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