improve efficiency of VL53L8CX sensor under direct sunlight ?

[LeeVanDoski]

Hello, I am using this sensor for a project where it is mounted on a cane to detect overhanging objects that could hit visually impaired people. This works fine indoors, but outdoors, when the ambient light is around or greater than 10k Lux—and keeping in mind the sensor is pointed upwards and hit directly by sunlight—it only catches obstacles when they are very close. I am currently using a 4x4 resolution with continuous ranging at 30Hz. My question is: is there a way to increase its efficiency? By efficiency, I mean increasing the detection distance through hardware, structural, or software solutions.

[Bin]

Hi:

Sunlight is a type of noise for TOF sensors. normally the performance of ranging distance will decrease as the ambient light increase. you can refer to chapter 8.2 of the datasheet for detailed information.

For your case, we likely suggest you reduce the ranging frequence to 10Hz or lower and increase the integration time from 20ms. To improve the quality of single frame signals.

Best Regards,

Bin FAN

[John_Kvam · Accepted solution]

The blindman's cane has always been of special interest to me. (but alas, I've retired.)

And the sensor does work - but as you have seen only indoors. 

The trouble is the sensor only really works well indoors. The Single Photon Avalanche Diodes (SPADs) are very sensitive, which makes the sensor possible. To be eye-safe, only a tiny bit of laser light is allowed. And it's why no one minds shining a laser-based sensor at a baby. 

But the sun has no such constraint. That tiny flash of IR light from the sensor is completely overwhelmed by the IR light from the sun. 

There is a VL53L9 coming out which uses a slightly different arrangement. It's got some better sun immunity, but it's bigger, uses more power, and is more expensive. But if you can overcome those issues, it might work well for you.

Go to ST.com and find a sales outlet from the Support and Community tab. Pitch your project.

ST is still limiting the number of projects it takes on before releasing the sensor to the world, but if you were willing to work with them I'd hope that solving your problem would be worth it - even if the economics isn't favorable. 

- john