A Dynamics Analysis of a Double-Legs Robot

Abstract

A passive-walking of a double-legs planar Robot is considered. The dynamic equation of the system walking down a shallow slope, powered only by gravity is established according to Lagrange method. After the equation was transferred to a dimensionless one, it shows the motion is depended not only on the free parameter, the ramp slope γ, but also on the ratio of m/M, m is mass of the foot of the model and M is the mass of the hip as well; The analytic calculations show that at the identical ramp slope γ, the whole moving has different phases: stable period walking and chaos with the increasing of m/M. Its phase portraits and graph of step time interval show the influence to the motion because of the ratio of m/M.