How to Lower PX4 GPS Precision for Unlock?

PX4 Autopilot
1

PX4 requires high GPS precision to unlock, is there a way to relax the accuracy requirements?

2

Hi there!

I believe this page will be of interest to you:

EKF2_REQ_EPH and EKF2_REQ_EPV are most likely what you are looking for.

1 Like
3

this is correct answer.
EKF2_REQ_EPH and EKF2_REQ_EPV are parameters that will set acceptance accuracy for GPS data to be treated as valid which will trigger GPS lock.

Further more, take a look into related LPE and COM_POS parameters.

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@mtca @nitru Currently, we have 10 or more satellites with an HDOP < 1.0, but EFK2 reports “drift too much!” However, we don’t observe significant position drift or shift on the QGC map. Is there a way to lower the threshold?

@mtca Would you recommend adjusting these two parameters to address the issue? LPE_EPH_MAX / LPE_EPV_MAX ?

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@lida2003
First of all I would suggest sharing any ulg log files for easier debugging if possible.

To address your question:
LPE_EPH_MAX and LPE_EPV_MAX are parameter of Local Position Estimator,
for module to initiate successfully some parameters must be in range, therefore I would suggest to “release” this parameter to 5m for start and then reduce it gradually, to value you can accept.
Also take a look into LPE_GPS_*. Idea is the same, allow system to accept even “bad” values as good ones, and try to reduce allowed error.

As you are mentioning EKF2 error reporting;
EKF2_REQ_EPH and EKF2_REQ_EPV will take effect for acceptance in EKF2 module
EKF2_REQ_FIX is also parameter that will affect the behavior. Make sure your GPS module have at least 2D fix and is detected by Autopilot.
For drift directly you can setup EKF2_REQ_HDRIFT and EKF2_REQ_VDRIFT (again same idea, release the parameters and then reduce the allowed error gradually to accepted value).

I hope this helps or at least forwards you towards the solution.

Regards, M