Flowdeck with LPS? - Need help with position readings

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h4_n0j
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Flowdeck with LPS? - Need help with position readings

Post by h4_n0j » Thu Jul 26, 2018 1:27 am

Hello all,


I'm working on a research project utilizing the Crazyflie 2.0 quadcopter, Flowdeck, and Loco Positioning System (6 Nodes).
I need help with the LPS readings of (x, y, z) position.

I'm currently flying autonomous missions in which the quad takes off, flies a 1 meter x 1 meter square, and lands where it started.
This is achieved through the use of a Python script, and Flowdeck (for ensured stability).
I also used the LPS to try to measure absolute position data.
Linux is the OS used to execute the flight scripts and quad-computer communication.

I've been trying to obtain accurate position readings utilizing a Python script similar to the one called "AutonomousSequence" (found on my Crazyflie Python library).
I ran my missions, obtained position data via Python shell, and imported the raw data to MATLAB to generate 2D and 3D plots.

All my plots show the central (x,y) coordinates being (1,0). I do not understand why.

Is it because the LPS does NOT actually use absolute positioning? I thought LPS does use absolute positioning.
Or is there anything wrong with my LPS calibration, position set, or defective hardware?



willv
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Re: Flowdeck with LPS? - Need help with position readings

Post by willv » Thu Jul 26, 2018 7:58 pm

I'm trying to fly a similar pattern and have a few questions on your set up: are you using the system with the flow deck on the bottom and the LPS tag on the top? and how stable was your flight with this combination?

h4_n0j
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Re: Flowdeck with LPS? - Need help with position readings

Post by h4_n0j » Thu Jul 26, 2018 8:58 pm

I realized I didn't use the Loco Deck when I originally posted this question. I just performed another flight test with both the Flow and Loco decks (Flow on bottom, Loco on top). The flights were extremely stable regardless if the Loco decks were used or not.

HuzayfaaN
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Re: Flowdeck with LPS? - Need help with position readings

Post by HuzayfaaN » Fri Feb 08, 2019 11:16 pm

Hi,

I am currently working on a project very similar in regards to this matter and and having achieved some what stable and successful flight using LPS (in TWR and 6 nodes) I would like to now make use of the flow deck + LPS deck for further stability. I have spent some time working towards this and have managed to combine a few scripts which use both the LPS deck and flow deck to fly an automated sequence, whilst also acquiring (by printing in IDLE) the X, Y and Z positions during automated flight.

However, it has been noted that 1 to 2 minutes after powering the Crazyflie on, with both the LPS deck and flow deck, the the LPS deck stops working. Whereby the lights on the LPS deck just turn off and the lights on the nodes which indicate communication between the drone and the reference set-up also change (they pulse a steady green as would when not connected to a CF in TWR mode). This indicates that the issue lies somewhere with the LPS deck on board the Crazyflie. I would like to ask if you had experienced any similar issues and if these have been addressed?

Also, how is it that you have managed to firmly connect both decks onto the Crazyflie? I currently have utilised the longest female pins and placed the flow deck below and LPS deck above. However, the LPS deck just about sits on well enough and I believe this may be part of the problem of it disconnecting. However, this is contradicted when I use a z-ranger and LPS deck, as then, the LPS deck remains powered on (unlike when connected in combination with the flow deck).

Any tips and knowledge from your experience with dealing with both the flow deck and LPS deck would be highly appreciated. I am also happy to share the code which gathers the X, Y and Z positions if this has not yet been achieved. Also if you have any good scripts to test/monitor this set up that too would help.

Many thanks,
Huzayfaa

estrategico
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Re: Flowdeck with LPS? - Need help with position readings

Post by estrategico » Sun Feb 10, 2019 7:52 pm

I had the same issue but only in TWR mode, when i change to TDMO2 or TDMO3 the deck have a normal behavior, so i discard that the cause was a bad connection.

I used a flow deck but deactivating the flow information and only using z distance information in the test, with the same results.

HuzayfaaN
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Re: Flowdeck with LPS? - Need help with position readings

Post by HuzayfaaN » Fri Feb 15, 2019 4:07 pm

Hi,

Thank you for your response, I have switched to TDoA2 and it has seemed to have improved performance significantly and the LPS Tag remains connected with a z-ranger

Thanks again

Huzayfaa

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