distance & quantity input...what kind of sensor?

I am doing a project that requires the input of distance info and the number of people surrounding a sensor. What kind of sensor should I use? Some kind of sonar......like a Ultrasonic Ping or Ultrasonic rangefinder? I know nothing about this stuff, except that one of those collects more info than the other. Please help.

webcam + some simple form of pattern detection ?

if you’re limited to using an arduino, you could try a narrow beam ultrasonic ping sensor mounted on a servo and do a 360° scan.
then you’d get distance vs. angle as data. assuming you know how “wide” a human being is… and so on. I take it that still would be very crude.

If people are really close and talk, you might just determine their number with a microphone :slight_smile:

thanks for the ideas man....I am using arduino only.

If I did the servo I would be able to use less sensors and save some money. How fast can the servo go and the sensor still be able to produce accurate/trustworthy data?

Ya that's what my teacher said.....a webcam, but he said that I would need Jitter and MAX MSP and that takes some time to learn. I don't think he's going to teach us that this semester.

hm...

as long as you don't move the servo during a single PING all should be ok. if i remember right, those servos can make a full turn in under about 1/2 second, maybe faster. so if you look at e.g. www.sparkfun.com and choose a sensor, you'll get a number for max-range. then it is easy to calculate how long a single scan takes. speed of sound, distance ... just a few milliseconds for a given angle.

if you go that way, maybe visualizing the stuff with "processing" is the way to go. from what I've heard it can talk to arduino boards. drawing stuff seems to be quite easy too.