Posture control for biped robot walk with foot toe and sole

Abstract

Foot toes of biped robots have not been used until landing of a swing-leg in the almost of all past researches. When a sole of a robot keeps surface contact with floor, usual control methods for normal robots, which are fixed on floor, can be used. This means that the motion of a body is limited to quiet motion. However, robots should be able to go on walking even when the contact becomes a point contact, if the body posture and a landing point can be controlled. In this paper, a new control method for biped robots, of which the contact between the sole and the floor becomes a point contact, is proposed. By this method, the ZMP (the Zero Moment Point) is not necessary to be the inside of the support phase at all time, therefore the motion of the body has not to be limited to the quiet motion. So, fast walking and abundant motions of biped robots can be implemented by the proposed method. When the torque can not be applied between the sole and the floor, robots must follow a forward falling. In the proposed method, robots track desired trajectories while robots are falling forward. Simulation results show that the COM (the Center of Mass) and the heel position of the swing-leg can track a desired circle path and heel joint angles can be controlled to desired angles while a biped walking mode is forward falling, and it able to walk continuously, in addition, a walking time cycle is automatically, decided, which is fit to dynamics of each walking model.