Tuning the PID

Tuning the PID parameters can be a frustrating experience.

In all of the plots below I'm trying to make the bot step through a series of four waypoints describing a square: {(0,4), (4,4), (4,0), (0,0)} (in feet).

I believe the integration is dominating. Looks like a drunken sailer who left the bar, went back for a couple more drinks, then got lost and finally passed out.

Honey, I'm home!

Doing better, but still losing its brains temporarily between WP2 and WP3

Daydreaming on the second turn.

I figured out that I need to use a leaky integrator on the error. But why does it keep turning clockwise at WP2? And not WP1 or WP3? Very curious.

Here it minimizes the radius of the turn, but still goes clockwise 270 degrees instead of counter-clockwise 90.

Whoops - gone off the wagon again. I've added too much leakage it seems.

It's late — I have no idea

Looks like automata

Crash and burn

Much better. You can see the ringing due to too much integration.

Getting much better - still some turn bias though.