Systems and methods are presented that use the rate of change of a legged
robot's centroidal angular momentum ({dot over (H)}.sub.G) in order to
maintain or improve the robot's balance. In one embodiment, a control
system determines the current value of {dot over (H)}.sub.G, compares
this value to a threshold value, and determines an instruction to send to
the robot. Executing the instruction causes the robot to remain stable or
become more stable. Systems and methods are also presented that use a
value derived from {dot over (H)}.sub.G in order to maintain or improve
the robot's balance. In one embodiment, a control system determines the
location of the Zero Rate of change of Angular Momentum (ZRAM) point (A),
determines the distance between A and the location of the center of
pressure of the resultant ground force, compares this value to a
threshold value, and determines an instruction to send to the robot.