Roomba Progress, 3/7/09
The robot is now fully wireless! It’s amazing that I’ve gotten this far without a major setback like having something expensive burn out (knock on wood).
Since Monday, I have mounted the motherboard to the lid of the Roomba and squeezed the breadboard inside. The breadboard doesn’t entirely fit, so the lid does not close all the way. Sometime soon I would like to solder the microcontroller circuit to a perfboard or a custom PCB so the circuit will fit inside.
Next, I soldered some wires to the battery terminals inside the Roomba to bring power up to the motherboard and its supply. When I purchased the supply on eBay, the seller did not send me a short piece of wire that connects the supply to the motherboard’s power switch pins, so until I implement a better solution I have resorted to starting the motherboard by crossing the power switch pins with a coin.
These two changes mean the robot is now mobile. Here’s some pictures and video clips:
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- It’s not pretty but it get’s the job done for now.
One concern I have right now is that the robot appears to be quite zippy in the first minute of driving and noticeably slower as time goes on. I fear that the computer may eat through the Roomba’s battery alarmingly fast. If this is true, I can either get more batteries for the robot or remove the computer. Since the motivation for having an entire on-board computer was to enable the robot to be a fully autonomous cognitive agent, it would be a shame to scale back the processing power. As a precaution, last night I purchased a lead acid battery with almost twice the capacity of the original Roomba battery. It will way almost four pounds and will be physically bulky, but it will triple the juice.
On the other hand, I can certainly scale back the processing by using any programmable device with a serial port (e.g., Gameboy Advance, PDA, graphing calculator, Cybiko, etc). The drawback is that I would then need to wirelessly link to a base station computer that would run SNePS and execute vision algorithms. I hope it doesn’t come to that, but it is appealing to consider the low-power design of something like a Gameboy… the Gameboy Advance SP lasts for something like 15 hours on its own rechargeable battery.
Whatever the case, it’s a relief to have the bulk of the electrical work done so I can focus on software.
Tags: Roomba
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