How accurate and precise are Arduplane's groundspeed and heading?

ArduPlane Plane 3.9
1

Hi people.

Assume a plane is flying in a straight line, level flight at a constant power setting. Assume that the GPS unit has a good fix on as many satellites as it needs. How precise and accurate is the groundspeed and heading in Arduplane at any point in time ?

Would the error be random or have a certain bias or distribution ?

How often are ground speed and heading updated ?

Thanks

2

Heading and ground speed based on GPS are very accurate under the conditions you describe. Uncorrected positional GPS shift is slow, so a moving speed or bearing is very accurate. Faster is more accurate. That said Ardupilot heading is a function of the compass or dual GPS inverse. A moving GPS compass is not used as far as I know. It would be excellent for plane or anything that does not stop or hover.
(if gs<1ms then use compass)

5-10hz normally depends on your GPS.

3

Thanks for the reply.

4

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The red line is the speed accuracy is without RTK.

5

I saw that graph.

Are units in m/sec ?

Was the GPS/IMU stationary or moving ?

If it was moving, how do we know that is the error ? What was the “correct” reference from which the error was calculated ?

If it wasn’t moving, how do we know what the positional error is when moving ?

What is the error after the RTK is applied ?

6

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You can see the big RTK improvement for position, not so much in speed accuracy. The speed of your craft is what helps the speed accuracy the most.

7

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Here are results from a F9P (multi band GNSS) without RTK applied.
Speed accuracy is under .2 meters per second.