DIY EMG Uses An Audio Recorder

June 17, 2012 by Mike Szczys 15 Comments

[Ericdsc] is looking to capture the electrical impulses of his muscles by using an EMG. He went through several prototypes to find the right recipe for sensors to pick up the electrical signal through his skin. Above you can see the version that worked best. Each sensor is made starting with a piece of duct tape and laying out a patch of stripped wire on it. A 5cmx1xm piece of aluminum foil then covers this, and second smaller piece of foil covers the cable’s shielding (not pictured here). This will stick to your skin to hold the sensor in place after applying a dab of sugar syrup to help make a good electrical connection.

In this case, an audio recorder is taking the measurements. [Ericdsc] had been having trouble sleeping and wanted to find out if he’s restless in bed. The audio recorder can log hours of data from the sensors which he can later analyze on the computer. Of course, it wouldn’t be hard to build your own amplifier circuit and process the signals in real-time. Maybe you want to convert that mind-controlled Pong game over to use abdominal control. You’ll have a six-pack in no time.

Electro-active Polymers

July 1, 2011 by Mike Szczys 22 Comments

What’s that you say? You’ve got rigid materials that change their shape when exposed to electric current? Sign us up for some! Although the fabrication process looks a bit daunting, we love the results of working with electro-active polymers. These are sheets of plastic that can flex by contracting in one direction when the juice is turned on. It has an effect very similar to muscle wire but distributed over a larger area.

From what we saw in the video after the break it looks like this is not the most resilient of materials. Several of the test shots have broken panes, but we’re sure that will improve with time. It looks like there is some info out there about fabricating your own EAP but the processes seem no easier than what’s going on at the research level. We might stick to building our own air muscles until EAP is easier to source for projects.

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Inventing Robot Athletes

December 14, 2010 by Mike Szczys 19 Comments

The human body is an amazing instrument from an engineering standpoint. Replicating just one part of it proves extremely difficult but these athletic legs show a lot of promise. This is the work of a Japanese researcher named [Ryuma Niiyama]. He’s been working on the design for years, and is now using pneumatic actuators to mimic the muscles in a human leg. The lower portion of the leg uses a spring mechanism that resembles some running prosthetics currently in use. These serve as a spring to store energy and reuse it by bouncing against the ground. He’s trying to teach his robot to use these legs; taking it through a learning process necessary to use the thigh actuators for locomotion and balance. We were surprised at how life-like the motion in the video after the break is. Even when falling down the movements are very life-like. We thought the movements of Little Dog were real enough to be creepy, and this robot may be close enough to our own mannerisms to fall into the uncanny valley.

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Ecce Robot

August 12, 2009 by Caleb Kraft 28 Comments

[youtube=http://www.youtube.com/watch?v=cI9H4FoA0b4]

According to the video, Ecce Robot is a new paradigm in robotics. We don’t know if that’s true or not, but we really enjoy the drive system. They have mimicked the biological structures in humans using elastic cables and cheap drill motors as muscles. It is intriguing to watch the complexity that even a simple arm lift requires. This does show inefficient this type of set up is, but we still think it is cool. We don’t understand the desire to use cheap drill motors though. Cost aside, the control problem they mention seems like it could be resolved with a little better motor setup. Then again, we’re sure they thought of that. This seems like a perfect time to bring up a common question. Is it worth the inefficiency of trying to mimic our natural biological structures with hobby robotics pieces? What technology would have to be present to make it worth the complexity?

[via Engadget]

Scratch Built Air Muscles

December 21, 2008 by Eliot 9 Comments

airmuscle2

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.

New From SparkFun

August 3, 2008 by Eliot 3 Comments

SparkFun is rolling out interesting things to play with every week. They’ve added a NanoMuscle actuator that uses a shape memory alloy to lift nearly 70 times its own weight. Their LilyPad collection has expanded to include small momentary switches and a thermistor type temperature sensor. Lastly, they’ve got an FM receiver module. It just needs an antenna and uses I2C or SPI for control.