Update #2 10th June, 2011
Added another video showing the robot doing tight pirouettes on a small kitechen scale.
Update 10th June, 2011
Added new pictures, which represents how the robot is looking today. Also added links on the bottom to all key components I've used. I switched out the small breadboard for a cleaner look and soldered the components directly. I also added a PIR motion sensor (what to do with it?) and a ultrasonic distance measurement module.
This is the first robot I submit to LMR. I wanted to get into robotics so I started looking for a platform. I came across the LMR Mr. Basic on dealextreme.com, so I bought it. I now kind of regret that, as I think the chassis is overly complex, and a better solution would just be some laser cut sheets with two geared motors instead of the whole 4wd setup.
But anyways, the robot is not yet finished, I'm not sure if I will keep the bluetooth controls or the chassis. This is just for showing off what I've got working so far. The motor controller is based on the St Micro L298, which is perfect because of its 2A specifications, and my motors stall at ~1.8A. The bluetooth module was bought on goodluckbuy.com (~$10), one of my favorite sites for bulk electronic components and other cheap modules. Both the motor controller and the bluetooth module are described in detail on the external links. Of course, you can choose where you'd want to post questions.
It doesn't have any sensors or other inputs yet. I have outputs for the current sense resistors on the L298 breakout board (which is etched mirrored, that's why the copper is on the top side, big pain to solder), but the current uC AtTiny2313 doesn't have ADC inputs. I have PIR motion sensors, temp, sensors, ultrasonic modules, GPS module, compass modules laying right next to me, but no idea how to implement them in any "fun" way yet :( I'm happy for some input on this. Well, I guess there's not much more to say here. I'm gonna change the 3xAA battery pack for a 7.4V lithium i think. Theres a big voltage drop on the L298 so it will effectively be closer to a maximum of 6 volts to the motors. Just hope the nylon gears on Mr Basic handles it!
Key components and modules used on this robot (with links to exactly where I bought them):
LMR Mr. Basic 4WD robot chassis
PIR Motion Sensor
Bluetooth SPP Module
Ultrasonic Range Finder
L298 Motor Driver Chip