LT-PAM: A TOUGH PNEUMATIC ARTIFICIAL MUSCLE FOR ABOUT FIVE DOLLARS
A soft actuator that contracts under air pressure, assembled from silicone tube, braided sleeve and printed plugs for roughly five dollars in parts.
by Naniwa K, Sugimoto Y, Nakanishi D, Masuda Y
RoboticsOpen-hardware
- difficulty
- ●●●○○
- time
- an evening
- license
- CERN-OHL-P-2.0 (hardware), CC BY 4.0 (documentation)
- repo
- repo FINISHED0 stars
●●●○○ · an evening · CERN-OHL-P-2.0 (hardware), CC BY 4.0 (documentation) · 0 stars · repo FINISHED
WHAT YOU’LL NEED
Partner
COMPAREE VERDICT
LT-PAM is a pneumatic artificial muscle of the McKibben type: a silicone tube inside a braided sleeve that contracts when pressurised, exactly the kind sold commercially as the Festo Fluidic Muscle and used in soft robotics research. The Hokkaido and Osaka team published it in HardwareX with proper characterisation — contraction against tension at three pressures, extension behaviour, and 100-cycle fatigue tests — rather than just a demo video. The material cost is genuinely low: about 800 yen or five US dollars per 150 mm actuator, assuming you already have a 3D printer, a crimping tool for the hose clamps, and access to compressed air at 0.8 MPa. The single thing most likely to go wrong is underestimating the air supply: 8 bar is not a bicycle pump, and cheap fittings will leak or blow off under load. If you are exploring soft actuation or need a dozen muscles for a walking robot and do not want to pay Festo prices, this is exactly what you want. If you do not already have pneumatics experience and a compressor, the cost and learning curve are both higher than the headline figure suggests.
IN THE REPO
NOT IN THE REPO
- —STL and Fusion 360 CAD files are on Zenodo along with a demonstration video.
- —The HardwareX paper contains the full bill of materials, assembly procedure with photographs, and performance characterisation data.
- —No firmware — this is a purely mechanical/pneumatic actuator.
- —Hardware files are CERN-OHL-P-2.0, documentation is CC BY 4.0, both permit commercial use with attribution and share-alike for hardware modifications.
- —You need a compressed air source capable of 0.8 MPa (roughly 8 bar or 116 psi) and a crimping tool for hose clamps.
- —The $5 figure is marginal material cost per 150 mm actuator — it excludes the crimping tool, 3D printer access, and the air compressor.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the HardwareX paper(The paper contains the full bill of materials, assembly photographs, and performance data — start there, not the STL files.)
- 2.Download the CAD and STL files from Zenodo (Fusion 360 source files and STLs for the end plugs and assembly holders.)
- 3.Source the silicone tube and braided sleeve(The paper specifies the tube inner diameter, wall thickness, and sleeve braid angle — match those or the contraction ratio will be wrong.)
- 4.Print the ABS plugs(ABS is specified for temperature and pressure resistance; PLA may deform under repeated cycling.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- The $5 cost is material only — you need a compressor capable of 0.8 MPa, a crimping tool, and 3D printer access, none of which are cheap if you are starting from zero.
- Cheap pneumatic fittings will leak or blow off at 8 bar; use rated one-touch fittings and crimp the hose clamps properly or you will spend the evening chasing leaks.
- The contraction ratio depends on the braid angle of the sleeve — if you substitute a random braided sleeve from a hardware store, it may not contract at all or may burst.
- The paper characterises a 150 mm actuator; scaling to a different length changes the force and contraction behaviour in ways that are not linear.
- Compressed air at this pressure is a real hazard — wear eye protection, secure all hoses, and do not put your face near a pressurised actuator.
- If you have never worked with pneumatics before, budget time to learn about pressure regulation, safe fittings, and leak testing before you build a dozen of these for a robot.
Can I use PLA for the end plugs instead of ABS?
The authors specify ABS for a reason — it has better temperature and pressure resistance. PLA may deform under repeated cycling at 0.8 MPa or in a warm environment.
What air pressure do I actually need?
The paper tests to 0.8 MPa (8 bar, 116 psi). You can run it at lower pressures for less force, but you need a compressor and regulator that can safely deliver the rated pressure.
Is this safe for a prosthetic or wearable robot?
The paper does not address wearability or medical safety, and 8 bar of compressed air near skin is a hazard. This is a research actuator, not a certified medical device.
How does this compare to a Festo Fluidic Muscle?
Same working principle, much lower cost, and you can repair or modify it. The Festo version has tighter tolerances, certified pressure ratings, and comes with fittings — this is the DIY alternative for research or hobby use.
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Discussion1
FROM THE COMPAREE TEAM
The paper reports 100 contraction cycles under load without failure, and the whole actuator costs about 800 yen in parts. If you were building a quadruped or a soft gripper, how many of these would you need and what would break first?
Naniwa K, Sugimoto Y, Nakanishi D, Masuda Y
A research team from Hokkaido University of Science and Osaka Institute of Technology published LT-PAM in HardwareX to give soft robotics labs and hobbyists a low-cost alternative to commercial pneumatic muscles. They tested it properly — 100 contraction cycles, three pressure levels, extension behaviour — rather than just posting a demo.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM7h ago
Practical notes from our verification: the Zenodo record contains Fusion 360 source files, STLs for the plugs and holders, and a short demonstration video — the full experimental data and assembly photographs are in the HardwareX paper, which is open access. The $5 figure is honest but incomplete: it is marginal material cost per actuator, assuming you already own a 3D printer, a crimping tool, and a compressor rated to 8 bar. If you are starting from zero, the real entry cost is the air supply and the learning curve is pneumatics safety. The authors do not link to specific suppliers for the silicone tube or braided sleeve, so you will be matching the specs (tube ID, wall thickness, braid angle) rather than ordering a kit.