Everything you want to know about Betaflight Iterm Relax
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- Опубликовано: 28 апр 2019
- Support my work / pawelspychalski
Betaflight Iterm Relax. Sure, "everybody knows" you should use it but there is not very much on the internet about how it works. This is why in this video:
- what is Iterm like I in PID
- why we need Iterm
- why Iterm has a tendency to windup
- why Iterm has to be constrained
- how Iterm Relax helps to limit the windup
- relax types: RP, RPY, RP_INC, RPY_INC
- Iterm Relax Gyro vs Iterm Relax Setpoint
- Iterm Relax cutoff frequency
Finally understand this, after watching the UAV tech videos too. Sometimes the whiteboard explanation just works better for me. Thank you!
Good stuff, Pawel! Thanks!!
Yes, it makes so much sense to me when talking about it in terms of passive filters. It’s pretty much the same thing as adjusting lowpass and high pass filters on a synthesizer
VEry nice looking forward to 2.2
Really interesting! Thanks! 😊
@Pawel Spychalski , is it accurate to say that iterm relax should play no effect when sticks are centered or does it affect max accumulated error?
I'm trying to figure out why my iNav equipped fixed wing aircraft cannot hold its attitude in ACRO mode against larger turbulence like my old Vector FC could in 3DH mode. It acts like the I-term windup is being reset when the accumulated error exceeds some threshold. So sticks centered, aircraft flying straight in turbulent air. If the bumps are small, then it reacts to them and average attitude remains stable. But if the bumps get too big, then I'll see it get knocked off axis, it reacts to correct, but doesn't return back to original angle. So.. say wind knocks it 25 degrees off angle to the left, it only returns 15 degrees back to the right and then stops. I have to move the sticks to get it back to original attitude. It acts like the I-term only responds up to a given threshold, and then just gives up.
With Vector 3DH it would fight to return to original attitude pretty much forever, so even if the plane was knocked 45 degrees off angle, it would bring it back to zero (or whatever angle I was at) every time.
In INAV Iterm relax applies only to Multirotors and only to internal PID stabilization loop.
Hi Paweł, amazing video. Did you also have something about TPA?
LOL seriously bro, "lets learn something today?" 🤣 A great homage to one of my quadcopter heroes, aka JB, but I hope that it's just a one off and not a rip off 😂
hmmm... (stick - stick lpf) = stick hpf, nice explanation Pawel. Also for planes ? I know current implementation for planes.
No, planes will still have current Iterm limiting, we are not changing that. Planes are not that agile as drones and it would require very low cutoff frequency for Iterm relax to work