Sending Data over the Network --> First Success

So I figured out that Processing has a network library. Its a step in the right direction. Raises the question weather this can be used for sending data via the Internet. Probably not. Actually, yes it can :-) But hey. One step at a time

Enjoy the clip:

Some Pictures of new Prototype in Action

Connecting Thermoplast to Sensors

(I will comment on these later. Right now I just want to upload these so I can fool around with some new stuff.)

Turbocast: Low Temperature Thermoplast (Streifeneder)

A couple of days later I received a parcel from Streifeneder with some of the 'Turbocast' which they produce.

 

Turbocast was much more difficult to mold. It stuck glued to my tools. It glued to the hair on my hand, which was sort of painful ... (I ended up shaving my hand before continuing experimenting with Turbocast). Somehow this material just felt more stubborn than Apolit.

However, eventually I got used to the material and was able to get some decent results out of it. More on that topic soon.

Apolit: Low Temperature Thermoplast (Minke Props)

A couple of days ago a received a sample of Apolit, a low temperature Thermoplast by Minke Props.

First off, I have to say that I love this stuff. Where it not rather expensive, I would buy a ton of it...

It was quite easy to mold, I did not burn myself, nor did it pull out any hair after having hardened on my hand. If you need material for instant prototyping this is very interesting stuff.

Take a look at how my first encounter with Thermoplast went.

If you toss it into boiling water it turns soft and transparent in under a minute. I assume you could also bake it in the oven, though it would definitely need a much higher temperature. I was a bit worried that this material might melt if left in a car or something. However I think that would require very, very high temperatures (not saying these are impossible) as air is not all that good in transporting heat. I think its really the fact that water 'transports heat' so well which makes this work so effortlessly.

If you don't like the way its molded, just throw it back into the water. It will go back to its original (flat) shape and become moldable again.

Cutting it is no big deal, however if you use thicker material that could be a pain. I figured this out later, but obviously if you cut it while its still soft. A knife or scissors would go through it like butter.

I also tried sanding it, which did not work very will. Sanding it feels like rubbing an eraser on paper. Carving it with a sharp knife works better. Sawing it should work fine.

I added some self adhesive Velcro. This works sort of fine, but if you want something really permanent, you may want to additionally secure it with screws or something. 

By the way. I hope to soon receive a ton of sensors by images. This 'wristband' will then be used for mounting the stretch sensors for measuring arm rotation. More on that in a later post thought.

Getting better aquainted with the Stretch Sensors

As mentioned in a previous post, I now have a stretch sensor by Images in my possession. Though I was first a bit skeptical I am beginning to see more and more ways of using this. I sort of had a hunch that the relationship between stretch and resistance might not be linear (yeah admitted, nothing strange in that, I would be more surprised *where* there a linear relationship.)

I am a visual person and I need to see things to understand them, so I made these graphs:

Stretched to 125 % of original length.

Stretched to 150 %

Stretched to 175 %

Stretched to 112.5 %, 125 %, 137.5 %, 150 %, 162,5 %, and 175%

Stretched with incrementions of 6.25 %

 

Due to the fact that I am lazy the graphs might be a bit confusing to read. The x-axis represents time and the white vertical lines represent seconds (I just double checked my math and the white lines are more like half seconds - maybe I will redo these if I get around to it. However you still get the generally picture). The y-axis measure the change in resistance. The light gray area is the resistance of the sensor. I did not add units, as the interesting part is the relative change and that is all I measured. 

The fact that the signal is non-linear can, with some tinkering, be used as a bonus. The resolution in the first couple percent of stretch is quite high - so if I where to use two stretch sensors simultaneously but in opposite phase (if one is loose, the other one is stretched) I should be able to maximize the resolution available :-)

Feedback Circuit - Signal Flow

Had a productive meeting with the other PEERS / Research Based Learning people. I finally feel like I have an overview of all the different areas I have to tackle for this. I like making graphs to sort my ideas: This roughly represents the feedback loop which I hope to create.