Is it possible to increase multi-target distance resolution on VL53L3CX?

[GHuan.2]

Hi ST team, I"m developing an application of proximity sensors on a robot with VL53L3CX. The robot moves not very fast and we have already implemented proximity sensors with  VL53L0X on it. Now we want to add multi-target capabilities with L3CX chip.

The problem is we want higher multi-target distance resolution with the new sensor. With some experiments we found the min detected separation between objects/targets is around 70cm, and as I found in previous questions/posts you only formally support 80cm separation/resolution.  If we don't need long range, for example if 80cm to 100cm is the max range, is it possbile to customize a driver to support higher multi-target/object distance resolution for our application?

Thanks in advance.

[John E KVAM]

the sensors work by emitting a train of 2micro second pulses and then collecting the number of photon strikes per clock. Each clock is one bin of a histogram. There are about 4 bins in that 2micro second period. 

For that reason, the two targets have to be separated by 80cm. It's the length of the VCSEL (Laser) pulse.
If the two targets are closer together in depth, the histogram does not show two distinct 'lumps', but one sort of elongated shape. 

From this shape we can warn you that the target is 'complex'. We call it a merged target. But we really cannot tell you more about where the second target really is. 

 the solution is the VL53L8. It has a faster clock, meaning the targets can be a bit closer together - 60cm. But what it has is an 8x8 grid of zones - each 5 degrees square. I'm betting that any second target will show up in an adjacent zone. 

Unfortunately, the VL53L8 is more expensive. But it will solve your issue.

- john