Redesign Evaluation 1

Redesign Evaluation

Introduction

Competition Background
The MATE ROV competition is a three event competition that occurs yearly at the Massachusetts Maritime Academy in Buzzards Bay. The three events include an oral presentation (topic: design, reasoning, and process of construction of ROV), a technical report, and an underwater obstacle course. The obstacles involved in the pool phase formulate a series of requirements that the ROV, as a whole, must have. The events of the pool phase simulate a submarine search and rescue mission and includes the following tasks:
Survey the submarine for damage points.
The damage points on the submarine will be labeled with letters
Transfer ELSS [Rescue] Pods from an ELSS carousel into a milk crate.
The milk crate is closed with a hatch which must be opened by turning a latch.
Supply an air source to the submarine.
The air source will be provided to the submarine by opening a door as well as rotating a hatch one hundred and eighty degree.
Mate the ROV to the submarine.

MAST Design Tasks
The MAST team singularly, at first, devised their own plans in order to develop their respective parts. Kevin Iannacone developed the hull and propulsion, Nicole DePasquale developed the electrical system (Control System), and Thomas Ferrara developed a system to complete the task (Arm and Claw). Over the course of seven months each team member completed the following assignments, which have been used to support their ideas:
Many AutoCAD or Pro Desktop Drawings of the designs, including both orthographic and isometric views/three dimensional views
Several mentor contacts with an expert in the team member’s respective fields, which has bolstered the design
A Plan of Procedure outlining the steps to be taken during the construction phase of the project
A Science, Technology, Engineering, Mathematical, and Manufacturing Analysis which explored the multitude of areas that the design touched upon, as well as proved the effectiveness of the design with science and math concepts

Project Progress
By March of 2009 each of the team members has either completed the construction of their design or finished a high percentage of the construction. As of the beginning of March of 2009 each team member has developed their own ideas fully. However, through several complications over the course of the year Thomas Ferrara needed to alter his plans. The following document will include the reasoning for the changes made as well as support for the changes made. The remainder of the document will focus upon the claw aspect and its relationship to the overall design and competition.

Summary:
Thomas Ferrara’s Design Process

The following information will chronicle the six months spent designing the claw for the MATE competition. The information will include all of the tasks (with brief descriptions) reasons for changes, and the development of errors.

Syringe Method
At the beginning of the year the MAST team had based a majority of their design choices on the tasks that previous years teams were required to complete. In past years, especially in the 2008 MATE competition, the ROVs needed to be able maneuver around the underwater course, record data (i.e. temperature, salinity, pH), and retrieve objects (in the 2008 competition this retrieval was a simple snatch and grab mission). At the beginning of the year the release of 2009 MATE competition information was not released so designs were made with past tasks in mind.
After a series of alternate solutions and selection/rejection reports Thomas Ferrara decided upon a hydraulic-type design. This design (as seen in Appendix A) included two syringes that would control a claw. Connected by a surgical tube that spanned a total of twenty feet (required distance of travel to cover entire obstacle course), the syringes would push and pull on each other using water pressure. By pushing or pulling on the controller’s syringe, located at the base of the pool, the second syringe (which would have a claw attached), located inside of the pool, would then push or pull as well.

The design process for the Syringe Method, including the remainder of the drawings, STEMM Analysis, and Plan of Procedure was never completed due to the release of competition tasks in late December of 2008.

Change of Mission Tasks
Days before 2008 Winter Recess the MATE Competition released the mission tasks for the New England Regional Competition. The tasks, which were outlined in Competition Background, were completely different then what any of the teams had seen. After seeing the tasks and briefly breaking each part down the MAST ROV team decided that the only piece of the ROV affected was the arm and claw design. With the new mission specifications described the MAST ROV team decided upon the following requirements of the ROV arm and claw:
In order to pick up and drop of the ELSS Pods, the claw would need to open and close just like any other one-function claw.
In order to open and close the hatch (the drop-off point for the ELSS Pods) the arm and claw would need to face downwards (vertically) and rotate one hundred and eighty degrees clockwise and counter clockwise.
In order to open and close the air valve the arm and claw would need to face outwards (horizontally) and rotate one hundred and eighty degrees clockwise and counter clockwise.
In order to open and close the door the arm would need to grab the handle and hold on as the ROV propelled forward and backwards.
In order to transfer the air hose the arm and claw would need to be able to grab and hold onto the material and transfer it from the top of the pool to the bottom.

Looking at these tasks Thomas Ferrara needed to either alter the syringe method so that it could rotate or completely redesign a claw. With a due date for all developmental work only a few weeks away, a decision needed to be made quickly.

Servo-Motor Method #1After discussion of each part with both team members and mentors it was decided that there would be too many conflicts with a rotating syringe method; a design was developed.

