Experimenting with an air muscle and sensor feedback

Check out this setup that [Ruenahcmohr] is using in his air muscle experiments. The orange mesh contains an air bladder that is connected to a hose on the right side. The bladder can be filled, or emptied with two solenoid valves not seen here (but you can get a good look in the video after the break). The muscle attached to chain on the other end and is kept under constant tension by a spring. The chain bends 180 degrees around a gear which is connected to a potentiometer. This gives feedback to the ATmega32 which controlling the whole thing. This way, the slider seen above can be used to control the apparatus.

We don’t know if [Ruenahcmohr] has a use in mind for this setup, but it certainly looks promising! We’ve seen these air muscles used for haptic feedback before, but right now we’re drawing a blank when it comes to ideas. What would you use it for?

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Haptic feedback joystick uses air muscles

[Ben Krasnow] is working on a force-feedback joystick. It centers around the concept of an air muscle which transfers pressure into linear motion. He cites another air muscle project as part of the inspiration in his build, but where he’s gone with it is one of the better uses for these blow-up components that we’ve seen.

Basically you have a bladder, in this case rubber tubing. A mesh surrounds it to reinforce the material and cause inflation to shorten the length of the package. In the image above there are four black air muscles that connect the base of a joystick with the outer frame that houses it. How and when each muscle is pressurized determines the type of motion the user will feel on the joystick. This is where his pressure controller comes into play. It uses a voltage-to-pressure transducer to feed a manifold, the combination of which not only makes each muscle addressable but allows him to dial in the force sent to the muscles. Check out the video after the break for his start-to-finish walk through.

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Scratch built air muscles


We first talked about air muscles in 2005 while lusting after Shadow Robotic’s dexterous hand. The pneumatic devices are known for being lightweight and compliant. They’re designed to be used in robot arms and legs. [jelengar] stumbled across this guide to building your own air muscles. We’re not exactly sure what the original source is since it reads like a machine translation. The core is a piece of silicone tubing used in aquariums. It’s sealed at one end with a bolt. Braided electrical sheathing is slid over the tube and secured using multiple wraps of 24gauge wire. They say to test it using 20psi, but there’s no mention of what the limits are.