Let's Make Robots!

The Beginnings of My 1st Robot - Bigtrak Jr hack

This is my first attemp to step into a world that has interested me for years.

NOTE: If anybody see's something I've done wrong or could do better please let me know. I'm here to Learn :-)

I have a very limited knowledge of electronics, an OK understanding of programming, Not much spare time, Alot of enthusiasm and google as a teacher. Hence I landed here at LMR, Such a wealth of knowledge is contained in these pages that actually got me started!

So... Finally having some spare cash, I did my best at buying parts I though I could use.

An Arduino, A low voltage motor controller, a couple of servo's, 2 IR sensors, a couple of DC motors and a pile of components. Everything turned up apart from the motors!

First test... Getting a servo to move (after blink of course), Arduino Supplied the code so to easy!

Second... Adding a Sharp IR rangefinder, Learnt a bit about electronics here and the wonders a capacitor could do in generating "more accurate" readings. Add that to some code averaging loops and i made a range finder that detected the closest object in a 180 scan, "looked" at the object and made the led blink.

Then reading the Start Here bot and some bits on Automation I conveted a cardboard box into an object avoidance, path finding platform. I used LED's to simulate what would hopefully be motor directions :-)

object avoidance, path finding platform

It continual scan's straight ahead (Green LED on meaning moving forward), when an object gets to close it scans left and right, determines which has the longest distance and turns that way (Red or Yellow LED would light up for a couple of seconds) then away it went again.

2 weeks later & still no motor's, I was out doing the christmas shopping and found this....

Bigtrak Jr

For £10 I thought I could dismantle it and might even find some interesting parts since it was programmable in the first place. 5 minutes later I had it in pieces, found that it looks to have encoders built in(not sure how they work yet so left them there), removed the PCB and started to solder a bit of extra length onto the wires. I learnt that....

I suck at soldering, but I'm sure I'll get better! Finally getting to hook up the low voltage motor controller..Hooking up the Motor Controller

The code got a bit patchy here until I did a bit of a refresher on Hex to Dec conversion, and then the MOTOR's SPUN!!! and then they didn't! then they did, then they didn't. 4 hours of google & LMR research later and trying a few different options I came to the conclusion that my lovely soldering and wire extensions were creating a bit to much resistance, adding a fourth AA to the motors power source solved my problem (I don't know if this is the best way, but it worked).

Well, Got it all together, wrote & refined (to my knowledge) the code.

And Now I have my first working Bot.

One thing that did confuse me... What's the "Completed" tick box for? ;-) I'm sure this little bot is going to just keep evolving.


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I always like the use of old parts to build something new. It's a kind of recycling, reuse.

You use LEDs to indicate the motor movement but use only three LEDs. But the image shows that you have two motors. All together you would need six LEDs to have a precise simulation.

There is one LED for each of these directions: Right Stop, Right FWD, Right BWD, Left Stop, Left FWD and Left BWD.


Wow, it just shows what can be done with a £10 "toy".

I have just finished the process of dismantling a dvd drive (a large old one) and I am hoping to use many of the parts for my first bot.

I am going to use the cd bay chasis as the actual bot chasis, with alot of "hot glue" :)

I will keep everyone posted when I get started.

By the way, does anyone know what can not be glued with the good old hot glue gun? Can one glue metal parts together?



Metal can be hot glued together, but it won't hold if the glued surfaces are smooth and shiny.
You can drill some holes for the glue to seep into, but at that point you might as well just bolt the parts together anyway =)