My first robot project.
I realized my Raspberry Pi had been collecting dust in a drawer, for some time. I started thinking about suitable projects, and stumbled upon this site. Building a robot seemed like a nice challange, as I usually only do software projects. A chance to expand my knowledge about electrical components, and to make use of my Pi.
I decided early that I wanted to do everything in Python, as that's my langauge of choice. I started doing some research, and it turned out that the Pi is rather limited when it comes to controlling robots. It only has one pin capable of hardware PWM, no analog inputs, etc. There are lots of available addons which makes it easier, but I decided to try to use as few additional components as possible; mainly to keep the cost down.
So, I ended up using a L293D for motor control. Two 50:1 ratio gear motors, powered by 4x2500 mAh AA's. I salvaged a LiPo battery from an old tablet, hoping to use that to power the Pi. Unfortunately, the output of the LiPo seems to be 3.2v, and the only voltage regulator I have is a step-down (the Pi needs 5v). I tried using the 4 AA's powering the motors, and they seem capable of powering the Pi and the usb wifi dongle I use. So, I guess my best option is to get another 4xAA holder, as I happen to have another 4 2500 mAh AA's lying around.
I also need to find a better front wheel (caster?). At the moment I'm using a small pair of lego wheels. This project has been alot of fun, and more challanging than I originally thought. It is very much a work in progress - I intend implement some sort of sensors in the future, making it as autonomous as I can - but as I'm about to move, I most likely won't be able to spend alot of time on it for a while.
Update - I solved the power issue, by getting a 6xAA battery pack for the motors. The 4xAA battery pack that used to power the motors, is now used to power the Pi.