Stability and fine tuning

ArduCopter Copter 4.5
1

hello everyone, i am trying to build a drone to do some speedruns and getting to top speed of +120km/h
it’s about 2.5 kg, 8040 props, quad, V3008 t motor, hobbywing Xrotor 65, 6S 5000 mah 75C, cube orange, tbs radio and reciever
i did the tuning and everything and everything looks fine in stabalize mode till 20 m/s speed which i tested
i am slowly increasing lean angle to gain more horizontal speed, but i was thinking i should double check my tuning or other parameters here
so here is my parameter file and a bunch of graphs:

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in auto mode just staying in 1 place:

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my questions are:

  1. how do you consider a tune perfect? following desired? output pwms? feel of the pilot? or what?
  2. how do you analyze viberation? i don’t know if my viberations are ok or not?
  3. i had a small runway for testing so i couldn’t cruise at max speed of that angle, so when i was manually braking with the quad i saw some wobbles(like i was using thrust for braking and the thrust vectors were in opposite direction of quad moving). i was wondering if it was a tune problem or is it just the dynamics of the quad which is caught in a spiral or some kind of aerodynamicly unstable situation?
2

  1. It is perfect when it followed all the steps on MethodicConfigurator/QUICKSTART.md at master · ArduPilot/MethodicConfigurator · GitHub including section 1.1 of How to methodically configure and tune any ArduCopter that will give you a good gain margin and phase margin as defined in control theory. Pilot fell might be dumbed down using some TC parameters, but the vehicle should be snappy to cope with the wind (noise disturbance rejection).

  2. Also explained in the How to methodically configure and tune any ArduCopter section 3.1

  3. Makes no sense in tuning it further without first having the basics described above covered.

3

Thank you for your response
I will make sure that i have considered all steps when i find time to do so asap. I have followed some of the main docs when i was setting the drone up though. But i had bot seen the links you provided, so i think i have work to do then.

I have seen some threads that developers or other experienced people, are commenting on performance of a tune and i was wondering how that would be possible only from looking at graphs of the quad

4

Spare the graphs and just post a link to the .bin log file. Whoever would be looking at this will ignore the posted graphs and plot them for themselves. Unless they are posted from a developer…

5

sure, here you go