Pixraxer as a RACER


@Mark_Whitehorn Have you tried dropping the attitude P gains to 15-50% of their current value with the rate gains you proposed? There should be a stable combination for them even with very high rate gains.


Yes, reducing the att P gains is all that was necessary to stop the oscillations


Could you help our German testers to reproduce this? Would be fantastic to have them validate the result.


Which att p gains do you mean?
it is a zmr250 that flys with the naze just fine.
Today installed the latest qgroundcontrol and flashed the latest master.
it ist generic 250 racer.
Multicopter attitude control are like this
ptchrate-d 0.005, -i .2; max 500 -p 0.1
pitch_p 7.0
rollrate-d 0.005; -I 0.1; rollrate_max 500; rollrate_p 0.1
Roll_p 7.0

When I now try to lower the Pitch_p it tells me “Paramter write failed:comp:1 param:MC_PITCH_P”

When reconnecting, the changes are lost.
And now?


That’s really odd - we believe its a Wifi issue with the ESP8266 since we see packet loss there, but not via USB. Could you try setting your gains with USB and a computer?

In general we noticed that dropping the ROLL_P gain and increasing the ROLLRATE_P gain is better for racing - could you help us testing that?

One experiment to try is to drop ROLL_P to 3 and increase ROLLRATE_P to 0.25 (same for pitch). You still need to tune, that’s just a starting point. I would be interested to know if you get that to a satisfactory result, because then rate mode should be a lot more stable.

V1.3.0 beta testing

Everything was done via USB and the Computer.
I will try to Flash a complete new Firmware and will Report.


I’ve posted my ACRO gains for PixRacer here: https://gitter.im/kd0aij/dual_FC_S250AQ?utm_source=share-link&utm_medium=link&utm_campaign=share-link
IMHO, acro mode performance of PixRacer on my dual FC S250AQ is as good as Naze32 now.


I just flew the S250AQ again using CleanFlight/Naze32, and the Acro mode orientation hold with default PID gains was not better than my current tuning for PixRacer. I tried P gains from 1.0 to 1.4 and D gains of 15 and 30. So, in my opinion, PixRacer can easily compete against Naze32 for Acro mode flight.
And both ALTCTL and POSCTL modes performed well on the S250 today under the trees in my yard. Position accuracy was not great, but it stayed within a roughly 3m radius circle and movements were smooth. Altitude held within 2m of starting altitude over the test (< 1 minute).


I’m looking forward to test the new values. Unfortunately your gitter link doesn’t work.


maybe this will work: https://gitter.im/kd0aij/dual_FC_S250AQ?utm_source=share-link&utm_medium=link&utm_campaign=share-link


Sorry. Still not working, even after signing in


oh well… my latest tuning for the S250AQ:


dose anyone fly the pixracer as a racer in a regular basis? I’m still looking for the right pid’s, for the right frame, to set the oneshot preopperly (pwm_disarm/min/max - 100/125/250).

At the moment at very low throttl it dosen’t have any osciations but if I rase the stick to the middle then it start shaking. Both slider are set to the right for pitch and roll.

I’m sure I’ll finde my setup for my raceblade 5" one day :slight_smile:


Hi everybody - I pushed the 1.3.0 release out, which has much better racer support (just better default gains, in fact). Please update your QGC version, flash the latest stable and RESET your airframe configuration (which will keep your RC calibration, but reset your gains to our recommended defaults).

Make sure to use the QAV250 or 250 generic (if you fly something other than a QAV 250) config and give us some good feedback.

The 1.3.0 release is in a “soft release” state, which means we might still make amendments - so any flight testing you can contribute will help us a lot in ensuring we made the progress we wanted to make.



What version of QGC should be used to flash this 1.3.0 release?

Suggestion, when there are new releases, be it QGC or PX4, could you also include what version of the accompanying sw/fw is required/suggested. I personally never know if I should be using the latest, released, beta?


The latest release as per the website or the last Android beta as auto-installed if you are a tester. I still owe you the flight mode docs, they will come on the weekend.

For now:

  • MANUAL / STABILIZED: The same thing on multi rotors, on fixed wing manual = like manual RC and stabilised is attitude control
  • ACRO: Rate control, for quads only right now
  • RATTITUDE: Stabilized around center, rate control on the edge of the stick range
  • ALTITUDE: Altitude hold, attitude stabilisation
  • POSITION: GPS and altitude control, you move the system around with the sticks. Planes fly a straight line with zero stick input, quads hold position
  • AUTO: Pre-programmed missions
  • TAKEOFF: Standard takeoff & holding position (circling for a plane)
  • LAND: Land at the current location (not tested with planes yet, but would work in general)
  • HOLD: Keep the current position, stick inputs disabled. You can update the current hold location via the tablet / GCS

I hope that’s good enough to get you off the ground initially.



With all due respect to the dev’s, is there a reason why questions like this and this (two questions with not one answer) get overlooked? I though it was just me but its looks as though others are confused about QGC flight mode assignment as well. For those new to PX4 FM or QGC SW, wouldn’t some well written documentation (or better yet, a video HOW TO from start to end) on how to set these flight modes up with QGC and TX be beneficial? It would help the forum in two ways, less questions to the dev’s, (more time to develop) and this forum (less clutter)? Any video that I have found is either about MP/ardupilot or some outdated PX4 video and isn’t useful at all. Could someone please help with this matter?

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snapshot of ACRO mode flip of my Aquacopter Quad:


This is the rate loop impulse response for the AquaQuad, calculated from 20 seconds of log data containing one roll and one flip (gains are in the plot header):

These gains are substantially higher than the defaults for a DJI F450, but they are probably too high to be optimal for operation in stabilized mode.


Could you post your Settings for a F450?