@article{duan_bryant_2023, title={Implications of Spatially Constrained Bipennate Topology on Fluidic Artificial Muscle Bundle Actuation (vol 11, 82, 2022)}, volume={12}, ISSN={["2076-0825"]}, DOI={10.3390/act12020079}, abstractNote={The authors wish to make the following corrections in Section 3 [...]}, number={2}, journal={ACTUATORS}, author={Duan, Emily and Bryant, Matthew}, year={2023}, month={Feb} }
 @article{hart_duan_bryant_2022, title={Experimental Investigation of Boundary Condition Effects in Bipennate Fluidic Artificial Muscle Bundles}, volume={12041}, ISBN={["978-1-5106-4957-6"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.2615896}, abstractNote={In this study, the implementation and performance of bipennate topology fluidic artificial muscle (FAM) bundles operating under varying boundary conditions is investigated and quantified experimentally. Soft actuators are of great interest to design engineers due to their inherent flexibility and potential to improve safety in human robot interactions. McKibben fluidic artificial muscles are soft actuators which exhibit high force to weight ratios and dynamically replicate natural muscle movement. These features, in addition to their low fabrication cost, set McKibben FAMs apart as attractive components for an actuation system. Previous studies have shown that there are significant advantages in force and contraction outputs when using bipennate topology FAM bundles as compared to the conventional parallel topology1 . In this study, we will experimentally explore the effects of two possible boundary conditions imposed on FAMs within a bipennate topology. One boundary condition is to pin the muscle fiber ends with fixed pin spacings while the other is biologically inspired and constrains the muscle fibers to remain in contact. This paper will outline design considerations for building a test platform for bipennate fluidic artificial muscle bundles with varying boundary conditions and present experimental results quantifying muscle displacement and force output. These metrics are used to analyze the tradespace between the two boundary conditions and the effect of varying pennation angles.}, journal={BIOINSPIRATION, BIOMIMETICS, AND BIOREPLICATION XII}, author={Hart, Rebecca and Duan, Emily and Bryant, Matthew}, year={2022} }
 @article{duan_bryant_2022, title={Implications of Spatially Constrained Bipennate Topology on Fluidic Artificial Muscle Bundle Actuation}, volume={11}, ISSN={["2076-0825"]}, DOI={10.3390/act11030082}, abstractNote={In this paper, we investigate the design of pennate topology fluidic artificial muscle bundles under spatial constraints. Soft fluidic actuators are of great interest to roboticists and engineers, due to their potential for inherent compliance and safe human–robot interaction. McKibben fluidic artificial muscles are an especially attractive type of soft fluidic actuator, due to their high force-to-weight ratio, inherent flexibility, inexpensive construction, and muscle-like force-contraction behavior. The examination of natural muscles has shown that those with pennate fiber topology can achieve higher output force per geometric cross-sectional area. Yet, this is not universally true for fluidic artificial muscle bundles, because the contraction and rotation behavior of individual actuator units (fibers) are both key factors contributing to situations where bipennate muscle topologies are advantageous, as compared to parallel muscle topologies. This paper analytically explores the implications of pennation angle on pennate fluidic artificial muscle bundle performance with spatial bounds. A method for muscle bundle parameterization as a function of desired bundle spatial envelope dimensions has been developed. An analysis of actuation performance metrics for bipennate and parallel topologies shows that bipennate artificial muscle bundles can be designed to amplify the muscle contraction, output force, stiffness, or work output capacity, as compared to a parallel bundle with the same envelope dimensions. In addition to quantifying the performance trade space associated with different pennate topologies, analyzing bundles with different fiber boundary conditions reveals how bipennate fluidic artificial muscle bundles can be designed for extensile motion and negative stiffness behaviors. This study, therefore, enables tailoring the muscle bundle parameters for custom compliant actuation applications.}, number={3}, journal={ACTUATORS}, author={Duan, Emily and Bryant, Matthew}, year={2022}, month={Mar} }