The second claw design (as seen in Appendix B) actually involved two claw systems, one facing vertically a second facing horizontally. Each of the systems would be identical of each other. Each system would include two components, and open/close component and a rotation component. When the two components were combined, the claw, as a whole, would be able to complete all of the tasks. The first component, the open/close component included a servo motor with a worm gear attached, using glue, to the drive shaft. The worm gear would then be used to turn two spur gears located on either side of it. Each of the spur gears would have attached to it a Plexiglas shaped claw. As an entire component, the system would open and close to grab and hold when the servo was turned on. The second of the components, the rotational, would be comprised of another servo motor. The rotational servo motor would have attached to it a Plexiglas rod (the rod’s length would be determined by the distance spanned between two PVC supports on the ROVs hull). When the servo was turned on the Plexiglas rod would be able to spin both clockwise and counter clockwise. The second component would be attached to the first component by gluing the end of the Plexiglas rod to the back of the first servo motor.

Servo-Motor Method #2
A small revision was made to the first method in order to simplify the design. After analysis it was discovered that the only task that required a vertical claw was the opening of the ELSS hatch (vertical rotation). Instead of creating an entire claw to complete this small task the team decided that it could be accomplished with the hull.

By attaching two downward facing prongs, much like a fork, the ROV would be able to come over to the hatch, insert the prongs and then use the ROVs propulsion to rotate around, effectively opening the hatch.

Servo-Motor Method #2a
A fundamental error was made during the design of the servo motor method. This error was overlooked by team members, instructors, and mentors until Ms. Green questioned Thomas Ferrara about it. The error was that the spur gears were free floating. In order for this design to be even somewhat successful, the spur gears need to be attached to the open/close component.
To remedy this issue, Thomas Ferrara modeled and then drew a support system that would stabilize the spur gears. Using Lego axles the gears would have free range of motion, circularly, but would be held in place in both the x- and y-axis. The support system can be seen in Appendix C.

Construction Process and Errors

The need for testing the ROV is a key factor in the success of the team as a whole. For the team to have ample time to master the use of the ROV the submersible needs to be “in the water” by the beginning of March. This deadline can only be reached if all factors of construction fall into place. In terms of the claw many things began to push back the date for testing.

The claw was first put back when the mission tasks were released. Due to the fact that the MATE competition deadlines due not completely line up with the MAST curriculum several assignments, key to the development of the claw, were already handed in before the first redesign occurred. One of these assignments was the Bid Process. When the mission tasks were released and the design was changed second round of the Bid Process was needed so that the materials could be found. Although the Bid Process was a way to receive the materials with the school’s budget, it was also a much slower way of getting materials. With the deadline for testing approaching Thomas Ferrara bought two servo motors ($35.99/ea.), a sheet of Plexiglas ($8.99), Plexiglas rods ($0.43/ea.), a PVC pipe ($1.43/ft.) and Rhino Glue ($25.00). Even though the materials were bought outside of the Bid Process, when they were received it was already past March 1st, 2009.

Several more obstacles occurred with the servo motors. These obstacles could have been easily avoided, however, if proper specifications on the motors were released by the manufacturer. The first of these problems was that the wiring of the servo motor was different then what had been planned for by Nicole DePasquale. In order to have the servo motors run in her design they needed to be permanently grounded and hard wired. Once this obstacle was hurdled the team soon found out that custom gears, inside of the motor, were broken due to over powering. With the servo motors out of order a new method of claw propulsion needed to be planned.

Due to the lateness of the ROV claw Thomas Ferrara was put into a Lunch study program in order to have more time to work on the construction.

Servo-Motor Method #2b/DC Motor Method #1
The third alteration to the servo motor method was actually to completely replace the servo motors with DC motors. The servo motors were manufactured to be waterproof; however the DC motors were not. To use the DC motors, a process of waterproofing needed to be used. With the replacement of the servo motors with DC motors the structure for the gears no longer fit. To allow this design to work a Plexiglas box would be used to mimic the size of the servo motor (the DC motor would sit inside the Plexiglas box).

The NO-Claw Method

With the progress of the claw almost two weeks behind schedule it was very necessary to speed up the construction. After a more detailed analysis of the mission tasks as well as a group discussion including Thomas Ferrara, Kevin Iannacone, Ms. Green, and Mr. Cuttrell it was decided that the DC Motor Method would be tossed. Instead of using a motor controlled method the team would use a design based on using the hull to accomplish the tasks. The design can be seen in Appendix D used a combination of the two prong fork (which can be manually pivoted upwards and outwards) and two stabilized outwards facing hooks. All of these materials would be made out of PVC.

Reasons for Change
There were several key issues occurring with the motor run designs. The issues occurring included difficulty with waterproofing and stabilizing the motors, attachment of the claw to the ROV, attachment of the rod to the motors, and the time that it was taking to construct the claw.

