Bipedal robots are currently either slow, energetically inefficient and/or require a lot of control to maintain their stability. This paper introduces the FastRunner, a bipedal robot based on a new leg architecture. Simulation results of a Planar FastRunner demonstrate that legged robots can run fast, be energy efficient and inherently stable. The simulated FastRunner has a cost of transport of 1.4 and requires only a local feedback of the hip position to reach 35.4 kph from stop in simulation.

Abstract-This paper discusses the mechanical kinematics solutions and design aspects of the biped robot SHERPA, a bipedal platform able to walk and carry load. Starting from the analysis of the human lower limbs, we figure out that 6 DOF per leg are fundamental for a correct walking motion and can be adopted in a mechanical design of a humanoid robot. A close investigation of the joints leads us to a novel modular mechanical design, with a parallel architecture mechanism characterized by and high degree of interchangeable components. The robot is using twelve high performance hollow shaft electrical actuators acting in pairs in a parallel manner, a remote compact and transparent actuation with zero-backlash cable transmissions, 2 DOF differential joints between each segment of the limb and a light-weight carbon fiber skeleton modeling and mimic the anatomy of the human legs. The modular 2 DOF cable differential joint has been implemented at the hip, knee and ankle level. Using our approach, actuation is more transparent (back-drivable, with low inertia) and will allow SHERPA to interact with the environment more smoothly which leads to better walking ability.