A Stable Walking Strategy of Quadruped Robot Based on ZMP in Trotting gait

Compared with wheeled and tracked robots, legged robot has significant advantages in unstructured terrain, but it is difficult for them to achieve the stability of wheeled and tracked robots. Therefore, it is of great significance to study the stability of legged robot. The traditional ZMP method is mostly used in the balance control of biped robot, but ZMP is also applicable to quadruped robot. This paper presents a strategy based on ZMP stability theory to plan the foothold of quadruped robot in trotting gait, to improve the stability of quadruped robot motion. This paper first introduces the calculation method of quadruped robot ZMP. Then, the optimal foothold to maintain the theoretical stability is derived from simple to complex motion from one direction to any direction. Finally, the stability criterion of ZMP is used to compare the situation before and after using this strategy. In this paper, the stone path experiment is carried out on the Unitree A1 robot platform. Finally, it is found that compared with before using this strategy, the distance from ZMP to diagonal leg support line is reduced to a certain extent, and the stability is improved.