Let's Make Robots!

Some items arrived for the balancing robot :)

Yay, i've just returned home from holidays, and i found that the package with most of the pieces of the robot has arrived :) There is the Arduino Diecimila board. I just quicktested it in linux and it works greatly :) it has an embedded led that is always connected to a specific pin, so that you can test the board without any other component!

The IMU board arrived too. I was surprised at how small the stuff is. Very small! i just have to find a new soldering iron (the current one is rusty and old) and i'll try to connect to the arduino and do my first readings.

Problems with i2c (and an LCD display)

So, i just wasted an evening trying to make an LCD with i2c work with my picaxe.

I connected the SCL and SDA of the board to the other end on the LCD. (of course not crossing them :P)  BTW on the picaxe the pins are: Digital input 3 = SCL; Digital input 4 = SDA, am i right ?

If so, other question is: do i need the two pullup resistors ? i've read somewhere that they're already there on the board. But if so, the pin should be high most of the time, shouldn't it ? testing with my voltmeter reads 0V. 

PS i have the picaxe 28x1. 

DIY laser cutter

Reading about all those lucky people that have access to a laser cutter, i was wondering: can we make one? I mean, build a custom (cheap) laser cutter?

I think it should be something like a plotter, so with a couple of fine-grained steppers and a frame structure (maybe some old scanner) that should be ok.

The problem is the cutting :P where can one find a good laser? i thought about CD-Writer but they have about 100 mW.. I don't know, maybe it's enought for a small dark acrylic sheet.. But i think the optical stuff won't fit :)

Some empiric signal processing

I wanted to do something for my balancing robot even if i don't have the parts yet, so i decided that i could do some study on how to smooth the signal. I read aroung that many peoples who had a balancing robot working used some kind of filter becouse small noise on the readings of the sensor can compromise the stability of the robot. Some people used standard filters, some other used hand made custom hacks. Unluckly i haven't studied signal processing at school so the best i could do was reading about on Wikipedia and do some empiric tests.

Encoders, what are they ?

So what is the difference between a motor with an encoder and one without?

i think it kinds of read how much the motor is rotating, but can't i see that from how much current i'm giving? what are the uses for these encoders?

The infamous Kalman Filter :)

So maybe any of you heard about it, but is there anyone who have made a working implementation?

Or eventually a nice site with a human readable explanation :) ?

Useful robots

Hello :)

I have this question: has any of you ever built a useful robot, that is, a robot with some real task that helps you, instead of just making it for fun ?

The other day a friend of mine was complaining about the time it costs him to cut the grass, and told me jokingly he could use a nice autonomous robotic lawn mower. I thougth that it could be a task within our building abilities.

What other useful robot could be realistically done?

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What about changing that default Drupal favicon to something custom ? :)
So i finally managed to have the Picaxe USB Cable working under linux. Not the programming editor of course, just the serial connection. You can use it to … Read more