The bigger and slightly less hacked together brother to my Autonomous Roomba is the Turtlebot. If you haven't heard of the Turtlebot, just let me say that it is probably the coolest creation of hobby and research robotics.
The downside is that the ready to go kits are pretty expensive at around $1000, which puts it out of the range for most hobbiests. If you have been here before, then you know what happened next. Here's the BOM for my homebuilt turtlebot. You end up spending a bit more on the mini-ITX board but this board has the advantage of comming with a built in step-up power regulator. That let's me get away with running it off of an 11.1V LiPo. Most of the boards I found needed 19V to run which means you would need to spend more to get a bigger battery and external power regulator.
|iRobot Create $130|
|Used Kinect sensor ~$50 on eBay|
|12x rechargable AA for the Create ~$30|
|11.1V 5Ah LiPo for the motherboard $22|
You will also need a laptop hard drive. Mine was free from an old laptop. The robot's frame was made out of 1/4 inch birch board that I bought at a hardware store. The standoffs were made from a 1/4 inch aluminum rod cut into sections and drilled on a lathe. In hindsight, I should have looked for standoffs online since building them on the lathe was more work than I expected. The total for all the structural parts was around $20, which puts the total for the homebuilt Turtlebot at $362-excluding any shipping charges. Still much cheaper!
Here's how the assembled layers look
The Create with the wood frame that will support the rest of the levels. The 12V battery sits in the cargo bay.
This layer holds the hard drive and a busbar for power distribution. The Kinect requires 12V and is connected directly to the busbar. Not pictured is a barrel jack that I added later in order to power the board off of a wall supply for running off battery.
Not much to see here. This is just the motherboard sitting on some small nylon standoffs.
Battery Voltage Alarm
I also made a low voltage alarm for the LiPo battery. It runs off of an ATtiny powered from the Create's 5V power. The battery's balance port plugs into the header and the micro monitors the votage on the first cell through a resistor divider. After a bit of calibration, I got the Red and Green LEDs to blink in different patterns based on the battery voltage.