Human body detection with ToF sensor(VL53L4CX)

Gabor23 · ‎2023-09-11

Hi, I'm new to the community and I hope someone could help me with the following. I was wondering is there any way to distinguish between a human body and a static object, like a piece of paper when detecting obstacles with ToF sensors(e.g. VL53L4CX, VL53L5CX)? Is there a way to detect some sort of body heat or any particular aspect of the body that will differentiate the human presence from other constant entity?

Are there any colour limitations of the ToF sensors such as very dark(black) surfaces that absorbs the photons and hence limiting the reflection of the emitted light?

I've read in some articles that these sensors don't like curved surfaces as the laser beam will not bounce back to the collector...would this compromise the human body detection?

I would appreciate any advise or input and thank you in advance.

Anne BIGOT · ‎2024-01-11

It may absorb most of the light emitted by the sensor, making it difficult for the sensor to detect the object accurately. This is because the sensor relies on the reflection of light to measure the distance of the object. But playing with the timing budget you could get an answer.

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Anne BIGOT · ‎2023-09-15

Hello @Gabor23

Time of Flight technology is based on the measurement of the light to "travel" a distance within a certain time. Knowing the speed of the light, you can easily get the distance by measuring the time of flight. Thus, ToF are not sensible to the color of the object. If the quantity of signal which bounces back to a receiver is high enough, you will be able to measure the distance.

ToF sensors can also distinguish an object moving from a static object thanks to its 1mm resolution and by doing several consecutive capture.

Anne

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Anne BIGOT · ‎2023-09-15

ToF are not sensible to the colour. The technology is based on the time for the light to travel a distance.

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Gabor23 · ‎2023-09-27

Hi Anne, thank you for the information and I really appreciate your feedback. You kind of highlighted my hole point. Certain coulours and surfaces can absorb the emitted photons hence it could heavily reduce the signal what has been reflected. How do we know what is the threshold or tolerance of these sensors? What happens if the object in front of the sensor is a very dark(black) matt surface?

Kind Regards,

Anne BIGOT · ‎2024-01-11

It may absorb most of the light emitted by the sensor, making it difficult for the sensor to detect the object accurately. This is because the sensor relies on the reflection of light to measure the distance of the object. But playing with the timing budget you could get an answer.

Our community relies on fruitful exchanges and good quality content. You can thank and reward helpful and positive contributions by marking them as 'Accept as Solution'. When marking a solution, make sure it answers your original question or issue that you raised.

ST Employees that act as moderators have the right to accept the solution, judging by their expertise. This helps other community members identify useful discussions and refrain from raising the same question. If you notice any false behavior or abuse of the action, do not hesitate to 'Report Inappropriate Content'