Brainstorming

All three designs for the frame and propulsion of the ROV are similar in several ways. One way is that all of the frames are skeletal in nature. What the means is that there are no outer covering on any of the designs, only the frame itself. Also, all of the ROV designs are meant to be made of aluminum structure. Another way they are all similar is that for propulsion, a propeller is used rather than any other instruments of propulsion. In all designs, supports can be added for the cameras, lights, robotic arm, etc.

The first design is shaped like a rectangular prism. The propeller is located inside the structure of the ROV. It is also located in the rear of the ROV to push the ROV forward.

The second design is similar to the first. The structure is shaped like a rectangular prism. This design also has a tail, onto which the propeller is mounted. The propeller pushes the ROV like in the first design. However, in this design, the propeller is located on the outside of the structure rather than inside.

The third design is also rectangular in nature. Rather than having a tail, this design has an aluminum nose. The propeller is located inside the nose of the structure. From here, the propeller pulls the ROV rather than pushing. This will provide more control over the ROV, similar to how front wheel drive has more control than rear wheel drive in automobiles

Testing Procedures

Expectations:

There will be a number of different aspects of the underwater ROV that will be tested before competing in the MATES competition. The testing procedures will be done at the Monmouth University swimming pool located on campus in the gymnasium. The ROV structure will be expected to support the weight of every object that will be mounted to it. The ROV propulsion will be expected to move the ROV in all directions, with and without added weight. The following testing procedures are specifically for the structure and the propulsion of the underwater ROV.

The picture above is the Monmouth University Swimming Pool
(Photo taken by me and my teammate)

Set-up

1. Assemble structure if necessary


2. Mount the propellers, robotic arm, video cameras, ect. to the structure


3. Attach tether to the ROV
   

Structure Testing Procedures

1. Add ten pounds to structure to make sure it is supportive.


2. Lift the ROV with two people to make sure it can be lowered into the water without a mechanical aid.


3. Put into water for buoyancy check. The ROV should have slight, positive buoyancy. This means that it will stay submerge to about 3 feet and then stay afloat there. If the ROV fails to submerge to 3 feet, then weight will need to be added to the ROV. If, on the other hand, the ROV sinks too deep, then a positively buoyant substance will need to be added to the ROV.
   

Propulsion Testing Procedures:

1. Move the ROV forward. Observe whether the ROV falls off to the right or the left.


2. Move the ROV in reverse. Observe whether the ROV falls off to the right or the left


3. Have ROV turn right


4. Have ROV turn left


5. Have ROV submerge all the way to bottom of swimming pool.


6. Have ROV surface from the bottom of the swimming pool.


7. Have ROV submerge to bottom again. This time pick up a 10 pound object from the pool floor.


8. Have the ROV surface from the bottom, while holding the 10 pounds object.

Summer Research

Buoyancy:
If the weight of an object is less than the weight of the fluid the object would displace if it were fully submerged, then the object has an average density less than the fluid and has a buoyancy greater than its weight. If the fluid has a surface, such as water in a lake or the sea, the object will float at a level so it displaces the same weight of fluid as the weight of the object. If the object is immersed in the fluid, such as a submerged submarine or a balloon in the air, it will tend to rise. If the object has exactly the same density as the liquid, then its buoyancy equals its weight. It will tend neither to sink nor float. An object with a higher average density than the fluid has less buoyancy than weight and it will sink. A ship floats because although it is made of steel, which is denser than water, it encloses a volume of air and the resulting shape has an average density less than that of the water.

Welding:
Base-metal preparation: To weld aluminum, operators must take care to clean the base material and remove any aluminum oxide and hydrocarbon contamination from oils or cutting solvents. Aluminum oxide on the surface of the material melts at 3,700 F while the base-material aluminum underneath will melt at 1,200 F. Therefore, leaving any oxide on the surface of the base material will inhibit penetration of the filler metal into the workpiece.
To remove aluminum oxides, use a stainless-steel bristle wire brush or solvents and etching solutions. When using a stainless-steel brush, brush only in one direction. Take care to not brush too roughly: rough brushing can further imbed the oxides in the work piece. Also, use the brush only on aluminum work-don't clean aluminum with a brush that's been used on stainless or carbon steel. When using chemical etching solutions, make sure to remove them from the work before welding. To minimize the risk of hydrocarbons from oils or cutting solvents entering the weld, remove them with a degreaser. Check that the degreaser does not contain any hydrocarbons.

Hydraulics:
The basic idea behind any hydraulic system is very simple: Force that is applied at one point is transmitted to another point using an incompressible fluid. The fluid is almost always an oil of some sort. The force is almost always multiplied in the process. The picture below shows the simplest possible hydraulic system: (Figure 4)
A Simple hydraulic system consisting of two pistons and an oil-filled pipe connecting them. If you apply a downward force to one piston (the left one in this drawing), then the force is transmitted to the second piston through the oil in the pipe. Since oil is incompressible, the efficiency is very good -- almost all of the applied force appears at the second piston. The great thing about hydraulic systems is that the pipe connecting the two cylinders can be any length and shape, allowing it to snake through all sorts of things separating the two pistons. The pipe can also fork, so that one master cylinder can drive more than one slave cylinder if desired.

