a first leg ZMP restraint condition restricts {TAIL ~ the first leg ZMP position} to {HEAD ~ the first leg ZMP permissible area}, 
a first leg ZMP restraint condition restricts { TAIL ~ the first leg ZMP position } to { HEAD ~ the first leg ZMP permissible area } ,
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH