Introduction: Making a Web-programmable, Weight-sensitive Backpack






I've been traveling a lot with my backpack, sometimes putting too much in it, which is bad for my back. Taking a cue from this weight-sensing tote on Instructables, I decided to build one using schemer.

Schemer is a tiny programmable button that helps you easily make interactive art and craft. Instead of using wires or bluetooth, you program it by holding it in front of a computer screen. You only need your web browser. No wires, and no extra hardware or software to install.  

It's an experiment and part of my Ph.D. research on ambient programming and wearable computation. Check out page 2 for a brief discussion of why I think simplifying the construction and programming of wearable electronics is an important goal.

 
With the schemer web interface on my iPhone, I can quickly calibrate it for my needs, or make it do random flashing patterns anytime I want, without breaking out a USB cable or anything.
 
The 3 volt felt battery holder is eye-catching too, no? 
 



Step 1: What This Means for the Future of Etextiles (aka What's the Point?)

There are two major reasons I decided to create this type of wearable electronic button. 
 
The first:
It hit me some time ago that the traditional ways of hooking up electronics are a big roadblock to broader acceptance of etextiles: for educators, for mass manufacturers, for DIYers, for artists, and so on.
 
On a circuit board, you can route all the wires carefully so they don't touch. This is easier to do on a hard, fixed, 2D circuit board where you have the luxury of routing wires under and above the circuit board.
 
However, in the case of sewing to fabric, the thread is typically stitched to both sides of fabric, making this kind of routing more difficult. Clothing is inherently "more" 3D than a printed circuit board: it has folds, creases, and dynamic spatial relationships (i.e. the whole fabric moves so your wiring has to account for this).

These factors add up, therefore sewing with conductive thread becomes  a mess really quickly. We need to rethink how electronics and fabric may better coexist, and I think simplifying and reducing the number of connections is a good way to start.
 
 
The second:
Programmable (wearable) artifacts still require a relatively beefy computer. By beefy, I'm referring to the bulk of all the things you need to reprogram anything in the field. I'm talking about the need for a computer with hardware ports, software, keyboard, etc. and not processor specs). Typically, I can't reprogram it from my PDA or phone.

I imagine a future where if I have a wearable electronic item and I need to change its behavior, I'd want to take out my phone, poke at the screen, and send the instructions to my shirt or pendant.
Currently, the typical way would be to break out the laptop (nettop), sit down, fire up an editor or development environment, type, compile, find a USB cable, download. Hopefully you brought all that, and you've already installed all the software and drivers you need.
 
Wearables give us a tremendous opportunity to rethink this very premise. Why can't we program directly from our phones for instance? This would be awesome especially for quick changes. Could we download a program embedded in a painting. Perhaps, by sliding my pendant in front of a painting, I could read in a program to dynamically change my pendant's colors? If I was a museum curator, could I make my visitors' light-up shirts behave differently depending on the exhibit they are in front of? What would that scenario or system look like? How would that be possible? 
 
I feel that web-programmable wearable buttons (like schemer) are a good - though tiny - step in enabling a more pedestrian approach to etextiles. I used the word pedestrian, not to mean boring or unimaginative, but to mean commonplace and straightforward - think cellphones vs. unix mainframes. 

Step 2: Ingredients, Preparation and Layout


schemer - Aniomagic's web programmable button
lightboards - smart lights that fade in out, also from Aniomagic
custom sensor board - Aniomagic
felt battery holder - Aniomagic
large 3V  battery - any place really
conductive thread - Lessemf, SparkFun, Aniomagic

I wanted to have have four different lights to correspond to the weight of my backpack: green, white, blue, and red. I chose to use three lightboards and a schemer, since schemer also has a light (ID 3).
 
If you have all five IDs of lightboards, the lowest one (ID 1) would always light-up even if the force sensor was not experiencing any load. Sometimes you want this, but for today's project, I wanted the bag to be unlit when it was on the floor, so I used IDs 2-5.

Everything on the schemer bus needs to have a microcontroller, because they all communicate in a custom protocol that delivers power and data on only two wires. 


The other components of this projects are the force sensor itself, and the custom sensor board.
Although you can get boards with light, temperature and touch sensors built in, for this project you need the custom sensor which allows you to connect other things - like this force sensor.
 

Step 3: Arrangement and Sewing Data Lines

The force sensor should be attached at the shoulder where it would experience the most pressure. Then the lights cascade down, with the battery holder at the end of the line.
 
The wiring is really simple. Unlike projects with other type of wearable boards, you only need two lines of conductive thread: data and ground, which go to all the lightboards and sensor.
 
Basically, hook all the dots of schemer, lightboards and sensor together, in one run. This connects all their data pins. 

