All you really need to know for the moment is that the universe is a lot more complicated than you might think, even if you start from a position of thinking it’s pretty damn complicated in the first place.

It turns out that the same applies for robotics. What started as a (in hindsight, ambitious) simple idea six months ago has led me (often blindly) through the winding alleys and backwaters of mathematics, kinematics, electronics and programming.

The Idea

Build a differential steering robot with with sufficient sensor capability to generate a map of a room (or, ideally, a single floor house) that can then instruct a smaller “blind” (or less capable) robot how to move about that space (ie. avoiding obstacles). Eventually the more complex robot could become an “advance party” sent into an unknown situation to survey it and then provide detailed navigation information to a swarm of simpler, cheaper actors.

The Execution

I wanted to start playing around either with a Beaglebone Black or a Raspberry Pi and after some research decided the BBB was going to be more flexible (although it turns out that flexibility doesn’t necessarily make things simpler, often it made things more complicated) and I liked the idea of having such a powerful platform to use as a motherboard (with future visions of OpenCV etc). With a 1GHz ARM A8, 512MB RAM, 2GB flash and as many peripherals and buses as you could possibly cram on a board, it’s pretty sweet.

I also wanted to home cook as much of it as possible, so rather than using existing BBB capes or fully fledged robot kits I went with buying lots of individual components to do it myself (some of these however are pretty black box already though, for example the DRV8833, which is amazingly compact for the power it can put out, and the Maxbotix MaxSonar-EZ1, which does a heap of signal cleanup gratis).

My initial BOM looked something like this:

  1. 1x BeagleBone Black ($51.90)
  2. 1x Pololu TI DRV8833 carrier ($7.70)
  3. 2x 100:1 micro metal gearmotor ($33.90)
  4. 1x Pololu ball caster with 1/2″ ball ($4.95)
  5. 1x Battery holder ($2.20)
  6. 1x Maxbotix HRLV-MaxSonar-EZ1 ultrasonic sensor ($38.50)
  7. 1x Pololu 32x7mm wheels with silicone tyres ($6.05)

For a total of AUD$145.20 – it turns out I’m not going to be giving hundreds of these away for Christmas any time soon. Everything except the BBB came from Robot Gear who were super fast on the delivery and really helpful.

I realised that I was going to need more kit in the future, especially in the wheel encoder department, but my initial aim was just to get something up and running that could drive around and not bump into things. Seems simple enough, right?

“Oh… You’re using a Beaglebone!”

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