GPS precision on pixhawk ?

Posted by heliboy on October 16, 2014 at 7:52am

Perhaps only the developers can answer this question. What is the resolution of the GPS2 input on the PIXHAWK ? If we had a decimeter precision GPS would the Pixhawk correctly use the higher precision NMEA lat/lon message ? Somewhere, I recall a discussion about double precision reals on the pixhawk.

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  • Developer
    Andrew Tridgell October 16, 2014 at 12:55pm

    The 2nd GPS will be selected if it either indicates it has a RTK position lock (currently only supported on the Piksi GPS) or if it has 2 more satellites than the first GPS.

    Ardupilot tries to stick to whichever GPS it is currently using, then switches if the other GPS has 2 more satellites. This prevents switching too often, which can cause erratic navigation.

    The GPS driver supports cm precision on both uBlox and NMEA if the GPS module is that accurate.

    Cheers, Tridge

    • RoboBill > Andrew Tridgell October 28, 2014 at 5:54pm

      I ran across some info about precision point positioning. I gather UBlox has a module that might give < meter accuracy. Is this module available for the Pixhawk? If it is and I plugged it into the 2nd GPS slot, would the Pixhawk switch over to the PPP GPS automatically?

      Thanks

      RoboBill

    • heliboy > Andrew Tridgell October 17, 2014 at 6:59pm

      Thanks for the info. The other issue that concerns me is that rovers run pretty slow (at least mine does only 1.5-2.5 m/s). At these speeds the GPS derived heading is not particularily accurate. I assume that compass is more useful between waypoints. Does the EKF allows you to assign different relative weights to the compass versus GPS headings ? What is the timeline for a usable piksi rover implementation ?

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