Paul explaines how to measure the power used for the heating of the fabric
I’m having a hard time with my wearable. There are different areas where I’m experiencing problems:
- The thermochromic ink deteriorates very fast. Under influence of UV radiation for which I haven’t been able to find a solution. The amount of electricity it needs to heat up is very much depending on the air temperature. Also the width of the strip of fabric (this has to be equal for the whole length) is crucial for successful colour change. So there’s a lot of testing ahead before this will work well. I have switched from reflective strip to using reflective fabric, I wonder if the performance will improve.
Arduino talking to Nokia
- I’ve been talking to a lot of experts lately but Friday last I got a pretty disturbing e-mail from the RIVM which is a leading Dutch centre of expertise and research, it advises and supports policy-makers and professionals in public health and environmental areas. The gases I’m measuring are a good indication of air quality but the sensors I’m using aren’t sensitive enough. I was happy to find gas sensors in the first place but now they appear to be worthless for my purpose.
- Programming the Bluetooth connection has made some progress. I can now connect with the Arduino board and send and receive bytes. Now I’m at the final stage of sending all of my sensor data in a single string to the Nokia. I also have to find out how to let Python check for incoming serial data continuously. Some sort of event listener.
- I keep having trouble using the internal GPS. It seems to break down after I’ve used it once. Only a restart will make it work again.
- On the bright side I’ve made two dummies for my vest. Saturday I worked together with my tailor on my second dummy, using the actual fabric. This gave me a lot of insight in what I want. Discussing it with AnnaMariaCornelia it became clear that I have to take a radical turn to make my vest look like true work ware. I’m really looking forward to designing my vest and make it look sturdy and cool to wear.
The second dummy which at this stage looks too much like an apron
Button made out of a zipper
This week I’ve worked on the interface of my air quality vest. I must say I couldn’t decide on how to solve the design of the button and the actual display.
The ‘button’ is my way to interact with the sensors. By indicating if it smells good or bad. The system will measure and send the air quality values when I use the button. But what should the button look like? Thinking really hard I decided I wanted to somehow duplicate the movements you make in real life if it smell good or bad. So opening or squeezing the nostrils. In clothes I suppose the equivalent would be opening or closing a zipper. And that’s how my ‘button’ has turned out.
A logical but rather boring first step
An even bigger challenge is the actual display. How am I going to visualize the sensor data? I took a look at my earlier experiments and actually started build some dummy examples. Some were plain boring, others too far fetched. Then it was easy to see the I’m going to go for the ‘stain’ metaphor. The visual is interesting. I want to line up three circles in different colours. While working I decided to add a scale in silver reflective strip. It’s informative and aesthetical as well.
Dummy example of two 'stains'
Picture showing when my camera failed, and at night
Yesterday I inspected my harvest of the first day of measuring. It was a little disturbing. I found out I had way to little pictures from my cam. Somehow I missed a couple of hours worth of material… I filled some holes with copies. But I spent hours doing so. Also calculating where the camera missed out cost a lot of time. It was quite depressing. I can’t go around for a whole week faking the life I already lived! So I decided that where there are holes in the picture series I’ll just show a prepared picture. This decision has given me a lot of peace. I will have to program this of course.
Thankfully yesterday the picture taking went very well. I only have to fill the gaps for the two second delay in the time lapse which is a lot less work. What didn’t go well was the GPS device. I sort of forgot about it and then it was almost dead. It’s still recharging now. It kept on logging though, even though it was almost out of power. Good stuff.