LONDON Embedded electronics design consultancy, ByteSnap Design (Birmingham, UK), has recently completed the electronics and interface designs for an absolute encoder by Rotalink (Crewkerne, UK), a provider of miniature transmission and control solutions.
The Rotalink Absolute Encoder provides accurate positioning information regardless of power loss and is self correcting in the event of electronic interference. The encoder is designed to provide a cost-effective alternative to potentiometers, having a longer operational life but similar per-unit costs and increased operational flexibility.
Industry applications include valves, lighting effects, antenna positioning, seat adjusters, curtain openers and instrumentation ” a key differentiator of the new encoder is that it can be powered on even if it is half-way along a hoist, eliminating the need for hoists to 're-dock' before measurements can begin.
“We've worked on all the electronics design for the encoder and have produced an elegant solution that meets the challenging performance requirements and miniaturisation required,” said Dunstan Power, director of ByteSnap Design.
“The sophistication of the movement sampling sensors, their longer operational life when compared to potentiometers and the inclusion of an onboard battery makes this encoder an attractive choice for niche industry applications.”
The encoder uses contact-less magnetic technology to provide either linear analogue output updated at about 5kHz or reliable 10bit positional data sent via SSI (synchronous serial interface) where the interrogating clock can run at about 330kHz. This makes for updates at approx 5 ksamples/s.
There are two versions, the single turn, which operates through 360 degrees of rotation, providing an output dependent on the current angle, and the multi-turn which gives a varying output depending on a pre-set number of turns ” essentially measuring the number of turns as well as the current angle. The multi-turn encoder operates through 32,000 revolutions, and has an integrated rechargeable battery to provide position monitoring for 20 hours after main power has been removed.
The encoder can measure the angle of rotation to 0.18 degrees resolution with an accuracy margin of 1.5 degrees, at temperatures between – 40 and + 85 °Celsius.
Related links and articles: