LPS unstable after second Crazyflie join

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Huibean
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Posts: 4
Joined: Tue May 02, 2017 4:19 am

LPS unstable after second Crazyflie join

Post by Huibean » Tue May 09, 2017 6:30 am

Hi Bitcraze,
Currently LPS works fine with One Crazyflie,But after second Crazyflie power on, it becomes unstable and location data no right
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arnaud
Bitcraze
Posts: 1248
Joined: Tue Feb 06, 2007 12:36 pm

Re: LPS unstable after second Crazyflie join

Post by arnaud » Tue May 09, 2017 7:22 am

Hi,
What mode are you running? In the default two-way-ranging (TWR) mode you cannot run more than one Crazyflie at a time.

There is experimental TDMA TWR that sacrifice update rate to fly more than one Crazyflie, this has to be compiled specifically in the Crazylfie.

There is also an experimental TDoA mode that allows unlimited amount of Crazyflie but the anchor placement then become crucial (the Crazyflies must be in the convex hull formed by the anchors). This can be activated in the Crazyflie and requires to setup the anchors in TDoA mode.

Huibean
Beginner
Posts: 4
Joined: Tue May 02, 2017 4:19 am

Re: LPS unstable after second Crazyflie join

Post by Huibean » Tue May 09, 2017 11:58 am

Thanks arnaud, It's the default two-way-ranging (TWR) mode, now I try to set TDoA mode
, compile Crazyflie with config.mk ESTIMATOR = kalman” and “LPS_TDOA_ENABLE=1, then I use Python Client to connect Crazyflie,Anchor 6 \ 7 didn't show up and both distance not display in top
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arnaud
Bitcraze
Posts: 1248
Joined: Tue Feb 06, 2007 12:36 pm

Re: LPS unstable after second Crazyflie join

Post by arnaud » Wed May 10, 2017 8:28 am

Hi,

Did you set your anchors in TDoA mode as well? See the wiki for instructions: https://wiki.bitcraze.io/doc:lps:earlya ... _tdoa_mode

For the number of anchors, the Crazyflie is currently compiled with 6 anchors by default. You will need to modify the Crazyflie firmware for 8 anchors: https://github.com/bitcraze/crazyflie-f ... deck.h#L55 and to set the anchor position: https://github.com/bitcraze/crazyflie-f ... deck.h#L55

Setting the number of anchor should be possible from config.mk in the future, there is a ticket to track this bug (https://github.com/bitcraze/crazyflie-f ... issues/212). In the future we should also be able to set the anchor position in the TDoA anchor the same way we do it in TWR anchor today.

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