since the last calibration {HEAD ~ a temperature} measured at {TAIL ~ a predetermined location} of the pick and place system has changed by more than a predetermined value 
since the last calibration { HEAD ~ a temperature } measured at { TAIL ~ a predetermined location } of the pick and place system has changed by more than a predetermined value
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH