Mech 202 Project 2 Report

Appendix C Cover Sheet Template

Group Number ____

Group Members Email Addresses

Section Pages where found a. Cover sheet 1 b. Title and photo of device 2 c. Project plan & hours spentd. Specification developmente. Engineering analysisf. Concept development and choiceg. Illustrated description of device functionh. Bill of materialsi. Description of testingj. Reliability and design margin analysisk. Safety analysisl. Service and support planm. Teamwork analysis

Supplemental Information Where located Wow factors thoughts 87-88

3-1112-1617-2526-3132-4344

45-4849-5354-5758-5960-86

Group 35 Project 2

1

jrwein

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35

jrwein

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Sten Larson

jrwein

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Justin Weinmeister

jrwein

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Jace Horak

jrwein

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Troy Johnson

jrwein

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[email protected]

jrwein

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[email protected]

jrwein

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jrwein

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[email protected]

jrwein

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[email protected]

jrwein

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jrwein

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jrwein

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jrwein

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jrwein

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jrwein

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Pickles

The Catapult Launcher

Mech 202 Project 2

Group 35 Project 2

2

Project Plan:

March 8, 2015: This is the original project plan. The plan called for 213 hours of work. The plan required the team meet over spring break which was okay with the group. The plan also had only tentative team assignments. One difference with this plan was that it did not have a very tight critical path as many project items could be done independently. Additionally, this plan did not have as many team meetings as there were.

March 15, 2015: At this point in the project, most tasks were on schedule. The project plan had taken longer than planned to finalize; however, it did get finished without affecting other parts. Additionally, the engineering analysis, mover, control, and bill of materials all started slightly late. The time was quickly made up and did not delay the project.

March 22, 2015: At this point in the project the device seemed to be doing better than predicted and the group believed that we could finish the project in less than the predicted hours. The group meetings over spring break greatly helped the project and were a good start. We had amassed 70 hours of group work at this point.

March 29, 2015: By the 29th of March we had continued to progress well on all points except the engineering analysis. Due to the course load of Troy, the engineering analysis was delayed until there was more time available for him to complete the analysis. Initial calculations had been made, but they were just not finalized. Other parts were still on schedule; however, they were soon to be delayed as certain tasks were not finished as of the date. Our group was still not overly concerned with finishing on time as the only issue that was still unresolved was the reliability of the ping pong ball staying in the licenses plate.

April 5, 2015: This is the week where our project stared to fall behind. The engineering analysis and device parts were all over-schedule at this point as the ping pong ball’s ability to stay in the license plate holder was unresolved. Additional team meetings were made and additional report sections were put on hold until the device could be further refined. At this point the group had spent 124 hours working on the project.

April 12, 2015: By the 12th of April the group had finalized our design for the device and had completed some of our report sections. Additional changes had required that the engineering analysis be re-vamped as well.

April 16, 2015: The project was finished today as the project report sections were finished along with last minute testing of the device. The project took a total of 199 hours for the group. The group could have used more work earlier on in order to alleviate some of the last minute work that was required to finish the project out.

Group 35 Project 2

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The project was projected to take 213 hours and actually took 199 hours. There was also probably some undocumented hours worked as it was difficult to track accurately with irregular schedules. This means that the group worked approximately the projected amount of hours for the project. The tasks that took more time were concept generation and selection, testing, and team meetings. The remaining tasks took either the predicted amount of time or slightly less than predicted. Most tasks did not fit the predicted timeline for the project as the device parts took longer than expected to finish. This delay pushed the report sections further back until most of their work was done in the final week of the project. Additionally, this created extra team meetings at the end of the project including successive team meetings on the Sunday, Monday, Tuesday, and Wednesday before the project due date. Additional created days for team meetings occurred during spring break as the actual meeting days were not decided in advanced. These meetings were understood within the group, but just not on the official project plan. Finally, these meetings became inefficient for the project as the team atmosphere was relaxed and was not always focused on work. It is estimated that these additional meetings added 8 hours to the project.

