turn these down to, it should make its movements much less aggressive when you do pitch and roll inputs.
Q_A_ANG_RLL_P = 2
Q_A_ANG_PIT_P = 2
Hi Geofrancis,
The tuning you have done has improved things a lot!
Changes in throttle inducing pitch changes have been reduced about a factor of 5 while maintaining the setpoint drift at ~1 deg pp. You basically achieved this by using more I than P in Pitch PID loop, which makes the Loop act more as a low pass filter, slowing the system down, and reacting more slowly to changes.
But your tuning is basically masking the problem.
What do you think is cause of this throttle affect on pitch. I have never seen this in VTOLs. Perhaps we should consider going after the cause of the problem?
I think the following Link explains the problem:
"In the real world, no two ESC’s, motors or propellers are identical, thus they will provide different levels of thrust even when spinning in the same air. When you do a punch out and immediately lower your throttle, one motor might increase and decrease RPM faster than the others, this will cause an unwanted dip movement.
You can increase I gain to “fix” these tiny details in the flight performance. To avoid bringing in undesired “stiffness” to our quads with high I gain, a new feature was introduced in Betaflight called “Anti Gravity“. In a nutshell it allows you to have lower I gain when cruising, and only increase your I gain when doing punchouts."
The following Link discusses IPD tuning, which is what you have done:
Thank you for pointing out this alternative way of tuning!
William
Here is a log for A Pitch bench test with previous pids: P=0.3, I=1.5, D=0.005. Throttle const and using Elev stick to control balance (Log16):
https://drive.google.com/file/d/1l6O5nCHLMg4fMjHP9TMQBptvkzlyHKdA/view?usp=sharing
Here is Log for P=0.4 (Log 17):
https://drive.google.com/file/d/15JJI7FE3pUwkifFPCbLoGn6AyVtJfgT0/view?usp=sharing
Here is a log for P=0.35 (Log 18):
https://drive.google.com/file/d/19AI2hjXzq7oj-ykhNqXI09lV12MibmT8/view?usp=sharing
To me, the orrigional pid values ie Log 16 (P=0.3) yields the smallest setpoint drift.
William
try
Q_A_ANG_RLL_P = 2
Q_A_ANG_PIT_P = 2
with the 0.3 rate P,
It should react much slower to larger stick inputs making it more controllable.
Here is the Log for:
using P rate =0.3
Q_A_Ang_RLL_P=2 (4.5 before)
Q_A_Ang_PIT_P=2 (3.0 before)
https://drive.google.com/file/d/1KDdy74QA7StGhhq21Y-plvGPGUwKQU7A/view?usp=sharing
I think your at the point where there is not much more I can do until it’s actually flying, it should hover now without much effort Ang_RLL_P is only used once you start giving it big movements.
Shouldnt we check the Roll using the Roll bench test just to make sure. It will just take about 15min to setup?
sure but it should be ok
I will try it just to be sure and post the results. By the way, the vehicle is now repaired and gluing. I should be able to test vehicle in low hover tomorrow.
Your original tune had almost zero I gain, that’s why you were getting such wild pitch movements when you gave it throttle and why it couldn’t level itself. we might have to turn it up to to 2 or 2.5 on the pitch once its flying. it the D gain might need to go down further too.
Here is the log for the 1st Roll bench test. Throttle constant
P=0.4, I=1.0, D=0.01, Q_A_Ang_RLL_P=2
https://drive.google.com/file/d/1_n-6cDR2GAEnpc1D1PVB_fVMayZd4OLP/view?usp=sharing
that looks ok for a test hover.
Ok. Vehicle glueing now. Will try test hover tomorrow and report results.
Thank, William
try the Roll I at 1.5 if you find the roll unstable.
Hi, I tested the vehicle in hover today several times. It behaved well and their were no crashes. The vehicle was held in ground effect lifting at most 1 foot. Because of its close proximity to the ground, it touched the ground sometimes. The acceleration in the logs will give you an idea when it touched. The vehicle hovered the highest in the last 2 flights. Here are the logs for today:
https://drive.google.com/file/d/1AMo4AcV-on91pp4wnZB4zQApb4EamyrR/view?usp=sharing
https://drive.google.com/file/d/1stDvT8Q1UzIm-oO38INANn3CJm0V4xZM/view?usp=sharing
https://drive.google.com/file/d/1b5SFRaxgx397EfKvPNwWbk2WeWQ9QhZJ/view?usp=sharing
https://drive.google.com/file/d/1YvHSTdKG1MtgDMRS9Niq6TeM_Oc671pO/view?usp=sharing
https://drive.google.com/file/d/1oH86VDrZwvO7Xk_LPc8G6zTG64DYPSLu/view?usp=sharing
https://drive.google.com/file/d/1wDOBqWBb_a2oIlBYurCCmn29CsV0TDTm/view?usp=sharing
https://drive.google.com/file/d/1JSJhSMuOGnBbbMUNTT_aA7E6KfV5DSnr/view?usp=sharing
I should mention I accidentally had about 30% Right Elevon trim during all flight (residual from bench tests and forgot to reset). All other trims neutral and level was set in MP before tests. This is probably why the vehicle kept turning right a little.
Videos of first 6 flights:
https://drive.google.com/file/d/1_V2MW29ErSz7N0MKA1qklTM-qcdghiZF/view?usp=drivesdk
Video of last flight:
https://drive.google.com/file/d/1_Z04ZxUMaSzOqKGioAnw6EqWJaam19DY/view?usp=drivesdk
much more I gain, increase the roll I to 1.5 and pitch I to 2.0
Ok. But closer inspection of vehicle shows damage to back wheels that needs to be repaired before another test can be done.