Variohm-EuroSensor is introducing a new range of non-contact multiturn angle sensors that benefit from Nobel Prize-winning technology. Offering much improved resolution, better repeatability and longer life than contact-based potentiometers, and with significantly lower costs than absolute optical encoders, the RSM 2800 from Novotechnik is a compact 28mm diameter sensor providing a 12-bit absolute position resolution over a selectable range of up to 15 turns (5400degrees). With a choice of voltage or current output as standard, a digital version with 0.1degree resolution is also available.
The new generation RSM 2800 uses the GMR (giant magneto resistance) effect, a technology used in hard disk drives, where thin-film deposits of sandwiched magnetic and non-magnetic layers can be combined with sensors on ‘spiral arms’ to return an absolute position value over a single rotation. To provide an absolute position value over a multi-turn range, a 360-degree Hall effect sensor is included with multiple spiral arms that correspond to each rotation. Furthermore, the position is available with true power-on sensing for first-time operation on start-up, with no calibration required.
Peter Grundberg and Albert Fert were awarded the Nobel Prize for Physics in 2007 for their discovery of the GMR effect almost twenty years earlier, and for subsequent major work on all aspects of this technology.
The robust and durable RSM2800 has a rated temperature range of -40 to +85degC (125degC on request) and features a thermally stable plastic housing and a stainless steel input shaft with a choice of an indexing flat or push-on coupling. Supply voltage is 24V DC and 5V DC.
The contact-free technology used in the RSM2800 will suit long-life applications for steering angle detection in cars and trucks or mobile machinery, for valve and flap positioning in industrial processing and as a low-cost absolute feedback system for servo controls. The sensor can also be combined with the winding drum of a cable extension transducer to provide an extremely compact sensor for long-travel linear position measurement.