Eightlines Creations » Controlling Rain

Passing the kid test

Brent — Mon, 11 Aug 2008 01:24:23 +0000

I’ve had the Solenoid project working for about a week and a half now, but the rain and lack of sunlight was getting in the way of making a video of everything in action. It worked out well because it gave me the chance to demonstrate the project to a number of visitors today, all at once. And, as the photo above demonstrates, the project passes the kid test.

The project is still in need of refinement, but I’m thinking that’s where things would get expensive. I’ve sourced out some new solenoids that could be used in a multimedia environment, I’m just unsure of the cost. The solenoids I have used are $7 washing machine parts. Specialty valves are bound to be more expensive. Some of the valves leak, and I’m pretty sure it’s not occurring in the sections I’ve sealed, the valves may be defective, or they may have a scratch in the plastic I created when I was reconfiguring the orientation of the connectors.

The brace you can see in the photo on the left was constructed to correctly position the hoses in sequence. the centre photo demonstrates the digital radio, Arduino, and transistor controller. The green wires leading out of frame are wired to the Solenoids. On the right, the solenoids are hooked up to the hoses. (All the photos have notes visible in Flickr)

Solenoid Project from Eightlines on Vimeo.

In the above video, I’ve got the device filled with water, and directed through flexible hoses. Valves 2, 4, 6, 7, and 1 turn on. They then cycle off, leaving valve 1 open. The camera then pans up to the controller where it zooms in on the LEDs which I’m using as indicators of which valves are turned on. We then go through a test of all the valves on and off to demonstrate the flow when everything is open. A couple of the valves don’t work, and I’ve traced that back to a point on the controller circuit that I think has not been soldered correctly.

I think it would be important to note the projects out there that are doing the same thing. The Jeep waterfall was unveiled at a Detroit autoshow in 2000. This waterfall was published on the Make blog just the other day. MIT’s building made of water is scheduled to open at the 2008 Expo, they’ve hired Lumiartecnia to produce the valves. Also check out this water keyboard for its innovative use of sensing electric resistance when you touch the water to control the solenoids — in this case controlling air flow in a liquid. All these examples show that the envelope can be pushed that much further, and that there’s a large degree of possible variatons.

Still lots more ideas to play with, but many of these will be with the code. I’ve got some really interesting image processing ideas coming up.

XBee Solenoid Controller

Brent — Sun, 13 Jul 2008 19:27:39 +0000

This Solenoid controller has been filled with a ton of small successes. Today I’m chalking up one more success to the list. I’ve got the XBee portion of the controller working. I had been working on this for a long time now, and the more I work on it the more I see the potential in this platform.

XBee Solenoid Controller from Eightlines on Vimeo.

The issues I had getting the XBee to work appear to be common based on the message board threads I have seen:

Upgrade your firmware. The listing on the website is not necessarily in order. I had assumed that since I had 1.0.8.4 I was one version off the most current. After reading the tech docs there were not that many features I appeared to be missing. The 1.0.A.n firmware appears to be a far more advanced stream, use it whenever possible. X-CTU appears to order this list in a more straightforward manner.
If you don’t have a USB-TTL adapter you can run an Arduino headless (remove the ATMega168 chip) to communicate directly to the XBee. Remove the chip with an IC extractor so you don’t bend the pins. Even better, you can leave the IC in place and communicate directly with the XBee via the Software Serial library. I ended up doing all three methods.
M. Yarza has an excellent sheild for the Diecimila. I’ve since switched over to the Arduino Nano, but I’m still using this one as a remote connection.
Build out Tom Igoe’s XBee Terminal to communicate with the XBee. It correctly sends the “+++” Command mode initialization without a carriage return (“\r”). It also displays results on a new line making for reading the settings much easier. I had started by using the OS X Shell but this was much easier. In fact, buy the book Making Things Talk. It explains all this stuff in plain english.
The RSSI Graphing was useful. You can see how this could be used to trangulate position of three+ Xbee’s.
Check out the XBee API Library for Processing written by Dan Shiffman and Rob Faludi. This makes the connections to the XBee API mode simple.
The XBee Analog Duplex script was somewhat confusing, but explains the methods used to communicate from peer to peer. Note, in all of the tutorials, I’d love to see more documentation stating which is the base XBee and which are the remotes. It gets confusing when you can’t figure out which is which.
Mark the radios themselves with indicators. I’ve added permanent marker dots to designate which XBee I’m looking at. Write down the corresponding configuration settings somewhere you can see them. It will save you polling the chip every time you need it.

A Simple redesign

Brent — Thu, 03 Jul 2008 02:21:42 +0000

If you can’t explain it simply, you don’t understand it.

