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Auteurs principaux: Johnston, Garrison L. H., Orekhov, Andrew L., Simaan, Nabil
Format: Preprint
Publié: 2023
Sujets:
Accès en ligne:https://arxiv.org/abs/2306.12971
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author Johnston, Garrison L. H.
Orekhov, Andrew L.
Simaan, Nabil
author_facet Johnston, Garrison L. H.
Orekhov, Andrew L.
Simaan, Nabil
contents Collaborative robots must simultaneously be safe enough to operate in close proximity to human operators and powerful enough to assist users in industrial tasks such as lifting heavy equipment. The requirement for safety necessitates that collaborative robots are designed with low-powered actuators. However, some industrial tasks may require the robot to have high payload capacity and/or long reach. For collaborative robot designs to be successful, they must find ways of addressing these conflicting design requirements. One promising strategy for navigating this tradeoff is through the use of static balancing mechanisms to offset the robot's self weight, thus enabling the selection of lower-powered actuators. In this paper, we introduce a novel, 2 degree of freedom static balancing mechanism based on spring-loaded, wire-wrapped cams. We also present an optimization-based cam design method that guarantees the cams stay convex, ensures the springs stay below their extensions limits, and minimizes sensitivity to unmodeled deviations from the nominal spring constant. Additionally, we present a model of the effect of friction between the wire and the cam. Lastly, we show experimentally that the torque generated by the cam mechanism matches the torque predicted in our modeling approach. Our results also suggest that the effects of wire-cam friction are significant for non-circular cams.
format Preprint
id arxiv_https___arxiv_org_abs_2306_12971
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Design Considerations and Robustness to Parameter Uncertainty in Wire-Wrapped Cam Mechanisms
Johnston, Garrison L. H.
Orekhov, Andrew L.
Simaan, Nabil
Robotics
Collaborative robots must simultaneously be safe enough to operate in close proximity to human operators and powerful enough to assist users in industrial tasks such as lifting heavy equipment. The requirement for safety necessitates that collaborative robots are designed with low-powered actuators. However, some industrial tasks may require the robot to have high payload capacity and/or long reach. For collaborative robot designs to be successful, they must find ways of addressing these conflicting design requirements. One promising strategy for navigating this tradeoff is through the use of static balancing mechanisms to offset the robot's self weight, thus enabling the selection of lower-powered actuators. In this paper, we introduce a novel, 2 degree of freedom static balancing mechanism based on spring-loaded, wire-wrapped cams. We also present an optimization-based cam design method that guarantees the cams stay convex, ensures the springs stay below their extensions limits, and minimizes sensitivity to unmodeled deviations from the nominal spring constant. Additionally, we present a model of the effect of friction between the wire and the cam. Lastly, we show experimentally that the torque generated by the cam mechanism matches the torque predicted in our modeling approach. Our results also suggest that the effects of wire-cam friction are significant for non-circular cams.
title Design Considerations and Robustness to Parameter Uncertainty in Wire-Wrapped Cam Mechanisms
topic Robotics
url https://arxiv.org/abs/2306.12971