The pressure sensor comprises {TAIL ~ either a door}, whose movement is measured without {HEAD ~ contact}, or a sensor, whose movement is measured optically 
The pressure sensor comprises { TAIL ~ either a door } , whose movement is measured without { HEAD ~ contact } , or a sensor , whose movement is measured optically
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH