The Electric Cable Differential Leg: a Novel Design Approach for Walking and Running

This paper documents the mechanical system of the Electric Cable Differential leg, and its incorporation into a monopod hopping robot named Thumper and a bipedal robot named MABEL. The ECD Leg is designed with physical springs and other passive dynamics to match a mathematically simple, bio-inspired mass-spring model, which can exhibit robust and economic walking and running gaits. With this design approach, existing spring-mass theory-based controllers can be used to control the robot. The scientific goals of this work focus on finding an energetically optimal leg stiffness for running, and results from experimentation on Thumper and on a simulation of Thumper are presented.