I would like to autotune the yaw for a Bell 47 G Scale mechanic with a rotor diameter of 1.8m and a weight of 8.5kg. I don’t have a telemetry connection, so I can’t see the messages from the FC during the autotune. Only after the flight I can read the messages.
I wanted to get the P_ and D_ values.
After the helicopter stopped oscillating after a few minutes, I switched to Autotune_Stop and then back to Autotune. The whole game started all over again. I flew until my battery was empty. In the last few minutes of battery life, the rpm dropped too much, hence the “yaw imbalance” messages.
After reading out the log, I saw the message from Autotune: “Exceeded frequency range” and “Autotune: Failed”.
Am I making a mistake with the parameters for Autotune? If so, what do I need to change?
Hi Heri,
First I think there is a bug in my code because when you restarted the autotune, it didn’t try and finish determining the max gain. It continued to oscillate at the same frequency until you stopped the autotune. So I will have to look at it.
That shouldn’t stop you from being able to use it to tune our heli. Here are a couple of things that I think will help with the autotune. First, I reviewed the max gain determination and it nearly finished so I was able to manually pull of the max gain data and determine the max gain values for Rate P and D.
here are parameters that I would like you to change based on that. I suggest you make FF zero as this is typically the case for the yaw axis of heli’s
ATC_RAT_YAW_FF 0
ATC_RAT_YAW_P 0.25
ATC_RAT_YAW_D 0.01
Next I want you to raise the Autotune max gain parameter to allow the max gain part of tuning to finish. So make this change to the autotune parameters
AUTOTUNE_GN_MAX 80
Since you can’t monitor progress from a computer, I have some tips on how to track its progress. Here is the autotune sequence of inputs
Max gain determination
starts with a Frequency sweep
3-4 lower frequency dwells (constant frequency oscillations)
3-4 higher frequency dwells (constant frequency oscillations)
at that point max gain determination should be complete
Rate P and D tuning now begins
Starts with a frequency sweep
Next you will see a series of dwells tuning rate p and rate d gains
This could take 10 -20 dwells you’ll just need to wait it out and hopefully it finishes before you have to land due to a low battery
The increased gains that I gave you should help reduce that time.
