the modified grounding timing is computed so as to satisfy the ZMP equation under {HEAD ~ the first leg ZMP restraint condition} and {TAIL ~ the second leg ZMP restraint condition} 
the modified grounding timing is computed so as to satisfy the ZMP equation under { HEAD ~ the first leg ZMP restraint condition } and { TAIL ~ the second leg ZMP restraint condition }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL