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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Neurorobot. | doi: 10.3389/fnbot.2019.00020

A Variable Stiffness Actuator Module with Favourable Mass Distribution for a Bio-inspired Biped Robot

 David Rodriguez Cianca1*, Maarten Weckx1,  Rene Enrique Jimenez Fabian1,  Diego Torricelli2,  Jose Gonzalez-Vargas3, Mari Carmen Sanchez-Villamañan2, Massimo Sartori4, Karsten Berns5, Bram Vanderborght1,  Jose L. Pons2 and Dirk Lefeber1
  • 1Vrije University Brussel, Belgium
  • 2Cajal Institute (CSIC), Spain
  • 3Otto Bock (Germany), Germany
  • 4University of Twente, Netherlands
  • 5University of Kaiserslautern, Germany

Achieving human-like locomotion with humanoid platforms often requires the use of variable stiffness actuators (VSAs) in multi-degree-of-freedom robotic joints. VSAs possess 2 motors for the control of both stiffness and equilibrium position. Hence, they add mass and mechanical complexity to the design of humanoids. Mass distribution of the legs is an important design parameter,
because it can have detrimental effects on the cost of transport. This work presents a novel VSA module, designed to be implemented in a bio-inspired humanoid robot, Binocchio, that houses all components on the same side of the actuated joint. This feature allowed to place the actuator’s mass to more proximal locations with respect to the actuated joint instead of concentrating it at the joint level, creating a more favourable mass distribution in the humanoid. Besides, it also facilitated its usage in joints with centralized multi-degree of freedom (DoF) joints instead of cascading single DoF modules. The design of the VSA module is presented, including its integration in the multi-DoFs joints of Binocchio. Experiments validated the static characteristics of the VSA module to accurately estimate the output torque and stiffness. The dynamic responses of the driving and stiffening mechanisms are shown. Finally, experiments show the ability of the actuation system to replicate the envisioned human-like kinematic, torque and stiffness profiles for Binocchio.

Keywords: Variable stiffness actuator, Bio-inspired biped robot, Mass distribution, multi-DoFs joints, Human-like locomotion

Received: 23 Jan 2019; Accepted: 17 Apr 2019.

Edited by:

Kosta Jovanovic, School of Electrical Engineering, University of Belgrade, Serbia

Reviewed by:

Veljko Potkonjak, Belgrade Metropolitan University, Serbia
Stefan S. Groothuis, University of Twente, Netherlands
Vincent Bonnet, Université Paris-Est Créteil Val de Marne, France  

Copyright: © 2019 Rodriguez Cianca, Weckx, Jimenez Fabian, Torricelli, Gonzalez-Vargas, Sanchez-Villamañan, Sartori, Berns, Vanderborght, Pons and Lefeber. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mr. David Rodriguez Cianca, Vrije University Brussel, Brussels, 1050, Brussels, Belgium,