01
Identify a goal
Import a character, define the rig, sketch a motion path, and adjust pacing or smoothness.
CHI 2026 Full Paper
MotionSmith: A Sketch-BasedDesign Systemfor Automata Making
Sketch motion, compare mechanisms, refine the result, and export fabrication-ready automata.
1 Georgia Tech2 UC Santa Barbara
Overview
Built to connect creative intent, mechanism design, and fabrication.
MotionSmith is a sketch-based design system for automata making, developed through participatory design with three expert makers. It helps users sketch a desired motion, explore generated mechanisms, refine a chosen design, and export fabrication-ready files.
Across a year-long design process, we found that makers needed tools that support creative intent, fluid iteration, and mechanically simple outcomes. The final workflow keeps users in control while bridging early motion ideas to working, fabricable mechanisms.
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Participatory design shaped the workflow. Controls, pacing, and fabrication support were refined through long-term collaboration with expert makers. -
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Three stages keep the tool readable. The system moves from motion sketching to mechanism generation to export while keeping the intermediate steps visible. -
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Three finished artifacts ground the contribution. A shy elephant, a cheering man, and a tin robot demonstrate the expressive range of the workflow.
Demo
System
Three stages keep the workflow easy to follow.
MotionSmith moves from motion-path sketching to mechanism generation to fabrication export in one continuous pipeline.
02
Generate mechanisms
Compare four-bar, cam-follower, and gear candidates, then refine the selected mechanism directly on canvas.
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Support fabrication
Export SVG or PDF blueprint packets that bridge the digital design to a physical automaton.
Interface
One workspace for drawing, simulation, editing, and export.
The application keeps authoring, mechanism comparison, parametric refinement, pacing review, and blueprint export in one place, so the workflow stays continuous as the design becomes more concrete.
Cases
Three artist-led deployments show how the system holds up in practice.
Each deployment spans the full handoff from MotionSmith authoring, to mechanism choice, to fabrication and the finished automaton.
Case 01
Lu Lyu / Shy elephant
The piece evolved from a simpler leg lift into a quieter flower-holding gesture with a distinct shy rhythm.
- Mechanism. LL chose a four-bar linkage because it supported a clear raise-pause-settle rhythm within the explored mechanism set.
- Fabrication. MotionSmith SVG output was extruded in Fusion 360, then combined with 3D-printed linkages, cardstock layers, and brass fasteners.
- Why it matters. The case shows how expressive intent and motion matching can be considered together during mechanism selection.
Case 02
Tom Haney / Cheering man
This deployment turned iterative arm-raising sketches into a cleaner, more humorous cheering gesture.
- Mechanism. TH selected cams because they created a clear apex accent and supported the intended cheering gesture within the explored mechanism set.
- Fabrication. MotionSmith blueprints became asymmetric paper cams, wire linkages, and wooden followers mounted in a synchronized frame.
- Why it matters. The case highlights how simplicity, visual clarity, and trajectory accuracy can be balanced together.
Case 03
Marc Horovitz / Tin robot
The robot expanded from arm motion to a fuller angel-like gesture with coordinated arm and leg accents.
- Mechanism. MH composed a compound cam using larger arm cams and smaller leg cams to balance presence, comprehensibility, and fabrication effort.
- Fabrication. Printed blueprint packets were used as cutting guides for paper and wood parts before assembly on a backing board.
- Why it matters. The case shows how MotionSmith can hand off most of the process even when multi-motion synthesis still needs manual completion.
Citation
Read the paper and cite MotionSmith.
The full paper is available as a local PDF. The DOI and BibTeX are included below for quick reference.
BibTeX
MotionSmith
@inproceedings{synn2026motionsmith,
title = {MotionSmith: A Sketch-Based Design System for Automata Making},
author = {Synn, DoangJoo (Alan) and Guo, Zhifan and Ha, Sehoon and Oh, HyunJoo},
booktitle = {Proceedings of the 2026 CHI Conference on Human Factors in Computing Systems},
year = {2026},
doi = {10.1145/3772318.3791545}
}