Tuesday, July 31, 2007

Moisture Sensors Operational

The first six soil moisture sensors for the Technology garden are now operational. In order to get them operational we needed to create some electronics to convert the soil resistance between two metal probes, to a signal that can be read by the data acquisition device (DAQ). Marcel developed the circuit and soldered it together. (Thanks to the ACE Lab for the use of their oscilloscope!) There are some hobby shops that sell kits to do similar things, but they all came with extraneous features and we saved a lot of money by building our own. Bryant developed all the software to read the output from the DAQ. Pictured are six circuits on one breadboard, sitting on top of the USB DAQ that we purchased from LabJack.

After we receive our 2nd DAQ, we'll have the rest of our sensors working. Currently we're waiting on a bunch of materials in order to have everything ready for our pilot study which is tentatively scheduled to start on August 20.

Tuesday, July 17, 2007

Tech Garden Springs to Life

The Technology Garden has come a long way in a short time. When we moved into Bren Hall in the Spring, every time I went by Office 5054, now the site of the Garden, I had an irrepressible urge to see what was then an empty office, filled with plants. That’s how the project got started.

The Garden office is well situated – at the end of a line of sight in a main corridor on the fifth floor of our beautiful new building, the Donald Bren Hall of Information and Computer Sciences. The office has a pretty window and good light. I pass by 5054 on the way to my own office probably a dozen times a day as I walk around the fifth floor. Thank you David Redmiles, our Department Chair, for seeing the potential to use this office as a community space.

Through one of those gifts from the gods, the talented and creative Charlotte Lee agreed to collaborate on the project. Charlotte has contributed more than I can possibly say, but her blog posts indicate the nature of her resourcefulness, thoughtfulness, and organizational prowess. She is working closely with one of our best undergraduate students, Bryant Hornick, on the software to support the project. I will always have a fond memory of going plant shopping with Charlotte ;)

Silvia Lindtner provided important inspiration as we were designing the project, as did Don Patterson, Bill Tomlinson, Shadi Shariat, Beverly Andrews, Miryha Gould, Eric Kabisch, Jim Doyle, and Marcel Blonk. We hope to fold in further contributions from all as the project proceeds. One of the things I like about the Garden is that its development has been effortlessly interdisciplinary – we have expertise in social science, computer science, the arts, media, facilities, and environmental psychology -- not to mention plants!

Our Dean, Debra Richardson, has provided crucial support and we appreciate the way she views the building as a living space to be worked with and shaped through human activity and creativity.

Solar Water Fountains and Datafountain

With help from Silvia, I have beens shopping around for solar water fountains for the Technology Garden. We found that most commercial water fountains are pretty ugly and are overpriced. The situation only gets worse if one wants solar power. I decided to try experimenting with building my own as it is possible to get a solar powered pump on ebay for as low as $30. I'm still waiting for my pump and solar panel to arrive, but I have certainly been thinking about water fountains.

Lately, I have been thinking about how much the Technology Garden would benefit from an ambient display. I also thought of how cool it would be to use the ambient sound of water flowing to convey the sensor data that we are now working so hard to capture. Perhaps the sound and visual of greater or lesser amounts of water flowing could provide information about soil moisture. After all, if people are chilling out in the TG, which doubles as a lounge, they probably won't want to stay fixated on the display on our monitor. We've got our hands more than full at the moment just trying to get bare bones system working, but this is an idea that is worth exploring.

Of course after doing a search, it turns out that someone has already done something similar. The Datafountain is connected to money currency rates on the internet. Refreshed every five seconds, the fountain displays the Yen, Euro and Dollar (¥€$). This mobile fountain measures 5x4x3 meters. The Datafountain is supposed to show how the interdependence of currency rates is interconnected, but I imagine that you'd have to watch the fountain a pretty long time in order to get the message. I'm not troubled that someone has already done something similar as the goals of the Technology Garden are focused on how we can create awareness of plants and nature and the technology is just one element of our research. We're interested in the what the technology facilitates more so than the technology itself.

Thursday, July 12, 2007

Measuring Soil Moisture

One of the linchpins of our early prototype will be soil moisture sensing. We're still figure out how exactly we're going to do this although we are making progress. A big problem with almost all of the soil moisture sensors available is that they are industrial grade. They're big, waterproof, require all sorts of elaborate accessories, and are very expensive. I found a company that creates kits for educational settings, but it comes with one expensive soil moisture sensor and proprietary software that won't work for our application. A couple weeks ago we were just about to purchase some pricey sensors only to discover at the last minute that it required an additional expensive piece of equipment that would not provide a real time data feed without he addition of yet another piece of equipment. So we had to start from the drawing board again.

The only significant body of hobbyists dabbling with moisture sensors seem to be weather geeks who are specifically interested in "leaf wetness sensors" to measure dew. It does seem, however, that much of the hardware and software appropriate for that is also appropriate for soil moisture sensors.

Marcel has volunteered to make the sensors himself based partially on a schematic that Bryant found. It turns out to be pretty easy to make a soil moisture sensor with a bit of electrical engineering know-how and a few dollars. We already have a data acquisition and control device from LabJack. Of course the hard part is getting everything to work together! Now we just have to decided if we're going to go with the homemade set up or with the Watermark sensor. Probably the decision will be made tomorrow. We also have to decide whether to use the moisture meter from
Hobby Boards. We weren't sure if the Hobby Board moisture meter set would work for us, but I found this paper Intelligent Plant Monitoring System online today by Ya-Shian Li. Ya-Shin may have used the moisture meter in conjunction with a home made sensor. Might be some useful clues here how to set up our system and how to write the API at least. As the soil moisture sensing is a means to an end for us, I'm hoping that we will get this part of the system up and running ASAP.

MIT plant sensors

A while ago I ran into this reference to a plant sensor project at MIT tangible bits group. I went back to get more information and I can't seem to turn up anything but this very limited project page (and neither could my friend Mr. Google). Anyone else find anything about this endeavor?

Monday, July 9, 2007

Teracycle's Worm Poop: Composting for Lazy People

While watching an hour or two of Live Earth and saw a presentation by Teracycle on their organic plant food that is made by feeding premium organic waste to millions of worms. The worm poo is liquified into plant food and bottled directly in used soda bottles.

At first I was a little skeptical, I mean everyone knows about feeding your household's organic waste to worms to produce rich, nutritious, free compost, right? But then I realized that even though I have friends who do this and even though I know how easy it is, I don't do it myself. Nor am I really motivated to start. (If you are, here's a website that will help you learn more about composting with worms.)

More food for thought (if not for worms), I have Miracle Gro in my cabinet which is a synthetic fertilizer with problems of its own sustainability-wise. Since we're gardening indoors in containers we don't need to worry about polluting groundwater necessarily, but urea is one of Miracle Gro's main ingredients and according to Wikipedia urea is produced commercially from synthetic ammonia and carbon dioxide and that the production process sometimes involves petroleum-based products. Maybe I'll get some for the Technology Garden. So hey, maybe compost for lazy people isn't such a bad idea after all.