Direct Current
Direct current is the constant flow of electric charge. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams. In direct current, the electric charges flow in the same direction. Direct current installations usually have different types of sockets, switches, and fixtures, mostly due to the low voltages used, from those suitable for alternating current. It is usually important with a direct current appliance not to reverse polarity unless the device has a diode bridge to correct for this. DC is commonly found in many low-voltage applications, especially where these are powered by batteries, which can produce only DC.

Propulsion
A propeller is essentially a type of fan which transmits power by converting rotational motion into thrust for propulsion of a submarine through a fluid such as water, by rotating two or more twisted blades about a central shaft, in a manner analogous to rotating a screw through a solid. The blades of a propeller act as rotating wings and produce force through application of both Bernoulli's principle and Newton's third law, generating a difference in pressure between the forward and rear surfaces of the airfoil-shaped blades and by accelerating a mass of water rearward.
Water jet propulsion is a type of propulsion in which water is pumped through a nozzle, which propels the vehicle forward. Jet propulsion is especially useful in shallow waters.

Background Info

Remotely operated underwater vehicles (ROVs) are the common accepted name for tethered underwater robots in the offshore industry. ROVs are unoccupied, highly maneuverable and operated by a person aboard a vessel. They are linked to the ship by a tether, like the one scene in Figure 2. A tether is a group of cables that carry electrical power, video, and data signals back and forth between the operator and the vehicle. High power applications will often use hydraulics in addition to electrical cabling. Most ROVs are equipped with at least a video camera and lights. Additional equipment is commonly added to expand the vehicle’s capabilities. These may include sonar, magnetometers, a still camera, a manipulator or cutting arm, water samplers, and instruments that measure water clarity, light penetration and temperature.












(Figure 1) (Figure 2)

ROVs range in size from that of a bread box to a small truck. Deployment and recovery operations range from simply dropping the ROV over the side of a small boat to complex deck operations involving large winches for lifting and A-frames to swing the ROV back onto the deck. Some even have “garages” that are lowered to the bottom. The cabled ROV then leaves the garage to explore, returning when the mission is completed. In most cases, however, ROV operations are simpler and safer to conduct than any type of occupied-submersible or diving operation.
Conventional ROVs are constructed with a large flotation pack on top of a steel or alloy chassis, to provide the necessary buoyancy. Syntactic foam is often used for the flotation. A tool sled may be fitted at the bottom of the system and can accommodate a variety of sensors. By placing the light components on the top and the heavy components on the bottom, the overall system has a large separation between the center of buoyancy and the center of gravity; this provides stability and the stiffness to do work underwater. Electrical cables may be run inside oil-filled tubing to protect them from corrosion in seawater. Thrusters are usually located in all three axes to provide full control. Cameras, lights and manipulators are on the front of the ROV or occasionally in the rear for assistance in maneuvering.




(Figure 3)


The disadvantages of using an ROV include the fact that the human presence is lost, making visual surveys and evaluations more difficult, and the lack of freedom from the surface due to the ROV’s cabled connection to the ship. An ROV operator controls the vehicle from a system on board the ship. Using a joystick, a camera control, and a video monitor, the operator moves the vehicle and the camera to desired locations; the operator’s eyes essentially “become” the camera lens.

Limitations

Structure

• The ROV must be able to move without electrical devices
• The ROV will contain at least three video cameras on board
• The ROV can have no onboard power except for lights

Propulsion

• The ROV will operate on less than 13 volts of power 25 amps
• The ROV must function on DC voltage
• The ROV must be able to move without electrical devices
  
  
  

Specifications

Structure:

• The ROV must be able to submerge and surface between depths of 4 meters
• The ROV must be capable of performing in varying water temperatures
• The ROV must be able to be assembled within five minutes
• The ROV must be slightly positive in buoyancy
• The ROV must be capable of supporting a mechanical arm

Propulsion:

• The ROV will be remote controlled
• The ROV must pass a safety test set forward by MATES
• The ROV must be able to move in all directions
• The ROV must be capable of performing in varying water temperatures
• The ROV must be able to be assembled within five minutes

Design Brief

To design and create the structure and propulsion of an underwater ROV to be operated by a team of three

Calendar

September:
17th – Weblog created
19th - Contact Mentor
20th – Calendar created and hard copy handed in
21st – Design Brief, Specs & Limitations updated on blog
25th – Weblog update
26th - Contact Mentor and give update
26th – Background info & Summer research updated on blog
27th- Testing Procedures updated on blog
28th – Weblog update

October:
1st- Weblog update
3rd – Brainstorming and Alternate Solutions put on blog
3rd – Outline for presentation
3rd – Testing and Final Solution ideas
5th – Weblog update
6th – Contact Mentor and give update
8th – Weblog update
12th – Weblog update
13th – Contact Mentor and give update
14th – Choose final solution
15th – Weblog update
16th – Contact Mentor and give update
16th – Start Selection/Rejection report
18th – Finish Selection/Rejection report
19th – Start model
19th – Weblog update
23rd – Weblog update
24th – Contact Mentor and give update
24th – Finish model
26th – Weblog update
27th – Contact Mentor and give update
30th – Weblog update
31st – Mentor contacts handed in
31st – Model and Selection/Rejection report finished
31st – Outline for formal presentation

November:
1st – Presentation Day
2nd – Weblog update
5th – Weblog update
9th – Weblog update
9th - Make 2nd Marking Period Calendar
12th - Weblog udate

Test post

Testing