Have been battling with the robot again. The last theory was that running the stepper motor as well as four other motors was part of the problem so I removed the stepper and added 3 sonar sensors in fixed positions.
After more testing I found that the FTDI breakout I was using to connect the Pi to a homebrew ATMega328 board was freezing when the 4 main motors got above a certain speed. Couldn’t find any way to fix it so have changed my own board for an Arduino UNO. Works just fine now.
I’ve cobbled together a bit of python code to try and avoid obstacles. It could be better but I need to learn python properly first. Going to do that next then I can add a compass, an accelerometer and (at some point) a RaspberryPi Foundation camera. That should set me up nicely for an attempt at SLAM which is the ultimate aim.
Here’s a crap video – it was suggested that I hold my phone horizontally to get a better aspect ratio. Google just displays the video on its side though. Hmmm….