Kinegami: Computational Design of Kinematic Mechanisms
Overview: 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 and are currently working on 3D printed module designs.
Algorithms
Our algorithms automatically design kinematic chains (and soon 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.
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.
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.
@conference{feshbach2024kinegamiPython,
title = {Kinegami: Open-source Software for Creating Kinematic Chains from Tubular Origami},
author = {Daniel Feshbach and Wei-Hsi Chen and Daniel E. Koditschek and Cynthia Sung},
url = {https://github.com/SungRoboticsGroup/KinegamiPython},
year = {2024},
date = {2024-07-16},
urldate = {2024-07-16},
booktitle = {8th International Meeting on Origami in Science, Mathematics, and Education (8OSME)},
abstract = {Arms, legs, and fingers of animals and robots are all examples of “kinematic chains" - mechanisms with sequences of joints connected by effectively rigid links. Lightweight kinematic chains can be manufactured quickly and cheaply by folding tubes. In recent work [Chen et al. 2022], we demonstrated that origami patterns for kinematic chains with arbitrary numbers of degrees of freedom can be constructed algorithmically from a minimal kinematic specification (axes that joints rotate about or translate along). The work was founded on a catalog of tubular crease patterns for revolute joints (rotation about an axis), prismatic joints (translation along an axis), and links, which compose to form the specified design. With this paper, we release an open-source python implementation of these patterns and algorithms. Users can specify kinematic chains as a sequence of degrees of freedom or by specific joint locations and orientations. Our software uses this information to construct a single crease pattern for the corresponding chain. The software also includes functions to move or delete joints in an existing chain and regenerate the connecting links, and a visualization tool so users can check that the chain can achieve their desired configurations. This paper provides a detailed guide to the code and its usage, including an explanation of our proposed representation for tubular crease patterns. We include a number of examples to illustrate the software’s capabilities and its potential for robot and mechanism design.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {conference}
}
Arms, legs, and fingers of animals and robots are all examples of “kinematic chains" - mechanisms with sequences of joints connected by effectively rigid links. Lightweight kinematic chains can be manufactured quickly and cheaply by folding tubes. In recent work [Chen et al. 2022], we demonstrated that origami patterns for kinematic chains with arbitrary numbers of degrees of freedom can be constructed algorithmically from a minimal kinematic specification (axes that joints rotate about or translate along). The work was founded on a catalog of tubular crease patterns for revolute joints (rotation about an axis), prismatic joints (translation along an axis), and links, which compose to form the specified design. With this paper, we release an open-source python implementation of these patterns and algorithms. Users can specify kinematic chains as a sequence of degrees of freedom or by specific joint locations and orientations. Our software uses this information to construct a single crease pattern for the corresponding chain. The software also includes functions to move or delete joints in an existing chain and regenerate the connecting links, and a visualization tool so users can check that the chain can achieve their desired configurations. This paper provides a detailed guide to the code and its usage, including an explanation of our proposed representation for tubular crease patterns. We include a number of examples to illustrate the software’s capabilities and its potential for robot and mechanism design.
@workshop{chen2024robogami,
title = {Robogami Reveals the Utility of Slot-Hopper for Co-Design of DOQ’s Body and Behavior},
author = {Wei-Hsi Chen and J. Diego Caporale and Daniel E. Koditschek and Cynthia Sung},
url = {https://www.robotmechanisms.org/activities/icra-2024-codesign},
year = {2024},
date = {2024-05-13},
urldate = {2024-05-13},
booktitle = {ICRA 2024 Workshop on Co-design in Robotics: Theory, Practice, and Challenges},
keywords = {},
pubstate = {published},
tppubtype = {workshop}
}
@workshop{chen2024bio,
title = {Bio-inspired quadrupedal robot with passive paws through algorithmic origami design},
author = {Wei-Hsi Chen and Xueyang Qi and Daniel Feshbach and Stanley J. Wang and Duyi Kuang and Robert Full and Daniel Koditschek and Cynthia Sung},
url = {https://www.colorado.edu/lab/jayaram/RoboSoft2024},
year = {2024},
date = {2024-04-14},
urldate = {2024-04-14},
booktitle = {7th IEEE-RAS International Conference on Soft Robotics (RoboSoft) Workshop: Soft Robotics Inspired Biology},
howpublished = {n the workshop: Soft Robotics Inspired Biology Workshop, held in 2024 IEEE-RAS International Conference on Soft Robotics (Robosoft), San Diego, US.},
keywords = {},
pubstate = {published},
tppubtype = {workshop}
}
@workshop{chen2023DOQ,
title = {DOQ: A Dynamic Origami Quadrupedal Robot},
author = {Wei-Hsi Chen and Shane Rozen-Levy and Griffin Addison and Lucien Peach and Daniel E. Koditschek and Cynthia R. Sung},
year = {2023},
date = {2023-05-29},
urldate = {2023-05-29},
booktitle = {ICRA Workshop on Origami-based Structures for Designing Soft Robots with New Capabilities},
keywords = {},
pubstate = {published},
tppubtype = {workshop}
}
Chen, Wei-Hsi; Yang, Woohyeok; Peach, Lucien; Koditschek, Daniel E.; Sung, Cynthia R.
