Mission Impossible · Group 5 - Mission Impossible - 12 Construction Procedure The first cart...

Mission Impossible

Michael Antoine, Jack Connolly, Khalid Jebari

Intro to Engineering Design (ENGR 1500) Section 43

Group 5

April 14th 2017

Group 5 - Mission Impossible - 1

Table of Contents Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Alternative Design Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Final Design Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Construction Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Record of Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Peer Evaluations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Gantt Chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Logbook samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18-20

Meeting Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Communication Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

CAD Drawings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23-28

Cart Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Axle Mounts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25-26

Wheel and support fins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Ramp Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28


Abstract A cheese delivery system was created using foam core, hot glue, and other

materials. This would deliver a block of cheese to an 8 inch hole 20 feet away without human interference. The project took two months to complete. Despite last minute setbacks, the delivery system was very effective.

Introduction

The aim of the cheese delivery system is to get the cheese to the main nest 20 feet away using only the given materials. These materials included:

1. Foam core (30 in x 40 in x 3/16 in) 2. Poster board (20 in x 30 in) 3. Wooden dowel (1/4 in outer diameter 36 in length) 4. Aluminum foil (12 in x 36 in) 5. Paper clips (4) 6. Water bottle and water (½ pint) 7. Hot glue gun (with glue) 8. String (15 feet) 9. Scotch tape (3/4 in x 36 yds) 10. Rubber bands (2) 11. Balloons (2) 12. Air

In addition to these materials, a Honeywell® HT-800 fan was supplied and could

be switched on from behind the start line (main nest). Using these materials the group had to design and build a system to deliver the

cheese that operated without human interference.


Introduction (continued):

Needs Assessment Group 5 began to understand the problem by approaching the task from a

broad perspective. It was important in this step to understand what was asked to achieve and define the current and desired states. A diagram was drawn and the assessed in its simplest state (see Figure 1). The goal was to move 2 ounces of cheese to the main nest 20 feet away. The accuracy of the delivery system was important.

Figure 1

Problem Formulation

To simplify the challenge and make it easier for the group to brainstorm, a problem statement was created using the needs list:

“How can we accurately move 2 ounces of cheese 20 feet?”

This problem statement framed the problem such that the delivery system

had to meet the 20 foot requirement and do so in an accurate way. It allows for creativity without suggesting any preconceived ideas.


Background Originally, the Mission Impossible criteria stated that the cheese would be a two

ounce cube of cheese with side lengths L (see Figure 2). To calculate the size of the cheese, various standard cheese densities were used.

Figure 2

Cheese Density oz/in3 Cube Side Length (L) in

Mozzarella 0.27 1.95

American 0.56 1.53

Cheddar 0.63 1.47

Brie 0.59 1.50

Average 0.51 1.61

It was observed that cutting the cheese to the perfect size to create a two ounce

cube would be challenging. The mission criteria was updated with the following modification:

The cheese will be a cube with side lengths (L) of 1.5 inches (regardless of the weight).


Background (continued):

In addition to the cheese specifications, the supplied fan also had the following specifications (see Figure 3):

Figure 3

Dimension Value

Diameter (d) 8 inches

Center line to floor (CL) 6.25 inches

Using an anemometer, the wind strength of the fan was measured from 0 to 20

feet away. Data was not measured specifically; however, the general trend was that the air flow had diminished significantly after about 8 feet from the main nest. For this reason, the group strayed away from designing around the fan.


Methodology To solve the problem, the engineering design process was followed:

1. Understanding the problem (Needs assessment) 2. Framing the problem (Problem formulation) 3. Exploring solutions (Abstraction and synthesis) 4. Narrowing the solutions (Analysis) 5. Build/Prototype and Test (Implementation)

↳Repeat if necessary.

Abstraction and Synthesis Once the problem was well-framed, the group brainstormed without any concern

for constraints (see Figure 4).

Figure 4


Methodology (continued):

Abstraction and Synthesis (continued): Once the group brainstorming was complete, individuals began designing more

specific ideas from the brainstorm list. At this point, the group moved on to the narrowing stage. Analysis

After the brainstorming session was complete, solutions that did not meet the specifications and/or used materials that were not provided had to be crossed out from the list. Only four solutions were conserved at the end of this funneling process. To rank these four solutions weighting and decision Matrices were used, and Atwood’s Cart design was chosen at the end. After not being able to get good results it was time to switch to the next design on the list which was the Ramp design.

Narrowed Solutions

1. Atwood’s Machine Cart 2. Rubber band torsion Cart 3. Giant Stick Solution 4. Ramp Solution

Alternative Designs:

Atwood’s Machine Cart

Figure 5 This was the design that was first attempted but couldn’t get good results with.

