Week 7: Moo Concrete Deployment [On-site]

Last week was spent mostly on-site at the house setting up the readers and Moo devices for deployment.  We began by first flashing the 20+ working Moos from the lab with the latest working firmware (see past post for details).  Half of the Moos were flashed to default to a temperature sensor and the other half defaulted to the accelerometer sensor.  After recording the status of each device and encoding its unique ID type in the EPC field, Denis began epoxying the devices to ensure their protection from the elements.  Image

After epoxying the devices, we ran some tests to see how water and moisture would affect the tag rate and overall communication with the reader.  We found that when the Moo is completely submerged in water it is not able to communicate with the reader.  This motivated us to perform some additional experiments to see how the the tag rate would vary with the moisture content of concrete.  After obtaining some wet concrete (mixed with pebbles instead of sand), we performed an experiment to see how the Moo would perform as the concrete dried.  We used the thermal chamber (at 65 degrees) to speed up the drying process.  We found the tag rate increase as the concrete began to dry.  We plan on using this test as a baseline for what to expect from the actual deployment process.  Details of the experiment available below.

concrete_experiment_061813

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After purchasing all of the necessary equipment from Home Depot (Plywood, electrical tape, zip ties, power cord extensions, ethernet cables, etc.), Denis constructed the stand to hold the antenna and readers in a vertical position at various heights (2 ft, 4 ft, and 6 ft).

Photo Jun 19, 8 22 52 AM

The rest of the week was spent on-site setting up the readers at the house and waiting as the concrete blocks got built up to a sufficient level on the back wall.  We agreed upon the following positioning for the Moo devices in order to give us maximum coverage and provide measurements near where the wall had cracked in the past.

Moo Placement – Rear Wall View

We decided to use the duraWall ladder (placed every 2 ft high) to attach the Moo directly to the inner front face of the cinder block via a zip tie.  This allowed us to place the Moos as close as possible to the readers – reducing signal attenuation from the concrete.

Photo Jun 21, 9 58 27 AM

Rear wall before cinder blocks got laid (Wednesday).

Photo Jun 19, 12 59 45 PM

Once the contractors were ready to pour the concrete, we immediately began the data logging from the readers to hopefully capture the curing temperature curve of the concrete.

Photo Jun 21, 11 08 06 AM

First batch of Moos get deployed inside concrete (two temperature-defaulted Moos plus a supercapped Moo).  Note: we experienced more difficulty when trying to reader from the supercapped Moo (middle antenna).

Photo Jun 21, 10 37 08 AM

Second round of Moo’s get deployed at 4 ft high level (one accel and one temp)

Photo Jun 21, 4 41 51 PM

Note: we are limited by the number of reader that we currently have on-site (four total) and thus we will not be able to take measurements from more than four Moos at any one point in time.  Since the wall is being slowly built up (and hence cured in the mean time), we are hoping to capture most of the curing process by repositioning the reader antennas as the concrete dries.

Photo Jun 20, 1 29 39 PM

Next Steps

In the coming week, we will continue to remain on call as the contractors build up the rear wall to the 9th row of cinder blocks.  After this point, all eight Moos will have been implanted in the back wall and we can record all necessary data.

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