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