Soft Robots: Make An Artificial Muscle Arm And Gripper

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Picture of Soft Robots: Make An Artificial Muscle Arm And Gripper

Using artificial air muscles, a very flexible robot arm and gripper can be made.

This soft robot is powered by compressed air and each one of the 11 muscles can be controlled by a standard infrared universal remote control or an infrared LED connected to a micro controller that can output Sony code.

This is a hack of silicone caulk. It is in fact mostly made of silicone caulk.

This robot was a test of hand cast, silicone based air muscles which I plan to use in an inexpensive prosthetic robot hand that I am working on. A laser cutter would be very useful to make the precision sheet plastic molds necessary to cast the hand muscles. The cutter could also be used to create the "bone" structure of the hand out of plastic or plywood.

The very short video shows the robot picking up an egg and moving it.
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Step 1: How It Works

Picture of How It Works
I am convinced that soft robots are the way to finally create inexpensive and flexible robots that can work well with humans. They may make possible the first really practical robots for everyday use. Soft robots use flexible materials to create the frame and actuators of the robot.

The artificial air muscles for the hand and arm are made from Oogoo, an inexpensive mix of silicone caulk and corn starch that can be cast into many shapes. For this robot, the Oogoo was cast into layers to create stacked air bladders that can be expanded or contracted with pressure or vacuum.

A standard infrared universal remote can control individual muscles or pre-programmed sequences. It does this by sending signals to an air muscle controller that is controlled by robot neurons. The air muscle controller can control up to 11 air muscles using solenoid valves and a 12 volt air compressor that provides pressure or vacuum.

This is a tethered robot that has 11 air lines connected that power the air muscles. Eventually it should be possible to fit the valves and compressor on board. A less noisy compressor could also be made.

Dear: Mike

You should know I am trying to build your robot except do a few modifications. You see instead of building a robot arm I am trying to build a 3d printing robot arm that is soft. So far I am running into a lot of problems. I am trying to figure out how you casted the arm. I built this mold and this was the results. Where did I go wrong? I followed all your steps including putting plastic on top of the mold. Please help me?

From: Noah

mikey77 (author)  nschreiber0813yesterday

I am always happy to see anyone try do duplicate some part of any of my instructables. It almost never happens.

That said, you should understand that soft robots are not the best way to create the ultra precise positioning that 3D printers require.

While it might be possible, the flex and downright floppiness of artificial muscles made of silicone make it extremely difficult to control the movement precisely.

Even so, you should try it anyway. What you learn could be useful for other things even if it is not useful for your original goal.

I cannot tell from your pictures what you did or did not do. The idea is to lay down a layer of Oogoo and then separate it with thin sheet of polyethylene from a second layer of Oogoo.

It might be useful to start with a single muscle instead of the multiple muscles you are trying.

Good luck.

That solves it. I was wondering why when I did it why I wasn't understanding how it works. You should know that when I put a layer of oogoo down I made one layer of Oogoo not two. That would explain why when I put the plastic on it seemed a little funny. I also didn't put the plastic inbetween the oogoo I just put it on the top. Thank you I will give it a shot. Wish me good luck...

chubby83 months ago
I mixed my first batch of oogoo today. very cool stuff.
I'm going to begin to build a hand that uses air muscles,I find robots combined with prosthetics very interesting.

on a very different note, I'm also thinking of casting some oogoo insoles for my shoes, made to fit my feet perfectly. ;D

thank you, you are very inspiring.
chan20058 months ago

there is a nova on an arm like this

wsmith528 months ago
This is so cool, how many arms can you run at one time with this setup?
mikey77 (author)  wsmith528 months ago

With the controller I have now it can only run one arm at a time.

I am working on making my own valves which should make it possible to scale up the system.

Hey I actually have tried this exactly and have actually made 3d printable designs next week, I'll share them on an instructables... But the solenoids I got that you references totally let air through with the sparkfun pump, so I have to use this small fish tank pump that is way less strong.

Do you know of other solenoids that might handle higher psi, or do you know how I can prevent this or how I can check for this when purchasing? Or do you know other resources for solenoids like this that might be a little stronger?

Awesome thanks this is an amazing project that inspired me to make my own pneumatic snake robot :)
mikey77 (author)  gabriellalevine1 year ago
Cool, I'd like to see them.

If you look closely at step 1 at: I used a pressure relief valve so that none of the solenoids receive more than 9 PSI which is close to their limit. When all of the solenoids are closed the air goes out through the relief valve. I used a drip valve from a drip irrigation system but a ball valve could be used and restricted to 9 PSI when the valves are closed. I also used a motor controller to run the air pump at 75 percent of its maximum.

