The walking stability controller is designed for researching the biped robots with knee and hip walking in 3D
(three-dimensional) space. By constructing the almost-cyclic Lagrange function, the biped robot dynamic system is
decoupled into sagittal and lateral portions. The potential molding controller is designed for the sagittal portion, so that
the stable walking gait can be obtained. The output zero dynamic controller is used to control the lateral counterpart, which
satisfies the dynamic decoupling conditions of the system. The simulation results show the effectiveness of the proposed
method.