Ohm On The Go
Going where no Ohm has gone before
Going where no Ohm has gone before
Ohm is a towable cart that measures soil resistivity while in motion, simplifying archaeological fieldwork.
Programming Lead
AUG 2023 - MAY 2024
Brian Duree
Calvin Booth
Josh Losole
Aiden Campbell
Kyle Scott
Current methods of gathering soil resistivity are time consuming, take several people, and require large amounts of effort. Archaeologists would like an efficient method of gathering data to increase the rate of findings. The goal of this project is to design and fabricate a cart which can take these readings while rolling, drastically increasing efficiency of finding underground structures.
Our design includes many gussets and brackets that were cut on the water jet. This design made the cart easy and fast to create.
This is a four-step process, which includes cutting to length, reducing the radius of one end, creating the point, and adding a slot.
The basic frame was made of aluminum extrusion and gussets. The electrode deployment was also made from aluminum extrusion.
The electrodes are placed on an electrically insulating rod to isolate them from the cart. They are then connected to the PCB through a slip ring.
The deployment mechanism consists of a lever to deploy and retract the electrodes, a linkage to connect the front and rear electrodes, and a gas spring to ensure contact with the soil. The lever is at the front of the cart and features a locking pin to keep the mechanism deployed or retracted. This lever directly pivots the two front electrodes from a horizontal to a vertical position.
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The cart uses a Raspberry Pi as its control center, with a custom PCB designed to measure voltage at four points in a square array of electrodes. Voltage flows through two electrodes, while potential is measured at the other two electrodes, allowing for resistance calculations that can detect buried objects. Positional data is provided by an Emlid Reach RS2 GPS, which sends signals to the Raspberry Pi in the ECEF coordinate system.
The GPS data is utilized to update the grid when data is collected. A slider allows zooming to view larger grids. The status bar on the right displays the percentage of the total area surveyed along with the current absolute position of the cart, ensuring precise monitoring and data accuracy.
All surveys are stored according to the date and time of collection for easy identification. Individual surveys can be expanded to display output graphs as seen in the results section. Users can also rename or delete these files and have the option to transfer them to a USB stick for external use and storage.
All Senior Design teams are guided by a faculty advisor and are supposed to report to their respective clients with updates on the project.
