The replacement wishbone arrived so the cars in good shape, but still no luck with the heading controller. I can get it to slowly oscillate along a straight line by using a low Kp and restricting the steering, but the step response is poor.
The heading controller is basically working. The big changes were reducing the maximum steering angle to reducing how much trouble the controller can get itself into, and putting the gain on the dial so I could tune it while driving.
The car controller is dropping out now and again for no obvious reason. I thought it was due to the cold changing the internal RC oscillator frequency and making the serial communications unreliable, but I’ve switched to a 12 MHz crystal and it’s no better.
Lesson for the day: always put the big ICs in sockets. I fitted a crystal to the AVR on the interface board yesterday and managed to brick the chip by setting the fuse values to use an oscillator that didn’t exist.
The heading controller didn’t work out as well. I had one bug when converting from 0..360 degrees to -Pi..Pi radians, but most of the problems were due to reliability and a lack of speed.
The speed controller is working well. It’s a simple PI controller but was easy to tune and handles the moderate slope of the road OK. The speed wasn’t very stable at 10 km/s as the motor and gearing doesn’t like going that low, but it was much better at 17.
I’ve hooked in the demands from the rover to the control board and added a simple PID based speed controller. The three position switch on the remote takes the car from manual control to auto with speed=0 to auto with speed=10 km/h.
I found a good container to house the electronics on my never-complete autopilot project. Here’s some pictures of it mounted onto the car:
The car is a Conrad Rhino III buggy.
The supervisor for my autopilot is working. This is a fairly critical piece that runs on the AVR I/O board and handles the handover between the manual remote, the autopilot, and any safeties.
I’d like to learn Go, so I’m considering using for the command side of my never complete self driving RC truck project. Here’s some quick notes after a night of hacking: