Triangulation with 3 DWM1000

Hello. I have three DWM1000 sensors, two anchors and one tag. To know the position of the person, I only have to obtain the distance from the person to the two anchors, but the direction is unknown, that is, it can be forward or backward. How do I know if the person is in case 1 or case 2?

Does the DWM1000 module say the address? Otherwise I think I will have to use an extra sensor. What dou you recommend?


I’m going to explain myself better.

I have 2 anchors and 1 tag in total. I’m making a person follow robot like this: Follow me - part 4 | Details |

The two anchors are inside the robot:

I have to follow the person who is the one with the tag. How do I know which of the following two points the person is on? Should I place another sensor on the robot or where?
case copy

As you can see on that person’s page: Follow me - part 4 | Details |

It says that by default the location of the label will be programmed in front of the two anchors and that is what it takes, but, in my robot, the person can be in front or behind. How can I find out the correct address?

Because the robot thinks that in theory the person is in CASE 1 and in CASE 2. What is the person in reality? Let’s say the person is CASE 1, how do I say that to the robot?

You are quite correct, with only two measurements and an assumption that the problem is 2d there is an ambiguity as to where the person is.
Adding a 3rd range would fix this issue but also add cost and complexity.

The other option is to use it by remembering the system state. If the person is in front of you for one position then as long as your measurement rate is high enough they will probably still be in front of you for the next position. If you can keep rotating so that they can’t ever get to the point where they are in line with your antennas then once you know which side they are on you will always know which is the correct solution. For a following robot you would probably want to rotate to face them all the time anyway so this requirement shouldn’t normally be an issue.

If on start up you can’t be sure then ask the person to remain stationary and move forwards or backwards a small amount, that should make it obvious which is correct. If you had a simple buzzer or light on the robot you could use this to indicate to the user that it’s lost track of this ambiguity and to remain still while it works things out.

Or you could go for the really simple solution, always assume they are in front of you not behind. If you try following them then it should very quickly become obvious that you’ve made an incorrect assumption.

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Thanks for your help. I solved that problem (in theory) with 3 anchors. Now I have a new problem and it is in relation to the connections, you can see it here (I separated it so as not to mix the topics).

Thanks once again.