Simultaneous Motion Tracking and Joint Stiffness Control of Bidirectional Antagonistic Variable-Stiffness Actuators

Since safe human-robot interaction is naturally linked to compliance in these robots, this requirement presents a challenge for the positioning accuracy. The class of variable-stiffness robots features intrinsically soft contact behavior where the physical stiffness can even be altered during operat...

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Bibliographic Details
Published in:IEEE robotics and automation letters 2022-07, Vol.7 (3), p.6614-6621
Main Authors: Harder, Marie, Keppler, Manuel, Meng, Xuming, Ott, Christian, Hoppner, Hannes, Dietrich, Alexander
Format: Article
Language:English
Subjects:
Actuators
Compliance and impedance control
compliant joints and mechanisms
Damping
Forearm
Human engineering
motion control
Robots
Springs
Stability analysis
Stiffness
Symmetric matrices
Tracking control
Trajectory
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Summary:Since safe human-robot interaction is naturally linked to compliance in these robots, this requirement presents a challenge for the positioning accuracy. The class of variable-stiffness robots features intrinsically soft contact behavior where the physical stiffness can even be altered during operation. Here we present a control scheme for bidirectional, antagonistic variable-stiffness actuators that achieve high-precision link-side trajectory tracking while simultaneously ensuring compliance during physical contact. Furthermore, the approach enables to regulate the pretension in the antagonism. The theoretical claims are confirmed by formal analyses of passivity during physical interaction and the proof of uniform asymptotic stability of the desired link-side trajectories. Experiments on the forearm joint of the DLR robot David verify the proposed approach.
ISSN:2377-3766
2377-3766
DOI:10.1109/LRA.2022.3176094