Introduction: ROV Frame and Propulsion
The ROV team must design and construct an ROV system that is capable of being submerged and remotely performing tasks like picking up underwater rings using a mechanical arm and placing them into crates in separately designated locations. Each team member is given a certain task and area of research and development. The rationale below is focused towards the area of frame and propulsion for the ROV. Summer work involving research and development and two months of joint team meetings have contributed to four separate designs for the ROV frame and propulsion systems.
Alternate Solution 1 
Introduction
Alternate solution one resembles a rectangular prism using
PVC piping as the frame. The top front section is missing to reduce drag; it is
also non-essential for structural support since PVC is used. The piping is
jointed together using 90 degree and three way joints. A cross section is
located in the middle of the frame. Two motors for horizontal propulsion and
one for vertical propulsion are placed on the cross section. The top of the
frame holds ballast for positive buoyancy.
Pros
Solution one is stable and relatively easy to maneuver due
to the cube like shape. The geometric shape makes solution one easy to
construct and design. Solution 1’s hydrodynamics through the water is also
stabile due to the shape and location of vertical and horizontal propulsion.
PVC construction also makes design one relatively cheap to build.
Cons
Solution is simple yet effective but does not specialize for
any type of mission. The shape and location of propulsion is typical of most
ROV’s and is not special for any one mission. The only adaptation for a
mechanical arm is the absence of the top forward cross section. The prism like
shape also makes the ROV look boring and gives the wrong mood for the mission.
Conclusion
All in all, solution one is a good, simple and sturdy
design. Yet, it is too generic of a ROV for the specific mission and use of a
mechanical arm. The prism like design also gives the incorrect mood of exploration
and adventure. But the construction of PVC makes constructing and purchasing
materials very easy.
Alternate Solution 2
Introduction
Alternate solution two is constructed of plastic pieces from
common physics demo kits. The plastic pieces themselves are perforated with
small holes through the entire length of the rods. The frame is in the shape of
a cube with two support struts at the rear of the frame to provide stabile
mounting for the propulsion systems. Empty film canisters serve as positive
buoyancy ballast atop the frame.
Pros
The cube shape allows for easy handling and maneuverability
through the water. The use of plastic physics kit pieces makes purchasing
materials cheap or easy to look for. The plastic physics kit pieces also make
the frame easy to build and manipulate wherever needed.
Cons
One drawback of design two is the cube shape. The cube shape
prevents room for a mechanical arm to maneuver within the frame and allows for
less room to mount equipment. The method to assemble the pieces also reduces
the amount of weight it can carry since the plastic rods cannot stick together
with too much stress.
Conclusion
In conclusion, design two provides a small cube like frame
made of plastic physics kit rods. It allows for easy assembly and purchase but
it means that it is weaker and has structural issues. The cube shape gives some
more structural integrity but it also hinders the movement of a mechanical arm
and room to mount potential equipment.
Alternate Solution 3
Introduction
Alternate solution three is slightly different from the
other solutions. Design three also uses PVC piping and pool noodles for
flotation, but the shape is what sets it apart. The bottom of the frame is a
flat rectangular plane. The frame possesses wing like projections, which are
flared out from the bottom of the frame at a forty-five degree angle. At the
top of the “wings” are the foam ballast to provide some positive buoyancy to
the craft. The horizontal propulsion motors are located at the rear of the
“wings”; the vertical propulsion motors are located toward the left and right
sides of the bottom of the frame.
Pros
The PVC construction of the frame makes purchasing materials
cheap and construction simple. The wide and positively buoyant top of the craft
make the entire frame very stabile. Since the base of the craft is heavier and
narrower than the top of the craft, the frame remains steady during maneuvering
due to basic physics. The wide top and narrow base also gives much more room
for the mechanical arm to maneuver and to mount electrical equipment on the
frame. Horizontal propulsion is located mostly toward the rear of the craft to
account for the weight of the mechanical arm and the vertical propulsion is
located in the middle of the craft. The locations for propulsion make handling
smoother.
Cons
The wide top and narrow base of the frame may make
maneuvering and steering stabile and smooth but speed is slower. The wider the
frame the more drag is in the water. Although the horizontal propulsion
compensates for the weight of the mechanical arm, it also means that left and
right turning is not very accurate since steering is not located directly in
the middle of the frame.
Conclusion
Overall, design three is the most stabile of all four
alternative solutions. The splayed “wings” allow for greater control and
stability of the craft during maneuvers and allows for more to mount the mechanical
arm as well as electrical equipment. The PVC construction makes purchasing
parts cheap and assembling them easy. But, the wide top frame makes turning
slow and cumbersome. Horizontal steering located towards the rear also makes
turning a bit of a hassle.
Alternate Solution 4
Introduction
Design four is also constructed of PVC piping for the frame.
The entire frame is essentially a flat plane. The top of the frame uses empty
bottles, which can be filled or emptied of water to control buoyancy on the
craft. The bottom of the craft has small PVC pipes, which can be filled with
weight to further help balance the weigh of the craft. The middle of the frame
is empty and filled with either plastic or metal netting to allow equipment to
be mounted in the middle of the rectangular frame.
Pros
The frame is very cheap and easy to manufacture. Parts are
easily accessible and equipment can be easily mounted to the frame.
Cons
Since the frame has no vertical structures the frame is
somewhat unstable. Balancing the craft is hard and the movement of the
mechanical arm may cause the frame to list during maneuvers.
Conclusion
To conclude, the design is essentially too simple for the
tasks the ROV must be able to perform. The flat plane design is too unstable
and risky to use. But the PVC piping with weights is a great way to help bring
the frame to neutral buoyancy.
Overall Conclusion
After using a rationale chart to determine the highest scoring designs, design three had the highest point score. Design three of all four designs was the most stabile because the ballast system was spread farther than the base of the ROV frame. Because the ballast is removed farther from the actual frame and there is no overhead support struts or structures, the ROV frame allows for more storage capability in terms of electronics and mechanical equipment such as a mechanical arm. However, the wide ballast structure also makes turning slightly more difficult. Lastly, an additional PVC pipe running down the center of the frame needs to be added due to mounting concerns for the mechanical arm.
