Position calculation using only 2 anchors and 1 tag with a known path

Wireless Connectivity Ultra-Wideband
1

I need to find the position of a single tag along a known path. I think I should be able to do that by taking both anchor to tag distance measurements and, using geometry, find the overlapping circles that fall on the path. Will the ‘les’ command give me enough information to do that?

Some initial calibration might be needed in my program but that’s ok.

Regards,
Sam

2

Hi @radioman1000
yes, if the path is know then you can use LES to get the distance between Anchors and TN. Then you can estimate its position.

Just to be sure: You will get this only on TN!

Cheers
JK

3

If I add a listener that has contact with TN would the listener also have the necessary data?

4

Hi @radioman1000
no, listener can show only TN calculated position and that will be NaN.

FYI: the position is calculated on the TN so the is sending the final position and not distances.

Cheers
JK

5

Ok Thanks. Watching the readings on the web page display I do see location values of the TN along with occasional NaNs. If I wanted to extract the TN location values (x,y,z) to a UART, which would be the better way? Modifying the code in the DWM1001 or modifying the code in the RPI?
I have a lot of experience with embedded code but not RPI or Python.

6

To clarify, I will be using 4 anchors for TN location.

7

I have loaded the dwm-range-iot firmware onto the TN after making the suggested changes to the code to send continuous data and also call the dwm_usr_data_write function.
I see all 4 anchors and 1 tag on the web manager.
I am looking at the USB port of the gateway DWM1001 module with Teraterm but see no data in either generic or shell mode. In shell mode I send the udi command to get “show on”. If I look at the message screen of the TN on the web manager I see hex code values rapidly updating in the received box.
Example: 049fca8814000031954913000003c6661c0000b50bd71c0000251826180000000000
What am I missing here?

8

As a solution, I have setup another anchor in passive mode on the network that will pump out the TN position information on the USB port. That should be enough for my application. The bridge configuration works only for the web manager. No need for custom firmware on the DWM1001.