“…9 For a restricted range of initial condition inside a basin of attraction, the SLIP model shows stable walking and running gaits, but outside this region SLIP has periodic unstable gaits. Thus, researchers have proposed several active SLIP, or ASLIP, architectures and controllers, for example, an energy-level control in stance phase, 10 swing leg retraction, 11 dead-beat control, 12 and variable free-leg length and stiffness. 13 Due to the SLIP model's advantages (including stability and energy efficiency), using it as a simple reference model in order to produce walking and running biped gaits for more complicated machines is a possible approach -one pursued in this paper.…”