AeroFlex is an open standard for braided pneumatic artificial muscles (PAMs): documented geometry, repeatable performance, and standard connection interfaces, so muscles and the parts that drive them work together no matter who built them.
Pneumatic muscles have been in labs since the 1950s. They are light, strong, compliant, silent, and cheap to make, yet they never went mainstream, because every muscle is a one-off: undocumented geometry, unknown force curves, and no standard way to connect one to anything. AeroFlex fixes the boring part. It specifies the muscle and its interfaces the way a servo's spline, plug, and PWM signal are specified, so an entire ecosystem can build against it.
flowchart LR
subgraph STD["The AeroFlex Standard (this repo)"]
G["Muscle geometry<br/>and materials"] --- P["Performance<br/>characterization"] --- I["Connection interfaces<br/>(mechanical + pneumatic)"]
end
STD --> D["Delta Robotics<br/>product line"]
STD --> T["Third-party<br/>products"]
STD --> Y["Your own<br/>builds"]
Delta Robotics ships its own AeroFlex product line, and anyone else can build muscles, controllers, kits, and machines for the same ecosystem. The standard is Apache-2.0: free for anyone to implement, commercially or otherwise. Only the AeroFlex name is reserved (see Ecosystem).
The current build is hand-assembled from about $10 of off-the-shelf parts in under an hour:
- Order the parts in the muscle BOM: latex tubing, PET overexpanded braided sleeve, adhesive-lined heat shrink, barb connectors, push-to-connect cartridges, and crimp ferrules.
- Follow the assembly sequence in
manufacturing/muscle-assembly.md: cut, sleeve, shrink, crimp, and pressure-test. - Drive it with regulated air or CO2 in the 30-100 psi range. A correct build contracts smoothly and holds pressure; current builds target the 20-35% stroke range, with about 50% as the design goal.
Before pressurizing anything, read the validation and safety notes in
docs/design.md. Compressed gas stores real energy.
| Path | Contents |
|---|---|
docs/design.md |
The reference muscle design: materials, geometry, manufacturability, validation plan |
docs/theory.md |
Force-pressure equation, stroke theory, design references |
docs/components.md |
BOM: fittings, threads, regulators, valves, CO2, sourcing links |
docs/background.md |
Why artificial muscles have not gone mainstream, and what changes that |
manufacturing/ |
Muscle BOM, assembly process, and airtight manifold printing |
apps/hud/ |
Zero-install browser telemetry HUD for muscle controllers (Web Serial), with a documented protocol any Arduino can speak |
research/ |
Cited research library: PAM modeling, sensing, fabrication methods, vendor surveys |
datasheets/ |
Vendor spec-sheet index with source links |
Inside a printed connector block - the airtight-printing guide covers how walls, infill, and finishing make FDM parts hold pressure (manufacturing/airtight-3d-printing.md).
The standard is pre-1.0 and under active development. Documented today: muscle construction, materials, theory, and the working fitting and thread choices.
The hardware iterates alongside the docs - regulator mount, inline regulator, and connector block prototypes.
On the way to a 1.0 release:
- Formal interface specification (mounting, pneumatic connections, sensing)
- Published force-pressure-stroke curves for reference builds
- Conformance checklist for "AeroFlex compatible" claims
Watch CHANGELOG.md and the proposals for changes. Nothing is stable until 1.0.
You do not need permission to implement this standard, sell products built on it, or say your product "works with the AeroFlex Standard". The name "AeroFlex" itself is a Delta Robotics trademark; the short rules for using it are in TRADEMARKS.md.
Doc fixes and build reports can go straight to a PR; changes to the standard start as a proposal issue. See CONTRIBUTING for the process (including DCO sign-off) and SECURITY.md for reporting safety-relevant errors privately.
Apache-2.0 (SPDX-License-Identifier: Apache-2.0). See LICENSE
and NOTICE. The license grants patent rights but not trademark
rights; trademark use is covered by TRADEMARKS.md.