Uh oh. Well, have fun!

She will be unsuccessful in lewding me, I promise

Oh? Is that so. Well If she fails with you I'm more then willing to help~

No thanks,  TheFancyGayDragon has me taken care of c:

Attempting to summon them forth? Well played.

Stinky

Now that you've made some air muscles it's time to put them to use.

Stretch out the muscles so they reach their maximum extension by adding weight. A good test rig would be to use a hanging scale- unfortunately I didn't have access to one so I had to use some weights. Now slowly start adding air in increments of 20psi until you reach 60psi.

The first thing you notice is that the muscle contracts a progessively smaller amount with each incremental increase in air pressure until it fully contracts. Next you'll find that as the load is increased the ability of the muscle to contract decreases at an increasing rate until it can no longer lift the increased load. This is very similar to how a human muscle performs.

It is immediately noticeable that a change in the size of the muscle has a huge effect on the performance of the muscle. At 22lbs. @60psi, the smaller muscle can still lift, but it is nowhere near obtaining full contraction while the larger muscle can very easily obtain full contraction.

The dynamics of air muscles are fairly difficult to mathematically model, especially given the number of variables in their construction. For further reading I recommend having a look here:
http://biorobots.cwru.edu/projects/bats/bats.htm

Several applications of air muscles include robotics (especially biorobotics), animatronics, orthotics/rehabilitation and prosthetics. They can be controlled by microcontrollers or switches using three way solenoid air valves or by radio control using valves operated by servos. A three way valve works by first filling the bladder, holding the air pressure in the bladder and then venting the bladder to deflate it.

The thing to remember is that air muscles must be under tension to work properly. As an example two muscles are often used in conjunction to balance each other to move a robotic arm. One muscle would act as the bicep and the other as the tricep muscle.

Overall, air muscles can be constructed in all sorts of lengths and diameters to suit a wide variety of applications where high strength and light weight are critical. Their performance and longevity varies according to several parameters regarding their construction:

1) Length of muscle
2) Diameter of muscle
3) Type of tubing used for bladder- testing I've read states that latex bladders tend to have a longer service life than silicone bladders, however some silicones have greater expansion rates (up to 1000%) and can hold higher pressures than latex (much of this will depend on the exact tubing specification.)
4) Type of braided mesh used- some braided meshes are less abrasive than others, improving bladder life span. Some companies have used a spandex sleeve between the bladder and mesh to reduce abrasion. A tighter woven mesh allows for more even pressure distribution on the bladder, reducing stress on the bladder.
5) Pre stressing of the bladder (the bladder is shorter than the braided mesh)- this causes a reduction of contact area (and hence abrasion) between the bladder and braided mesh sleeve when the muscle is at rest and allows the braided mesh to fully reform between contraction cycles, improving its fatigue life. Pre stressing the bladder also improves the initial contraction of the muscle due to initial lower bladder volume.
6) Construction of muscle end housings- radiused edges reduce stress concentrations on the bladder.

All in all, given their power to weight ratio, ease/low cost of construction and ability to mimic the dynamics of human muscles, air muscles offer an attractive alternative to traditional means of motion for mechanical devices.

Have fun building them! :D

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32 4.5Kmuscle will contract to a greater degree than figure C given an equal increase in bladder pressure).The videos show this effect as well. Air muscles can contract up to 40% of their length, depending on the method and materials of their construction.

Gas law states that if you increase pressure you also increase the volume of an expandable cylinder (provided temperature is constant.) The expanding volume of the bladder is ultimately constrained by the physical properties of the braided mesh sleeve so in order to create a greater pulling force you need to be able to increase the effective volume of the bladder- the pulling force of the muscle is a function of the length and diameter of the muscle as well as its ability to contract due to the properties of the mesh sleeve (construction material, number of fibers, interweave angle) and bladder material.

I constructed two different sized muscles using similar materials to demonstrate this principle- they both were operated at the same air pressure (60psi) but had different diameters and lengths. The small muscle really starts to struggle when some weight is put on it while the larger muscle has no problems at all.

Here are a couple of videos showing both of the constructed air muscles in action.


