Hello,
A while back Leonard had mentioned implementing the following in Bill’s thread about reducing instabilities, is there any chance some of this could make it into 3.5?
I am a traditional heli user and could see substantial benifets from these changes. Also with other flight control systems ive had great luck with a notch filter for eliminating instability issues with quads, so the implications reach further than just helicopters. I could see benifets for large X8 and Traditional Octa’s with large props as well.
Quote::
I intend to extend the normal copter pid loop to include:
separate input and D term filters
a notch filter
a feedforward term (input request times a parameter summed to P I and D output)
This also will enable running the pid loop in sync with the gyro read and at a different rate to the attitude angle controllers.
End Quote::::
Thanks,
Tim
I can’t speak on behalf of Leonard and Randy, but we are close to releasing 3.5 stable so I don’t think it will be part of it. I also have no idea if Leonard is planning that for 3.6 or not.
I would like to note, I am currently using a custom firmware that incorporates a “Notch Filter” and by using said filter I have been able to get a 75% increase in P term on my frame before instability/oscillation.
I really feel some more/different/better filtering schemes would help Copter as a whole greatly across many frames. I am in the process of collecting the data, but will upload logs etc. along with the progress when it is ready.
Tim
Tim,
Yes, the “notch filter” has come up in conversation even just yesterday. Although this isn’t included in AC3.5 it’s probably quite likely to be in a future version. This version has some improvements to control in any case though - IMU sampling is 8khz and the lag between the gyro input and the motor output has been greatly reduced… it’s very low now.
Thanks for the reply! As I stated earlier, I believe it would be a meaningful addition to the code.
It is great to hear other improvements have been made, I certainly am appreciative at the hard work everyone has put into this project.
Tim
