3D Printing of Passively Actuated Self-Folding Robots with Integrated Functional Modules

TL;DR

This paper presents a novel 3D printing method for creating self-folding robots with integrated electronics, sensors, and actuators, enabling scalable, low-cost, stimulus-free robotic modules.

Contribution

The authors introduce an elastic-driven self-folding fabrication process with a predictive folding model and demonstrate multiple functional robotic modules.

Findings

Validated a closed-form folding model predicting equilibrium angles.

Developed a workflow for fabricating polyhedral modules with integrated electronics.

Demonstrated applications including a self-folding cube, deployable gripper, and tendon-driven finger.

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.