A new range of non-contact multiturn angle sensors based upon Nobel Prize winning technology is available from Variohm EuroSensor. Offering a much improved resolution, better repeatability and longer life than contact-based potentiometer devices, 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 (5400º). With a choice of voltage or current output as standard, a digital version with 0.1º resolution is also available.
The new generation RSM 2800 uses the GMR Effect (Giant Magneto Resistance), 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 360º 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 20 years earlier, and for subsequent major work on all aspects of this technology.
The robust and durable RSM2800 has a rated temperature range of -40ºC to +85ºC (125º C 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 24 VDC and 5 VDC.