In {HEAD ~ one embodiment}, obstacles in the route area are identified and {TAIL ~ corresponding forbidden areas} are demarcated 
In { HEAD ~ one embodiment } , obstacles in the route area are identified and { TAIL ~ corresponding forbidden areas } are demarcated
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH