Tuesday, September 21, 2010

My First Robot, v1.0!

I read up on H-bridge ICs and controlling DC motors all last week and finally decided it was time to order the parts for my first robot. It's one of those things where I was nervous the whole time thinking "did I forget something?". Cus if I did, it would mean I would have to make a second order, pay a second shipping fee, and wait a second time for the parts. I didn't want to just buy a kit and build it. I really wanted to build something I feel I could call my own. Not that it's original at all, but it's my first and it works!

The robot uses a twin motor gear box to achieve differential drive, using an H-bridge IC to control the motors from an Arduino. The first version is controlled with the Wii nunchuck, since I've already interfaced with it previously and makes a handy controller. The cool thing is, I can use this robot as a base to continue building more advanced and interesting ones. My next project is an autonomous bot that will either run from darkness or run from light.

Here are some pics of the development process:

Here I'm testing the wiring for the H-bridge IC.

Here's the twin motor gearbox, disassembled.  Instructions in Japanese!

And here's the assembled gearbox.

After some programming, I got it running fairly well.  The biggest problem I see with it is that its alignment is off, veering to the right, and the friction for the wheels ain't so great.  Overall a success however!

As a reference for myself and for anyone else interested in building something similar, here's the parts list I ordered (I ended up not using the diodes since I didn't have room for them on my board and the H-bridge has them internally already anyways):

From SparkFun

Battery Holder - 4xAA Cube $1.95 1 $1.95
H-Bridge Motor Driver 1A $2.35 3 $7.05
Capacitor Ceramic 0.1uF $0.23 10 $2.30
Diode Rectifier - 1A 50V $0.14 20 $2.80
Toy Tires - Off Road $3.95 1 $3.95
Universal Plate Set $6.95 1 $6.95
Electrolytic Decoupling Capacitors - 10uF/25V $0.45 5 $2.25
Dual Motor GearBox $10.95 1 $10.95
Mini Photocell $1.50 4 $6.00
Ball Caster Metal - 3/8" $2.95 1 $2.95

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