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