In flight parameter tuning


It looks like there is a way to tune parameters in flight using available radio channels (tied to knobs on TX).

In QGC, in “Radio” settings I assign channels 7 and 8 to parameter tuning 1 and 2.
What is the right way to connect Param Tuning ID 1 to ROLLRATE_P and set the range?

I found some pictures/screentshots of the “Tuning” page in QGC that has two sections at the bottom - “Autotune” and “In Flight Tuning”.I do not see these sections in my latest dayly build of QGC. Are they supposed to be there or they are obsolete?

In “Parameters” page, when choosing ROLLRATE_P (or any other param), there is an “advanced” checkmark that lets me select Tuning ID 1 and range for this parameter. Is it the right place?

Is there any indication of the current parameter value? Let’s say tuning works and I found desired TX knob position… How do I read corresponding parameter value?
I have tried rotating the knob and opening/closing “Parameter” page in QGC and results were inconsistent. I think parameter got updated a few times, but on other attemtps it did not. Later QGC just crashed a couple of times.

Radio signal always fluctuates a bit. Does it mean parameters are constantly updated (due to fluctuations) and re-written to flash even when corresponding knob is not moving or there is a deadband of some kind?

Go to parameter editor, click on ROLLRATE_P. In the side dialog click Advanced. Click Set RC to Param.

Thanks. I have been doing that.
Do you know if later parameter editor will show current (new) parameter value as I rotate the knob on RC transmitter? For some reason it was not showing the new value yesterday.

The parameter protocol doesn’t work that way. So no way for QGC to do that. You need to manually refresh to get new values from the vehicle.

OK. It does not seem very important, at least at the moment, but I am still unable to display parameter value set by RC even with manual refresh. I can guess the value approximately knowing position of the RC knob. :slight_smile: In general, in flight tuning works well and it is a nice feature!
I will just describe what looks like a small UI bug here. Refreshing parameter view in Parameter Editor does not show new value of the parameter. Most of the times it shows old value (0 in my case), A couple of times it was displaying some value that did not make sense (i.e. not corresponding to RC knob position). Clicking RC-to-Param button brings up the window with range settings and the range displayed is different from the range I set using that window 5 min earlier.
it might be a bug with window or field initialization in QGC.

The usability for this dialog is pretty rough. Due to the way the protocol works for this support, the min/max values are not saved. So they will reset each time you go back to the dialog. Not sure why a manual refresh doesn’t update the param value in QGC. It should. I’ll take a look at that.

Any update on this issue. I did some testing with MPC_THR_HOVER. Any attempt to change the value in flight caused the value to go to the max - 80. Does this function work for any parameters? I can provide details…

@DonLakeFlyer Is there an issue with the slider in QGC?

Well, actually yes… The slider for hover works the reverse from the description. Slide to the left and motor rpm decreases. But the issue I was concerned about is assigning a parameter to one of the three available RC channels for tuning with the RC transmitter. Any attempt to use this for MPC_THR_HOVER drives the value to the max (80). I have had no success with assigning other parameters to RC channels.

This is correct behavior. As the text says: “Adjust throttle so hover is at mid-throttle. Slide to the left if hover is lower than throttle center. Slide to the right if hover is higher than throttle center.”

If your vehicle is hovering with throttle lower than center it is overpowered hence you need to decrease the motor rpm. Decreasing the motor RPM is sliding to the left.

Thanks for the response. I starred at this forever and did not make any sense… Now (for whatever reason) it is obvious. Where should I address the second issue with the RC channel/parameter settings?

Not sure what you are talking about. Are you talking about a problem with “Set RC to param”? Don’t see any question from you on that.

Yes, I am talking about “Set RC to Param”. Was in a post, back a few.
I tried setting “MPC_THR_Hover”. The min and max values are off by a factor of 100. When I move the input (from transmitter) slightly off center (0 value) the parameter goes to 80, and motors go the full.
I have tired multiple combinations of different parms and cannot get any to give me predictable results.
With little documentation, I cannot set my expectations for this functionality. If needed I can give a detailed sequence of events. Thanks…


any body here has Idea about writing new values to PX4 paramters during flight
I am no going to use radio control for this purpose and just want to use mission planner or QGround Control

thanks a lot

Just do it. What’s the question?

The point is that whether we will encounter with any failure or not

I feel that at anytime we write new parameters, the px4 resets and i am worried this reaction leads to crash

The px4 resets? That would be a massive safety bug. If that is happening I would report it to your firmware provider. Parameters which are dangerous to change mid-flight should require a vehicle reboot to take affect.

There are certainly some parameters which are in a middle-ground of safely being changed while in flight. Tuning params would be good examples of those. If you change to wild incorrect/off values it could lead to a crash. So yes, you have to be careful with what you are doing. But no, it is not a general problem to change a parameter while flying and have it cause flight problems.

Hello dear friend

the point is that no where it is mentioned that changing PID parameters need autopilot to be restarted in order to take effect. however I feel it may be a hardware problem that cause autopilot to encounter the shortage of power and consequently restart.

however I am looking for others experience to find whether they had similar problem or not

thank you for your comments and considering my issue

hope to find a solution together


That is because you don’t need to restart to have PID parameters take affect!

Yes dear friend
you are right

this problem was presesnt when we changed parameters while vehicle was disarmed. so we recognised a step in the actuators after changing parameters

but as we armed the vehicle and then we changed parameters, no step were observed and everything was fine

thanks every body for thinking and sharing your knowledge with me