Notch filter setup?

ArduCopter Copter 4.6
1

Hi!

My drone has the following paramters:

  • 4s1p battery pack made ov EVE 21700 40PL 4000mAh battery
  • Micoair H743 FS
  • 1750KV motors
  • 5x3.1inch props
  • Mateksys battery monitor via I2C bus.

I followed (at least, I tried :smiley: ) the tuning process description, when I reached the part, where I have to configure harmonic notch filtering.

I made the necessary settings to the FC and went to the field for a test ā€œdriveā€. Unfortunatelly there was an issue with the GPS because I mounted a small action camera with a screw, about 20mm from the GPS. This caused some issues at the beginning of the flight. After a few seconds this normalized.

The drone hovered properly and I was able to record the necessary flight data, that was loaded into Filter review tool.

Iā€™m a little bit uncertain at this point:

  • Shall I set the notch frequency to 180Hz?
  • The bandwidth should be the range, that is indicated with green arrows?

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Flight log: https://drive.google.com/file/d/1M0c_kdtdgbQdKGmqUFb3doLZ52qXqG_5/view?usp=sharing

Thank you!

2

Set these parameters, make another flight and have another go at it:
INS_LOG_BAT_MASK,0
INS_RAW_LOG_OPT,9

You have Dhsot configured (should be Dshot600 probably) can you not use Bdshot with the ESCā€™s you have?

3

Hi!

Iā€™ll do another test flight, thank you!

I was unable to set Dshot600 because the ESC configurator tool was able to connect to only one ESC, the other 3 ESC was not recognized.

Is this issue a red-stopper, that has to be solved before I go further?

The ESCs are supporting bidirectional dshot, I have changed the following two parameters to enable bidirectional dshot:

SERVO_DSHOT_ESC,1

SERVO_BLH_BDMASK,15

My ESC is the middle one of below picture:

4

Yes. Flash the Bdshot version of firmware to the Flight Controller if there is one and configure for BHeli_S bdshot. Bluejay is on it.

5

If I remember correctly, I have Ardupilot 4.6.2 on the FC. I have downloaded it from here:

There is BLH_SERVO_BDMASK option in Mission Planner, Full Parameter list.

This means, that there is Bi-directional support in the flight controller, isnā€™t it?

Or should I change the firmware on the ESC?

As far as I know Bluejay supports Bi-directional Dshot.

Or do I misunderstand something? :slight_smile:

Thank you!

6

You have it right. Some flight Controllers have a specific Bdshot firmware, some are inclusive of Bdshot. Yours is the later. Good to go to configure for Bdshot and then use ESC RPM as the reference for the notch filter.

7

Hi Dave!

Thank you for clarifying!

One more thing before attempting test flight: BDShot600 is absolutely mandatory or can I use the ESC in BDShot300 mode?

8

Bdshot600 is generally the most Stable. You need to set the Motor Ranges also

9

I was able to setup something with notch filters and I was able to perform an autotune a few days ago.

I did a hover-test today morning, but there was a little wind. I wanted to check the noth filter if I set it up correctly or do I need to adjust it a little bit.

I loaded the .bin into Filter Review tool, but whatever parameter I change, nothing changes on the chart.

.BIN file: https://drive.google.com/file/d/1XnYTkVmJnJQC-VW9RRSAfqytlRz4awtw/view?usp=sharing

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Is there something to be enabled in the settings of filter review tool?

I tried in two different broswers: Chrome and Edge.

10

did you pressed ā€œrecalculate filtersā€?

Do not change the freq
change att to 30
disable 2nd and 3rd harmonic
Activate multi-source

And try again.

11

Yes, I was pressing recalculate filters each time, I change something on the settings.

This screenshot was made on my company computer, and still does not change anything.

Hereā€™s the complete filter review tool screenshot. Maybe Iā€™m missing somethingā€¦

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12

I have just checked the filter review tool with the log file, in my first post (https://drive.google.com/file/d/1M0c_kdtdgbQdKGmqUFb3doLZ52qXqG_5/view?usp=sharing)

With this flight log, the filter review tool works.

Is there some issue with my second flightā€™s log? Maybe it was windy during hovering and this made too noisy the signals for filter review webtool?

13

The parameter changes only have an effect in the ā€œEstimated post-filterā€ curves. Not in the ā€œPost-filterā€ curves.

14

Estimated post-filter curves are empty :frowning:

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When I change to throttle based not filter, it seems to do something.

I have noticed, that my second flight log is made with raw sensor logging instead of batch mode.

15

I see the same issue on chrome. Might be worth putting in a bug report. Iā€™ll dig a little more

16

I had chance to perform a test flight, just a hover.

I need to enable ā€œMulti Sourceā€ to be able to have updated the charts.

Can I increase the attenuation, or can I leave it at 10dB?

Flight log: https://drive.google.com/file/d/1NKcvcm_WAtx4BgxWpxQL6OKd7CEsgtqp/view?usp=sharing

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17

10dB is fine and you do not need the 2nd and 3rd harmonic

1 Like
18

Thank you!

The goal is to have a more-or-less flat chart, instead of suppressing all the noise?

There are 2 gyros on the flight controller, and I think they are enabled. Is it normal, that I canā€™t enable Gyro2 ā€˜s measurements in the filter review tool?

When I make small changes in the filter settings, I need to re-perform the autotune, right?

19

The goal is to introduce as little filter lag as possible while keeping the result under -50dB

Yes, you need to re-do autotune after changing the filter

20

OK, I will re-perform the autotune.

The drone is now about 780g (with battery, everything) and Iā€™m planning to attach a camera, about 400gramms. If I know correctly I have to do the autotune with payload. When I remove the payload and fly without it, I donā€™t have to change tuning parameters.

Is this correct? Or is this more complicated than this?