{HEAD ~ Two electrical cables} of an articulated robot arm are in the form of helical cords which lengthen and shorten respectively during the rotation of {TAIL ~ the arm} 
{ HEAD ~ Two electrical cables } of an articulated robot arm are in the form of helical cords which lengthen and shorten respectively during the rotation of { TAIL ~ the arm }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL