A simple 2D straight-leg passive dynamic walking model without foot-scuffing problem

This paper presents a simple 2D passive dynamic walking model with straight legs based on a novel hip joint, called T-joint. The model directly solves the common foot-scuffing problem in straight-legged walkers without introducing any new degree of freedom or additional motion phase, which is unavoidable in kneed robots. The mathematic model of the new walker is a 4D hybrid dynamical system, which can be reduced to a 3D Poincaré map. A stable period-1 walking gait is found by searching the map with a proposed algorithm. Numerical studies show that the model performs well for disturbances on initial conditions and also on a large slope. The stable walking gait is verified by a virtual prototype in ADAMS. This study has been successfully used to make an efficient walking robot called Xingzhe, which has set a new world record for the longest distance after 134km non-stoping walking.