Footstep Planning for Hexapod Robots Based on 3D Quasi-static Equilibrium Support Region

The hexapod robots equipped with six legs have higher stability and adaptability to challenging terrains than other legged robots with fewer legs. The ability of hexapods to traverse challenging terrains largely depends on practical planning approaches on their footstep sequence. However, suppose the stability of the robotic system is insufficiently considered with the footstep planning method, it cannot track the planning results in some extremely complex terrains, e.g., foot slippage or robot overturn. In this work, we develop a quasi-static equilibrium footstep planning method for hexapod robots to traverse challenging terrains. The core of this planning method is the proposed 3D quasi-static equilibrium support region (3D QESR), which can be employed as a constraint for the planning method to ensure the quasi-static stability of the hexapod robots. A new graph search algorithm for footstep sequence planning is also presented. The simulation and experiment results show that the proposed 3D QESR method has superior performance in bypassing unstable irregular regions compared with the widely used support polygon method.