Hi -- it's unclear to me from the docs on the wiki whether 8 anchors are strictly required for TDoA 2/3 to work, or whether they just work better with 8 anchors. I've only got six anchors - am I limited to TWR or should I expect TDoA 2/3 to work too?
Thanks!
Anchor count for TDoA v2/v3
-
- Expert
- Posts: 153
- Joined: Mon Dec 28, 2015 3:23 pm
- Contact:
Anchor count for TDoA v2/v3
http://www.thejumperwire.com
Tips, tutorials, and science about DIY electronics, drones, and embedded software.
Tips, tutorials, and science about DIY electronics, drones, and embedded software.
Re: Anchor count for TDoA v2/v3
TDoA works best when the Crazyflie is within the convex hull, ie. within the space formed by the anchor. This is why 8 anchors is better: it is very easy to make a 'cube' convex hull. With 6 you can make two triangles, one on top and one on bottom, and you will have a decent convex hull. So in short, it will work with 6 anchors.
However it still works outside. You will just get more noise in the direction escaping the convex hull (I am not sure how to express this one . For example if you are outside on the Y axis, you will still have quite good position in X and Z, but the Y axis will become more noisy the further away you go. If you have more sensor like the Z-ranger, is is possible to put the anchors mostly on the top and use the Z-ranger for height (as long as you are in range ...).
However it still works outside. You will just get more noise in the direction escaping the convex hull (I am not sure how to express this one . For example if you are outside on the Y axis, you will still have quite good position in X and Z, but the Y axis will become more noisy the further away you go. If you have more sensor like the Z-ranger, is is possible to put the anchors mostly on the top and use the Z-ranger for height (as long as you are in range ...).