Simultaneous Motion Tracking and Joint Stiffness Control of Bidirectional Antagonistic Variable-Stiffness Actuators
Marie Harder, Manuel Keppler, Xuming Meng, Christian Ott, Hannes Höppner, Alexander Dietrich
Abstract
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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">David</i> verify the proposed approach.
BibTeX
@inproceedings{ral2022_simultaneousmoti,
title = {Simultaneous Motion Tracking and Joint Stiffness Control of Bidirectional Antagonistic Variable-Stiffness Actuators},
author = {Marie Harder and Manuel Keppler and Xuming Meng and Christian Ott and Hannes Höppner and Alexander Dietrich},
booktitle = {RA-L 2022},
year = {2022}
}