Preliminary Design Review

Preliminary Design Report

Submitted to:

Professor Wyslouzil

GTA Alec Sichko

Created by:

Team B

James Amann

Dan Buergel

Luke Johnson

Ryan Linnabary

Engineering 1182

The Ohio State University

Columbus, Ohio

March 26, 2015

Executive Summary

During the first set of performance test labs, students designed two prototypes capable of traversing the monorail track. Both of the Advance Energy Vehicles or AEVs utilized a simple set of code that included all of the Arduino commands. The simple set of code would allow a better comparison between the two designs. If one design performed more efficiently, the code wouldn’t be a variable. This type of testing is important to the scientific community because many big automobile manufactures produce many prototype concepts before producing a line of vehicles. So it is common practice to design a couple of prototypes, and perform tests to determine the proper choice.

Both of the designs utilized the EP-3030 propeller. This type of propeller had the most efficient advance ratio, this can be observed in figure F3. Both of the designs can be seen in the orthographic drawings located in the appendix. Design 1 utilized both a push and pull configuration, with one propeller on the front, and another along the back. The intent was to allow the AEV to travel both forward and backward with ease. This AEV design used a minimal amount of parts to keep a lower weight, the AEV also had a good center of gravity, but was not completely level side to side when sitting on the track. Furthermore the first AEV design had trouble with the turns in the track. Members speculated it was due to the imbalance on the track. The second design utilized a pusher configuration, and used minimal parts as well. The second design had a good center of gravity as well. The center of gravity was located toward the lower half of the design, in between the two wheels. The second design sat well on the track relatively level from side to side. The second design also handled better along turns when compared to the first design. Both designs yielded relatively similar looking graphs as seen in Figure F1, and Figure F2 in the appendix. It should be noted that design 2 traveled at a faster velocity and completed the code in a shorter amount of time.

It would be recommended to not schedule the first set of performance test on the day with two lab periods. Most of the time was spent disassembling, and reassembling the AEV kits. It took up valuable lab time, most of the students could have reconstructed new designs out of class. It would also be recommended to add a section for the performance test labs in the lab manual, this caused a great deal of confusion with many students.

Table of Contents………………………………………………………………………………………………2

Introduction……………………………………………………………………………………………………..3

Experimental Methodology……………………………………………………………………………….3

Results………………………………………………………………………………………………………………3

Discussion………………………………………………………………………………………………………….4

Conclusion and Recommendation……………………………………………………………………..5

Appendix……………………………………………………………………………………………………………6

Introduction

Jurassic park was reopened, and needed a vehicle to travel throughout the park. The advanced energy vehicle, or AEV for short, should be suspended in the air and utilize propellers to traverse the track. The AEV should be capable of moving both forward and backward. The AEV should also be capable of attaching to a caboose and pulling it along the track. The lab exercises showed many ways to evaluate the performance of the AEV. Students now have the capability to design, build, and test ideas. Then make conclusions based on their results to either confirm or rethink their ideas.

Experimental Methodology

Students used a kit provided by instructors to assemble the first design for the performance test. This was done outside of lab in order to maximize lab time spent on runs. A simple code was uploaded into the AEV. Students put the AEV onto the track and let the AEV run. The data from the run was collected from the AEV. The data collected was inserted into a program called MATLAB to generate the graph seen in Figure A1. Students then disassembled the AEV and put together their second design. This design also utilized the same basic program in order to make sure that the only differences in the run would be the weight and different design of the two AEVs. Students then tested it on the track, and again collected data from the AEV after the run. The gathered data was then inserted into MATLAB to generate the graph see in Figure A2.

The AEV operates based around a preset program. Control of the vehicle relies on Arduino hardware, the Arduino programming environment, and the proper implementation of a library of pre-written functions. The pre-written functions allowed students to use a series of commands to maneuver the AEV. Students used a simple code to test the efficiency of the two AEV designs. The code was simple enough to utilize most of the basic commands. After the AEV was tested on the track students could collect data from the AEV. The AEV recorded measurements digitally with a microprocessor, and then converted that data into meaningful physical parameters. Then analyzed the data using known equations for power and energy. During the performance test 1 labs students utilized a MATLAB app that used collected data from a wind tunnel, which primarily dealt with thrust. The MATLAB app then imported the physical parameters from the AEV and quickly generated meaningful graphs that illustrated types of power and efficiencies. Figures F1, F2, and F3 are examples of the types of graphs that were generated by the MATLAB app.

Results

In the process of designing a new vehicle which completes the operational objectives as stated in Figure F6 of the appendix, the team discovered several physical factors that affect AEV performance. Each new design incorporated characteristics of Design C from Table T1, including the assembly of minimal parts in a way that balances the vehicle on the track. The two designs tested are illustrated in Figures F4 and F5 in the Appendix. Design 1 uses two oppositely-oriented propellers on each end of a medium rectangular frame to increase efficiency traveling in both directions. It weighs approximately 0.32 lbs. and costs around 176 dollars to produce. Design 2 also used two motors but each was located in the rear of a t-shaped frame and the propellers faced in the same direction, pushing the vehicle. The two designs weight the same amount but Design 2 costs 2 dollars less to produce than Design 1.

After careful analysis and comparison of the EEProm data from each design after the tests, the team discovered that Design 2 used less overall power. Each design was tested using the same code and weighed the same amount, therefore the difference in motor configuration caused this contrast in energy use. The team expected this difference, and though the two designs consumed the same instantaneous power and energy, this power was consumed for a greater time period by Design 1 (roughly 5 seconds). The team was more confident with Design 2 after these testing procedures than the other and it was decided that future designs will resemble it closely.

