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