3D Printing of Passively Actuated Self-Folding Robots with Integrated Functional Modules
Gaolin Ge, Qifeng Yang, Haoran Lu, Tingyu Cheng, Martin Nisser, Yiyue Luo
AI summary
Problem
Prior self-folding methods rely on specialized materials, external stimuli, or complex post-folding wiring, which limits accessibility, repeatability, and scalable electronics integration.
Approach
The method uses flat 3D-printed conductive PLA nets with compliant hinges and printed hooks to route elastic bands, passively folding the structure into 3D shapes while allowing precise flat-state assembly of electronics and sensors.
Key results
- Closed-form folding model linking hinge thickness, band size, and hook spacing to target fold angles
- Design map enabling precise prediction of equilibrium fold angles without trial-and-error prototyping
- Flat-assembly workflow integrating ERM motors, Hall sensors, magnets, and capacitive electrodes in a single conductive PLA print
- Experimental validation across three functional platforms: a swarm cube, tendon-driven finger, and deployable gripper
Why it matters
Enables rapid, low-cost fabrication of scalable modular and swarm robots with built-in actuation and sensing, lowering barriers for education, research, and collective systems.
Abstract
We introduce an elastic-driven self-folding approach that fabricates robots directly from flat 3D-printed conductive PLA nets. Elastic bands routed through printed hooks store energy that folds the sheet into programmed 3D geometries, while the flat state allows accurate placement of electronics and magnets before deployment. The same substrate doubles as electrodes for capacitive touch and supports a reusable platform I/O palette with Hall sensors and eccentric rotating mass (ERM) motors for docking detection and vibration actuation. We also derive a closed-form folding model that balances hinge stiffness with elastic band moment to predict equilibrium fold angles; experiments validate the model and yield a design map linking hinge thickness, band size, and hook spacing to target angles. Using this workflow we realize multiple polyhedral modules and demonstrate three applications: a cube that highlights the potential of self-folding for scalable modular robot collectives, a deployable gripper, and a tendon-driven finger. The method is low cost, stimulus-free, and integrates actuation and sensing.