Marks256 said:
You can't tell me that talking about making expensive, complicated, and downright stupid projects isn't fun. I would think any geeky person would jump on that!
Discussing it is- typing a long one-way conversation about how to do it is not.
Marks256 said:
But i don't think that a ir sensor could detect object upto 40 feet away in the blairing sun now, can it?
Perhaps not, but what are the chances that there won't be an object 5 meters away? 10 meters away? Consider that when you are walking through a room (or outside) you don't really pay attention (as in start to avoid them) until they are within 20 feet or so.
You might start to avoid really large obstacles like walls from much farther than 20 feet, but such large obstacles are easy to detect from far away and you don't need to know their pin point location since they are so big (so sonar works). But for a small obstacle like a wet floor sign, don't try and tell me that you start adjusting your path to avoid it from 40 feet away. Chances are you'd deviate from your initial path within 5 feet of the sign.
And what are the chances you actually need to know where something is down to the sub-degree resolution when it's 40 feet away? To understand what I am talking about, stand somewhere, and point at an obstacle that you have to avoid that is some distance away. Now walk towards it WITHOUT adjusting your finger's aim at the obstacle (since as you get closer you can get more accurate information).
You certainly had no trouble avoid the obstacle even though your initial aim from 40 feet away was off. At a far distance you didn't need to really know where the obstacle was, but as you got closer it started to matter more but it also got a lot easier to get more accurate heading of where the obstacle was. In fact, chances are that you would miss the obstacle anyways if you started walking blindly toward it in a straight line from 40 feet- even moreso if you had wheels for legs.
So unless you only want to take one reading of an obstacle and then avoid it without taking any further readings such accuracy generally y isn't worth the effort or cost. But that's easy to overcome- just continue to take readings as you travel and get closer to the obstacle.
I know where you are coming from though- it's really tempting to find one be-all-end-all laser imager (a.k.a scanning laser rangefinder) that is immune to sunlight, wind, air temperature/pressure, target colour, and target softness so you can detect any and all obstacles within a 1cm to 1km radius with pinpoint accuracy. But it's a lot of money spent on something needless.