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MStra.8
Associate
July 21, 2022
Question

Is there any kind of document / application note for VL53L5CX available to guide how to calculate the number of sensors required given the ceiling height and the passage width?

  • July 21, 2022
  • 3 replies
  • 1077 views

We need to understand the best topology / positioning when considering some different situations, for example:

1) passage with of 0.8m with ceiling height of 2,60m

2) passage width 1,5m, ceiling height of 2,60m

3) passage width of 3m with ceiling height of 2,60m

4) passage width of 6m with ceiling height of 3,5m

Thansk

Mauricio

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3 replies

John E KVAM
ST Employee
July 21, 2022

Mauricio -

The Field of View is 45 x 45 degrees. The light goes out in a pyramid. So at 2m there will be a 2m x 2m square of light on the floor.

You get an 8x8 grid of answers corresponding to that the sensor 'saw' within that pyramid.

0693W00000QLoUbQAL.pngThink of it like this. If your passage is thinner than the image shown, then the zones at the edges will include some of the wall. Something like the figure below.

0693W00000QLoUqQAL.pngIn one of your examples you said the height was 3.5m. That would make a 3.5m square on the floor, So you would need two of them to cover a 6m wide passage.

There is a little trick in that this does not provide much coverage if the person walked very, very close to the wall. It is possible that one could sneak past the sensor.

Some experiment is required to prevent this. Perhaps an additional sensor would be needed to solve this.

So do the geometry. Note that the sensor will not resolve small objects at large distances.

So if only an ankle is in the Field of View at 3 meters, the sensor will not detect it.

 Good luck - it's an interesting problem.

John E KVAM
ST Employee
July 21, 2022

There is also a document that explores some of these issues although with the older VL53L1X sensor.

You might want to look at that.

STSW-IMG010 - PEOPLE COUNTING SW code example for VL53L1X - STMicroelectronics

MStra.8
MStra.8Author
Associate
July 21, 2022

Hi John, thank a lot for all information.

That was very helpful

Best regards