Search found 90 matches

by kristoffer
Mon Mar 18, 2019 3:05 pm
Forum: Loco Positioning System
Topic: Get distance tag to anchor in TDoA mode
Replies: 2
Views: 84

Re: Get distance tag to anchor in TDoA mode

Hi! In TDoA (Time Difference of Arrival) the data you get is the difference in distance to two anchors. An example: See this image https://wiki.bitcraze.io/doc:lps:tdoa:principles#geometry on the wiki. This is 2D to simplify the graphics, but it can easily be extended to 3D. The Tag is at (0.0, -0.5...
by kristoffer
Mon Mar 11, 2019 1:18 pm
Forum: General discussions
Topic: Use PC Client for 10 Crazyflies
Replies: 3
Views: 108

Re: Use PC Client for 10 Crazyflies

There is unfortunately no simple way to detect if the Crazyflie has found its position or not. There is a "hack" that we often use though (not fool proof) that might be interesting. You will find a python implementation in https://github.com/bitcraze/crazyflie-lib-python/blob/0.1.7/examples/autonomo...
by kristoffer
Mon Mar 04, 2019 1:52 pm
Forum: Loco Positioning System
Topic: Get LPS Node Position via CF2.0
Replies: 1
Views: 70

Re: Get LPS Node Position via CF2.0

Hi! The node positions are available through a memory mapping in the memory sub system, https://github.com/bitcraze/crazyflie-lib-python/blob/0.1.7/cflib/crazyflie/mem.py#L526. Use the memory type MemoryElement.TYPE_LOCO2 and the LocoMemory2 class. The anchor_data member is a dictionary containing m...
by kristoffer
Fri Nov 09, 2018 10:10 am
Forum: Quadcopters
Topic: tdoa data of Crazyflie
Replies: 1
Views: 898

Re: tdoa data of Crazyflie

The TDoA log data is a bit messy, sorry about that. It is unfortunately not possible to get a measurement of the distance from the CF to an anchor in TDoA, what you can get is the difference in distance to two anchors (see https://wiki.bitcraze.io/doc:lps:tdoa:principles). You can calculate the esti...
by kristoffer
Wed Oct 17, 2018 12:28 pm
Forum: Developer Discussions
Topic: Variance of Kalman Filter
Replies: 1
Views: 332

Re: Variance of Kalman Filter

Hi!

I tried it out with the Flow deck and get the same result as you. With the LPS system the variance is changing as expected but not with the Flow deck.

Unfortunately I don't understand why. If you find out, please share!
by kristoffer
Wed Sep 26, 2018 5:26 am
Forum: Loco Positioning System
Topic: LPS System - Altitude Hold (z-position) Problem
Replies: 7
Views: 879

Re: LPS System - Altitude Hold (z-position) Problem

Hi! A shortish answer, we are buzzy preparing for IROS... From your videos it looks like measurements to some anchors becomes noisy when they are "far" away. My guess is that the size of your system is on the edge of the reach of the system (with the current settings). There are two solutions for th...
by kristoffer
Fri Sep 14, 2018 12:45 pm
Forum: Loco Positioning System
Topic: LPS System - Altitude Hold (z-position) Problem
Replies: 7
Views: 879

Re: LPS System - Altitude Hold (z-position) Problem

Thanks for the extensive reply and a lot of useful information! Unfortunately I do not have a quick answer to you problem so I think we will have to do some more testing to try to figure out the root cause. First of all some answers to your questions and random thoughts: aiming to test if there is a...
by kristoffer
Mon Sep 10, 2018 9:17 am
Forum: Loco Positioning System
Topic: LPS System - Altitude Hold (z-position) Problem
Replies: 7
Views: 879

Re: LPS System - Altitude Hold (z-position) Problem

The first step is to make sure the positioning system is working properly, without good positioning information the Crazyflie will not be able to do a good job. You say "nodes 2,5 and 7 (placed exactly like in the tutorial) are turning red" - this is the first thing to address. Even though TWR is fa...
by kristoffer
Thu Aug 23, 2018 6:11 am
Forum: Loco Positioning System
Topic: [Solved] Z-coordinate issues
Replies: 6
Views: 602

Re: Z-coordinate issues

Thanks for the videos! In your second video there is a screen shot of the client and it looks as the Crazyflie does not get packets from all the anchors (three of the small boxes at the top right are red). This is most likely why the kalman filter has a hard time finding the position, it simply does...
by kristoffer
Wed Aug 22, 2018 6:59 am
Forum: Loco Positioning System
Topic: [Solved] Z-coordinate issues
Replies: 6
Views: 602

Re: Z-coordinate issues

What happens if you put the CF at other positions in the space? Is the estimated position wrong in other locations as well?