Math, Science, and Technology Analysis

Rov Arm Math, Science, and Technology Analysis

My final solution for the Rov arm is a simple design that relies on the basic laws of hydraulics to function. Through calculations, seen on the attached document, I have determined the size of tubing and syringes I need to not just make my design functional, but also make it strong enough to complete the tasks. I also have decided to use polycarbonate sheeting for the main material to construct my arm.
Hydraulic System:
The original purpose of choosing hydraulics was to reduce the electricity needed by the entire Rov. After researching the laws and properties many more advantages became apparent. The main difference between hydraulics and pneumatics involves the tendency of the substance that fills the system to compress. A pneumatic system involves the use of air which can easily be compressed, thus requiring greater pressure to accomplish a task. In a hydraulic system the fluid, often oil, will not compress and therefore transfers all energy with very minimal loss. This also shows why it’s very important to remove all air from a hydraulic system. Due to the high efficiency of a hydraulic line there is almost no force lost to friction. This is defined by Pascals law which states “when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container.”(Pascals Principle), or defined by the equation P1=P2. Therefore a hydraulic tube can be led through all sorts of bends and over large distances without any sacrifice in performance.
My hydraulic system will also make use of force multiplication. At the control station I will use a 2oz syringe as the hydraulic pump, while a 1 oz syringe will be attached onto the arm. Force multiplication is determined by comparing the surface areas of the pistons. The equation to be used is pi * r^2. If piston B has a surface area 10 times greater than piston A, then any pressure applied to piston A will show up 10 times greater on piston B, although the distance the piston must travel will also be larger. This is shown in Figure 1 below with piston A being represented by F1 and piston B being represented by F2.
For my design I have divided the force rather than multiplied it. The main pressure will be applied by hand from the control station piston, called the master piston, and approximately two thirds of the force will be delivered to the piston on the Rov, called the slave piston. This also means that for every inch the master piston is depressed, the slave piston will extend 1.5652 inches. While it may seem odd that I am purposefully lowering the force delivered to the slave piston, it fits in context with the contest tasks. The maximum weight that must be lifted will be 2 pounds, although this is a stretch and the most likely weight will be closer to 1 pound or less. By decreasing the force I am making it harder for myself, or any other controller, to accidentally overload the arm. If too much pressure is applied the hydraulic system may simply break as it has only been designed according to the specifications of needing to hold a maximum weight of 5 pounds. The control line also is in danger of rupturing at a pressure greater than 22 psi.. I also believe that it will be more important to have a swift moving arm as it is unknown how stable the platform will be under water, and it may be necessary to quickly grab the objects rather than slowly clamp onto them. To apply a force of 3 pounds to pick up the heaviest contest object, the “black smoker rocks”, a force of 4.6891 pounds must be applied at the control station which is well within the capabilities of the system. This is explained on the attached calculations sheet.

Rov Arm Materials:
I have decided to use polycarbonate sheeting with a thickness of ½” as the main material in my design. It will be used to construct the arms as well as the top mounting block. The reason for this was the lightweight and impact resistant properties of the material. Polycarbonate has many other uses as well which show its strength. Polycarbonate is used to make bulletproof glass, shop safety goggles, and water bottles. It is also very easy to cut with a band saw. I had also considered using fiberglass but the initial cost of materials is nearly three times larger and it will require at least 3 days of extra construction time. Since my design only requires rectangular shapes and no intricate designs, this material seemed to be the best choice.

Conclusion:
Overall my design has shown through both a working model presented in class and calculations on the attached sheet that it is capable of completing the competition tasks. Using the laws of a closed hydraulic system I was able to void many of the concerns associated with my design. I believe that once constructed my final design will once again prove itself effective and complete all the required tasks.