Hi, I was tuning the Rate controllers of my large drone today.
First log: https://review.px4.io/plot_app?log=2d535d24-7193-4373-b26e-062a9818eb08
Second log: http://localhost:5006/plot_app?plots=pid_analysis&log=1c7cb257-05f3-46c2-bbd4-78c4c58bd5c9
Could someone tell me if I can just stick to the PID values in the first log? It looks decent enough and I’m not sure why it still not reaching the value 1, should I increase I-term?
Also, the drone weight is around 9kg and motor-to-motor diagonal around 1.1m.
First tune:
Second tune:
@gfLv_amov Hi, I’d be grateful If you can input your expertise here.
Hello,
is this the stable v1.17.0 ?
how was it?
also how do you fixate your component on the drone?
I am using drone frame with mtow of 9kg and looking for way to lower emi, or any noise as much as possible
The accelerometer indicates that the vibration is quite significant. Has the flight control system been designed with shock absorption features?
@gfLv_amov
Hi, Yes. I’m using Cuav V6X V2 FC. They claim it has a shock absorption.
Also, On the frame everything is tightened. But I’m using 25mm OD and 1mm thickness CF tubes for the arms, could be the thickness contributing for the vibration?
I’m not using any dampeners for the FC.
Yeah, what do you mean by fixate my components? I’m using CF plates as the base plates for the drone, everything else is mounted.
@gfLv_amov Hi,
Today, I mounted the FC on Damper balls and this got things worse, the log below is for one of that. We tried even going back to default PID values, but things didn’t solve.
Removed the damper balls and mounted the FC back on double-tape foam. The logs below are from after we slightly change the PID values,
https://review.px4.io/plot_app?log=bb08c645-62ad-4309-8c1c-202d2e14358e
https://review.px4.io/plot_app?log=12e65716-2959-4398-b61f-e49aa934761f
So again today I made sure the frame is stiff and nothing is loosened. Before starting tuning I also limited MC_ROLLRATE_MAX, MC_PITCHRATE_MAX, MC_YAWRATE_MAX, MPC_MAN_TILT_MAX, MPC_TILTMAX_AIR.
I understand I need to increase the K for yaw rate, but isn’t the PID curve for Roll Rate and Pitch Rate enough as of now?
Any advice much appreciated!
Thank you!
The vibration effect is good, but I saw two issues in the log. One is that the cutoff frequency of the IMU can be appropriately increased to filter out some vibrations around 60Hz.
The second issue is that the tracking effect of the yaw rate control loop is not very satisfactory. It is recommended to slightly increase the value of MC_YAWRATE_P/K. However, this is not an absolute solution and it depends on the actual flight performance.
@gfLv_amov
Thank you so much! I learnt a lot from what you pointed out!
I tried tuning and increased the Yaw Rate K value higher and got good response. But at around K=3.4 when I had almost good time-series graph with Setpoint and Response I ran into some issue (not sure if it’s really).
I was doing sharp stick turns as I did with Roll, Pitch but with yaw, suddenly the drone just got lowered a few centimeters (Like drone dropped). I guess it’s due to that when doing the sharp stick turns that diagonal pair reduce it’s RPM suddenly. I’m not sure if it’s because of the drone weight is high, after that I set K=3 and Yaw Rate=90 deg/s and didn’t try sharp stick turns lol, I’m afraid to crash this big boy again.
Then also looked into the attitude controller and tuned it. What I see from the logs is that drone has overshoots with Velocity and Position control loops which I’ll be looking tomorrow to try them to get good values.
Is there any other advice you can give me at this point? I’m planning to fix some camera to the drone, but since I have already added the equivalent weight of the camera and few other things I plan to mount on the drone I think I will be flying the drone for a couple of flights and see the stability before mounting the real things.
This log is the last log I got.
https://review.px4.io/plot_app?log=227471a0-dc1e-4f13-9674-6a2ae7f21fbf
Thank you!
@gfLv_amov @bresch
Hi, could you please take a look into this and let me know what’s going on with this drone?
Issue : Drone get wobbly when it’s altitude is around 10m. At the time there was no much wind though. I didn’t fly it higher than 10m. You can see this in the first seconds of the video
Flight log : https://review.px4.io/plot_app?log=d233bade-4a93-458d-bb3d-c9657cf166c3
Video : https://drive.google.com/file/d/1lYG6ta7SwYtVSiaH3yBw5cbKiU7H-BJP/view?usp=sharing
Could the issue be with Optical Flow sensor?
I have tuned all the control loops.
Just wanted to mention here.
The wobbling happened because I had enabled conditional mode for EKF2 with Range Finder. Since I had the value 10m for it, after 10m it happens. Now I switched to ‘Enabled’ mode instead with conditional and works without issues,
