Friday, 15 September 2017
Our Braitenberg bots are coming along! After a change of course from what I wrote a few days ago — turns out the particular op amp I was using put out too little current to drive the motors — the new circuits are now tracking the light properly.
It’s subtle but can you see how that last bot turns away from the light? The student who built that one had an interesting time figuring out why his robot ran from the light. He loved learning that cross-wiring the left photo resistor with the right motor would give him the light-seeking behavior he wanted.
Today, we spent much of the period building robot chassis out of cardboard boxes because that’s what we have in abundance.
A Braitenberg vehicle built to the same specs as we use in the video requires the following parts:
- hook up wire
- 2 NPN transistors
- 2 diodes
- 2 photo resistors
- 2 geared motors with wheels (we’re using these from Solarbotics)
- a 9 volt battery with a battery connector
We’ll build for a few more days next week at which time the students will submit a project writeup. I’ve asked them to submit video of their robot performing all its functions, schematics, and a reflection.
I’m so glad that all the student Braitenbergs are working as expected and all that’s left is to finish the chassis. The students have learned breadboarding, how photo resistors work, and how basic circuit wiring. I think that’s great progress in a week of classes. We weren’t ready to learn transistors and diodes, in my opinion. I think between those components and the missteps on starting with op amps, this project was unnecessarily complex. So, in retrospect, I might not start the year with Braitenberg, though it’s definitely a keeper.