Now let's go make some muscles!
Step 1: Materials
Materials
Materials
Materials

All of the materials are readily available on Amazon.com, with the exception of the 3/8" braided nylon mesh- it is available from electronics suppliers. Amazon does sell a braided sleeving kit with several sizes of braided mesh but the exact material is not stated-
Amazon

You'll need an air source:
I used a small air tank with a pressure regulator but you can also use a bicycle air pump (you will have to make an adapter to make it work with the 1/4" poly hose.
Air tank- Amazon
Pressure regulator (will require a 1/8" NPT female to 1/4" NPT male adapter)- Amazon

1/4" high pressure poly tubing- Amazon
multitool (screwdriver, scissors, pliers, wire cutters)- Amazon
lighter

for the small muscle:
1/4" silicone or latex tubing- Amazon
3/8" braided nylon mesh sleeve (see above)
1/8" small hose barb (brass or nylon)- Amazon
small bolt (10-24 thread by 3/8 in length works well)- Amazon
steel safety wire- Amazon

for the large muscle:
3/8" silicone or latex tubing- Amazon
1/2" braided nylon mesh sleeve- Amazon
1/8" or similar sized drill bit- Amazon
21/64" drill bit- Amazon
1/8" x 27 NPT tap- Amazon
1/8" hose barb x 1/8" pipe thread adapter- Amazon
small hose clamps- Amazon
3/4" aluminum or plastic rod to construct the muscle ends- Amazon

Safety note- make sure you wear safety glasses when testing your air muscles! A high pressure hose that pops off a loose fitting could cause a serious injury!

Step 2: Making the Small Muscle
Making the Small Muscle
Making the Small Muscle
Making the Small Muscle
Making the Small Muscle
6 More Images

First cut a small length of the 1/4" silicone tubing. Now insert the small bolt into one end of the tubing and the hose barb into the other end.
tatebullrider
tatebullrider

6 years ago

I have been thinking of building an exo-suit, and these might just be the ticket. I bet paintball CO2 tanks would work great for this too.
CalebGreer
CalePneumatic artificial muscles
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Doumit et al. (2009) Awith fixed orifices, placed in parallel with the McKibben actuator, is proposed to improve the force-velocity performance. Simulation results of this practical design indicate a significant improvement.
Published in: 1999 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (Cat. No.99TH8399)
Date of Conference: 19-23 September 1999
Date Added to IEEE Xplore: 06 August 2002
Print ISBN:
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Tondu et al. (2012) Modelling of the McKibben artificial muscle: A review.
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Featuredan muscle and have a phenomenal strength to weight ratio- they can exert a pulling force up to 400 times their own weight. They will work when twisted or bent and can work under water. They're also easy and cheap to make!

Air muscles (also known as a McKibben artificial muscle or braided pneumatic actuators) were originally developed by J.L. McKibben in the 1950's as an orthotic appliance for polio patients.

Here's how they work:

The muscle consists of a rubber tube (bladder or core) that is surrounded by a tubular braided fiber mesh sleeve. When the bladder is inflated the mesh expands radially and contracts axially (since the mesh fibers are inextensible), shortening the overall length of the muscle and subsequently producing a pulling force.

Air muscles have performance characteristics very similar to human muscles- the force exerted decreases as the muscle contracts. This is due to the change in the interweave angle of the braided mesh as the muscle contracts- as the mesh expands radially in a scissors like motion it exerts less force due to the weave angle becoming increasingly shallow as the muscle contracts (see the diagram below- figure A shows that the e one end over one of the machined fittings. Then cut some 1/2" braided sleeve 10" long (remember to melt the ends with a lighter) and slide it over the rubber tube. Then slide the opposite end of the rubber tube over the remaining machined air fitting. Now securely clamp each end of the tubing using hose clamps.

The larger muscle works just like smaller version- just add air and watch it contract. Once you put it under load you'll immediately realize this larger muscle is much stronger!
Step 4: Testing and Additional Info
6 years ago

Not sure if my post went up or not but make a voltage controlled air regulator. A solenoid coil pulling on the spring or acting like the spring of a regulator.
dmartinez2560
dmartinez2560

6 years ago

What solenoids would you recommend to use these with?bGreere ends of the muscle, you can make the sleeve longer and then fold it back over the end of the muscle, forming a loop ( you have to push the air fitting through)- then tighten the wire around it.

Now connect your 1/4" high pressure tubing and pump a little air into the muscle to make sure it inflates without leaking.

