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Topic: Lilypad, accelerometers, frequency and best conductive material (Read 25910 times) previous topic - next topic

Dec 10, 2011, 09:32 pm Last Edit: Dec 12, 2011, 05:16 am by lgguts Reason: 1
Hello all!

First of all, I'm a brazilian undergraduate Design student, and I'm very new at developing electronic projects (specially with e-textiles). I'm currently working on a malleable hand-held interface for my graduation project, and have been posting its development at this website: http://theinstrumentproject.tumblr.com/

Well, I've come up with the attached simplified schematics (just to communicate my needs and current intentions), and some questions raised from it:

About soft circuits and e-textiles:

- What is best to transport data and power through this interface: conductive fabric, conductive thread or even a really thin wire? - It is important that it could be folded, twisted and very resistant through time.

- Could you indicate any kind of textile more suitable for this application? - It should be just a little stretchy, and very resistant.

- Any ideas of how should I protect the components from damage by rough hand manipulation?

- Any advice about sewing the whole application?

About Arduino and the schematic:

- Will the raw data of the whole schematic (5 accelerometers to lilypad to bluetooth) be fast enough generated? - a frequency of 10 "readings" per second should be enough for what I intend to do with them. *

- How much power will the schematic consume? Are three 20mm coin cell batteries going to do the job? In how much time would they be drown out? *

(*) Here are the links to the main components I intend to buy:
- Lilypad Arduino Mainboard: http://www.sparkfun.com/products/9266
- Lilypad Accelerometer ADXL335: http://www.sparkfun.com/products/9267
- Bluetooth Mate Silver: http://www.sparkfun.com/products/10393

Hope someone here can bring me some light to these problems, but any kind of help, opinion or critic is welcome!

Thanks!

luxxnatura

- What is best to transport data and power through this interface: conductive fabric, conductive thread or even a really thin wire? - It is important that it could be folded, twisted and very resistant through time.

Conductive thread is a good option, though it has a tendency to fray.  I would do some tests playing rough with it.  Here is a 6-ply that might hold up well: http://www.sparkfun.com/products/10119

There are lots of different kinds of conductive fabric, including soft, silky, and stretchy ones.  You could very easily incorporate into your design decorative paths of conductive material that join (via conductive thread) with the accelerometer in the centre.  Check out the range of materials here: http://lessemf.com/fabric.html

- Any ideas of how should I protect the components from damage by rough hand manipulation?

In a soft, malleable piece like this, people are going to want to test its limits and play rough with it.  Your best bet is to make prototypes and have people do exactly that.  Work it hard and see how it holds up.  The conductive fabric wouldnt be an issue, I dont think, you are more likely to see issues with the conductive thread, at the point where it meets the accelerometer (because it's stiff), and the battery (for the same reason).  You would want to protect the circuit from short-circuits, too.

- Will the raw data of the whole schematic (5 accelerometers to lilypad to bluetooth) be fast enough generated? - a frequency of 10 "readings" per second should be enough for what I intend to do with them. *

With acclerometers you'll want to do some averaging in order to have smooth data rolling in.  write the incoming raw data into an array, and pull every 8th, 10, or 50th number (depending how smooth you want it).  That number will be your reading, for you to do whatever you like with it.

Are you set on Bluetooth?  I've seen quite a few projects done with Bluetooth and there tends to be interference and general instability, imo.  I'm a fan of Xbees myself.  They are super reliable, and there is a sewable breakout board for the Lilypad Arduino:
Lilypad Xbee Breakout: http://www.sparkfun.com/products/8937
Xbee Radio: http://www.sparkfun.com/products/8664

As for battery,  I would recommend using a rechargable Lithium-Polymer battery.  They're cheap, relatively small and flat (so great for soft circuits), and reliable. http://www.sparkfun.com/products/9876



New Media, E-textiles, Wearable Technology:  www.erinlewis.ca

Twitter: @luxxnatura

Hello luxxnatura,

Thanks A LOT for your help!

Except about the Bluetooth, I've bought and will start experimenting with everything as soon as possible.
I didn't know of this issue with bluetooth - and since I'm brazilian, and have been waiting for almost a month for my package from SparkFun to arrive, lol, unfortunately asking for a xbee breakout right now wouldn't be possible. But let's see how it holds up...

Thanks!


- What is best to transport data and power through this interface: conductive fabric, conductive thread or even a really thin wire? - It is important that it could be folded, twisted and very resistant through time.

Conductive thread is a good option, though it has a tendency to fray.  I would do some tests playing rough with it.  Here is a 6-ply that might hold up well: http://www.sparkfun.com/products/10119

There are lots of different kinds of conductive fabric, including soft, silky, and stretchy ones.  You could very easily incorporate into your design decorative paths of conductive material that join (via conductive thread) with the accelerometer in the centre.  Check out the range of materials here: http://lessemf.com/fabric.html

- Any ideas of how should I protect the components from damage by rough hand manipulation?

In a soft, malleable piece like this, people are going to want to test its limits and play rough with it.  Your best bet is to make prototypes and have people do exactly that.  Work it hard and see how it holds up.  The conductive fabric wouldnt be an issue, I dont think, you are more likely to see issues with the conductive thread, at the point where it meets the accelerometer (because it's stiff), and the battery (for the same reason).  You would want to protect the circuit from short-circuits, too.

- Will the raw data of the whole schematic (5 accelerometers to lilypad to bluetooth) be fast enough generated? - a frequency of 10 "readings" per second should be enough for what I intend to do with them. *

With acclerometers you'll want to do some averaging in order to have smooth data rolling in.  write the incoming raw data into an array, and pull every 8th, 10, or 50th number (depending how smooth you want it).  That number will be your reading, for you to do whatever you like with it.

Are you set on Bluetooth?  I've seen quite a few projects done with Bluetooth and there tends to be interference and general instability, imo.  I'm a fan of Xbees myself.  They are super reliable, and there is a sewable breakout board for the Lilypad Arduino:
Lilypad Xbee Breakout: http://www.sparkfun.com/products/8937
Xbee Radio: http://www.sparkfun.com/products/8664

As for battery,  I would recommend using a rechargable Lithium-Polymer battery.  They're cheap, relatively small and flat (so great for soft circuits), and reliable. http://www.sparkfun.com/products/9876





luxxnatura

Given that you are so far away from Sparkfun, this makes sense :)
New Media, E-textiles, Wearable Technology:  www.erinlewis.ca

Twitter: @luxxnatura

Yup, a little! :D

Thanks for your help!
And great works, by the way! Congrats!


Given that you are so far away from Sparkfun, this makes sense :)

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