{TAIL ~ A second leg ZMP position} representing a ZMP position in {HEAD ~ the second single leg grounded period} is then calculated 
{ TAIL ~ A second leg ZMP position } representing a ZMP position in { HEAD ~ the second single leg grounded period } is then calculated
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH