a power supply unit including a rechargeable battery and a voltage regulator circuit for regulating and outputting {HEAD ~ a voltage} of said battery for supplying {TAIL ~ power supply voltage} to said sensor means, said wheel driving means, and said control means and 
for supplying
a power supply unit including a rechargeable battery and a voltage regulator circuit for regulating and outputting { HEAD ~ a voltage } of said battery for supplying { TAIL ~ power supply voltage } to said sensor means , said wheel driving means , and said control means and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH