Pixracer Feedback Thread

Just as update: Its the sort of initial feedback we expected, given this is the first step into that area. We found a couple of things we’d like to improve and will get back to you when its ready for another testing round.

olex and schlumpfteam,

Try setting parameter ATT_BIAS_MAX to 0.0, and increasing your roll and pitch rate P gains. I was able to double mine from 0.05 to 0.1, but the optimal value depends on your particular machine.
Do you have your own procedure for PID tuning?

Hi, did you solve your issue with the WiFi connection? I too made some change (I changed Channel from 11 to 4) and since then I am unable to connect via WiFi. If you solved your issue, please let me know how you did it.


Not yet. I’m probably going to have to reflash the firmware. It seems like changing any of the wifi params with QGC makes it unusable.

Sorry to hear that. I did let our developers know and we’ll provide a factory reset button in QGC. Bear with us, the racing effort is all carried by volunteers committed to offer a great user experience, but it will take a short amount of time to get everything right.

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Here are settings which should improve / fix the rate performance: Pixraxer as a RACER

that is really too bad! Actually, I tried to reflash the ESP8266 numerous times, with no success. Flashing worked when it first arrived using NodeMCU and FTDI Adapter. Now, flashing does not work. Yesterday, I gave up and ordered new ESP8266.
But again, funny thing is that I can actually still connect to the PixRacer Network with OSX, only QGC will not recognize the vehicle… anyways, will keep you posted.

I also flashed with MavLink ESP8266 Firmware from px4 website using NodeMCU and FTDI Adapter. I can connect my computer to 8266 but QGC doesn’t find it… The 3d radios work fine with TL1…

For me, QGC 2.9.4-31 running on Ubuntu 15.10 is taking about 30 seconds to upload parameters and connect via 8266. Connection via QGC/Android on a Nexus7 takes about half as long to upload parameters.

After flashing the latest px4master firmware (29.2.2016 21:30). I could arm my quad but the motors did not spin. Until today it was always working. I did a esc cali ration with the qgc 2.9.4 but itdid ot help.
I reflashed the pixracer with the stable version andit worked fine. Arming in stabilize work in stable but not in acro modus. Thats why I tried a second time to flash the master version but the motors did not turn at all. Arming in acro mode works as well as in stablize but no motor spin.
By plugin the battery the esc do not seams to start properly the beeping stop. With the stable version they start correctly.
I use bheli 20A
Anyone an idea?

An arming bug affecting PixRacer went into master recently (in my safety switch enable/disable code). I think this PR: https://github.com/PX4/Firmware/pull/3892 fixes it.

I merged the fix to master, so testing in ~10 mins for anyone affected would be great. I expect it to solve this, but please report back at any rate if it works for you.

Oh great I will try tonight and give some feedback. Thanks for the very quick response.

It’s working fine now, thanks very much…

Great! Thanks for reporting. Let me know if you have any feedback on ACRO mode, too.

I have tried out the v 1 case from Shapeways for the Pixracer with foam insert into the little box covering the baro chip… This is major improvement, concerning the altitude drop in AltHd… I am using it in my 3dr quad and 3.3.4 fw…

Here is a first try of my Pixracer with TBS (clone) upper center plate. Looks pretty good. I printed also case for Pixracer: PixRacer Basic Case by Painless360 - Thingiverse - and piece of foam included under baro.

Some more PX4 Acro feedback from my latest test flight in the other thread: Pixraxer as a RACER

To summarize: much better with ATT_BIAS_MAX = 0.0, but I’m still unhappy, and will now give the APM firmware a try.

+1 regarding the aforementioned issues with acro flight.

I’d like to add that my copter behaves far too twitchy in the center stick-ranges. Lowering pitch/roll sensitivity didn’t really improve that. Is there any way to add expo to pitch and roll? It would enable using high rates while maintaining fine-grained control in the center stick-ranges.

I don’t think there is a way to do that in PX4 at the moment. However, I added expo curves to pitch and roll on my transmitter (FrSky Taranis - easily programmed and set to only activate in Acro mode), that helped quite a bit.