Easy-to-actuate multi-compatible truss structures with prescribed reconfiguration

Easy-to-actuate multi-compatible truss structures with prescribed reconfiguration

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Abstract Multi-stable structures attract great interest because they possess special energy landscapes with domains of attraction around the stable states.Consequently, multi-stable structures have the potential to achieve prescribed reconfiguration with only a few lightweight actuators (such as shape-memory alloy springs), neflintw-r6mpw and do not need constant actuation to be locked at a stable state.However, most existing multi-stability designs are based on assembling bi-stable unit cells, which contain multitudes of distractive stable states, diminishing the feasibility of reconfiguration actuation.Another type is by introducing prestress together with kinematic symmetry or nonlinearity to achieve multi-stability, but the resultant structure often suffers the lack of stiffness.To help address these challenges, we firstly introduce the constraints that a truss structure is simultaneously compatible at multiple (more than two) prescribed states.

Then, we solve for the design of multi-stable truss structures, named multi-compatible structures in this paper, where redundant stable states are limited.Secondly, we explore minimum energy paths connecting the designed stable states, and compute for a simple and inaccurate pulling actuation guiding the structure to transform along the computed paths.Finally, we fabricated four prototypes to demonstrate that prescribed reconfigurations with easy-actuation have been achieved and applied a quadra-stable structure to the design of a variable stiffness gripper.Altogether, our full-cycle design fr5299 approach contains multi-stability design, stiffness design, minimum-energy-path finding, and pulling actuation design, which highlights the potential for designing morphing structures with lightweight actuation for practical applications.