EK3_GPS_VACC_MAX behavior questions

ArduCopter Copter 4.3
1

Hello,

I tryed on last Copter 4.3.2 to use this feature.

The UAV is setup with CUAV X7 and F9P.

Before takeoff Gps status is RTK, vacc goes down and it’s steady at 0.012.

I set VACC MAX to 0.025

I make the flight, and I don’t see rock solid altitude holding as expected.
Instead I observed the same behavior as if using the barometer with this parameter set to 0.0.

I remake flight always in RTK FIX status, by setting EK3_SRC1_POSZ to 3 “GPS” and I observed rock solid altitude holding…

So, How to have the same behavior as seting EK3_SRC1_POSZ by using the EK3_GPS_VACC_MAX ?

Kind regards.

2

I think you are comparing bananas to apples… you got a rock solid height by setting EK3_SRC1_POSZ to 3 because this parameter makes GPS the primary source of height. With this set to default, your height will be controlled by barometer, which can suffer from some problems like propwashing and wind etc.

I don’t know the details of EK3_GPS_VACC_MAX but you shouldn’t touch this kind of parameter without being 100% sure of what you are doing and how this affects EKF behaviour.

3

Hello, at any moment i can backup to stabilize.

Is for that that I ask for……

This feature is very interesting, and i want to know how to set it to be sure that passed below vacc max threshold the only source for eight is gps and no baro fused with gps…

Maybe there is anybody that can explain details about that ?

4

Sorry man, I have only basic knowledge on EKF. Can’t help you with this.

5

Can any body confirm that this parameter is useful when ek3_src1_posz is set to 3 (GPS) ? and that there is ek3_src2 _posz is set to 1 (baro)

Please let me know.

Kind regards.