VL53L5/L7CX target status validity

[lukaskn]

Hello,

the VL53L5CX and L7CX ULD guides mention that a target status of 6 and 9 should be considered with a confidence of 50 %, while a comment in the api.h file says that  "5 & 9 means ranging OK", which gives the impression of a higher confidence ration than 50 %. Therefore, my question is: how to exactly deal with measurements with the status 9?

[John E KVAM · Accepted solution]

The user manual says, "

VL53L5CX

• 0 – NO UPDATE (User should never see this)                     ​
• 1 – NO TARGET          ​
• 2 – RANGE PHASE CHECK               ​
• 3 – SIGMA THRESHOLD CHECK           ​
• 4 – PHASE CONSISTENCY              ​
• 5 – RANGE COMPLETE                 ​
• 6 – RANGE COMPLETE_NO_WRAP_CHECK   ​
• 7 – EVENT CONSISTENCY             ​
• 8 – MIN SIGNAL EVENT CHECK           ​
• 9 – RANGE COMPLETE MERGED PULSE    ​
• 10 – PREV RANGE NO TARGETS         ​
• 11 – RANGE IGNORE THRESHOLD          ​
• 12 – TARGET DUE TO BLUR   
• 14 – long tail filter

So 100% is the 5 - that is what you want. 

6 - This is the first range, and in order to do an anti-alias check we need the next range. (They happen in pairs, each half with a different pulse repetition rate. So if you know you cannot have a target more than 4 meters, then 6 is fine. (It only happens on the first range after boot.)

9 - means there is a target and something just past the target. A person standing in front of a wall would do it - if the shoulder of the person and the wall could be seen in the same zone. Only happen is the two targets are within about 60 cm of each other. Beyond that you get two targets. With a 9 we know something is there but are not quite as accurate due to the interference of the second target. 

You might get 7s and 4s with a bright target beyond 4 meters, but you also get it with a lot of motion. 

12 - is an interesting one in that if the edge of an object crosses into a zone by about 17 photons, you have to decide if that zone is occupied or not. The sharpener allows you to decide. If a zone has the same distance as its neighbor but only 10% of the signal, setting the sharpener to less than 10 would discount that target. (You still get the target - but with a 12 status.) 

So I tell people 5, 6, 9, and maybe 12 are good status returns. The 12 just says you found the edge of your target. 

- john