EKF variance and CMSIS nan values

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Guglie
Beginner
Posts: 7
Joined: Mon Mar 26, 2018 5:23 pm

EKF variance and CMSIS nan values

Post by Guglie » Tue Jan 15, 2019 11:39 am

Hi, I've noticed that sometimes the EKF reaches high variance in

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stateEstimatorScalarUpdate()
and that leads to a filter reset.
This is due to

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mat_mult()
(from CMSIS-DSP library) returning inf or nan values sometimes.

Have you experienced the same thing? How can I reduce this to achieve better positioning?



arnaud
Bitcraze
Posts: 2046
Joined: Tue Feb 06, 2007 12:36 pm

Re: EKF variance and CMSIS nan values

Post by arnaud » Wed Jan 16, 2019 9:02 am

With what firmware version have you observed this?

We have seen some occurence of the EKF diverging mostly when starting the Crazyflie well outside the TDOA system. We have tried to isolate the points where a NaN could appear and solve it over time but maybe there is still some left.

Can you see a pattern of for when this kind of problem happen?

Guglie
Beginner
Posts: 7
Joined: Mon Mar 26, 2018 5:23 pm

Re: EKF variance and CMSIS nan values

Post by Guglie » Wed Jan 16, 2019 11:24 am

Hi arnaud, thanks for your reply,
So the matrix multiplication from CMSIS library is known to have some specific values that do not work?

I'm using a custom firmware to understand and maybe test sightly changes of the TDoA2 localization algorithm, can you explain (or point me where to look at) how you isolated the points and solve it?

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