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Position Tracking
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khundeen View Drop Down
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Posts: 2 		Post Options Post Options   Quote khundeen Quote  Post ReplyReply Direct Link To This Post Topic: Position Tracking
    Posted: 01 August 2007 at 11:17am
Hello,

  I am trying to find solution to help track object location.  The general idea is that I would like to know where things are in the room.  I have heard that it is very difficult to do if I to have very accurate location.
 
  I just wonder if there is any cost effective way to do it?

  For specific application. I would like to be able to track object on a wall.  Imagine I have 5'x3' area and I draw a line to form a 1'x1' grid.   I would like to be able to know if an object move from one grid to another at what time.

  There will be a lot of object in the same grid.

  At first I though that we can have one card reader and it can really tell location on the wall, but it seems to be impossible.

  After reading the book, I though that it might be more cost effective to put the small low frequency card reader on each cell in the grid.

  But now, I will have 15 readers to worry about.  I need some advice on how to configure this and connect it to a computer like you did for the smart shelf example.  I know that we can have up to 256 usb device but this can be very mess if I have to wire every reader to a computer.  That's mean I need very long usb cord or have to put computer right underneath the wall.

  Any advice on how to do this or whether it is possible to do it using the low cost device like what suggested in the book.

Thanks,
Deen
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amal View Drop Down
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Posts: 1528 		Post Options Post Options   Quote amal Quote  Post ReplyReply Direct Link To This Post Posted: 02 August 2007 at 7:56pm

Hi there... this post is all about doing exactly what you are wanting to do. For a moment there, I thought this was a repeat post! The link above is a link to the first page of the post, but the second page is where we start talking about tracking objects on a grid on a wall (the 3rd post down from marrogant).
Amal ;)
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khundeen View Drop Down
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Posts: 2 		Post Options Post Options   Quote khundeen Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2007 at 11:39am
Hi Amal,

  Thanks for providing the link.  It was very good thread.  It seems that my scenario is a bit simpler that I think the size of wall would only be 1 wall. (10' x 5') or smaller.

  This is what the wall looks like this   http://www.jamesshore.com/Multimedia/Beyond-Story-Cards/card s.jpg

  I need to be able to identify each task card.  I also would like to be able to reuse the tags as the finished card will be removed out of the wall.

  After reading the thread, I also think that virtual wall would be better.  However, it seems that it is not easy to change user from using physical task card to electronic task card unless it can perform as good as the physical card.

  For the virtual wall, we could use this device to move things around.  http://www.mimio.com/products/interactive/index.php

  I have to look into the playanywhere to see if it can let us physically move the virtual card from one place to another.  Otherwise mimio should work fine.

  Anyway back to the physical object tracking questions.  In this scenario, user can move the task card (with tag) over the reader in different cell before attaching it on the wall.

  1)  Is the rfid tag or ibutton tag reusable? How much would those tags cost?

  2) For readers, do we need 1 reader for each grid cell?  if, so how could we connect every readers together?

  3) How does antenna works? can we have multiple antennas connect to a reader and able to identify different cell?  Say 1 reader per 4 antennas (4 cells)  This way we use fewer readers.

  4) Is it possible to have multiple readers connect wirelessly to a reader that connects to the computer.

  The more I think about it the more I agree that we should try to change user to use virtual application.  However, the technology is not there yet.  That's why I see that before we get the great virtual application, there should be something in between that help automatically track physical activities.

Thanks,
Deen

 
 


Edited by amal - 08 August 2007 at 9:18am
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amal View Drop Down
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Posts: 1528 		Post Options Post Options   Quote amal Quote  Post ReplyReply Direct Link To This Post Posted: 08 August 2007 at 9:31am

Originally posted by khundeen

1)  Is the rfid tag or ibutton tag reusable? How much would those tags cost?

  2) For readers, do we need 1 reader for each grid cell?  if, so how could we connect every readers together?

  3) How does antenna works? can we have multiple antennas connect to a reader and able to identify different cell?  Say 1 reader per 4 antennas (4 cells)  This way we use fewer readers.

  4) Is it possible to have multiple readers connect wirelessly to a reader that connects to the computer.

Sorry for the late reply, I've got a day job now ;) I like the mimio thing, but a completely projector based solution like the stuff seen in shopping malls would be sweet. Especially if you could touch an item and have a virtual keyboard pop up so you could update it right there on the wall.

In answer to your question:

1) Tags and iButtons are reusable, if you can remove them from the physical card and attach them to a new card. iButtons are a bit bulky, unless you have some kind of card holder or something that you can just remove the index card from and change out for a new/blank one. RFID tags usually have adhesive, so they would be difficult to move to a new index card, but they are far cheaper than the iButtons. You'd have to shop around to get the best price, and buying in bulk always results in lower prices... but tags can be had for around 30 cents to $1.00... even less if you buy in bulk.

2) You could place a single reader in the center of each cell, then when moving cards/tags, you would scan the card/tag first, then place in the cell. By doing it this way, you don't have to worry about reader overlap... the fields generated by each reader would interfere with each other if the readers are too close). You can connect serial readers to your PC through a multiplexer, or if you use USB Phidgets readers, you'd just need enough USB ports/hubs. The other aspect of this project is software geared to handle it.

3) If you up your budget, you can get expensive commercial readers that allow you to connect up to 4 different antennas to represent 4 different "zones", or in your case "cells"... but I think it would be cheaper to connect 4 Phidgets readers to your PC than buy a spendy reader that supports multiple antennas.

4) You could build a wireless mesh network of readers using TTL readers connected to Xbee modules, but I think your best bet for cost, easy software coding, and reliability would be to go the USB Phidgets route.

Hope that helps!



Edited by amal - 11 June 2008 at 11:32pm
Amal ;)
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amal View Drop Down
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Posts: 1528 		Post Options Post Options   Quote amal Quote  Post ReplyReply Direct Link To This Post Posted: 08 August 2007 at 9:43am

Oh, PS... an update to question 4 about wireless... you could do this:

http://www.rfidtoys.net/forum/forum_posts.asp?TID=52&TPN =2

It's not practical for what you're doing as all your readers would be in the same place, but it's wireless and interesting.
Amal ;)
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