To test the air muscle you have to stretch it to its full length by putting a load on it- this will allow it maximum contraction when it's pressurized. Start adding air (up to about 60psi) and watch the muscle contract!
Step 3: Making the Large Air Muscle
Making the Large Air Muscle
Making the Large Air Muscle
Making the Large Air Muscle
5 More Images

To make the large muscle I turned some barbed ends from some 3/4" aluminum rod- plastic will also work. One end is solid. The other end has a 1/8" air hole drilled in it and then is tapped for a 1/8" hose barb pipe thread adapter. This is done by drilling a 21/64" hole perpendicular to the 1/8" air hole. Then use a 1/8" pipe thread tap to tap the 21/64" hole for the hose barb fitting.

Now cut a 8" length of 3/8" rubber tubing for the air bladder and slid
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248 Comments
Fulano05
Fulano05



6 years ago

That's a lot simpler than I thought it would be. I can't imagine how I'd find a use for those, but someone is gonna figure out how to put those to work!
rsaelens
rsaelens

7 years ago

Hey there, I made an exo arm in which is like to include a pneumatic muscle. Probably the small one. But I was really wondering if I could you co2? Mainly because I can fit the cartridges right into the arm. Please let me know and I greatly appreciate it.
Shanethefilmmaker.
Shanethefilmmaker.

7 years ago

Ok I get how to make the muscle but how do you go abouts making an exo-arm
Honus
Honus

7 years ago
0-7803-5038-3
INSPEC Accession Number: 6440775
DOI: 10.1109/AIM.1999.803170
Publisher: IEEE
Conference Location: Atlanta, GA, USA
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Introduction: How to Make Air Muscles!
How to Make Air Muscles!
How to Make Air Muscles!
HonusBy Honus
Making to learnneumatic Artificial Muscles
McKibben air muscles were invented for orthotics in the 1950s. They have the advantages of being lightweight, easy Fabrication
Modeling
Testing
Case Studies
Bibliography

Obiajulu et al. (2013) Soft Pneumatic Artificial Muscles With Low Threshold Pressures for a Cardiac Compression Device. to fabricate, are self limiting (have a maximum contraction) and have load-length curves similar to human muscle. The muscles consist of an inflatable inner tube/bladder inside a braided mesh, clamped at the ends. When the inner bladder is pressurized and expands, the geometry of the mesh acts like a scissor linkage and translates this radial expansion into linear contraction.
Standard McKibbens contract in a linear motion up to a maximum of typically 25%, though different materials and construction may yield contractions around 40% . Though they can technically be designed to lengthen as well, this is not useful as the soft muscles buckle.
Some of the information contained in this web site includes intellectual property covered by both issued and pending patent applications. It is intended solely for research, educational and scholarly purposes by not-for-profit research organizations. If you have interest in specific technologies for commercial applications, please contact us here.
Table of Contents
Pneumatic Artificial Muscles
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Roche et al. (2014) A Bioinspired Soft Actuated Material.

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Conferences >1999 IEEE/ASME International ...
McKibben artificial muscles: pneumatic actuators with biomechanical intelligence
Publisher: IEEE
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G.K. Klute; J.M. Czerniecki; B. Hannaford
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Abstract:
Reports on the design of a biorobotic actuator. Biological requirements are developed from published reports in the muscle physiology literature whose parameters are extracted and applied in the form of the Hill muscle model. Data from several vertebrate species (rat, frog, cat, and human) are used to evaluate the performance of a McKibben pneumatic actuator. The experimental results show the force-length properties of the actuator are muscle-like, but the force-velocity properties are not. The design of a hydraulic damper
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About: I'm a former bicycle industry designer turned professional jeweler. I like working with my hands and am happiest when I'm in the shop building my creations. If you need help with your project just let me know! More About Honus »

I needed to create some actuators for an animatronics project I'm working on. Air muscles are very powerful actuators that work very similar to a hum Create Account
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They should easily handle 2 bar pressure.

Now cut the 3/8" braided sleeve about two inches longer than the silicone tube and use a lighter to melt the ends of the braided sleeve so it doesn't fray apart.

Slide the braided sleeve over the silicone tubing and wrap each end of the tube with the safety wire and tighten it.

