Thin and Multi-object detection using the VL53l3CX within small ranges.

[CWan.1]

I am trying to use the VL53l3CX sensor for multi object detection with thin objects within a small range (<30cm)

I can detect and range a thin target object (2mm) fairly easily however when using a high reflectance screen 10cm behind the target, the sensor rejects the thin target as an

"object" and outputs a range for the screen (although this seems to be slightly less than it should be).

Is this a result of the bin widths on the histogram causing the fairly close together (10cm separation) objects being combined? If so, what is the minimum separation distance (multi object spatial resolution?)

Would switching to Short range mode help at all?

Would it be possible to use the raw histogram to detect these as individual objects?

For reference I am currently using the GUI for the stm32.

[John E KVAM]

To fully detect an independent target, the separation should be 80cm. And I know that's a lot.

So try this....

Use the GUI, and find the button that gives the extra information.

It will plot a min and a max distance.

It provides a 'thickness" of your object. Or maybe a better word would be 'flatness'. It's basically the width of the bulge in the histogram data.

Lets take a simplified example.

Say the laser turns on for 2 clocks. And the object is 2 1/2 clocks away. (time=distance if you discount the speed of light.)

One would expect a bin 3 to contain a half measure, bin 4 to contain a full measure and bin 5 to contain a half measure.

Move the target back by a 1/4 clock, and bin 3 contains a quarter measure, bin 4 a full measure and bin 5 would be 3/4 full.

But if we have your scenario of two objects, bin 3 might contain a half measure, bin 4 a full measure bin 5 a full measure and bin 6 a half measure.

You cannot say there are 2 objects, but you can say there is a min and a max distance to the object.

So use the Eval kit, turn on the extra information and try your scenario.

Then use the logging function and really dig into the data.

You can see the min and the max.

You can use any extra information you have about your project and perhaps dig some data out.

• john

[CWan.1]

Hi John,

Thanks for that.

Using the eval kit you can see the min and max range measurements for objects on the GUI with the extra info turned on but this data isn't recorded in the data log, only "trueRange_cm" is available.

In the GUI manual, trueRangeMean and TrueRangeStdDev are supposed to be recorded but I can't seem to find them.

Am I going to need to use the API to access this info via  "VL53LX_TargetRangeData_t " and "VL53LX_GetAdditionalData" ?