when exist metal or wall, about tdoa3

All discussions related to the Loco Positioning system
Post Reply
justinleeyang
Expert
Posts: 179
Joined: Mon Dec 28, 2015 5:07 am

when exist metal or wall, about tdoa3

Post by justinleeyang » Sun Nov 24, 2019 4:16 pm

hi,

If there is some metal or wall occlusion in the environment, the TDOA3 algorithm be used, and the positioning is very inaccurate?



arnaud
Bitcraze
Posts: 2275
Joined: Tue Feb 06, 2007 12:36 pm

Re: when exist metal or wall, about tdoa3

Post by arnaud » Mon Nov 25, 2019 4:22 pm

Hi,
Have you seen problems in that situation or are you just wondering if that would be a problem.

TDoA3 measures time of flight between anchors in order to achieve time synchronization, so as long as the inter-anchor time of flight is stable enough and the tag has direct line of sight with enough anchors, things should work quite well.

estrategico
Beginner
Posts: 21
Joined: Mon Aug 13, 2018 3:20 am

Re: when exist metal or wall, about tdoa3

Post by estrategico » Tue Nov 26, 2019 4:34 pm

I use the tdoa2 and tdoa3 in a room with mirrors on the wall and the system has very poor performance, specially when the CFs fly near to the walls (mirrors) and there was a zone where z axis seems to be higher than in others,(all the cfs rise a bit when they flought above that zone).

I change the location (no mirrors) same settings and the precision increase.

arnaud
Bitcraze
Posts: 2275
Joined: Tue Feb 06, 2007 12:36 pm

Re: when exist metal or wall, about tdoa3

Post by arnaud » Wed Nov 27, 2019 9:01 am

Unfortunatly, hard reflection is known to he bard on the UWB tracking. Have you tried to place your anchors a bit further away from the walls and have you tried TDoA3? TDoA3 has a more random ranging pattern which might be able to help in that case.

justinleeyang
Expert
Posts: 179
Joined: Mon Dec 28, 2015 5:07 am

Re: when exist metal or wall, about tdoa3

Post by justinleeyang » Wed Nov 27, 2019 3:09 pm

hi,

Inter-anchors are LOS, but tag and anchors maybe exist occlusion,

kristoffer
Bitcraze
Posts: 176
Joined: Tue Jun 30, 2015 7:47 am

Re: when exist metal or wall, about tdoa3

Post by kristoffer » Thu Nov 28, 2019 9:48 am

@justinleeyang as long as some anchors are LOS from the Crazyflie, it should work. One of the design goals of TDoA3 was actually to handle this type of situation. If the anchors that the Crazyflie receives, are at "good" locations, a position can be calculated.

Post Reply