Auto Tune came up with ~ 37xxxx (P_MAX & R_MAX) for a 3"
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On my 3" quad with 1104 5400KV motors and 2S battery I have:
ATC_ACCEL_P_MAX,240000
ATC_ACCEL_R_MAX,240000
ATC_ACCEL_Y_MAX,40000
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I set them to 0 - which means basically go as fast as you can. On big copters this is a bad idea because you can overload the motors but on small copters I donāt think there is much of a downside. Autotune will set these base on the fastest response it sees from the vehicle when twitching.
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Ok ā¦ Thanks a lot.
Now the problem is flow hold with CX OF optical sensor. In final part of this video the quad have fast oscillation like wrong PID.
has anyone had the same problems?
Can you get a log? It would easier to tell which axis is the problem - otherwise looks like D-term feedback to me, so reduce your D-term by 1/2 on each axis and see if that helps.
Yes 
In stabilize and alt hold now flies well, but the problem is only in flowhold mode with optical sensor
I donāt really understand flowhold, but you appear to have a lot of noise on the sensor:
What are your flowhold settings? I would try more aggressively filtering (i.e. reduce FHLD_FILT_HZ), but I am not sure how a small copter would respond to those kinds of changes.
Thanks Andy, my flow hold setting is default like wiki, and i force to 3 EK2_GPS_TYPE.
My FHLD_FILT_HZ is 5
EK2_GPS_TYPE = 3 to force the EKF to only use the optical flow sensor and not use the GPS
Good news!! with FHLD_FILT_HZ 2
it flies almost well with few oscillates!!
Can I go down to less than 2?
There are some P & D terms for FHLD you could also try reducing those instead
Thanks, do you remember which are?
Hi all,
have you seen this great job?
Are the parameters that come out correct for our little 3 "quadcopters?
Yes, that guide is great! I think his limits on the graphs are for 5" props, but you can interpolate down to 3"ā¦ I havenāt tuned from scratch in quite a while, but reading through the guide, I think it covers everything.
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Thanks!
It might be a good idea to put it on the wiki, especially for small quads.
Additional information on optical flow sensors for small quads that are often used indoors should also be added.
I am using this sensor (it can take about 10 usd on Aliexpress) and it seems to go quite well on a 3 "although it is still not perfect.
This is example of use from flowhold to althold on my 3 "(18650 powered)
Are you using the optical flow sensor without range finder?
yes! Only a clone of this:
Im away to build a new 3 incher,is the Hollybro Kakute F7 mini and Tekko 32 F3 4 in 1 esc A good setup to run ardupilot on
Hi Marty,
The FC is 20x20 mount, and the ESC is the 30.5x30.5 size. Also, my only experience using those metal FET ESCās was on a luminier razor, and it was super inefficient. I donāt know why or if it was related to the metal fetsā¦ But, I got about 2 minutes less flight time with itā¦ from over 6 min to under 5 min. I put a different ESC on it, and my flight time came backā¦ It was definitely the ESC.
Also, the kakute f7 mini is much more sensitive to vibrations than the omnibus nano. It has a different IMU. I had a hard time getting the vibrations low enough on a few copters I built w/ the kakute. I eventually got them working, but had to balance my props much better than I ever had before, and use softer mounting for the flight controller. had to check every wire and antenna and everything that could possibly be loose and moving around during a flight. I didnāt have to do any of that w/ the omnibus nano copters using the same frame and motors.
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Thank you maybe just go omnibus any other decent 20x 20 fb with baro and sca/sdl pads please
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