Friday, July 18, 2014

Nxt drill photo printer

Drill photo using Android and leJOS

This project consists of two parts. First is an android application which communicates via bluetooth with the Lego NXT cube v1.0. I update a NXT cube with leJOS firmware so I can write code in Java.


Android application contains more than a drilling a picture. First it was a controller for all the small programs like follow line, use accelerometer to move with robot, etc. You can also set the type of the robot with according programs. After pairing via bluetooth with NXT cube you can play with it. On pictures below you can see the screen shots of the application.

I also try to control the movement of Tribot with colors glued to my hand. I used a phone's back camera to recognize colors with the phone placed on a tripod. I had a playable demo but it wasn't as awesome as I imagined before. Anyway, my first idea was for the robot to recognize hand gestures, but it wasn't giving good results because of the transfer speed (I needed to to change directions in less than half second). Maybe I'll finish it later. So, I switched to the printer idea.


Some people say, build a robot, that can't take more than a few minutes. It's not true! It can take many hours/days to build something that works, is stable and you need lots of LEGO pieces (I had to order from three times). In the process of making it, I only encountered one bigger problem. Regardless of a very paintful debugging on small NXT screen which can carry only few lines of text, the problem was memory. NXT cube has a very limited memory so I couldn't send full picture to the cube. I had to send it by parts. As the printing is a very slow process I needed to set the phone on a charger, set screen to wake up and let it send the picture full time part by part (biggest picture took 24 hours!).

My last problem was that I needed a very thin and long drill. After visiting a few modeling shops, I realized that the length of the drill I wanted was not produced. So I had to make a workaround and superglue some sand to the rest of drill to prolong the drill part. And it works! I used a floral foam for printing which is one on the most fine material I found.

But wait there's more! The drill head is replaceable and you can draw a B&W picture (also a very slow process). You can see all the results on the bottom of this page.

What can I say, I finally full filled my child dream to build a robot that can do cool stuff. I'm planning to build more robots in the future.


As I mentioned before the printing process is very slow, so I added e-mail notifications after the printing was finished.