250 Quad with Pixfalcon help

Hi Henwilsch,

The tune on yaw looks good. I would suggest dropping the ATC_ANG_YAW_P to 9. Other than that it looks very good!

Please let us know how you find the flight characteristics.

1 Like

Thanks Leonard,

I will do some flights today(public holiday) with some wind hopefully.

My quad is currently on Ver 3.5. If I want to upgrade to a newer version what steps must I
do before and after upgrade? Do I just upgrade and are good to go?
I have looked on the Web but can find any answers. If there is any documentation, could
you please point me in that direction.

Henry

Hi Leonard,

Did some flight tests in mild windy conditions and found it still warble a bit.
Tried a flight with these settings:
INS_GYRO_FILTER,80
ATC_RAT_PIT_FILT,40
ATC_RAT_RLL_FILT,40
No autotune, to windy. Seemed a bit worse with those sttings.

I returned filter settings to 40, 20 and 20 respectively. I then set MOT_PWM_TYPE to 2 (OneShot125), calibrated the ESC’s, and it seems more stable.

Should I autotune again after changing to “OneShot125”?
Is there a way to program ESC’s using BLheli suite and the flight controller (pass trough)?

Sorry for all the questions, just can’t find answers on the internet.

Henry

Yes. From 3.5, just upgrade and you should be good to go.

Also,
Thanks Leonard for all the tuning help for everyone here!
It’s not something we get a lot of experience with…

1 Like

Hi henwilsch,

Yes you should do autotune but for the minimum latency and maximum performance you need to connect the esc’s to the auxiliary ports.

1 Like

Thanks for your reply,

The question is more in general. I own two other aircraft (F450 and F550) that is still on older firmware, can’t remember what exactly. What would the procedure be if I want to upgrade them?

Henry

Hi Leonard,

The Pixfalcon only have 8 outputs. No Auxiliary ports as far as I know.

Henry

Depending on how old, you might have to set a parameter or two…
Most likely, if upgrading from a version before 3.5 (or maybe 3.4) you’ll need to set a frame type and maybe board type parameter in the config. It will tell you in your pre-arm warnings (on the HUD in Mission Planner) if they are not set.
Otherwise it should automatically update any other values that changed. (as far as I know… that’s how it worked for me)

1 Like

Could you please elaborate on this use of the Aux ports with Oneshot125 enabled ESC’s? It doesn’t apply to my Pixracer mini quad but I have other craft with Pixhawks and Oneshot125 enabled ESC’s and I have always used the main ports.

Henry-I use a cheap Naze32 FC to configure BLHeli ESC’s.

1 Like

Hi Leonard,

Here is my ESC setup.
My motors is Siglomax 2204 2300kv and props Gemfan 5 x 4.5
Would You make any changes here.?

Thanks

Henry

I had a little time to try some tuning today…
Auto-tune always puts me at around .03-.04 for roll and .06-.08 for pitch.

It hovers great, but was wobbly when flying and in the wind. Rocked a little when stopping after a fast flight.
I tried lower PID’s… .02 and .03, and it was about the same… Good hover and slow flight, but wobbles on anything aggressive.
So, I tried .09 and .12… It seems great with these! No oscillations. And, it’s more responsive and seems to hold its position better.
I only had about 20 minutes to mess w/ it today and it’s not windy, so I’ll have to fly more before I know if these settings are good.

1 Like

Hi mate,
Could you send me an autotune log? If you have some rate noise issues you can often get a very low autotune unless you really bump up the autotune aggr.

I would be interested to see how you go with a good autotune with the AUTOTUNE_AGGR set to 0.2 (I assume you have it set to 0.1).

So everybody understands. The AUTOTUNE_AGGR value defines how far over the desired set point the aircraft moves. So when you ask for 90 degrees per second it increases the rate P term until it overshoots to 99 degrees per second. If you have rate vibrations that are 10 degrees per second (pretty easy with higher frequencies of mini quads) the aircraft is only doing 89 degrees per second but the added vibration takes it to the limit of 99 degrees per second and you get a lower value than you should. This is similar but a little more complex for the D term.

2 Likes

It might be a couple days, but yes, I will auto-tune and post a log.
I have not done an auto-tune w/ 3.5. My last was 3.4.
I might have even had the aggr set to .05 for one of the axis.

Thanks for all your help.

1 Like

Yeh, you are limited to the main output ports then. I am not familiar with the Pixfalcon so I can’t comment on exactly how they are set up.

You should be able to simply upgrade and select your frame type. Your tuning parameters should carry over. I generally do a fresh install then go through all the calibrations then do a “compare” with my old parameters and bring in my tuning parameters.

All looks good mate.

1 Like

So the Aux ports are directly connected to the main processor so they don’t have the additional latency of the IO chip. So for the best performance you should go with the Aux connectors. When I put forward the requirements of the Pixracer I specified the use of the Aux ports only so you don’t have to worry, just go to oneshot.

I hope that we will be able to increase our loop rate to 1kHz before long and lock the loops to the IMU read. This will further reduce the latency but more importantly improve our ability to filter. Finding the time is the challenge…

1 Like

Hi Leonard,

I think the Pixfalcon is a copy of the Pixhawk Mini and supplied by Holybro.

Thanks for you reply.

Henry

They first appeared here

I have a couple and they work quite well.
As with all things HobbyKing, your milage may vary.

Thanks Leonard-To be clear you are saying for Pixhawk with Oneshot125 ESC’s to use the Aux outputs for motors and configure the SERVOxx_FUNCTION to motors 1-4 (which is default anyway)? Any other parameters to change because when I try this I get no action from the motors.

Hi dkemxr,

This is what I do on my racer prototype.

MOT_PWM_MAX,1990
MOT_PWM_MIN,1010
MOT_PWM_TYPE,2
SERVO9_FUNCTION,33
SERVO10_FUNCTION,34
SERVO11_FUNCTION,35
SERVO12_FUNCTION,36

Then you need an ESC that supports it of course and make sure oneshot is enabled but I think any of the latest BLHeli is auto detected.

Hi all,

I have not used the pixFalcon but I have helped a few people out with it and found an issue with a couple of boards with IMU 1. There is a good description and demonstration here: