that's a little less than ½-inch in diameter. The length of the encoder body depends on the type of motor shaft but typically measures about 1 inch. Stevens says the MAE3 uses the same type of shaft mounting as common incremental encoders. “So it can be a drop-in replacement as long as the electronic interface accepts an analog signal,” he says. For more information, go to .