Computational Design of Kinematic Mechanisms
This project aims to develop computational pipelines for users to quickly and cheaply design and construct mechanisms from kinematic specifications. Arms, legs, and fingers of animals and robots are all examples of “kinematic chains” – mechanisms with sequences of joints connected by effectively rigid links. We create end-to-end design algorithms and interactive editing software for kinematic “skeletons” that can be fabricated as origami or 3D printed structures. This is part of a larger effort within the lab to provide tools for rapid prototyping and fabrication of custom robots and mechanisms.
Compositional Design of Tubular Structures
We construct kinematic chains and trees as tubular structures designed as compositions of rotational and translational modules. The methods are built upon a library of parameterized designs for revolute (rotating) joints, prismatic (sliding) joints, and rigid links. We have designed a library of modules constructed from origami for kinematic chains. Currently, we are working on 3D printed module designs, including branching modules to extend our work to kinematic trees.
Algorithms
Our algorithms automatically design kinematic chains and trees with given degrees of freedom. Given a sequence of axes of motion (lines in 3D space along which a revolute joint rotates or a prismatic joint translates), our algorithms calculate a position and orientation along each axis such that joints can be sequentially connected by tubular links. The core idea is to convert the design problem into a planning problem for module centerline paths. Since a tube cannot bend more sharply than its own radius, the paths have a minimum turning radius, making this a Dubins planning problem. The algorithms space joints far enough apart and orient them appropriately such that collision-free Dubins paths exist connecting them.
Human-in-the-Loop Design Tools
We are creating fully interactive design software to enable humans to create kinematic chains and trees with assistance from our algorithms, requiring no coding or engineering expertise. We currently have a python repository for creating and editing tubular kinematic chains, visualizing how they can move, and exporting origami crease patterns to construct them: see our github repo for more details.
Dynamical Robots
Our library of tubular origami module patterns enables rapid, cheap, semi-automated prototyping of dynamical robots with high power density. To demonstrate this, we are building the Dynamic Origami Quadruped (DOQ), an untethered mesoscale robot capable of walking, bounding, and pronking gaits. The light weight of the origami tubes enables the robot mass to be about 50% actuators.
Resources
Python code for creating and editing tubular origami kinematic chains (from our 8OSME paper, 2024): https://github.com/SungRoboticsGroup/KinegamiPython
MATLAB code for creating tubular origami kinematic chains (from our 2023 T-RO paper): https://github.com/SungRoboticsGroup/Kinegami
Instructional example videos for folding tubular origami modules. These examples have 4 sides and are made from .005″ thick PET plastic film. The crease lines are laser etched at 25 PPI, and mountain-valley coloring is hand-drawn in pen.