This solution consists of attaching a weight to one side of the string and rolling the other side on the wheel axle (see Figure 5). The string would later be hung on a pulley that is


high enough that it will enable the cart to move 20ft when the weight drops all the way down.

Giant Stick Solution

Figure 6

This solution consists of having the cheese in a box at the end of a 20 foot tall stick made of foam core. The stick would be placed at the starting position and released to swing and the cheese will therefore land at the center of the target (see Figure 6).

Weighting Matrix:

Quality Precision Sturdiness Reliability Aesthetics

Coefficient (weight)

5 2 5 3

Decision Matrix:

Quality → Design ↓

Precision Sturdiness Reliability Aesthetics TOTAL

Ramp 3 4 4 4 55

Atwood’s Machine

4 5 5 3 64

Giant Stick 4 1 3 1 29


Solution Ranking (according to the Weighting Matrix) 1. Atwood’s Machine Cart 2. Ramp 3. Rubber Band Torsion 4. Giant Stick

Final Design Solution The Ramp Design Solution

Figure 7

The Ramp Solution utilizes a ramp not too steep so that the cart doesn’t kick off when it hits the ground and high enough so that the cart has enough kinetic energy at the start to attain the target (see Figure 7). The angle of the ramp was determined through extensive testing. The cheese was placed in a small box in the front of the cart that was made small enough so that it does not hit the ground when the cart transitions from the ramp to the ground. A small piece of poster board was added at the end of the ramp to help smoothen the transition and keep the cart going in a straight line.


Final Design Solution (continued): The Ramp Design was one of the best ideas according to the decision matrix and

turned out to be very accurate during the prototyping phase. It was easy to modify the cart or ramp to achieve better accuracy and to move further or less distance.

Implementation

The group decided to first prototype the Atwood’s machine cart. To prototype, the group tried several pulley configurations with varying weights to accelerate the cart (see Figure 8).

Figure 8

The design proved to be unfeasible, the weight was too heavy to allow the cart to move. However, the group learned the base-cart style was effective on its own, which was very important to the develop of the system overall.


This style cart was used in the next design idea: the ramp solution (see Figure 9).

Figure 9

The group prototyped three different carts of varying widths and lengths. Through

testing of each cart, it was determined that the larger the cart (with a wider base) minimized drift.

Once the cart prototype was finalized, the ramp was prototyped. A sheet of foam core was used as an impromptu ramp to gauge the necessary length and angle. The angle and length were finalized as 30° and 30 inches (see Figure 10). The group could move on to building the final design from there.

Figure 10


Construction Procedure The first cart design was a part of the atwood’s machine prototype. It featured a main body with two side pieces that holstered the axles and wheels. The construction procedure for this body shape remained constant. Each part was cut out of foam core. The pieces that bent around the chassis were partially cut. This allowed the piece to be cleanly folded without breaking apart. The pieces were firmly glued together.

Manufacturing the wheels proved to be challenging. The first attempt was drawing a circle in the foam core and free-hand cutting them. It was ineffective. Then, a mechanical drawing compass was used, but it wasn’t strong enough to hold the knife at a constant radius. Finally, a custom compass created out of foam core such that the radius would be fixed. It’s results were mixed but promising. The foam inside the board often balled up, but the wheels were round. Another compass was manufactured, this time with a greater radius; the wheels were almost flawless.

To the keep the wheels orthogonal to the axle, triangular fins were added. These were hot glued to the axle and wheels.

The ramp was simply cut out and tested at different angles until an angle was decided upon. The dimensions were recorded for the final design.

These steps were generated through the prototyping phases. The final cart and ramp were fabricated and assembled in one day. However, iteration and prototyping ensured a smooth construction and effective final product.

First all of the following components were drawn out on the posterboard. Their CAD drawings are included in the appendix.

1. Main chassis 2. Front axle mount and cheese box 3. Back axle mount 4. Wheels (4) 5. Wheel fins (16) 6. Ramp 7. Ramp back support 8. Ramp support posts (2) 9. Ramp bottom support

These additional components were cut out.

1. Axles (2) (from wooden dowel) 2. Ramp transition (piece of posterboard)


These pieces were then cut out using a new, sharp x-acto knife. The components were then assembled using hot glue. With immediate testing, there was slight drift to the right. Rubber bands were added to the right wheels to compensate (they slightly increased the diameter) and corrected the drift.

Materials Used

1. Foam core (30 in x 40 in x 3/16 in) 2. Poster board (20 in x 30 in) 3. Wooden dowel (1/4 in outer diameter 36 in length) 4. Hot glue gun (with glue) 5. Scotch tape (3/4 in x 36 yds) 6. Rubber bands (2)

Conclusion

Results of Preliminary Testing Numerical data was not recorded prior to demo day. However, the results were

very satisfactory; the cart was reaching within 6 inches of the center point of the target each test. As frequently as every other test, the cheesebox would land 3 inches (or less) away from the center point. Results

Trial 1 Trial 2* Trial 3*

Region Score 100 60 90

*These trials were neglected due to the perfect score in Trial 1. How did the results compare to expectations?

These results were expected. In preliminary testing, the results were very consistent. However, there was some inconsistency that was unexpected. This was due to the imbalance of weight that was not anticipated. This imbalance is discussed further in the What went wrong? section. What went right?

● When constructing the cart the goal was to have it go in a straight line. After 3 carts of prototyping the group perfected the cart design and built one that could move 20ft in a straight line.


Conclusion (continued):

What went wrong? ● The first design idea the group had seemed like it would work but after building

and testing it the cart did not move. This was a major problem since test day was only a week away. To get around this new challenge the group came up with a new idea, the ramp and cart idea. After spending a few a hours prototyping the group decided to move in the direction of the ramp.

● When the cart transitioned from the ramp to the ground it would turn slightly which would lead to extreme inaccuracy. To fix this issue a piece of poster was placed at the end of the ramp for a cleaner transition.

● On test day when the cheese was inserted into the cart it caused the cart to slightly turn when leaving the ramp. This might have been caused by the sheer mass of the cheese; while testing the cart the group used batteries for weight, which did not take up as much space as the block of cheese. The batteries weighed 2 ounces, however the cheese felt as though it was more than 2 ounces.

● The wheels would slightly wobble around on the axles which decreased the accuracy. Hot gluing 4 identical triangles to the axle and wheel kept the wheels in place and kept the cart going straight.

Recommendations

If the group got a second chance to build and test, many changes would be implemented. For this design one thing that could’ve been improved was the ramp, a curved ramp would make for a smoother descent and transition to the floor surface. The mass of the cheese on test day was more than anticipated which therefore made the cart unbalanced. To account for this the extra weight, more counter-weight needed to be added to the back of the cart.


Peer Evaluations

Team Member Contribution (%) Comments Signature

Mike Antoine 33.3 Large part of brainstorming process. Worked to fabricate and assemble components of several designs.

_________________

Jack Connolly 33.3 Great leader. Finely cut each part of the project, kept the group focused and on track.

_________________

Khalid Jebari 33.3 Khalid brought many good design ideas and solutions to the team. Hardworking and responsible. Worked to fabricate and assemble components of several designs.

_________________

Bibliography

1donagin. (2009, November 24). Simple Mouse Trap Car goes 138 feet. Retrieved March 14, 2017, from https://www.youtube.com/watch?v=XZ23q0QXPx0

Kilo charlie. Perfect circles in foam board. (2015, September 13). Retrieved March 14,

2017, from https://www.youtube.com/watch?v=Ik8L0P87Zw4 Moonstarspell. (2010, May 20). How to build weight powered car. Retrieved March 14,

2017, from https://www.youtube.com/watch?v=MlsaFq_3dzI

https://www.youtube.com/watch?v=XZ23q0QXPx0

https://www.youtube.com/watch?v=Ik8L0P87Zw4

https://www.youtube.com/watch?v=MlsaFq_3dzI


APPENDIX Gantt Chart (pg 17)

This chart allowed us to plan our schedule to create the cart and ramp. Unfortunately, the chart was not followed perfectly because of scheduling errors. However, before demo day, corrections were made to ensure completion of the project.

Logbook Page Sample (pg 18-20)

These are sample pages from each team member’s logbooks. Khalid’s sample (pg 18) Jack’s sample (pg 19) Mike’s sample (pg 20)

Meeting Notes (pg 21)

This example shows what the group discussed in a meeting on March 2. In this meeting, the group discussed the constraints of the project and things to consider when narrowing designs.

Sample Communications (pg 22)

The group decided that text messages were the most convenient option to communicate. In this group message, team members discussed where and when meetings would take place, and what would be discussed. Team member also discussed progress made independently. An example of such communication is included (as a screenshot from Jack’s phone). The group met every Tuesday and Thursday at 5:00 PM. Meetings took place in the library or in a team member’s dorm room. They lasted between 30 minutes and an hour.

CAD Drawings (pg 23-28)

These drawings include the dimensions required to recreate the launcher that was designed.

1. Main chassis (pg 24) 2. Front axle mount and cheese box (pg 25) 3. Back axle mount (pg 26) 4. Wheels (4) (pg 27) 5. Wheel fins (16) (pg 27) 6. Axles (2) 7. Ramp (pg 28) 8. Ramp back support (pg 28) 9. Ramp support posts (2) (pg 28) 10. Ramp bottom support (pg 28)













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