No monitoring tool for EKF3 Affinity and Lane Switching available

[knudj]

For educational purposes I tried to set up some kind of monitoring for EKF3 affinity and line switching in ArduPilot/SITL/MAVProxy.
I asked ChatGPT for some help, however regularly it came up with obsolete commands and parameters (Thus I would be very careful to use ChatGPT for any inflight support of ArduPilot!!!)
Nevertheless it indicated an old module "ekf" in MAVProxy that would perfectly provide a kind of overview I had in mind:

Index Active IMU Baro GPS Mag Health Timeout Pos_Horiz/Vert Vel_Horiz/Vert Compass
0 Y 0 0 0 0 Good N Good Good Good
1 N 1 0 0 0 Good N Good Good Good
2 N 2 0 0 0 Good N Good Good Good

I couldn't find the module "ekf" in the respective Github MAVProxy repository. Would it still be available somewhere else?

The ArduPilot "EKF3 Affinity and Lane Switching" documentation also shows some nice examples for lane switching using a parameter "XKF4.PI" that however also is not available any more.

I think that the EKF affinity and line switching concept is a powerful tool to further enhance the reliability of ArduPilot in a multi-sensor environment. It seems however that after introduction of the concept developers made the attempt not to confuse users (just the EKF probably is some kind of mystery to many) and hide some nice tools from the development phase.

Proposal: For the more interested user monitoring tools for EKF affinity and line switching should be made available again!

Warning: Do not only rely on ChatGPT for support in a dynamically changing open source environment!

[mjohenneken]

Sounds not like the average user needs immediate and easy access. There are many possiblities in monitoring an Ardupilot UAV. Have you tried the graph module? If you want easy access to the monitoring tool you could add in to your startup aliases.

By default there is already one for general EKF status( type gekf in MAVProxy console):

@alias add gekf g EKF_STATUS_REPORT.velocity_variance EKF_STATUS_REPORT.pos_horiz_variance EKF_STATUS_REPORT.pos_vert_variance EKF_STATUS_REPORT.compass_variance

Regarding ChatGPT usage. If you want to use a AI tool for documentation you could use something like DeepWiki which indexes Repositories regularly and it works beyond the knowledge cutoff date of your GPT Model.

[knudj]

Hi Max, thanks for your feedback :-)

gekf was not available by default as well as g, however I added it in the MAVProxy console.

For test purposes I always start the CMAC circuit, which then resulted in the nice graphs as below. The first graph is from the two southern turns with some higher velocity variance at the turns. The second graph is from disabling and reenabling GPS1 (param set SIM_GPS1_ENABLE 0, param set SIM_GPS1_ENABLE 1). I still have to ponder about the results :-)

Also very interesting that after disabling GPS1 two planes apart from each other show up on the map - one seems to be a plane with EKF1 predicting and correcting, the other one a plane with EKF1 only predicting (since GPS1 is not available anymore).

Besides these nice insights I am still looking for some straight indication of the ekf affinity and lane switching as documented in the ardupilot documentation. I have in mind a table showing up all lanes and indicating which lane is active and which sensors are allocated to the lanes as well as whether the sensors are healthy or not.

Would you still help?

[mjohenneken]

Hi Knud,
i just thought i give you some pointers how you could easily add this yourself with existing features. For me its not a priority right now as i haven't encountered any issues with affinity lanes. The EKF_STATUS_REPORT.flags will just show general EKF health, not the lanes. You could try to add the flags to your graph nontheless.

It seems the lane used is not part of the telemetry which makes it impossible to graph in MAVProxy. If there is a message that would contain it you could graph it with the graph module.
Have you tried looking at the Dataflash logs (aka .bin logs)?

[knudj]

Hi Max, thanks for the pointers :-)

Lets start from the obvious:

AUTO> param show EK3_IMU_MASK
AUTO> EK3_IMU_MASK 7.0 # FirstIMU|SecondIMU|ThirdIMU
AUTO> param show EK3_AFFINITY
AUTO> EK3_AFFINITY 15.0 # EnableGPSAffinity|EnableBaroAffinity|EnableCompassAffinity|EnableAirspeedAffinity
AUTO> param show SIM_GPS1_ENABLE
AUTO> SIM_GPS1_ENABLE 1.0 # Enable
AUTO> param show SIM_GPS2_ENABLE
AUTO> SIM_GPS2_ENABLE 1.0 # Enable

Setting the parameters as above I guessed that now EK3 opens three instances aka lanes (according to three IMUs) and then allocates sensors to the lanes. Now after disabling GPS1 EK3 should switch to GPS2 (different lane?), which however does not happen (according to the graph and to the map). Why not?

There is certainly a need to check for proper functioning of the lane switching algorithm during a SITL session. Thus why is the old module ekf no longer available?

Maybe I missed something?

[mjohenneken]

Is this map from mavproxy or mavexplorer?

With Mavexplorer you can look at dataflash logs which provide more details.

e.g.:

https://ardupilot.org/dev/docs/using-mavexplorer-for-log-analysis.html#using-mavexplorer-for-log-analysis