"Bipedal" Spring-Loaded Inverted Pendulum (SLIP) model and an associated approximate return map in Python

The Package includes: 1. A Python Class creating a standard "bipedal" Spring-Loaded Inverted Pendulum (SLIP) Object to model bipedal walking. 2. A Python Function computing an approximate mapping from any initial condition to a particular event (e.g., touchdown, liftoff) at the end of certain mode of the Bipedal SLIP model. 3. A test scripts for demo. The derivation of this map has been presented in "Approximate analytical solutions to the double-stance dynamics of the lossy Spring-Loaded Inverted Pendulum, by M. Shahbazi, U. Saranli, R. Babuska, G. Lopes" (under review).