NAV - Use raw GPS velocity in calculations about inav HOT 13 CLOSED

This can be done by using GPS_speed and GPS_ground_course, but code MUST check that GPS unit provide these values - it is not a GGA message, it's a RMC message and it can be disabled in GPS module for some reason.

from inav.

GPS data validity addressed in 6375c485a53eea080cd23bf85c0b0b3a75548305

from inav.

you 'can' disable everything.
but you can subscribe for the velocities in the ned frame:
0xB5,0x62, // Header Turn On UBLOX NAV-VELNED Msg
0x06,0x01, // ID
0x03,0x00, // Length
0x01, // Msg Class NAV
0x12, // Msg ID VELNED
0x01, // Rate 1
0x1E,0x67, // CK_A, CK_B

depends on what you like.

from inav.

The navigation code should not depend on a specific hardware feature (in your example an UBLOX GPS module). If GPS for whatever reason does not provide velocity information, navigation code must still function properly.

from inav.

i just take what works - ublox does and the rest is not so reliable.

from inav.

Sticking with ublox-specific features would effectively remove support for nmea-only gps receivers. We can detect provided information and use what's best - that would be velocity info if available and coordinate difference as a fallback. This will improve things for ublox users and will not break anything for others.

from inav.

Done in 05c115ba6edb79f5f64f8c756c2787d14e1336d0. Untested.
Edit: It just occured to me that this patch also prevents a possible bug with polled GPS (i.e.I2C-NAV). When no new data is available a polled gps module would return previous data, Coordinate difference would then yield zero velocity which will probably be incorrect. Using last known velocity is a better option IMO.

from inav.

Did a test today. Didn't work as good as I thought it will be. However the test was done on poorly tuned copter, so it could be vibration messing up with velocity calculation from accelerometer. Need to re-tune and re-test. If it will work less reliable than coordinate derivative - this will be removed.

from inav.

Did another test today. Was working MUCH worse than plain old coordinate derivative. Closing.

from inav.

the current approach sucks.
bf and cf need a complete rewrite on this subject.

from inav.

@bubi-007
Please assist in getting this working,

from inav.

first i am integrating altitude hold using gps and accelerometer.
then i go into navigation.

from inav.

@bubi-007
Can you please share your code?

from inav.