The instructions “Managing Gyro Noise with In-Flight FFT” includes the attached graph as an illustration of the dynamic filter working.
But there’s no mention to what parameter is graphed (or in which software) that generates this graph.
Can someone please help me find how to bring up this graph for my test flight?
Thank you!
Unfortunately, the documentation isn’t up to date with the current FFT option from the CNTL-F menu in Mission Planner.
Only one of the graph options works “RUN ALL IMUS - IMU1-3 MSG” - and it doesn’t generate the same results as what I’ve depicted from the instructions on using FFT.
What I get is this:
It’s not going to work with a sample rate of 25Hz. Are you looking at a log which had batch sampling enabled? INS_LOG_BAT_MASK set to ?
If you did you would see something like this when loading with the IMU Batch Sample button:
Thanks Dave,
I saw someone else mention needing these two parameters:
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,2
As it happened, no IMU’s were set in the ins_log_bat_mask, and nothing was set for ins_log_bat_opt.
I set the mask to include all 3 IMU’s, and set the opt to 2. Then did another test flight.
The end result was the same graph - showing the same graph as before and still a sample rate of 25 hz. So somewhere in the pile of parameters it seems there’s something else that needs to be selected.
I appreciate your help! Joe
Hi Joe- Post your log or parameter file if you like, we can take a look.
INS_LOG_BAT_MASK,1 will log the 1st IMU which is all that is really required.
INS_LOG_BAT_OPT, 2 is post filter and what you would use to review the Dynamic Notch filter settings. If you set it to 0 it’s pre-filter and what you would use when you want to determine the proper filter settings. So:
_OPT to 0 and make a short AltHold Hover flight
Review the log and configure the filter
_OPT to 2 to see how well it’s working.
Thanks again Dave -
I’ve set “mask” to 1 and “opt” to 0 - and performed another test flight in alt-hold.
The BIN file is uploaded on dropbox:
Cool, you are good to go! I would disable the Static Notch for now while you configure the Dynamic Notch. And re-visit that if you need to.
How on earth did you get that graph from my BIN file???
I get it about disabling the static notch filter - I should have thought of that.
I have both INS_ACCL_FILTER and INS_GYRO_FILTER set. (20 and 42 respectively)
When I reviewed my tuning parameters, I couldn’t figure out how INS_ACCL_FILTER got set to “20” - maybe it was in the default parameters when I loaded the firmware.
INS_GYRO_FILTER was set to 42 upon the recommendation of the ALT-A plug-in.
Do I set both of these to “0” - or only one - and if so - which one? (are there any others?)
Many thanks - and please tell me how you managed to get that graph!!
Just hit the Batch IUM Sample button and chose that log. Try updating Mission Planner to latest beta. And make a habit of doing this often.
Have to run but if someone doesn’t get to you 1st I will tomorrow.
This graph is generated with mavfft_isb.py in pymavlink
Thanks Andy. As the new guy around here - could you please tell me where to download mavfft_isp.py?
pip install pymavlink
Let me see if I understand this:
I’m following the ArduPilot documented procedure: Managing Gyro Noise with In-Flight FFT
There’s a step where it shows a graph to generate validate what’s been done.
To run that graph a user has to use a Python program in some sort of Python library/repository - plus, of course, have Python available on the user’s computer.
Have I sized up the situation correctly?
Or use Mission Planner.
Nice. You can zoom in on mission planner by left clicking and dragging a box over the area of interest.
Excellent tip - many thanks!