— Albert Einstein

The big issue I was having with the Solenoids was too much pressure. So while on a trip to Sudbury my Stepfather and I redesigned it. Well, I just told him what I was thinking of doing, and he came up with a much simpler way of doing it.

It’s a good thing too, because I’ve easily broke the budget on this project! So this design uses a cap from a sewage pipe, and some garden hose adaptors. No soldering required. The pressure in the system is regulated by the height of the pipe and how much water is pumped in. When the solenoids are open and the water is draining a plunger falls, triggering an aquarium pump to refill the container. It stops when the plunger rises past a certain point.

Yes, this thing is now an electronically controlled toilet.

Off to buy some more parts, wire up the XBee controller, and waterproof the remote breadboard.

Listo Destructo

Brent — Wed, 25 Jun 2008 02:35:37 +0000

So the guys at the electronics stores are loving me lately. I’m pretty good at destroying things. While electronics is a reasonably affordable hobby, I’ve managed to turn it into something a little more extreme. So without further adieu, here’s my “listo destructo”:

ATMega168 IC — I was using a headless Arduino as a Serial connection. Removing the ATMega IC each time I had to reprogram the XBee chip. Missing one vital component, an IC extractor. The extractor is cheap, at least cheaper than a replacement IC. If you bend the pins once removing the IC by hand, don’t do it again… and again… and again. In the end I bought a new ATMega168, IC extractor, and USB-TTL module so I wouldn’t have to extract it again. (But at this moment the Arduino is sitting on my desk headless)
HM55B Digital Compass — Red wire, Black wire. Its not that difficult is it? I thought it would save time to just use my existing precut Green wire to wire up the Digital Compass. Wasn’t getting the response I wanted. Turns out I had the positive and negative reversed. Whiff of the burning silicone smell. Definitely not getting the results I want anymore.
Battery Holder & Two AA’s — Smelled that awful burning smell again last night. Ripped out the power going to the XBee’s, Arduino, USB-TTL. Now I see wisps of smoke coming through the air but nothing’s plugged in. Start throwing papers off my desk to find the culprit. Where there’s smoke there’s two AA’s shorting out. Unplug the AA’s with my IC extractor and promise myself to wire up a two pin plug and clean the desk. (It’s still messy)
Countless plumbing prototypes — I’ve resoldered the Solenoid structure about ten times now. Still don’t have a final result I’m pleased with. Still have another design up my sleeve but I haven’t spawned the courage to start building it.
DVD Player — This one’s a good one, I’ve identified hundreds of components scavenged from a DVD Player that didn’t work anymore. IR Emitter and receiver, momentary switches, capacitors, RGB Jacks, connectors, motors, and a frickin’ laser beam. To think this DVD player cost $30. Easily aved me that cost of buying all these little parts at Radio Shack.
Inkjet printer — Again, tons of little components. Varistors, servos, gears, USB jack, power supply, zener diodes, etc. I’m thinking someone should make a website documenting all the components we can dig out of discarded things. Made a mental note to get rid of the plastic casing before my basement fills up with junk.
Nintendo Powerglove — I think I just heard hearts shatter. This one was destroyed about two years ago, but it counts in this list because I’m using the parts for one of my project. Recovered Ultrasound emittors and receivers, flex sensors, etc.

One of the guys at work said I probably shouldn’t put a price list on this. I have to agree, it would hurt too much. Oh and this is by no means a complete list, I intend to update as I keep making stupid mistakes.

Iterative Steps

Brent — Fri, 09 May 2008 13:46:44 +0000

If anyone had have told me this project would cost slightly in the range of $300 I would have probably not have started it at all. Individually the components don’t cost that much, Arduino — $60, transistors — $10 for nine of them, copper connectors — $2, and so on. It all starts to add up, and when you factor in the failed attempts things really start to add up.

That’s the beauty of it. It isn’t fast, but the iterative steps of this project let you take a breath and work out the issues one item at a time. If I were to work this whole thing through from scratch and without the knowledge I’ve gleaned through the process the magnitude of the project would have seemed overwhelming.

Getting the leaks out from Eightlines on Vimeo.

Individually the process is quite simple. Right now I’m battling some leaks, and the tiny issue that the pressure in the system may be a bit too strong. In one of the early tests I blew a stream of water clear across the room. These issues taken in stride don’t seem to be that daunting. To think only a couple of days ago I was wondering if I should continue.

On the less wet side of the equation I’ve been working with the XBee module for the Arduino. It communicates wirelessly using the Zigbee protocol (802.15). After some initial failures I think I understand how to get this thing to work. I’ve still yet to bring this thing full circle, but its getting there. I’m thinking I’m going to wait for LadyAda’s Boardino USB to reach my local store Creatron before I pick up some more pieces, but the benefit of waiting is I could use this system to build a clustering/mesh network of Arduinos. This is something I’m looking forward to. One of the other advantages of moving to the XBee is that I can keep the computer at a remote location ~100’ (longer with line of sight). With all the leaks I’m having this sounds very appealing.

One other change in scope has to do with the web cam. I’m thinking of ditching it all together for the initial phase of the project. Don’t worry, I’ll definitely return to it later — I already have the code working! One of the early tests I built used LEDs to enact a Persistence of Vision system. This principle should be the same using the water drops as pixels as they fall through the air. Currently I’m developing a 9x15 matrix of shapes and typographic characters that should drop out as an audience member interacts with the system.

Now is this where I thought I’d be when I first drew the idea up? No where close. But the slow pace and iterative process has its advantages. It spawns a whole new set of ideas along the way.

Controlling the Rain by Arduino

Brent — Mon, 28 Apr 2008 01:56:30 +0000

This past January I was biking home in the rain when this thought hit me. I was stopped at a red light looking at the pools of water on the ground wondering if it would be possible to calculate the density of rainfall. I thought, even when they’re giving weather reports they never really tell you if it will be a hard rain, soft rain, or a mist. They just say “rain is in the forecast.”

Looking at the pools of water it seemed apparent that you could shine a spotlight on a puddle and perform some motion detection code on the ripples to locate the centre of a drop. You would only need a short sample in order to determine the average drops per minute or hour.

This is all fine a cool, but what would you do with the data? The traffic light turned green.

If you could calculate density of the water, you could no doubt calculate the distance between drops. It would be fascinating to generate an algorithm which predicts a path based on the least amount of rain drops. Does one exist? Could you find a pattern where I’m fairly certain none exists? All of these thoughts are purely hypothetical, and probably wouldn’t work in real life, but given a 20/20 hindsight it would be something to brag about, coming home after biking in a rainstorm, completely dry.

Another red light.

What if you could build a machine that rains, but when you walked underneath you never got wet? This was where the Rain Aversion project began.

First, I’d need the rain. If I produced a mechanism which controlled the flow of water out of some pipes, I could cause the device to pour rain in a controlled manner. Ideally I’d like to collect the fallen water and pump it back into a reservoir so as to not waste liquid. But that would require a much more involved development cycle, so part of that was pushed out of the prototype phase. To begin I’d just attach a hose and feed it off the water supply.

Second I’d need a controller. Something to activate and deactivate each pipe as a sensor detects an object underneath. Having recently received an Arduino it was the controller of choice.

So I had several pieces of technology at my disposal. An Arduino, a webcam, some solenoids, and some Flash and Processing skills. Ignoring the dead ends the prototype phases lead me through, the project is set up as such:

Arduino is loaded with the Firmata Protocol enabling it to communicate through a serial connection to the host computer.
Protolab’s Arduino2Flash Java serial proxy stood in for serproxy when it wouldn’t communicate properly.
AS3Glue handles the Serial Events as they are broadcasted to and from the Arduino.
Joa Ebert’s ImageProcessing library manages the Web Cam manipulations such as the pixel averaging and threshold detection.
The Arduino sends signals to a high voltage circuit through a series of transistors, the schematic can be found on the Arduino Tutorials page.
Water Solenoids (I used 9 to produce a 3x3 matrix)
Each of the solenoids is connected to a 19V power supply. (This underperforms on the amperage side of things when all solenoids are firing at the same time, but seems to do the trick)
The solenoids are also connected to a hose feeding the water, with a series of copper splitters to divide the flow.

I needed a sensor to detect where someone stood so I could disable the stream of water. There’s several alternatives here, but I’ve chosen to go the webcam route. Flash was chosen over Processing due to my inexperience with the latter. I have no doubt that I could entice Processing to work faster than Flash in future renditions of the code.

The copper piping and feeds are simple plumbing supplies. Flexible hosing was used so I could reconfigure the setup if needed. This was the most costly side of the project aside from the solenoids.

The final result is a ~$200 apparatus which leaks, but in just the right places. And it won’t leak on you. I’m still assembling some final videos of the device in action, but in the meantime I have some demonstrations of an earlier protoype in action:

Solenoid Controller #3 from Eightlines on Vimeo.

Additional videos are available here. Photos of the process are available here.

In the next couple posts I’ll detail the final assembly of the project, and also discuss some of the future possibilities of the device. The whole setup has massive potential.