Is there a known good way to set the PID controllers on a hexcopter? I moved from an underpowered quad to an overpowered hex and it's (at least by comparison) very "squirrely". Very sensitive to manual inputs, and when I tried to fly it with the default PIDs it was borderline unstable (+/- 20 degrees in the roll) with no inputs applied. With half of the P gain, it flies, but it's not as stable as I'd wish it would be.
I'm imagining a tutorial or a recipe for setting the PID gains must be somewhere. Where?
Thanks,
Mihai
Replies
Are you sure you're using the stabilized mode and not the 'acro' mode?
Tuning PID values takes time and any changes in total weight could require a new calibration. A classical method is the "Ziegler Nichols" method. You should make I and D zero, so you only deal with a P controller. If you use APM, you can use a dial knob on the tx to modify the P value between two extremes. This way you can just fly and find the most suitable value, instead of disconnecting/reconnecting for every PID change. So to tune this, change P a little with the knob and apply a small step input to the quad. At some point you should see it react more aggressively until it starts oscillating. That's when you can stop.
When you have a suitable P, then tune I and D after that. The I term is the integrator that removes a constant error / bias. The D term responds to how fast the process is approaching the setpoint and decreases the output to reduce overshoot and reach the final setting faster.