{HEAD ~ sensor means} for providing an output which varies as a function of {TAIL ~ said parameter}, located distal to said bend on said first segment; and means for measuring the output of said sensor 
{ HEAD ~ sensor means } for providing an output which varies as a function of { TAIL ~ said parameter } , located distal to said bend on said first segment ; and means for measuring the output of said sensor
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH