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Current State

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Current state is that we have procured a Beagle Bone, 2 XBees and a GPS module, all of which are working.

The next steps are to: 1. Start writing code for unit testing. 1. Solve the problem of distance measurement between the anchor points and the tags.

jbd's picture

The prototype "anchor point" (and one "ear tag") was in a bag lost by American Airlines on 1 Nov 2012. Its been 3 days since the loss, and the bag has not been located yet. This is a setback for the project (well, at least for my involvement), as it will take a while to find the funds to get replacement hardware.

Up to now I was working on the software: testing the real-time scheduler, latency tests, looking at the serial device driver,... I can continue this work to a limited extent, but I really need the hardware for real answers.

jbd's picture

Evidently, the bag never left Boston! The prototype unit is now in my possession. I'm not sure if it works yet or not, but will find out in a few days.

jbd's picture

Everything in the bag was intact and operating. Now back to work for me!

Louis's picture

That's a relief!

jbd's picture

After discovering that the real-time scheduler was not in the Angstrom distribution shipped with the Beaglebone, I've decided to pursue the statistical method of determining position. There are several other reasons for this:

  • It allows for better portability between platforms.
  • Removes the need for a fast processor.

Note that I'm still planing on using the tri-lateralization method of determining exact position (versus the triangulation method frequently mentioned in this project), but the various legs will be measured using statistical methods instead of direct time-of-flight.

The downside(s):

  • Coding time will be longer for the anchor points.
  • Testing time will be longer.
  • It will take a lot of additional testing to establish reasonable baselines for statistical measurements.
  • It will require more "samples", which will probably adversely impact battery life on the remote sensors (ear tags).
jbd's picture

I've gotten the "pingtags" application coded and working. But now I have to build out more hardware for a better test. This means eartags and more base stations (anchors).

What people won't be seeing is all the software I had to write to figure out the Beaglebone Black, GPS and XBee's. But I hope most of that is now past.

jbd's picture

I've got most of the software written, but have run into some design problems (turns out tracking time-of-flight for XBee radios won't work), which will require some software re-writing. But, I'm making lots of progress. 

Goal is to have a demo by the end of December.

jbd's picture

Well, I've got 3 base stations and 5 ear tags working. Still waiting for nickel & dime hardware (connectors for batteries, boxes, ...)

The base station software is 95% complete - all that's left is (maybe) coding the failover logic when we lose wi-fi access and including the time-of-flight numbers for each ear-tag (even though it will be wrong).

Also, configuration of the system is non-trivial, so I'll probably have to code some auto-configuration logic into the system - but not before the end of the month.

The ear tags are a lot heavier than I wanted; the batteries are over 2/3 of the weight, but I wanted 1 mile distance between tags, and that consumes a lot of "juice". I may be able to conserve power by setting sleep intervals for the tags, but not in the first release!

Otherwise the base stations and "ear tags" are ready for outdoor testing. I just have to cut holes in the boxes and shrink wrap the ear tags. Then we can do some testing - so probably not until next weekend!

I expect to publish all the code and do presentations in January 2016. And maybe do some documenting...

The images are of a base station (out of the white weather-proof enclosure), and a top view of the base station. The last picture is of the "ear tag" transceivers - left one is a debugging connection hooked up to the computer, and the right one (with battery) will be shrinked-wrapped and applied to an ear tag.