Using 2 adjacent TFmini Plus LIDARs?

CarlFisher

I'm building an Arduino project to get vehicle counts, speed and direction, but I need a way to detect the vehicles without running rubber hoses across the road. It looks like the TFmini Plus sensors might be good for this application, but I need to keep their signals separate. I've never used these before. Any thoughts on how best to do this? Are the Lidar sensors available that operate at different wavelengths to avoid crosstalk?

Thanks!

Phil Pilgrim (PhiPi)

It doesn't look like there's any way to trigger the unit to take a sample. What you can do, however, is to set the n values of the frame rates to two numbers that are relatively prime (i.e. that have no common prime factors). That way collisions will be minimized.

-Phil

Duane Degn

My first thought would be to use some sort of blinders to minimize light coming from the wrong sensor.
The sensor includes the strength of the received signal so that might be useful in filtering out bad data.

Another idea is add a polarized filter directly in front of both sensors. Rotate one of the polarized filters 90 degrees.
This might block too much light to work but it would be interesting to see if it works.

Mickster

Wouldn't some form of line-array be a better option? Simply offset them?

CarlFisher

The product manual for the TFmini (not the Plus, but they are very similar) offers this in the Q&A:

Q4: Will TFmini-S affect each other when there are 2 TFmini-S work together?
A4: When they are face the same direction and two light spots overlap, there is no effect on each other, but
if the amount is over 2, they will affect each other. When they are face to face, they interfere with each
other.

TFmini:
https://cdn.sparkfun.com/assets/8/a/f/a/c/16977-TFMini-S_-_Micro_LiDAR_Module-Product_Manual.pdf
TFMini-Plus:
https://cdn.sparkfun.com/assets/1/4/2/1/9/TFmini_Plus_A02_Product_Manual_EN.pdf