Proceedings ArticleDOI
A nonlinear series elastic actuator for highly dynamic motions
Ivar Thorson,Darwin G. Caldwell +1 more
- pp 390-394
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TLDR
A novel revolute nonlinear series elastic actuator called the HypoSEA is presented, which uses a hypocycloid mechanism to stretch a linear spring in a nonlinear way and has exceptionally low reflected mechanical impedance, making it robust against repeated impact loads.Abstract:
A novel revolute nonlinear series elastic actuator called the HypoSEA is presented. The actuator uses a hypocycloid mechanism to stretch a linear spring in a nonlinear way. The actuator is optimized for highly dynamic tasks such as running and jumping, as it features a 120Nm torque capability and more than 30J of passive energy storage. When combined with a suitable controller, using the spring as an energy buffer can greatly reduce the work done by the rotor during periodic motions. The design has exceptionally low reflected mechanical impedance, making it robust against repeated impact loads. The nonlinear stiffening spring is optimized for the nonlinearities typically found in revolute-jointed hopping robots, and may be adjusted offline using a pretensioning mechanism. Finally, the low effective stiffness around the zero-torque equilibrium allows for extremely sensitive force control.read more
Citations
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Journal ArticleDOI
Variable impedance actuators: A review
Bram Vanderborght,A. Albu-Schaeffer,Antonio Bicchi,Antonio Bicchi,Etienne Burdet,Darwin G. Caldwell,Raffaella Carloni,Manuel G. Catalano,Manuel G. Catalano,Oliver Eiberger,Werner Friedl,Gowrishankar Ganesh,Manolo Garabini,Markus Grebenstein,Giorgio Grioli,Sami Haddadin,Hannes Höppner,Amir Jafari,Matteo Laffranchi,Dirk Lefeber,Florian Petit,Stefano Stramigioli,Nikos G. Tsagarakis,M. Van Damme,R. Van Ham,L. C. Visser,Sebastian I. Wolf +26 more
TL;DR: A classification based on the principles through which the variable stiffness and damping are achieved is proposed and allows for designers of new devices to orientate and take inspiration and users of VIA's to be guided in the design and implementation process for their targeted application.
Journal ArticleDOI
Design and Control Considerations for High-Performance Series Elastic Actuators
TL;DR: In this paper, the design and control of a prismatic series elastic actuator with high mechanical power output in a small and lightweight form factor is discussed. And the actuator's performance is demonstrated through a series of experiments designed to operate at the limits of its mechanical and control capability.
Journal ArticleDOI
Proprioceptive Actuator Design in the MIT Cheetah: Impact Mitigation and High-Bandwidth Physical Interaction for Dynamic Legged Robots
Abstract: Designing an actuator system for highly dynamic legged robots has been one of the grand challenges in robotics research. Conventional actuators for manufacturing applications have difficulty satisfying design requirements for high-speed locomotion, such as the need for high torque density and the ability to manage dynamic physical interactions. To address this challenge, this paper suggests a proprioceptive actuation paradigm that enables highly dynamic performance in legged machines. Proprioceptive actuation uses collocated force control at the joints to effectively control contact interactions at the feet under dynamic conditions. Modal analysis of a reduced leg model and dimensional analysis of DC motors address the main principles for implementation of this paradigm. In the realm of legged machines, this paradigm provides a unique combination of high torque density, high-bandwidth force control, and the ability to mitigate impacts through backdrivability. We introduce a new metric named the “impact mitigation factor” (IMF) to quantify backdrivability at impact, which enables design comparison across a wide class of robots. The MIT Cheetah leg is presented, and is shown to have an IMF that is comparable to other quadrupeds with series springs to handle impact. The design enables the Cheetah to control contact forces during dynamic bounding, with contact times down to 85 ms and peak forces over 450 N. The unique capabilities of the MIT Cheetah, achieving impact-robust force-controlled operation in high-speed three-dimensional running and jumping, suggest wider implementation of this holistic actuation approach.
Journal ArticleDOI
Actuator Control for the NASA-JSC Valkyrie Humanoid Robot: A Decoupled Dynamics Approach for Torque Control of Series Elastic Robots
Nicholas Paine,Joshua S. Mehling,James Holley,Nicolaus A. Radford,Gwendolyn Johnson,Chien-Liang Fok,Luis Sentis +6 more
TL;DR: The actuator-level control of Valkyrie, a new humanoid robot designed by NASA's Johnson Space Center in collaboration with several external partners, is discussed and a decentralized approach is taken in controlling Valkyrie's many series elastic degrees of freedom.
Journal ArticleDOI
The Variable Stiffness Actuator vsaUT-II: Mechanical Design, Modeling, and Identification
Stefan S. Groothuis,Giacomo Rusticelli,Andrea Zucchelli,Stefano Stramigioli,Raffaella Carloni +4 more
TL;DR: In this paper, the rotational variable stiffness actuator vsaUT-II is presented, which is characterized by the property that the apparent stiffness at the actuator output can be varied independently from its position.
References
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Proceedings ArticleDOI
Series elastic actuators
TL;DR: It is proposed that for natural tasks, zero motion force bandwidth isn't everything, and incorporating series elasticity as a purposeful element within the actuator is a good idea.
Book
Legged Robots That Balance
Marc H. Raibert,Ernest R. Tello +1 more
TL;DR: Legged Robots that Balance as discussed by the authors describes the study of physical machines that run and balance on just one leg, including analysis, computer simulation, and laboratory experiments, and reveals that control of such machines is not particularly difficult.
Journal ArticleDOI
The spring mass model for running and hopping
TL;DR: The model predicts the mass specific energy fluctuations of the center of mass per distance to be similar for runners and hoppers and similar to empirical data obtained for animals of various size.
Journal ArticleDOI
Compliant leg behaviour explains basic dynamics of walking and running
TL;DR: A simple bipedal spring–mass model is shown that not stiff but compliant legs are essential to obtain the basic walking mechanics and reproduces the characteristic stance dynamics that result in the observed small vertical oscillation of the body and the observed out-of-phase changes in forward kinetic and gravitational potential energies.
Journal ArticleDOI
Fast and "soft-arm" tactics [robot arm design]
Antonio Bicchi,G. Tonietti +1 more
TL;DR: In this paper, the authors considered the problem of designing joint-actuation mechanisms that can allow fast and accurate operation of a robot arm, while guaranteeing a suitably limited level of injury risk.
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Design and Control Considerations for High-Performance Series Elastic Actuators
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