Now make some wire loops and wrap them around each end of the braided sleeve. As an alternative to using wire loops on th10 months ago

Is there a way to calculate how big and how much pressure I would need to make a McKibben muscle to lift 5 tons?
ruthkuma
ruthkuma

2 years ago

Hi Honus, just wanted to say my team is using your Instructable for a class project! We're making a prototype of a rehab device that actuates foot flexion/extension and I just received the parts to make two of your large air muscles. (The gif I attached is from this article and served as inspiration, it's not our implementation.) Thanks for making this guide.
Harvard GIF-downsized_large.gif
djsaintsrow14
djsaintsrow14

Question 4 years ago on Step 3

You said that you machined the aluminum or plastic rods. Do you have the file for it?
HTSystems
HTSystems

6 years ago

Also to make up air, same as electric car braking, high pressure air pump in legs. May be use the air out to the pump's intake too.
HTSystems
HTSystems


Leonardodiserdavincy
Leonardodiserdavincy

8 years ago

Guys can someon tell me if it's possible to connect ot to the human body?
How to Make Air Muscles! by Honus
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Chou & Hannaford. (1996) Measurement and modeling of McKibben pneumatic artificial muscles.

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From Wikipedia, the free encyclopedia
Air muscle contracting and extending.
Pneumatic artificial muscles (PAMs) are contractile or extensional devices operated by pressurized air filling a pneumatic bladder. In an approximation of human muscles, PAMs are usually grouped in pairs: one agonist and one antagonist.

PAMs were first developed (under the name of McKibben Artificial Muscles) in the 1950s for use in artificial limbs. The Bridgestone rubber company (Japan) commercialized the idea in the 1980s under the name of Rubbertuators.

The retraction strength of the PAM is limited by the sum total strength of individual fibers in the woven shell. The exertion distance is limited by the tightness of the weave; a very loose weave allows greater bulging, which further twists individual fibers in the weave.

One example of a complex configuration of air muscles is the Shadow Dexterous Hand[1] developed by the Shadow Robot Company, which also sells a range of muscles for integration into other projects/systems.[2]
Advantages

PAMs are very lightweight because their main element is a thin membrane. This allows them to be directly connected to the structure they power, which is an advantage when considering the replacement of a defective muscle. If a defective muscle has to be substituted, its location will always be known and its substitution becomes easier. This is an important characteristic, since the membrane is connected to rigid endpoints, which introduces tension concentrations and therefore possible membrane ruptures.

Another advantage of PAMs is their inherent compliant behavior: when a force is exerted on the PAM, it "gives in", without increasing the force in the actuation. This is an important feature when the PAM is used as an actuator in a robot that interacts with a human, or when delicate operations have to be carried out.

In PAMs the force is not only dependent on pressure but also on their state of inflation. This is one of the major advantages; the mathematical model that supports the PAMs functionality is a non-linear system, which makes them much easier[citation needed] than conventional pneumatic cylinder actuators to control precisely. The relationship between force and extension in PAMs mirrors what is seen in the length-tension relationship in biological muscle systems.

The compressibility of the gas is also an advantage since it adds compliance. As with other pneumatic systems PAM actuators usually need electric valves and a compressed air generator.

The loose-weave nature of the outer fiber shell also enables PAMs to be flexible and to mimic biological systems. If the surface fibers are very badly damaged and become unevenly distributed leaving a gap, the internal bladder may inflate through the gap and rupture. As with all pneumatic systems it is important that they are not operated when damaged.Hydraulic operation
Although the technology is primarily pneumatically (gas) operated, there is nothing that prevents the technology from also being hydraulically (liquid) operated. Using an incompressible fluid increases system rigidity and reduces compliant behavior.In 2017, such a device was presented by Bridgestone and the Tokyo Institute of Technology, with a claimed strength-to-weight ratio five to ten times higher than for conventional electric motors and hydraulic cylinders.[3]Seealso
Artificial muscleElectroactive polymerExoskeletonNotes"Dexterous Hand Series – Shadow Robot Company"."Air Muscles". Archived from the original on 2017-05-07. Retrieved 2013-02-06.
Development of a Hydraulic Drive High-Power Artificial Muscle through the Cabinet Office Tough Robotics ChallengeExternal linksWikibooks has a book on the topic of: Robotics/Components/Actuation Devices/Air musclePneumatic Artificial Muscles: actuators for robotics and automation
Bas Overvelde's ballooning muscles
Pneumatic artificial muscles
Biped robot powered by pneumatic artificial muscles
Soft Robot Manipulators with McKibben muscles
Air Muscles from Images Company
Air Muscles from Shadow Robots

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