Each vehicle traversed past the entrance gate and the storage facility. To correct this the team has decided to brake the vehicles at a distance that would allow each to coast and stop in the correct position. Coasting was not considered until the team completed this lab. It may help to reduce power consumption when completing the mission objectives in future labs.

Discussion

The overall objective of the AEV design project is to design an Advanced Energy Vehicle that uses minimal supplies while still maintaining energy efficiency. As described in the Mission Concept Review, the AEV must be able to achieve a number of things during its run: 1.) The AEV must ferry visitors to Jurassic Park in a safe and timely manner 2.) The AEV must be able to pull a caboose full of dinosaur eggs 3.) The AEV must be able to run consistently with no mishaps 4.) The AEV must complete all of this in the most efficient way possible as there is a limited supply of power on the island.

In order to do this in the most efficient way possible Team B designed two AEVs using minimal parts with one piece for the base. Orthographic and isometric views of these two designs can be seen in Figures F4 and F5. Each design was then run with the same test code, as seen in Figures F1 and F2. The efficiencies appear to be the same, however when one looks at the time scale, design 2 finished its run around 5 seconds before design 1 finished. This is most likely because of the way the propellers were set up. As seen in Figure F5, design 2 had both of its propellers in the rear of the vehicle pushing together, however design 1, Figure F4, had one propeller in the front and one in the rear of the AEV. This was an attempt to increase the efficiency of the AEV. When traveling in the reverse direction design 1 would be able to keep the same power as when it was traveling in the forward direction. However as seen in Figures F1 and F2, the efficiencies are relatively the same, with no great difference between them. This would point to design 2 being the more efficient design as it completes the same run in less time with around the same efficiency.

The phase breakdown can be viewed in Table T4 located in the appendix. The phase breakdown and incremental energy in the table only contains data regarding the first design. The data for the second design wasn’t saved even though the group members though it was. The greatest incremental energy resulted from the motorspeed command with the gotoabsoulteposition command.

Concept screening and scoring was done for preliminary designs, seen in Table T1 and T2, and features of the preliminary designs were incorporated into designs 1 and 2. Design C included a flat base using only one piece of material with the propellers in the tractor configuration. This design was lightweight and durable, and it scored high on the screening and scoring. However, when making design 1 members of group B decided to compromise and instead of having both propellers in the tractor configuration, they put one propeller in tractor and one in pusher. This was an attempt to increase efficiency, even though power would be split, the AEV would be able to achieve the same amount of power going forward as it would backward. In contrast to design 1 and design C, design 2 utilized a pusher configuration. As well, design 2 utilized the T-shaped base from the preliminary design D. The T-shaped base allows for better balance which will increase efficiency of the system. With bad balance the AEV begins to swing back and forth around the track because of the turns, which decreases the distance the AEV is able to travel.

When discussing data and trends in data, it is also important to consider any possible error even if there was no error. Potential error for this lab could have been caused due to improper mounting of one of the propellers. This would decrease efficiency of the AEV, which would in turn invalidate all of the data. Another form of possible error would be a loose screw. The part being held in place by the screw would have a very high chance of falling off, which would then cause the AEV to become unstable. Resolving this would involve making sure all of the screws are tightened. As these were not the final runs any mistake in the code is not so much an error as it is a discovery about what is and is not efficient. However, any error in the code could be resolved by debugging the code.

Conclusion and Recommendation

Two designs were constructed and tested. The two designs utilized the same type of coding when tested on the track so the coding wouldn’t be a variable when comparing the two designs. The first design weighed less than normal due to part choice, but was unbalanced from side to side when placed onto the track. This caused the first design to have trouble with the corner section of the track. The first design utilized both a pusher and a puller configuration, group members speculated that the design would travel in reverse better. However, this design would need to be reevaluated to connect to a caboose. The propeller in the front would get in the way. The second design utilized a pusher configuration. The second design balanced better than the first design, and traveled at a greater velocity. Both designs weighed about the same, and have approximately similar costs. This can be viewed in the two orthographic drawings located in the appendix. Both design utilized two motors with the EP-3030 propeller, which proved to be more efficient than the smaller propeller. The propulsion efficiency versus the advance ratio graph can be seen in Figure A3 in the appendix.

The second design proved to be the better AEV choice for the task. It performed better on the track and meets the design requirements better than the first choice. The first AEV design would need to be almost completely redesigned so it could move the caboose. The second design completed the scenario in a lower time. So this means the second AEV design traveled at a greater velocity even though it utilized the same amount of Arduino percent power. This means the second design was more efficient because it completed the task with a lower time. This can be seen in the power versus time graphs located in Figures A1, and A2 in the appendix.

The biggest source of error was due to operator error. The biggest instance dealt with saving the excel data from the second AEV design. Group members were unable to complete the incremental energy with its phase breakdown, and total energy used due to the circumstance. Group members thought the data was saved, even though it wasn’t. Syntax errors, and spelling errors also contributed to some of the errors within the class period. Some of the parts on the AEV would loosen up after many trail runs. That could potentially affect the collected data.

During this design process the team spent un-necessary time correcting mistakes made that could have been avoided. A valuable habit for the group to adopt would be to double-check Arduino code before it is compiled and transferred to the controller. Several times, the system mal-functioned. The team also spent crucial time disassembling and reassembling the AEV during class time. In order to save valuable class time, the group needs to plan ahead to avoid tasks that could be completed at home.

Appendix