I have a playground of 4 by 3 meters.
There are 4 objects placed in here of which I want to determine
the position. Untill now I did this by webcam tracking from the top
but it is not a good method in a light room. Children will play with these objects, that is why I can not place sensors at the surface.
Besides this postion tracking I want to send a very small amount of data
to my arduino. If the object is pressed or not. Any suggestions, thanks!
Some how you have got to make it work like a GPS.
Eg place a sensor on each of the corners and working how close it is to each corner to triangulate the position.
I'm not sure how you can do that , infa-red or radio wave etc.
Yes I get that. The problem with infrared is though that it needs direct transmitter reciever contact, which is not possible in my case since children will cross through the signal. I am not sure but I guess the same problem will occor with ultra sonic. I have no experience with RF so far. Does the signal get different when somebody is between transmitter and reciever?
I don't think you can do it with the strength of the signal; it should be based on the time the radio signal gets to the sensors.
it should be based on the time the radio signal gets to the sensors.
In a room that size, time-of-flight of a radio signal is less than 20 nanoseconds (1 nanosecond = 29.9cm)
Not sure the Arduino by itself is going to be that much use.
How about a high-power IR strobe, synced to an ultrasonic chirp?
Reflections won't be a problem for the IR, but may be for the ultrasound, unless you can soften the walls, ceiling and floor
OK my two cents worth.
How about an RFID tag in each toy. Then the RFID reader coils can be under the playground surface in a grid of as many coils as you want resolution. You need the sort of tag / reader that can handle multiple tags in the field. You will also need to multiplex the reader coils, activating only one at once. By making the coils large you can greatly increase the range of a passive tag.
No really precise and cheap.
I have the same problem with a different prototype now. It is actually quite simple problem but I can not find a good solution. Let me try to restate it:
I want distance calculation between A and B where both A and B are moveable objects. It is possible that people walk in between both.