The last picture illustrates how you just need one piece of thread to connect all components together. That's what cool about the schemer bus: simplicity.
 

Step 4: Minus Connections for Lightboards & Sensor

Normally, I'd start sewing the minus connections now, but to make things easier (in this case), I sew down one of the inputs to the custom sensor. Leave a long piece of thread, since you'll connect it later to the force sensor.

Next, connect all the minus holes. On schemer, when you align it with the + sign up, the bottom 2 holes are all minus. For lightboard, the minus hole is opposite the dot hole, and for sensor, it is the bottom hole when the text is right-side-up.

Step 5: Battery Power

Now sew down schemer's + hole to the right side of the battery holder, then sew down schemer's - hole to the left side of the battery holder. I really like how easy this is. I'm not just saying this, but for wearables, wiring should always be this easy. 

Two reasons I'm working on the schemer system:

The first:
It hit me some time ago that the traditional ways of hooking up electronics are a big roadblock to broader acceptance of etextiles: for educators, for mass manufacturers, for DIYers, for artists, and so on.

On a circuit board, you can route all the wires carefully so they don't touch. This is easier to do on a hard, fixed, 2D circuit board where you have the luxury of routing wires under and above the circuit board.

However, in the case of sewing, the thread is stitched to both sides of fabric, making this kind of routing more difficult; it's in 3D; and the whole fabric moves; so it becomes  a mess really quickly. We need to rethink how to electronics and fabric may better coexist, and I think simplifying and reducing the number of connections is a good way to start.


The second:
Programmable artifacts still require a relatively beefy computer (I'm talking about the need for hardware ports, software, keyboard, etc. and not processor specs). If I have a wearable thing and I need to change its behavior, the typical way would be to sit down, fire up an editor or development environment, type, compile, find a USB cable, download. 

Wearables give us a tremendous opportunity to rethink this very premise. Why can't we program directly from our phones for instance? This would be awesome especially for quick changes. Could we download a program embedded in a painting? If I was a museum curator, could I make my visitors' light-up shirts behave differently depending on the exhibit? What would that mean? How would that be possible? 

I feel that web-programmable wearable buttons are a good - though tiny - step in enabling a more pedestrian approach to etextiles.

Step 6: Testing

Insert the battery, plus side facing you. You should see schemer doing its initial sequencer pattern, unless you've reprogrammed it.
 

 
 

Step 7: Force Sensor

Now it's time to hookup the force sensor. This type has less resistance as more pressure is applied to it.
 
Choose a place where it's likely to experience the most pressure when you carry your bag. The heavier the bag, the more pressure in this spot.

Connect the two pins on the force sensor to the two side holes of the custom sensor board. It doesn't matter which one goes where. 
  
  
Once sewn in, you can attach the sensive bit to the soulder pad. Reprogram using the schemer interface to get your desired response. See the video at the top of the page, or go to the introductory page to learn more.

Comments

author
biolethal made it! (author)2011-04-18

nice idea! reading through the comments, i noticed something about zippers as switches. that could be a really interesting idea... colour changing, rgb led lit jacket that changes colour depending on how far it is zipped up? just an idea.

author
swetambri made it! (author)2010-05-24

hii , its really awsome

i am also doing similar research work, i need to measure pressure exerted by backpack straps on shoulders.

i thought of doing it with piezosensor, but now i find ur idea to be more inspiring.I would love to try it.

Cheers!!!!

swetambri

author
nanosec12 made it! (author)2010-04-04

This evokes some seriously interesting possibilities.  I hope you expound on this with more instructibles, keeping it available as a free enterprise and not some corporate money machine.

Great Work, and good luck with the Doctorate

author
aniomagic made it! (author)aniomagic2010-04-05

Thanks! I hope to continue talking about this issue, and I'm happy *somebody* sees some possibilities. I plan to continue publishing and making the information public, with the hope that I can earn a living from this field.

author
AnaLou made it! (author)AnaLou2010-05-06

I work in the apparel and design field and I love experimenting with your products in my private art studio. I have made custom bags with toggle velcro switches inside that turn on leds (so you can see the contents of your bags).  Not only for those who love artistic clothing and want a little bling, but your products have great potential for the outdoor gear market.

Great instructable. When I train to climb, I always where a back pack and a system like this would be a great training device for climbers.

author
aniomagic made it! (author)2010-04-05

 Yes, in fact, I'm exploring how you can transfer programs from clothes to clothes, and to other media (walls, paintings), without using the computer.

author
drakesword made it! (author)drakesword2010-04-06

You should look at a short range transmitter of sorts. Seeed studio has a 433mhz transmitter and receiver combo for ~$5

author
mycroftxxx made it! (author)mycroftxxx2010-05-05

 The aniomagic schemer system programs microcontrollers via pulses of light. I'm guessing the author wants to further develop the system so that they can use one unit to program others in the field.

author
computer_guy made it! (author)computer_guy2010-04-06

 LOL. i just had the idea of transfering data from clothes to clothes but what type of clothes?... "panties" came to my mind xDDD

author
pedla made it! (author)2010-04-09

The battery holder looks good NO IT DOES NOT unless you are a 12 yr old girl. why bother with all the electronics sewing etc etc when you can buy a fish scale that is size of cigarrete lighter will tell you exact weight and will not die the first time you get caught in the rain I can appreciate the thought and effort of what you have done but Why is beyond me

author
dfc849 made it! (author)dfc8492010-04-09

Your comment was very encouraging NO IT WAS NOT unless you are a fool. Don't take your precious time to post negative feedback if you can't take said time to even READ the introductory paragraph: "It's an experiment and part of my Ph.D. research on ambient programming and wearable computation. Check out page 2 for a brief discussion of why I think simplifying the construction and programming of wearable electronics is an important goal."
Instructables is a community of new and unique ideas. The author was eager to develop with Schemer, and was successful at doing so.

aniomagic, great instructable! If I had the time (and money), I would no doubt already be planning this as my next DIY. Keep up all the good work!

author
pedla made it! (author)pedla2010-04-12

OK Everyone I retract my uninformed opinion and ask forgiveness. I admit that I thought there was a neat new gadget to replace my trusty but somewhat inaccurate fish scales so was dissapointed with instructuble and yes you are right I did not take the time to read and consider the full text.    may I make ammends by suggesting that you place the sensor in the hand stap located between the shoulder straps where it will be not only be in the centre of gravity but will be subject to none of the shock loads produced on shoulder straps as you walk etc..Hope i can one day buy a pack with an accurate digital read out for weight, would save hastles at airport check in etc...Cheers.

author
aniomagic made it! (author)aniomagic2010-04-10

Thanks for your kind words. Like any new approach to doing anything, one of the biggest challenges is explaining and convincing others that it's worthwhile.  


author
aniomagic made it! (author)aniomagic2010-04-10

It's funny you should imply that this would appeal to 12 year old girls, and I hope this reply will explain some of the "Why" .

My favorite short paper on this is Leah Buechley's "LilyPad Arduino: How an Open Source Hardware Kit is Sparking new Engineering and Design Communities." You'll find in it a much more articulate version of what I'm trying to say here. 
 
llk.media.mit.edu/courses/readings/democratized_LilyPad.pdf

http://l3d.cs.colorado.edu/~ctg/Craft_Tech.html
http://hlt.media.mit.edu/?cat=5
 
Part of our work at the Craft Technology Group (and at various research labs throughout the world) has been to widen the range of things we can do with all the new technology available, and to widen the audience this stuff appeals to.

Personally, I agree with the rhetoric that current electronics (at its core) is very utilitarian and has been designed with little regard to aesthetics: black box chips, angular green copper clad boards, plastic battery holders, etc. As we see electronics migrating from the desktop into clothing, this is as good a time as any to seriously think about how electronics would better fit couture. 

This means (at least for me) manufacturers should start considering how to make (e.g.) LEDs in attractive sequin shapes, microcontrollers that look like colorful buttons, switches that look like zippers, battery holders that look like applique (and so on).

Yes, you could accomplish the same thing with a fish scale and be done with it. The point is not the weight sensing. It's saying: "here's another example to show how we can mix electronics and clothing in ways that appeal to the eyes.

To your question "Why bother with the sewing?", I'd reply, "why bother learning a programming language when you can just buy/download any program you'd every possibly want? Why bother learning to solder or woodwork, or play guitar when you can buy the electronics, furniture or song and be done with it?" I hope there's no implication that doing something (painstaking though it may be) is not valuable in its own right.

In spite of technology's internal ugly, we have found ways to mask it with eye candy: gentle curves on a well made car or contours on a cellphone; there is no reason to think this will not apply to wearable electronics. 

The whole point of this tutorial (and many like it) is introducing electronics to a new audience of designers, children, and craftspeople who want to incorporate some smarts into a project without it looking like a robot car."  

For all we know, the 12 year old girl who gets into wearable tech (just) because of this felt battery holder might well become the woman who designs the world's most innovative microprocessor suited for wearable computing.

 
author
Oreko made it! (author)2010-04-05

Gakt, nice.

author
aniomagic made it! (author)aniomagic2010-04-05

 Definitely a favorite of mine. :-)

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