The field of the invention relates to barrier operator systems and, more specifically, to {HEAD ~ impact force measurements} that are made using {TAIL ~ these systems} 
are made using
The field of the invention relates to barrier operator systems and , more specifically , to { HEAD ~ impact force measurements } that are made using { TAIL ~ these systems }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL