The idea for this project came from one of my favorite 'ibles: the polargraph. I loved the drawing style and thought how cool would it be to do this on the side of a building? Unfortunately the challenges to setting up such a large polargraph on a student budget pushed me to find an alternate solution, and thus started the window painting robot! This is a fairly simple robot that uses two neodymium magnets to stay up on glass walls, windows, or any surfaces less than 1" thick (one magnet is attached to the robot and the other is on the opposite side of the surface. It also work on floors, but not nearly as cool). Check it out in action! Link to video is also HERE.

With Accelerometer:

Without Accelerometer:

I am entering this project into the UP contest so if you think it is at all neat/delicious/gets you thinking then please give me a vote and help me, help you with more awesome projects =]

What I think is so enticing about this design is the wide applicability. It allows expression of ideas and creativity in normally unused spaces. The real challenge is what's the biggest glass window can you find? This also has other applications as it could clean windows, or survey the sides of buildings, draw just on floors, etc.

The advantage of this design over a polargraph or other drawing method is that it is really easy to set up and draw on any size of window. Later in the 'ible you will find the processing program I wrote for this, which takes input about your window size and robot specs and lets you to draw what you would like the robot to mark on your window; with a touch of a button it turns it into arduino code that fits in the arduino program I have supplied, so it can be easily uploaded to the robot. Then you just put the robot on the wall and watch it go to work! The autonomous nature of this design makes it free of wires while also not relying on any sort of wireless connection to do its work.

I did this project with scrap VEX metal and motors I had lying around, but don't be discouraged if you don't have those!!! It will work with any 3 wire motors (and others as well but may take minor changes to code) and whatever materials you have available (wood, metal, plastic, etc). DO NOT be discourage, you can do this project! I always challenge myself to build with what I have and this project cost me a total of $20 so really not an investment. 

Step 1: Parts List

Parts List
2x  3-wire Motors (I used vex 393 motors with motor controllers to make them 3-wire but any will do.)

1x  3-wire Servo (used to raise and lower the pen, I'm using a really small one. Size doesn't matter, in this case.)

1x  Arduino Board (I used an uno but any should work!)

2x  Neodymium magnets (I got mine from magnet4less.com and went with N42 counter-bored circular magnets 1" diam by 1/2" thick. These are the real crux of the whole project as they need to be strong enough to hold the robot against the wall. My robot weighs 2.5 pounds and these magnets keep it easily attached to windows up to 1" thick! Remember you can always add spacers if they are a little strong.)

1x  Battery Pack (These are to power the arduino and drive the motors, I used the vex 7.2v pack but use whatever works for you.)

4x  Wheels (You can use two but I found four to be alot more precise. Whatever they are make sure they have a rubber coating or some grippy surface.)

1x  Tiny Breadboard (This is optional as you can just wire things directly to the arduino, but it help plan the paths out.)

1x Single-Axis Accelerometer (Optional but highly recommended) I'm using one that is twenty years old so really anything will do (they can be found online for cheap). Just remember for our application the lower the g rating the better, mine is +-4g so anything around there will do.

Materials for the body (Use what you have!!!! Those who have a 3d printer, try making a chassis that way. I don't have access to something like that but the lighter, the better! I used some scrap metal.)

Gears (I used vex ones, these are needed to drive wheels if you are doing a four wheeled design. People with 3d printers can make their own but for those without access lego gears are a possibility if the mounts are drilled out. Be creative!)

Window Markers!

Random bits of wire/screws to hook everything up.
<p>how is that magnets sticking to the glass ?<br></p>
<p>I see a lot of potential in this. You are a student? Go to businesses on holidays and put designs on the windows, have you thought of etching? Or a lace design would really be nice on any home window. You could make a pretty penny with this.</p>
Can you give me that websit with the accelerometers
Sparkfun.com sells IMU's, I recently purchased the 9150 (I think) and they also have just accelerometers.
Ah. I didn't see this mentioned in the instructable and I couldn't tell with picture if one was on the inside of the window. <br>Oh I have see someone selling a window cleaning robot but it used vacuum to hold on to window and needed to be plugged in for the power so not as portable as your idea. And was noisy from the vacuum.
Thanks, I updated the intro paragraph so hopefully it's clearer.
You must be a great hit on Halloween. Now make the clean window robot.
Haha I'll have to fish out a squigee and see what I can do!
I don't get this either... <br>hrm this should be for how it can climb on glass with magnet ? but doesnt seem to be working down there. Can you explain some of that Mizchief100 because I guess I missed my science class that day.
So basically there's one magnet attached to the robot and one on the opposite side of the window. The wheels of the robot are grippy rubber and the magnet is mounted just off the glass so only the wheels are touching, allowing it to move around on the window. Hope that helps!
Dude magnets were genius. Are the magnets strong enough to hold up a person??
The magnets are strong, the glass isn't.
how it can climb on glass with magnet ?
I was thinking, about using a round metal disk, with three or four small casters to hold it just a milimeter off the window surface, might make the device roll freely over the window. <br>
Go for it! Let me know how it turns out. <br>
Cool and interesting way of sticking a bot to a window! :-) Thank you for sharing this idea with us; I like the VEX gears and tools as well.
Thanks, and yes the VEX adds a lot to it.
greate instructable, giving food for thought, thanks for sharing
Hi, Mizchief100 <br>Well done, I have not thought of using magnet to hold this robot. <br> <br>
You could sell these to big box stores for ad writing as well as your idea of window cleaning. This looks very patent worthy. Good job dude!
Hah hadn't even thought of that but now you have me thinking!
well done! looks robust <br>I would definitely add obstacle detection and get curvy with some sinus functions driving PWM levels!
Great ideas! Curved lines would be something for sure. I will keep this in mind.
Impressive work.
Hey ! What about window cleaning ???
Definitely possible, you just need to attach a squigee or something to clean to the back and draw it a route to clean on the window!
Hey ! What about window cleaning ???
Hey ! What about window cleaning ???
I was expecting something that would paint the edging on the window frame ;-)
Am I right in presuming other magnet on the far side of the window? If so, does if ever get stuck on crud or scratch the window slightly?
Yep, it's on the other side of the window one. And I've never had a problem with scratching/sticking the magnet has a really smooth metal surface, but I've also wrapped it in a soft bed sheet and attached it to the window like that and it worked great as well!
I've been wanting to work on something like this, but for boring practical purposes like cleaning my windows, or a submersible fish tank cleaner robot and this info will be a huge help. <br>I haven't used an accelerometer before, how well is that working for keeping the turning accurate? <br>Great instructable btw!
It's doing quite well, accurate to within 3 degrees normally. Will keep you posted!
Very cool project!! Well done. Neat clean design. Thanks for sharing this with us! It has inspired me.

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Bio: I hope to help people with the things I make.
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