Stability analysis of the zero moment point–center of pressure algorithm for biped robots in unstructured environments

The motion stability control of biped robots in unstructured environments is a prominent research hotspot in the field of robot control. The biped robot model features variable topology, strong nonlinearity, and multi-degree-of-freedom coupling, allowing for strong environmental interaction. The unstructured road environment imposes more significant requirements on the robot’s gait stability, joint coordination, and adaptability to its environment. In this study, a stability analysis of the motion of robots in unstructured environments was carried out using a disturbance balance control strategy and an application based on Zero Moment Point (ZMP)-Center of Pressure (CoP) testing for feedback control. The approach included a control strategy based on compensating for ankle joint trajectory and was tested using the Webots simulation platform and a real experimental platform. Multi-scene experiments involving NAO robots on stairs and in unstructured sandy environments were conducted to compare and analyze the gait stability and environmental adaptability of NAO robots in unstructured environments.