# Problem with EKF position estimation

**URL:** <https://discuss.px4.io/t/problem-with-ekf-position-estimation/3043>\
**Category:** Flight Testing & Log Analysis\
**Created:** [April 17, 2017, 4:11pm UTC](https://discuss.px4.io/t/problem-with-ekf-position-estimation/3043 "2017-04-17T16:11:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Firefly](https://discuss.px4.io/user_avatar/discuss.px4.io/firefly/32/6553_2.png) [@Firefly](https://discuss.px4.io/u/Firefly)\
**Post date:** [April 17, 2017, 4:11pm UTC](https://discuss.px4.io/t/problem-with-ekf-position-estimation/3043/1 "2017-04-17T16:11:04Z")

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Hello,

I’ve entered some strange issues with my copter with flying in offboard mode. Sometimes it flies away not taking into account velocity setpoints from my program. During log analysis I found that local position is calculated wrongly, the data from my accurate gps(its rtk) is somehow ignored. What can cause it? And could you advice me a proper way to analyze EKF working process? I found parameters EST\*, but I couldnt find their descriptions.

Here is image with GPOS\_Lat vs TIME\_StartTime (red continues line) and GPS\_Lat vs TIME\_StartTime (dashed line)

 ![](https://discuss.px4.io/uploads/default/original/1X/5f47f0e47465060ccd7e2ec126f7e9e31e2bf6e9.jpg)

Thank you in advance,  
Firefly

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**Author:** ![shawinmihail](https://discuss.px4.io/letter_avatar_proxy/v4/letter/s/f0a364/32.png) [@shawinmihail](https://discuss.px4.io/u/shawinmihail)\
**Post date:** [April 18, 2017, 4:43pm UTC](https://discuss.px4.io/t/problem-with-ekf-position-estimation/3043/2 "2017-04-18T16:43:40Z")

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Hi. i have the same problem. pls, let me now if u can fix it =)

> [@EKF solve gaps](http://discuss.px4.io/t/ekf-solve-gaps/3033):
>
> Hi there. I trying to solve problem with ekf. Deal is i have bad solution ekf pose estimator GPOSE (with gaps) when GPS data is accurate. I have no idea what the reason. May be someone can give me advise how I can analyze it or what can be the reason. x,y,z red - gpose green - gps lat(t) red - gpose green - gps would be thankful for any idea or help P.S. unfortunately i haven’t a new log format file, only old “.px4log”