As for valves, I have found some surplus ones that will handle 20 PSI but they are no longer available. New valves are very expensive, so check online surplus places.

If you adjust your system to limit the max pressure, you may find that 9 PSI is plenty powerful for most small to medium sized robots.
Oh great - thanks a lot! I'll get some of those valves, and additionally, if needed, decrease the power to the motor.
thanks a lot for the tips.

BTW (i attached a photo of what each 3d printed air "pillow" is composed of. I printed them on the Objet 3d printer which can print "tango plus" , a flexible rubber material. But it is expensive. Anyhow, I've made them by hand thus far and will post my work to instructables once i get something working. )
would this work :
mikey77 (author)  gabriellalevine1 year ago
It might work, but a better, easier to adjust valve would be 0-30PSI.

Less expensive is the valves I used. I got them from a hardware store. These are drip valves for water that reduce the flow using micro channels. Raintree drip irrigation fittings (couplers, Tees, elbows, drip valves, stop valves) for 3/16" tubing available from
I was just also wondering if you or anyone knows where to purchase suitable valves. Or what specifically to search for? Air valves that flip when powered with over nine psi but handle over 20?
Congratulations on winning Michael.
novelchip1 year ago
Impressive work. I also am dreaming of making a soft-micro robot , possibly smaller. But for the moment I am only working on micro-pneumatic controller circuits (such as the ones made by M.Burns and other research groups . ). With such controllers you do only need a single electro-valve to control as many pneumatic lines as you want. The idea is that the single valve generates a serial train of pneumatic impulses that are then translated by a shift-register into parallel pneumatic "signals" . So with one electrovalve + one micropneumatic chip you can control as many pneumatic lines as you want. In this way all the pneumatic (which is micro-pneumatics) should fit into a volume of few cm. You don't need high-tech equipment to make such circuits. A simple CNC mill will do a good job as you can see on my first instructable. Would be cool to collaborate once I (and you) have reached further in my work .

mikey77 (author)  novelchip1 year ago

Cool idea.

I, too am working on making smaller valves and have been experimenting with servo controlled valves. The large size of valves and pumps is the only thing keeping us from making really small robots.

You have hit on one of the main problems with soft robots, each muscle requires at least one valve and valves tend to be heavy and high volume.

It does however, seem to me that any time you convert from serial to parallel, the shift register would require a valve for each output channel and the number of total valves would not be reduced.

If you could post a clear schematic that shows how less than eight valves could control eight channels it would be greatly appreciated.
Below you can find a schematic that I am trying to reproduce. Its from research work of Minsoung Rhee (mark Burns group at University Michigan)

There are 8 pneumatic output channels in the pneumatic integrated circuit.
What needs to be verified is wether there is sufficent air-flow through the output channels to actuate air-muscles. I think yes, especially if small air-muscles are used - which after all is my  aim - and also yours as I understand. I am still experimenting with building and testing such circuits. Once I have good results i will make a new instructable about it.
mikey77 (author)  novelchip1 year ago
Very cool.

Valves that are powered and controlled by air pressure could be very useful for air powered robots.

I have lately been experimenting with casting small robot muscles and valves using 3d printed molds.

If you are interested, you could PM me and we could toss around a few ideas.

We might be able to come up with some really small air powered robots.
I've been out of touch for a while but I was very impressed with your earlier experiments with air muscles. It's great to see this development.

For a light weight and simple "valve" you might want to look at musical history. Particularly the development of the ORGAN. Leather and wood would be much lighter and simpler, not to mention CHEAPER, than the precision machined metal components, and I bet you could develop the idea to use the same Oogoo material.
mikey77 (author)  Dream Dragon1 year ago
Thank you,
for the research idea.

Organ valves are very interesting and fairly simple.

You have recognized the point of the exercise: to discover simple and easy to make components that work well.

I have been experimenting with several designs of various types of electric and passive valves that are made with Oogoo.

I hope to publish an instructable on the best ones, after they have been tested in the real world.

mikey77, you are just too awesome.
CrLz2 years ago
Fantastic project! Thanks for sharing the construction, design and idea!
flic2flac2 years ago
Hello, I understand this is becoming cliché but I must say it ... AMAZING :-O

I have a PhD in biomechanics and I study the mechanics of human soft tissues. Although robotics isn't at all my field I've seen in conferences and scientific papers the concept of pneumatic muscles but never as organic, elegant ... and let's be honest ... blue as yours.

