a control means including a CPU for controlling {HEAD ~ said wheel driving means} in {TAIL ~ accordance} with the outputs of said sensor means 
in
a control means including a CPU for controlling { HEAD ~ said wheel driving means } in { TAIL ~ accordance } with the outputs of said sensor means
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH