How fast does the senor take a reading? How long do I need to wait between taking another distance reading (1 msec, 10 msec, 100 msec)?
At about 1.5 feet out, how wide is the distance reading? Since it is a “laser”, I was assuming it is a fairly thin range. Given a project I’m working on, it appears to maybe be 6 inches wide. I’m trying to locate boxes, and the sensor is making two boxes that are 6 inches apart appear as one box. At 7 - 8 inches apart, the sensor can detect them as two boxes. Does anyone have specifications how wide the beam is?
Yes, that’s what I meant. +/- 12 degrees from center line.
The sensor switches over to a slightly different algorithm at shorter distances, in that case the FOV is larger, approximately +/- 18 degrees. switch over is at ~8 inches.
Thank you jpearman and RunsWithScissors for the details. That is more specificity than I thought I’d get. Much appreciated.
The FOV is much wider than I anticipated. It does validate what I’m seeing in my program. I definitely got thrown off by it being called a laser. If possible, I’d encourage VEX to create a distance sensor with a much narrower FOV. Ideally, it would be a sensor where you could adjust the FOV.
Does anyone know of any tricks to narrow the FOV for measuring distance? Maybe somehow use two sensors, etc.???
It actually is a real laser on a chip (we define laser as light that is coherent and does not diffuse, because all photon beams have same frequency), it’s called VCSEL (Vertical Cavity Surface Emitting Laser). VCSEL chips are very affordable and simple, also emit more light and consume less power than traditional laser diodes . The other tech is called Edge Emitting Lasers, that’s the ones that make the beam super concentrated (and there’s optics involved as well). Not a scientist just a good Googler, but I’m assuming one reason VEX went with VCSELs (other than low price and increased power efficiency, important to our power hungry competition robots) is because they are not dangerous to human eyes. An IR edge laser can actually leave you blind by burning your retina and you will not even feel it as we don’t have any defense mechanism against that - we don’t blink because we don’t see it and there are no pain receptors so we don’t feel it. Plus with the 24 deg FOV James was able to create that crazy firmware that tells you (with some subjective precision known only to jpearman) an approximate size of the “object” it hits. Also, with a “dot”, if you hit a surface under an angle (like the dimple in this year’s VRC game’s balls), you might lose that “ping” and have to create an insane filtering and error correcting algorithm, whereas with the slight cone, there’s enough info coming back and things are just simple. That being said, the adjustable FOV idea above would be insanely cool. Please correct any of the stupid things I said.