Development of torque controllable leg for running robot, AiDIN-IV

Intrinsic problems for legged robots are `low energy efficiency' and `slow speed'. In this paper, we introduce a possible solution achieved through biological observations and developed a robotic leg applying the proposed method. The proposed robotic leg, AiDIN-IV Leg (Artificial DIgitigrade for Natural environment version IV) has high torque density actuators(τ
_peak
= 152Nm, 127rpm), high fidelity force/torque controllability(under 5% torque error) and large energy storing capacity(18J) suitable for high-speed running robot. As a core part, Series Elastic Actuator(SEA), achieve large passive deflection angle(47.6°) for storing the energy as much as possible(maximally 37.9J), and constant joint stiffness coefficient. Additionally, oscillation compensator for rejecting the oscillation of SEA and Harmonic Drive efficiency compensator are introduced and successfully tested in the proposed robotic leg.