By changing the design of the claw it would solve all of the problems above as well as hasten the construction process. Also in the end the NO-Claw Method would be more reliable in the water. The initial support for the change came from the MAST team members as well as Ms. Green and Mr. Cuttrell; however support from the mentor is still needed.

In order to really describe the support the reasons for changing the developmental work as well as the use of the new design will be documented.

Developmental Work:
The NO-Claw Method

A large amount of developmental work is being worked on at the moment. A brief analysis, regarding the mathematical and scientific principles, of the new design will be made. In addition to this a plan of procedures to assemble the new design is going to be organized. Third, a file of Pro Desktop drawings depicting all aspects of my ideas will be assembled.

In addition to these documents support from my mentor is being worked on through emails. Once a response is retrieved it will be included in the report.

As of 19 March 2009 all construction work is completed. The remainder of the work is to show the support for the design, which includes the above mentioned material. Below is a time line of when those materials will be completed:

19 March 2009: Presentation of Construction
23 March 2009: Completion of Plan of Procedures for Construction
24 March 2009: Completion of Pro Desktop Drawings (Including Orthographic and
Three-Dimensional Views with labels and dimensions
25 March 2009: Completion of STEMM Analysis (Including support from mentor on
scientific and mathematical concepts)
26 March 2009: Beginning of 3rd Marking Period Report

Conclusion

Summary
The claw for the ROV is an essential part for success during the competition. Like any other group or system each of the members and components must work well together. Due to the nature of the MAST curriculum each of the team members was required to complete a large portion of their work by themselves. This isolation of work was larger due to the split in class periods for Thomas Ferrara, Nicole Depasquale and Kevin Iannacone. To complete each assignment throughout the year each team member had to work by themselves to finish but this should have been different. From the outset, each of the team members should have had requirements to help each other with their respective parts. When the project came down to the wire is when the team members began to work together. This coordination between the team members was very good and several meetings were held in and out of school, however by this point in time team meetings were too late to be effective. At this point in time designs and materials for each component had already been chosen; the team meetings only provided assembly coordination.

Looking at the claw’s initial design one can see a flaw. When the tasks were released each piece was still looked upon as its own design rather than the ROV as a whole. Because of this, when the analysis of how to design the new claw (which became the servo-motor claw) was made, even the team as a whole, it was designed as if it would be used by itself during the competition. Due to this, the claw seemed to need all the functions that it was given such as rotational and open/close capability, making the design more complex. However when the team began working together more closely, at the end of the year, the tasks that need to be completed at the competition was analyzed with the entire ROVs design in mind. While thinking of the whole ROV one can easily see how the system as a whole could be used to maintain the capabilities that were given to the claw (by using the propulsion on the ROV).

If the analysis of the tasks were looked at and prepared for with the ROV systems in mind then the claw design would have been the same as it is now in January.



Self-Evaluation
This, however, is not what happened. Instead, I have had to go through three different design processes, which have summed up to countless hours spent on catching up on assignments, a number of missed classes, a lot of money spent and many lunches working in systems. Even with all of this extra work and time spent (on a design that is not even going to be used) I feel like I have improved over the course of the year. It might seem that I have messed up, as evident in all the work I have had to redo, but I know that this was not all my fault. A lot of the extra work that had to be done was because of small faults in how the year worked out. Because of bad scheduling, unaligned requirements between MATE and MAST, and unexpected tasks for the competition I have had to complete assignments in haste.

All of this has given me a great experience. As much as I have hated what I have had to do, I have gained skills in time management and organization. I have had to deal with more stress that ever before in a class in addition to having to cope with semi-real world experiences. For me and my team mates we have learned the importance of working together and looking at a task as a whole. This project has given me something that not many other assignments can give. In this respect I feel that this year has been a success in Systems Engineering II.

As for the design and construction process, I feel that I have grown as well. Having to go through the design process more than once has pounded the ideas in my head. Using AutoCAD and other design programs such as Pro Desktop have become skills of mine. By designing several different claws I have learned to think outside the box. By changing my designs I have had to understand how to criticize my own material. By submitting to others opinions and advice I have learned to be better in communication. During the construction phase I gained a more defined ability to look at a predesigned idea and put into reality. By the time I had halted the construction of the Servo-Motor Design, it had already gone through a majority of the process. Through the process I have learned again how to use power tools and think analytically. Even with the final change in the design I have learned so much. Even though it is not complete now (but will be), I will have had to revisit assignments in order to complete last idea. In this light I feel that even the construction and design process this year had been a success.

In conclusion I feel that I have progress this year, despite the roadblocks that my team and I have hit. I think that even though some parts of the project were gone about in an unconventional manner they were, in the end still completed to par. I still have a lot to learn about this topic but this year has really helped.