Graph traversal of tendon constrained inflatables segmented motions

Achieving multimodal kinematic paths (i.e. having more than one path) in adaptive structures often requires active manipulation, such as actuation or locking, which increases system complexity. This paper addresses the gap in naturally engaging and disengaging constraint with external loads through tendon constrained inflatables (TCIs), without reliance on active control. A TCI consists of an inflatable bladder and rigid end caps, connected by tendons. Upon pressurization, these tendons become taut, constraining select degrees of freedom (DOFs). The movement of one end cap relative to the other depends on the remaining unconstrained DOFs. By strategically designing the tendon configuration, a TCI can reconfigure its constraints to selectively allow or constrain motions based on the applied external loads without actuation, sensing, and control as different tendons become taut and slack. This paper introduces load-activated multimodal tendon constrained inflatables that can adaptively provide spatially sequential 1 DOF motion segments by traversing between segment points (i.e. fully constrained positions). A 3D kineto-static equilibrium model is proposed to predict the loads needed to slacken specific tendons and define the TCI’s workspace. Optimization is applied to design tendon configurations and a prototype TCI was fabricated and experimentally validated.