Wherein, {HEAD ~ the control unit} 1 is mainly to provide {TAIL ~ the driving device} 5 with the function to move forward and change direction 
Wherein , { HEAD ~ the control unit } 1 is mainly to provide { TAIL ~ the driving device } 5 with the function to move forward and change direction
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH