What is the difference between GPS and Global Position and Local Position?

PX4 Autopilot
1

Hello.
I’m asking you a question because I’m confused while analyzing SITL.
What is the difference between GPS and Global Position and Local Position?
Especially, GPS and Global Positon are similar, but they seem to be used a little differently.

Thank you for your reply in advance.

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2

GPS stands for Global Positioning System. The term GPS is also used to describe the end user hardware (a GPS system) that is used for navigation based on positional data from GPS satellites. Global Positon is used to describe the physical geographical position of an end user GPS aided system.

3

GPS is the “raw” GPS data as provided by the sensor. The global position is the estimate of the EKF2 running and fusing all sensor information including GPS. And the local position is also the estimate of the EKF2 just in the local frame where the estimator is initialized in.

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4

Thank you for your help! have a nice day :slight_smile:

5

Thank you for your help! have a nice day :slight_smile:

6

So the local position estimate doesn’t fuse GPS data to EKF2?

7

The EKF uses GPS and other sensors and publishes global and local position estimates. The global and local position estimates are essentially the same, just in different frames and units.

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