Sorry if I am not following guidelines.
I am a noob trying to build a Robot for learning purposes – I want to play with navigation algorithms using particular measurements – distance to the obstacle along a straight line. I know there are many other ways to skin the cat, but I want it this way.
I have been looking online for a sensor that would help me, but there are so many options and none of the are ideal. My requirements:
- Can sense distance between 1 foot (30 cm) and and 15 feet (5m); ideally between 10 cm and 10 meters (I'll accept infinity as the upper bound 🙂 ).
- Is directional, not shotgun-like. Ideally, at 10 feet (3 meters), the sensor would bounce back if the bounding sphere the size of a tennis ball would contain a wall. (Hopefully this makes sense – this translates to a cone with a certain angle).
- Is small – no bigger than a human eyeball including casing.
- Is low voltage/power – so that I can make it draw power from a usb cable, perhaps adding some sort of converter, but hopefully not.
- Functions in complete dark, or near-dark.
- Is under $20 per piece (I might buy 10 in bulk).
- has distance resolution of at least 10 cm (4 inches); higher is better.
It does not have to be sample the data very fast; even 10 times per second will do.
Hopefully this question is withing the guidelines. Again sorry, I do not have previous robotics experience.
Best Answer
I think you might have to compromise on at least one of those requirements. The normal way of doing this sort of thing on small robots is ultrasound, e.g. http://dx.com/p/ultrasonic-sensor-distance-measuring-module-138563
That fails your "directionality" and probably "size" requirement, but is cheap and effective. There are smaller, narrower ones: https://www.sparkfun.com/products/639
If directionality is really important, I don't think there's any substitute for doing it with a laser. There's a discussion here: Any published designs for time-of-flight laser distance measurement , but the engineering involved is not simple and I can't find any modules implementing it. The "time of flight resonance" technique looks best to me, although the round-trip time for 15cm is 1ns => 1GHz signal. That's going to make for tricky PCB design and isn't feasible for a beginner.