  Flexible robotics are capable of achieving various functionalities by shape
morphing, benefiting from their compliant bodies and reconfigurable structures.
Here we construct and study a class of origami springs generalized from the
known interleaved origami spring, as promising candidates for shape morphing in
flexible robotics. These springs are found to exhibit nonlinear stretch-twist
coupling and linear/nonlinear mechanical response in the compression/tension
region, analyzed by the demonstrated continuum mechanics models, experiments,
and finite element simulations. To improve the mechanical performance such as
the damage resistance, we establish an origami rigidization method by adding
additional creases to the spring system. Guided by the theoretical framework,
we experimentally realize three types of flexible robotics -- origami spring
ejectors, crawlers, and transformers. These robots show the desired
functionality and outstanding mechanical performance. The proposed concept of
origami-aided design is expected to pave the way to facilitate the diverse
shape morphing of flexible robotics.
