The distance between {TAIL ~ the center} of said sensing chip 31 to the center of {HEAD ~ said wheel body} 11 is represented by r 
The distance between { TAIL ~ the center } of said sensing chip 31 to the center of { HEAD ~ said wheel body } 11 is represented by r
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH