Carl — A compliant robotic leg featuring mono- and biarticular actuation

An increasing number of biologically-inspired control approaches for bipedal walking are demonstrating impressive capabilities in simulations. Although many of them share the main assumptions about the simulated biped, so far no physical system has been presented that meets the requirements. Thus, in this paper we are presenting the Compliant Robotic Leg (Carl) - a fully actuated bio-inspired planar robotic leg that incorporates mono-as well as biarticular actuation. Its development is motivated by the vision to validate the Bioinspired Behavior Based Bipedal Locomotion Control (B4lc) on a physical platform. This paper provides an overview of the driving requirements for the different subsystems and the derived implementation. Two experiments were performed to proof the functionality of the system. Specifically, some key requirements - transparency, impact tolerance, force and impedance rendering - are demonstrated. To our knowledge, this is the first fully actuated robotic leg including biarticular elements that demonstrates distributed high-fidelity force and impedance control at the actuator level.