And what do you mean by vv?
Oops thats a dutch/latin acronym. It means "and back"
What is the third for?
If you have 3 sensors you can detect an up/down movement and left/right movement but also from upper-left to lower-right.
That means you can generate different triggers as with 3 sensors you have at least 6 possible sequences.
And what is meant by small or large interval?
time. You can state something like
"if two sensors are triggered within 1 second then it is considered the same movement" (small)
"if two sensors are triggered with an interval > 1 second it is considered two movements" (large)
Also was thinking of using these, do you think appropriate?
I think they are at least appropriate to get started, sharp has a whole range of sensors and you must really check which distance you want to detect.
Do not try to be on the edge of a sensors range.
Sorry for all the questions.
No need to apologize, questions that is what the forum is about.