Rolling SLIP: A model for running locomotion with rolling contact

We report on the development of the model for running locomotion with rolling contact, R-SLIP, to simulate the motion of the robot with circular legs. Thus, two significant characteristics which cannot be correctly modeled in the traditional SLIP, rolling contact with varied equivalent linear spring during locomotion, can be adequately captured. The stability of the R-SLIP model was analyzed numerically by varying the factors which affects the dynamic performance of the model, including stiffness of the torsion spring, touchdown angle, touchdown speed, and landing angle. In addition, the return map was utilized to check the state transition of the touchdown angle with given other three factors. The results reveal that the R-SLIP model has self-stable gaits, just like the traditional SLIP. Thus, with adequate initial conditions and system parameters, the model can run stably around the fixed point without control effort.