Fixed Wing Control Integral Gain not working? [resolved]

PX4 Autopilot
1

Hi,

I am doing some testing on the autopilot in the lab before flying.

So the aircraft is sitting on the table, I put the aircraft to stabilized flight mode and FW_P_TC > 0.

If FW_PR_P > 0 (pitchrate gain), when i tilt the aircraft in pitch, the elevators responds. So the proportional gain loop is working

However, if I set FW_PR_P=0 and FW_PR_I > 0, the elevator doesn’t respond when i tilt the aircraft. This suggest the integral control loop is not working,

I have looked through the code fw_att_control.cpp and no where suggest the integrator is locked/disabled.

Anyone faces the same issue?

This is PX4 firmware v1.4.1

2

They’re reset until the vehicle is no longer landed. https://github.com/PX4/Firmware/blob/master/src/modules/fw_att_control/fw_att_control_main.cpp#L1046

1 Like
3

That explains much. Thanks @dagar

On a side note, is it possible to disable the land detector to test the integral loop on the bench?

Ziyang

4

Try blowing into the pitot tube or significantly reducing the parameters for the sake of testing and then walking around.
https://dev.px4.io/en/advanced/parameter_reference.html#land-detector

5

Unfortunately, the UAV is a 6m/10kg research platform and a little unwieldy to walk around with. lol

I could blow the pitot tube to “initiate” takeoff but very quickly it will revert back to “landed” state even with small landing detector parameters.

I guess i could modify the c++ code and comment out the reset_integrator portion, but that’s the last resort.

Ziyang

6

It might be worth adding a command line option to force the land detector for the sake of testing.

7

Thanks @dagar. I will look into that