Kinegami: Algorithmic Design of Compliant Kinematic Chains From Tubular Origami (Journal Article)
In: IEEE Transactions on Robotics, vol. 39, iss. 2, pp. 1260-1280, 2023, (Honorable mention for 2023 IEEE Transactions on Robotics King-Sun Fu Memorial Best Paper Award).
@article{chen2022kinegami,
title = {Kinegami: Algorithmic Design of Compliant Kinematic Chains From Tubular Origami},
author = {Wei-Hsi Chen and Woohyeok Yang and Lucien Peach and Daniel E. Koditschek and Cynthia R. Sung},
url = {https://repository.upenn.edu/ese_papers/884/
https://www.youtube.com/watch?v=IT58JeMoAr0
https://github.com/weinitor/Kinegami},
doi = {10.1109/TRO.2022.3206711},
year = {2023},
date = {2023-04-01},
urldate = {2023-04-01},
journal = {IEEE Transactions on Robotics},
volume = {39},
issue = {2},
pages = {1260-1280},
abstract = {Origami processes can generate both rigid and compliant structures from the same homogeneous sheet material. In this article, we advance the origami robotics literature by showing that it is possible to construct an arbitrary rigid kinematic chain with prescribed joint compliance from a single tubular sheet. Our “Kinegami” algorithm converts a Denavit–Hartenberg specification into a single-sheet crease pattern for an equivalent serial robot mechanism by composing origami modules from a catalogue. The algorithm arises from the key observation that tubular origami linkage design reduces to a Dubins path planning problem. The automatically generated structural connections and movable joints that realize the specified design can also be endowed with independent user-specified compliance. We apply the Kinegami algorithm to a number of common robot mechanisms and hand-fold their algorithmically generated single-sheet crease patterns into functioning kinematic chains. We believe this is the first completely automated end-to-end system for converting an abstract manipulator specification into a physically realizable origami design that requires no additional human input.},
note = {Honorable mention for 2023 IEEE Transactions on Robotics King-Sun Fu Memorial Best Paper Award},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Origami processes can generate both rigid and compliant structures from the same homogeneous sheet material. In this article, we advance the origami robotics literature by showing that it is possible to construct an arbitrary rigid kinematic chain with prescribed joint compliance from a single tubular sheet. Our “Kinegami” algorithm converts a Denavit–Hartenberg specification into a single-sheet crease pattern for an equivalent serial robot mechanism by composing origami modules from a catalogue. The algorithm arises from the key observation that tubular origami linkage design reduces to a Dubins path planning problem. The automatically generated structural connections and movable joints that realize the specified design can also be endowed with independent user-specified compliance. We apply the Kinegami algorithm to a number of common robot mechanisms and hand-fold their algorithmically generated single-sheet crease patterns into functioning kinematic chains. We believe this is the first completely automated end-to-end system for converting an abstract manipulator specification into a physically realizable origami design that requires no additional human input.
This project has been supported by the National Science Foundation under grants 2322898 and 1845339, and by the Army Research Office under the SLICE Multidisciplinary University Research Initiatives Program grant W911NF1810327. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Army Research Office.
