Implications of Spatially Constrained Bipennate Topology on Fluidic Artificial Muscle Bundle Actuation

In this paper, we investigate the design of pennate topology fluidic artificial muscle bundles under spatial constraints. Soft actuators are great interest to roboticists and engineers, due their potential for inherent compliance safe human–robot interaction. McKibben muscles an especially attractive type soft actuator, high force-to-weight ratio, flexibility, inexpensive construction, muscle-like force-contraction behavior. The examination natural has shown that those with fiber can achieve higher output force per geometric cross-sectional area. Yet, is not universally true bundles, because contraction rotation behavior individual actuator units (fibers) both key factors contributing situations where bipennate topologies advantageous, as compared parallel topologies. This paper analytically explores implications pennation angle on bundle performance bounds. A method parameterization a function desired envelope dimensions been developed. An analysis actuation metrics shows be designed amplify contraction, force, stiffness, or work capacity, same dimensions. addition quantifying trade space associated different topologies, analyzing boundary conditions reveals how extensile motion negative stiffness behaviors. study, therefore, enables tailoring parameters custom compliant applications.