TY - JOUR
T1 - An Open Torque-Controlled Modular Robot Architecture for Legged Locomotion Research
AU - Grimminger, Felix
AU - Meduri, Avadesh
AU - Khadiv, Majid
AU - Viereck, Julian
AU - Wuthrich, Manuel
AU - Naveau, Maximilien
AU - Berenz, Vincent
AU - Heim, Steve
AU - Widmaier, Felix
AU - Flayols, Thomas
AU - Fiene, Jonathan
AU - Badri-Sprowitz, Alexander
AU - Righetti, Ludovic
N1 - Funding Information:
Manuscript received September 10, 2019; accepted February 8, 2020. Date of publication February 27, 2020; date of current version March 24, 2020. This letter was recommended for publication by Associate Editor A. Jafari and Editor N. Tsagarakis upon evaluation of the reviewers’ comments. This work was partially supported by New York University, the Max-Planck Institute for Intelligent Systems’ Grassroots projects, the European Unions Horizon 2020 research and innovation program under Grant Agreement 780684, the European Research Councils under Grant 637935, the National Science Foundation under Grant CMMI-1825993, a Google Faculty Research Award, and an Independent Max Planck Researcher Grant. (Corresponding author: Ludovic Righetti.) Felix Grimminger, Majid Khadiv, Manuel Wüthrich, Maximilien Naveau, Vincent Berenz, and Felix Widmaier are with the Max Planck Institute for Intelligent Systems, 72076 Tübingen, Germany (e-mail: felix.grimminger@tuebingen. mpg.de; majid.khadiv@tuebingen.mpg.de; manuel.wuthrich@mpg.de; maximilien.naveau@gmail.com; vberenz.tuebingen@mpg.de; felix.widmaier @web.de).
Publisher Copyright:
© 2016 IEEE.
PY - 2020/4
Y1 - 2020/4
N2 - We present a new open-source torque-controlled legged robot system, with a low-cost and low-complexity actuator module at its core. It consists of a high-torque brushless DC motor and a low-gear-ratio transmission suitable for impedance and force control. We also present a novel foot contact sensor suitable for legged locomotion with hard impacts. A 2.2 kg quadruped robot with a large range of motion is assembled from eight identical actuator modules and four lower legs with foot contact sensors. Leveraging standard plastic 3D printing and off-the-shelf parts results in a lightweight and inexpensive robot, allowing for rapid distribution and duplication within the research community. We systematically characterize the achieved impedance at the foot in both static and dynamic scenarios, and measure a maximum dimensionless leg stiffness of 10.8 without active damping, which is comparable to the leg stiffness of a running human. Finally, to demonstrate the capabilities of the quadruped, we present a novel controller which combines feedforward contact forces computed from a kino-dynamic optimizer with impedance control of the center of mass and base orientation. The controller can regulate complex motions while being robust to environmental uncertainty.
AB - We present a new open-source torque-controlled legged robot system, with a low-cost and low-complexity actuator module at its core. It consists of a high-torque brushless DC motor and a low-gear-ratio transmission suitable for impedance and force control. We also present a novel foot contact sensor suitable for legged locomotion with hard impacts. A 2.2 kg quadruped robot with a large range of motion is assembled from eight identical actuator modules and four lower legs with foot contact sensors. Leveraging standard plastic 3D printing and off-the-shelf parts results in a lightweight and inexpensive robot, allowing for rapid distribution and duplication within the research community. We systematically characterize the achieved impedance at the foot in both static and dynamic scenarios, and measure a maximum dimensionless leg stiffness of 10.8 without active damping, which is comparable to the leg stiffness of a running human. Finally, to demonstrate the capabilities of the quadruped, we present a novel controller which combines feedforward contact forces computed from a kino-dynamic optimizer with impedance control of the center of mass and base orientation. The controller can regulate complex motions while being robust to environmental uncertainty.
KW - Legged robots
KW - actuation and joint mechanisms
KW - compliance and impedance control
KW - force control
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U2 - 10.1109/LRA.2020.2976639
DO - 10.1109/LRA.2020.2976639
M3 - Article
AN - SCOPUS:85083034205
VL - 5
SP - 3650
EP - 3657
JO - IEEE Robotics and Automation Letters
JF - IEEE Robotics and Automation Letters
SN - 2377-3766
IS - 2
M1 - 9015985
ER -