Re: [Paparazzi-devel] GPS Problems

[Simon Liebold]

Hi Megan,

I have a M8N and experience the same issue with my multicopter. Any autonomous flight is essentially impossible. 

During CCCamp Felix helped my to understand the issue: Somehow (still not fully understood) the ucenter module fails to apply the Paparazzi U-Blox standard configuration and the module will continue to operate with its default configuration. That is a update rate of just 1/s and a dynamic model (CFG-NAV5-dynModel) of "0 - portable". Especially the latter causes sudden position changes to get filtered out and only slowly to move to a new position. This would work great for a pedestrian, but causes the mentioned problems in our application. 

To verify you can activate a debug flag in the XML configuration of the ucenter module. This will cause a debug message to be sent during startup. The message is sent just once, be sure to have the telemetry messages displayed before powering up. There may be more than one debug message. Look for the one with 16 (or so, cannot look it up right now) digits. If it returns a bunch of non-zero digits then it managed to apply the configuration. If it is all zero you have the same issue I see with my module. 

I now created the configuration manually using the U-Center application from U-Blox and will try to make it work with the ucenter module in Paparazzi deactivated. My module seems to have problems with its flash memory because it keeps forgetting its configuration when left without power for an extended amount of time further complicating my debugging efforts. 

Preferably, the M8* will work with the ucenter module. But so far I wasn't able to find anything obviously wrong in the module code. 

If there is anyone with an M8 module that just works nicely with the ucenter module, please let us know. 

Simon

Am 14. September 2015 01:28:52 MESZ, schrieb Meghan <address@hidden>:

Hey all,

We flew today in Auto2 and the ground control station showed the airplane flying in a loop 60m ahead of us, while the airplane was going straight over our heads, not attempting to continue the loop. The plane first started to go into the loop, and at about 3/4 of the way around, it experienced the problem. It showed the same problem 3 different times. There was a bit of a crosswind, but the GCS should show the GPS reading from the airplane. We are using the NEO M8 GPS module, so we are not sure why this was happening with such an accurate GPS module. I assume that the position accuracy spiked up for some reason, but during the flight, all I saw was around a 6m position accuracy.

The GPS module is mounted on the top of the airplane, facing up, and at least 6" away from any source of potential interference (motor, ECS, servos, radio). Any ideas why this might have happened?

Thanks,
Meghan



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