proximity-sensor
I am looking for a sensor that could be mounted on the front of a car, to tell the distance to the car ahead, to detect safe driving distance.
I was thinking of the possibility of a laser perhaps, but I am unsure of where to get a sensor like this, or if I am going to have to build my own.
What are some feasible and inexpensive ways/products to sense this distance?
Please note, I do not intend to break the rules by asking for specific products, I am just asking what should I search for.
Mouser's latest mailing mentioned this one: Vishay VCNL4000. For the price of the proximity sensor you also get an ambient light sensor. 4mm x 4mm, 0.75mm high, though it has three blobs on it which make it somewhat higher. Still looks like it's less than 3mm.
Detection range for the proximity sensor is only 20cm, though.
disclaimer: the mention of Mouser is not a shopping advice :-)
Russel has some good ideas, but not sure about feasability. I would suggest a safe way to treat bats is to tell them to keep out of the 50 m radius with an ultrasonic distress signal known to bats. the they will avoid any collisions and you don't need any fancy remote monitors. Or just jam the airwaves on the Bat's comm channel with piezo tweeters with pulses filtered from 25 to 100Khz at a variable rate from 100 to 1KHz and then. go test it near a cave of bats at night and consult with experts and get testimonials.
Best Answer
Pretty sure they use radar for adaptive cruise control in cars. Check this sensor out:
I've heard them called "headway sensors" or "radar headway sensors". There are other technologies like acoustic but I'm not sure if they'll have the range you're looking for. Laser could work but it's aim is pretty narrow, dust dirt and fog can get in the way etc.
Good Luck!