Distance measurement

[tobee11]

Hello,
I am in need of a device that can measure the distance between a small sensor and a fixed object dynamically. My objective is to measure the distance from a small, slow-moving object to a wall, etc. continuously as the object is moving. I am working on using a Sharp IR sensor connected to an Arduino board to accomplish this and am wondering if there is another way. Is there a radio frequency solution to this problem? Any ideas are welcome...it would be very helpful if I can figure this out.

Thanks!

Tobee11
San Diego, CA

[airman00]

I'm not sure what you are saying.

do you want a robot to be able to go back to it's "home base'?

some sort of RF question I asked a while back, http://www.societyofrobots.com/robotforum/index.php?topic=1748.0

More details please: size of robot, what the robot should do, your budget, your experience ,etc.

,Eric

[tobee11]

Hello,
My objective is to achieve certain alignments between (2) robots and certain objects in the room. Ideally, I'd like to put a small sensor on each robot along with sensors on the objects in the room and be able to, for example, align the robots so that they are equi-distant from a chair and 10" from one another, etc. My hope is to be able to achieve this alignment down to the millimeter scale. Sometimes the object the robot would be aligning to will be attached on a wall, etc. and will not be near the ground. For this reason, I'm thinking RF would be more desirable than IR.
The size of the robot is small, appx the size of an adult's foot. My budget is not too big, not too small Unfortunately, I am not very experienced....any help is greatly appreciated!

Thanks,
Tobee11

[Admin]

Since there are multiple robots, that rules out sonar (cross interference) . . .

You will need multiple sharp IR to do an alignment . . . get the one that has range of less than 12" for the highest accuracy . . . and you have to make sure that they don't cross interfere, too . . .

[tobee11]

Thank you for your reply Admin.
I would like to throw a few hypothetical wrenches into the situation....
Would the Sharp IR sensor solution work if I wanted to know the distance from the robot (located on the ground) to an object attached to a wall - say, 4 feet off the ground? Wouldnt the sensor need to be pointed (more or less) directly at the object? That is why I was hoping there might be an RF solution - one that wouldnt require pointing sensors and that might have a longer range.

Thanks again!! I really appreciate everyone's help 

Tobee11

[Admin]

It would have to be pointed directly at the object.

The RF solution would have horrible accuracy (several feet at least).

Consider combining multiple sensors, such as a camera for accurate targeting, and the rangefinder for accurate ranging.

[airman00]

probably should modulate the IR sensors , to avoid interference between the two ( or three) rangefinders

[Admin]

you can't modulate them (they already have built in modulation) . . . there are techniques that are done with sonar that you can try, such as patterning.

[ed1380]

radar?
or is that the same as sonar?

[paulstreats]

radio operates in a higher frequency (also some radars operate close to the far microwave range meaning they are unsuitable for use in populated areas. boats usually have to turn their radar off when they go into port)

[Tsukubadaisei]

radar?
or is that the same as sonar?

Radar -> electromagnetc waves
Sonar -> mechanical waves