I truly believe the biomimetic approach is the way to go. I agree with you regarding the potential for human/machine (or orga/mecha) interaction of combining small electric motors and artificial pneumatic (or hydraulic) muscles.

As I see it, a scaling down of this approach i.e., build artificial muscle fibers (to be controlled in fiber bundles to form muscle groups), would allow the possibility (if the nightmarish automation and control challenges can be surpassed) of truly biomimetic robotics opening the door for applications such as prosthetics (ex. artificial sphincters - the existing are effective but very crude). Once again, UAU
godfish2 years ago
I am shocked at what you've made here this is wonderful, I only wish I could do something as cool.
sciencetor22 years ago
well, this is quite an amazing use of air muscles in robotics, but if you have the resources to build all this, don't you already own everything in the prize pack? Im trying to come up with a hack so i can win the stuff and get the supplies i need to finish my fully open sourced musical tesla coil.
mikey77 (author)  sciencetor22 years ago
This soft robot cost about $230 in materials and several years of research and development.

I don't enter contests because I need to win or think I will win.

I enter them because it makes the information I am providing available to a wider world wide audience. For me, my instructables are an attempt to share information that is somewhat hard to perceive or discover--the hidden trends. The best part of Instructables, is that you can post information on it and it will be available world-wide in an hour. Impressive.

I hope you win and get more than you are looking for.
Lord Fawful2 years ago
How much can this little guy lift?
mikey77 (author)  Lord Fawful2 years ago
In the position used to lift the egg, it can lift 1 pound 2 ounces. This is with the compressor running at 2/3 speed.
spaceman8742 years ago
would i be able to make a doc ock costume from spiderman. for halloween
Graytail2 years ago
Is anyone else reminded of Robot B-9 from the original Lost in Space series?
I love how, well, non-robotic the motion of this piece is. Its giving me ideas for a project of my own
sitearm2 years ago
@mikey77; Hi! Another very cool example of compressed air robotics and I've tweeted it. Cheers! Site
Sketch982 years ago
Would using higher pressure air make the arm stronger and faster or would it damage it?
mikey77 (author)  Sketch982 years ago
Higher pressure would make it stronger and faster, but it would require scaling up the whole system. The valves, compressor, and air muscles would have to be replaced with more heavy duty units. Bigger and heavier.

Ultimately, I am interested in creating autonomous, battery powered soft robots that are a minimal size. So, I am experimenting with varieties of low pressure air muscles, sensors, and compressors that could make that possible.
ERELCE2 years ago
Well done, very good
Long time ago I've also made some experiments with servo-robots, like this for example;
But we just have to wait for the artificial muscle, then the real robots will be born.
In combination with the new technologies they wil be incredible better than us.
Even better than the robots in the film ' I Robot '. It's just a matter of time.

I really enjoy the stuff you make. Could I please ask your area of expertise. I've noticed you use air muscles, but have you ever considered being fully electric?
mikey77 (author)  Ironsloth19932 years ago
My area of expertise changes with necessity.

The cool thing about building robots is that you get to learn about and experiment with many interesting subjects including: electronics, light and optics, pneumatics, mechanical systems, sensors, programming, microcontrollers, 3d printing, astronomy, sound, speech, psychology, design, drawing, painting, and sculpture.

I have built over 24 fully electric robots and their limitations have become apparent. Electric motors and the gears they require, are too bulky, heavy, and expensive to provide all the muscle power needed. I think some combination of electric motors and air muscles could eventually make it possible to create inexpensive, practical robots for everyday use.

Here are a couple of fully electric robots I have made:
Sketch982 years ago
How long did this take to make?
mikey77 (author)  Sketch982 years ago
It was built off and on over a period of about five months.

About 21 full days of work.
Edgar2 years ago
It's cool, and it works!
Misac-kun2 years ago
I remenber that on Deus Ex there was an augment that boosts your strengh with artificial muscles. i aways think it was something like this :)
A M A Z I N G ! ! ! ! ! !
rimar20002 years ago
WOW! Congratulations!
great work!!i just can't stop thinking about the possibilities of its uses!!though the one that comes to mind most is a giant bane-like-robot :D
Mic1002 years ago
Nice instructable :)
This is incredible! Great wok.
randofo2 years ago
Wow. I have been experimenting a little bit with similar things recently, and this leaps and bounds beyond even some of the stuff I have been coming across at research universities. The motion and amount of control is quite impressive. Look forward to seeing further advancements.
after following the whole Oogoo , i saw the independent air muscle and i got inspirited by the helping hand from Festo, then mikey made one and its awesome. Can't wait till further development .