In {HEAD ~ a space} between {TAIL ~ the wall} and bag, a plurality of pressure sensors are positioned 
In { HEAD ~ a space } between { TAIL ~ the wall } and bag , a plurality of pressure sensors are positioned
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH