Project Purpose
Mines have historically been the
industrial centers of many communities. As these communities
have sprung up around mining “booms”, they also have had to
learn to re-adjust during “bust” periods. Dr. Timothy
Scarlett, in large part the inspiration for our project, has
an idea that might make these communities centers of
industry again: using abandoned mineshafts as enormous
batteries.
Energy demand isn’t consistent throughout the day. There
will be times when the power being produced will exceed
demand and excess power gets wasted. Some power plants, such
as one in Luddington, MI use reservoirs where water is
pumped to higher elevation during times of energy surplus
and drained through a turbine during times of energy
deficit, using water for energy storage similar to a dam. A
flooded mineshaft is a pre-excavated reservoir, with lower
levels filled with water and upper levels available for
water to be pumped to.
Consider the growing renewable energy industry. Energy
storage is a huge issue with renewable energy because in
many cases the production is even more inconsistent than the
demand; it’s not always windy or sunny. Conventional
batteries are not economically viable for energy storage
plants, and reservoirs are expensive to build. On the other
hand, according to Dr. Scarlett’s research, there are
hundreds of flooded mineshafts in the US that could be
suitable for conversion into Pumped Underground Storage for
Hydropower (PUSH) facilities, and these may be able to be
converted at a fraction of the cost of a conventional
reservoir.
Before a mine can be converted into a PUSH facility,
however, it must be inspected. There are several factors
that need to be considered for a PUSH facility, most
important being structural integrity of the mine. Most mines
are far deeper than can be explored by a conventional diver.
To explore Quincy Mine for example, it's an 8000 ft trip to
the bottom, and that’s not exploring tunnels branching out
to either side. A Remotely Operated Vehicle (ROV) or more
likely an Autonomous Underwater Vehicle (AUV) of
extraordinary robustness would be instrumental to the
exploration of these mines.
2022-2023 Project Focus
This is where we come in: a robust,
deep-diving robot that’s designed for an environment more
unforgiving than the expanse of outer space: enormous
external pressure, no communication, no recovery if
something goes wrong. Differences in water temperature at
different depths cause currents that can pull our robot in
changing directions. No GPS means that our robot may have
to localize from its environment which means more computing
power. But more computing power means more space, weight,
energy consumption, and cooling requirements. But how do you
cool an enclosed capsule surrounded by 90 degree water?
These are the sort of problems that our team needs to
tackle.
This year we aim to develop our prototype to gain credibility
for our project, as well as practice building a robot.
Mechanically, we plan to develop our prototype’s
localization, testing for mobility in 3 dimensions, and
modifying our robot to maintain position and heading in
dynamic currents. Much of this testing is planned to take
place in the MEEM wave-tank.
For our electrical system, work needs to be done to make it
more robust with over-current protection. Sensors will also
be tested for accuracy, and more will be integrated into our design.
Mechanical system
The prototype above was designed in CAD,
and then constructed using an 80-20 frame, and components
such as thrusters and water-tight capsules. The prototype
uses “vectored thrust”: two thrusters on the x-y plane at 90
degrees from each other. Combinations of thrusts from these
two thrusters can result in translational or rotational
motion. Two z-axis thrusters are used to adjust for depth
and pitch of the robot. To design for the robot’s center of
rotation, the CAD model was used to estimate the robot’s
center of gravity. Counterweights have been considered as a
way to shift the robot’s center of gravity to the center of
the robot.
ELectrical & Power System (EPS)
The current electrical system for the
DIVER prototype is a Raspberry Pi-controlled system, with a
LiPo Battery, power distribution board (PDB) and peripheral
devices as shown in the flowchart above. The LiPo battery is
a 6S, and the PDB manages power between the electronic speed
controllers (ESCs, not shown) for the thrusters, to the
lights of the system and to the Raspberry Pi. The rest of
the peripherals get power from the Raspberry Pi. The
Raspberry Pi communicates with a shore-side computer where
user-input is fed to the DIVER.