Let's Make Robots!

IR vs Ultrasonic Sensor

I have used ultrasonic sensors in the past. However, i have noticed they have a wide arc of vision. I want very precise sensor readings for my new project, and I was curious as to the pros and cons for either sensor option, or something else. I am mainly looking for affordablilty and precision.

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IR is definitely not so cool for projects outdoors, the ambient light would literally "troll" your project :D 

But it is pretty efficient if your project is taking place indoors. 

For eg: line following indoors using IR would be great, but outdoors, without any shielding or other measures, it's a bad idea.

I have used the HC-SR04s. They are accurate, but i wouldn't say that they are totally efficient. I guess the nature of the surface would determine the results. I got constant readings without any flaws on a perfectly smooth surface, however, results varied a lot when the surfaces where rough or bumpy.

What project is it that you are trying to implement ultrasonic/IR communication?  

It is an indoor robot, so that is not a problem. The surfaces will be relatively regular. What I am looking for is the narrowest beam possible.

I think that particular sensor works by sensing the amount of IR reflected by the target. It doesn't really give accurate distance measurements if your targets aren't all identical.

IMO, those are more useful for sensing if an obstacle is present, not how far away the obstacle is. 

I've seen foam wrapped around one of the transducers used to narrow the area scanned. IIRC, they wrapped the material around the receiving transducer.

Something like Parallax's Laser Range Finder is another option for precise distance measurement.

I really like OddBot's laser range finder. It's another option but probably not a simple solution.

I think the easiest and least expensive option for a laser range finder would be use a laser with a Wii camera.

Thanks for the help.

Blinkers..we called'em blinder's.. ;)

heres something else to think about ..Native people carved a narrow slit into a whale rib and made goggles ..The tiny slit would only allow a little light through ..this prevented snow blindness....

Light and sound ..two different things ..but wave's none the less..

a guy could probably experiment with something as simple a black tape and foam food trays to get a sweet spot with either sensor.

because the inuits weren't emitting the lightwaves they were shielding out from their eyes-try to do this with an ulttra sonic and it will only read up to the slit.  Even a golf pencil placed between the cups will cause the maximum distance read to be the end of that pencil (an experiment I tried recently.)  I would imagine results would be much the same with SharpIR.

To do what you want to do you need to blinker your horse. That is, to limit it's view. It probably won't work well with an IR rangefinder because they use triangulation and blinkers will prevent the triangulation from working at close distances. Ultrasound range finders will work better for this.

You will need to blinker the receiver but not the transmitter so it can only receive a soundwave reflected back from an object directly in front of it. You might need some sound absorbing material like they use in speakers.

 

Their setup would be very useful for getting precise readings.