The device 6, wherein {HEAD ~ the means} of detecting rotation parameters comprises {TAIL ~ a sensor} secured to the non rotating ring and an encoder secured to the rotating ring 
comprises
The device 6 , wherein { HEAD ~ the means } of detecting rotation parameters comprises { TAIL ~ a sensor } secured to the non rotating ring and an encoder secured to the rotating ring
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH