For about 2 years, I have dabbled with pneumatic animatronics and I have recently concluded that I probably could have had a better and easier start into my journey if someone had have handed me a handbook explaining the ins and outs of working with such an old form of Robotic Animation. I would have thought, since the artform of Audio Animatronics has been around for a few decades, that there would at least be something even remotely useful on the internet, informing readers about compressed air and how they could make the most of their time and research.
Clearly, I had assumed wrong. There were various tutorials out there, but they weren’t helpful for me because they were just explaining very basic props for Halloween sets and simple animated characters, none of which had given me any decent insight into what I would need to build my first character. Looking at all of the other characters that had been made by complex companies such as Disney and Creative Engineering Incorporated, I really started to crave my own form of robotic entertainment; and I wanted to fulfil that urge with my own animatronic character, like the ones in restaurants and entertainment centers all those years ago.
Let’s say you are starting to take a heavy interest in animatronics and don’t know where to start. All the technologies involved in this field are now using electrical motors and or hydraulic systems. There are servo motors out there that give an easier and simple range of movement, making a lot of mechanical structures obsolete due to the fact that all the movement is happening right at the base of the joint. It also makes using a heavy air compressor redundant, since all that is needed for servo motors to work is power, usually from a DC power source.
HOWEVER, gathering materials and servo motors that can lift and easily move a wide range of joints is expensive. You need to get the right servo in regard to torque and then come up with a control system that can move your heavy-duty servo motors to music or any audio track.
Now I am sure that with some basic coding knowledge, you could create a program that does what you need, but there doesn’t seem to be any simple commercially available animatronic control systems with easy software to use for sale. I am assuming if you are reading this for a head start into animatronics, then you probably don’t know much about animatronic programming either. I will get into that topic further along in the handbook.
So, in short, you could use electrical options, but there are many pros to using such an analogue form of animation. It's fairly in-expensive and can be applied in many situations. Apart from the compressor, the sound is also rather limited and can’t be heard under relatively loud audio files playing. Compared to the awful screeching of hobby servos, pneumatic setups really outweigh the competition in the noise department.
It also outweighs the servos in the variety of weight it can lift, depending on how much pressure you are pumping through the lines. There are also a ton of images using complex pneumatic systems on the web that can be used as really good reference.
As a starting point at least, I would recommend using pneumatics for any animated character or attraction you are planning on building.
We breathe the stuff. The human race has been harnessing its power in the form of compressed air since 1762. The first compressor could produce up to 14.5 pounds of pressure per square inch. The first commercial use of air powered animated characters was by Walt Disney in 1963 in the Enchanted Tiki Room. Pneumatic Cylinders are plungers that usually only have two movements, in and out. There is no precise control over how and where the cylinder stops. so, flow control is used to slow down the actuation without having to turn down the pressure on your compressor.
Unlike hydraulics, which use pumps and fluid for accuracy, the only things needed to run a functional pneumatic setup is a pneumatic cylinder, some fittings, a solenoid valve, some air tube (usually polyurethane), and a functional compressor. Pneumatics are usually preferred over hydraulic setups for animatronics if accuracy is not a huge issue, due to the fact it is far more difficult to maintain and if the fluid inside the lines leak, then there is a chance electronics and cosmetics could be affected.
Now due to the fact that basic pneumatic cylinders only have two movements as I mentioned before, it is significantly hard to find a mounting point best for whatever joint you are attempting to create if you don’t know exactly what you are doing. The aim is to mount the cylinder in a place where it still moves the joint correctly and doesn’t bind with itself and bend the rod out of shape. This could damage the cylinder and its seal, leaving the possibility for air leakages and incorrect actuation further down the track after many uses and casual wear and tear.
Another thing to keep in mind is how well you fix the pneumatic to whatever mount you decide to use. Using bolts are a good option but has a high chance of undoing or breaking during excessive movement, especially during the testing phase if you don’t have the PSI down pat.
I personally have found that screwing the pneumatic to a flexible strip of aluminum which is then fixed to the part of the joint being moved, works perfectly as it leaves the cylinder to function freely with a small varied range of adjustable flex so that the cylinder doesn’t bend and bind during actuation and I don’t need to worry so much about getting the angle of the mounting bracket perfect.
Picking the right materials to use in your upcoming project is one of the biggest steps. Wood is handy because it's easy to cut and easy to screw, bolt and fix things to. The only problem is, it isn’t very sturdy, especially if the cylinders are actuating fast and jolting any part of the character. I usually use welded steel for the spine or the “ T “ which consists of the spine and shoulders of any given character.
It’s a great joint to begin with if you don’t have any idea on where to start. Making it out of steel makes the base structure really sturdy, but also makes it heavier and requires welding for a proper fixed structure.
I do understand though that many wouldn’t have the workshops and tools to make this work, so bolting together some sturdy aluminum would be a functional alternative.
This is one of the hardest parts of making your animatronic character work. Now, most solenoid valves have a button on them for manual actuation, but for any form of programmed movement to audio needs to be electrically wired up to a control system. My early test consisted of two Gilderfluke BR Mini-Brick 8’s, wired together to make a 16-output system. That was all well and good until I realized that the solenoids I was using required more power to trip, so I purchased a relay board and hooked it up to the control brick to supply more power to the solenoids.
Now the way solenoids work consists of electro magnets. The gate that opens and closes, letting air in or out, can be controlled via an electro magnet that is energized using a small relay.
Warning! Do not take the easy way out and buy cheap solenoids of the internet. Although they work just fine, the relays don’t last very long if you are not pumping exactly the right amount of current through them, and there is a ton of leaks around the valve itself due to its poor manufacturing. HOWEVER, I have found that cheap pneumatic cylinders from the internet function just fine, so really it comes down to your budget, common sense and decision-making skills.
Cosmetics are not completely necessary for small projects, in fact it would be better to leave cosmetics off to display what is really going on underneath and how the robot works. But for bigger projects, cosmetics give a rather finished look to the character when operating. It’s what makes a character a ‘character.’
Many other examples of characters made in the past use latex masks that are then painted and fitted onto the character to give the mouth a seamless joint. Done right, these masks can look incredible, but latex and the process of making these masks are extremely hard without the correct tools and setup. The mask needs to be sculpted from clay first and then casted in plaster of some sort to make a negative mold, which then can be used to make the mask or a plug which is then re-cast to make a more accurate and strong fiberglass mold.
Sometimes on professional characters, there are body shells and head shells made to shape the body under the costume. This could easily be replicated cheaply, using PVC piping cut, heated up and shaped.
The secret to programming a half decent looking show is making the movements look as realistic as possible. In reality, programming an animatronic character is like operating a ventriloquist puppet. When the talking or singing is programmed, aim to make the mouth move as little as possible while still maintaining that main syllables. Too much mouth movement looks really jittery and uncontrolled.
It would be wise to make a diagnostics program for your character as well, so your previous program always flows with the characters movements. Flow control is difficult to get right and if one cylinder changes its actuation speed, it could through off all your previous programming. Make the diagnostics show run through all the characters movements to a tone or your voice explaining to yourself the pressure and flow set so your little forgetful human brain won’t get frustrated in the future when you are trying to reset flow control after some form of transportation.
Here are a few things to remember before embarking on your quest to create your own personal animated character;
Don’t let someone tell you your designs suck. Even if they do ‘suck,’ the designs are yours and seemingly satisfy your own needs. To non-creators, your design has the potential to be the most interesting thing on the planet. The knowledge you learn during this time might seem accustomed to you, but in fact, it’s a hefty amount of knowledge not many other people will have and be able to share.
And finally, don’t give up. As fun as it is to make your first animatronic character, you will most definitely run into many issues and complications through out your build process that might dull your confidence, remember it is your first attempt. If you are truly interested, you will continue down you path, improving your designs and finalizing them for the world to enjoy.