Group 35 Project 2

4

R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F S S M T W R F

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 33 3 1

2 Specification Development 3/8/2015 3/8/2015 SL 0 4 0 --

3 Concept Generation & Selection 3/9/2015 3/11/2015 2 SL 0 8 0

4 Engineering Analysis 3/11/2015 3/22/2015 2,3 TJ 0 16 0

5 Mover 3/11/2015 3/29/2015 2,3,4 JH 0 25 0

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 0 20 0

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 0 20 0

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 0 10 0

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 0 40 0

10 Reliability and Design Margin Analysi 3/30/2015 4/5/2015 4,9 SL 0 10 0

11 Safety Analysis 3/30/2015 4/5/2015 4,9 JW 0 6 0

12 Service and Support Plan 4/6/2015 4/12/2015 9,10,11 JW 0 4 0

13 Device Description 4/6/2015 4/12/2015 4,5,6,7 JH 0 8 0

14 Bill of Materials 3/11/2015 4/12/2015 JW 0 2 0

15 Teamwork Analysis 4/13/2015 4/15/2015 JW 0 6 0

16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

18 Review Document 4/16/2015 4/16/2015 SL 0 4 0

19 Team Meetings Team 24 14

20 Team Checkups Team 1.5 0.16

21 Bob Meeting Team 0.5 0

Total Hours 0.54% 213 15.16

Units Inch Planned Time

Software Google Sheets Actual Time

Buddy Troy<->Justin Critical Path ----------

System Sten<->Jace Milestones

Number Task Start Finish Dependencies Resources % CompleteEstimated

HoursActualHours

March April

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----------------------------------------------------------------------------------------

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JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson

JW = Justin Weinmeister

Group 35 Project 2

5

Justin

Typewriter

March 8, 2015

Justin

Typewriter

Justin

Typewriter

Justin

Typewriter

Justin

Typewriter

Justin

Typewriter

Justin

Typewriter

Justin

Typewriter


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2



4 Engineering Analysis 3/11/2015 3/22/2015 2,3 TJ 6.25 16 1

5 Mover 3/11/2015 3/29/2015 2,3,4 JH 16 25 4

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 0 20 0

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 10 20 2

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 0 10 0

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 0 40 0





14 Bill of Materials 3/11/2015 4/12/2015 JW 25 2 0.5


16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0





Total Hours 12.23% 213 36.66






HoursActualHours

March April

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----------------------------------------------------------------------------------------

---------------------------

----------------------------

JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

6

Justin

Typewriter

March 15, 2015

Justin

Typewriter

Justin

Typewriter


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2




5 Mover 3/11/2015 3/29/2015 2,3,4 JH 40 25 10

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 40 20 8

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 45 20 9

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 40 10 4

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 15 40 6







16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0





Total Hours 30.16% 213 69.66






HoursActualHours

March April

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----------------------------------------------------------------------------------------

---------------------------

----------------------------

JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

7

Justin

Typewriter

March 22, 2015

Justin

Typewriter

Justin

Typewriter


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2




5 Mover 3/11/2015 3/29/2015 2,3,4 JH 40 25 20

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 70 20 14

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 60 20 12

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 50 10 5

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 40 40 16







16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0




21 Bob Meeting Team 0.5 0.5

Total Hours 42.66% 213 105.5






HoursActualHours

March April

-------

----------------------------------------------------------------------------------------

---------------------------

----------------------------

JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

8

Justin

Typewriter

March 29, 2015

Justin

Typewriter

Justin

Typewriter


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2




5 Mover 3/11/2015 3/29/2015 2,3,4 JH 88 25 22

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 80 20 16

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 70 20 14

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 50 10 5

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 55 40 22







16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0





Total Hours 56.79% 213 123.75






HoursActualHours

March April

-------

----------------------------------------------------------------------------------------

---------------------------

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JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

9

Justin

Typewriter

April 5, 2015

Justin

Typewriter


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2




5 Mover 3/11/2015 3/29/2015 2,3,4 JH 100 25 22

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 80 20 16

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 100 20 16

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 100 10 6

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 90 40 36







16 Cover Sheet 4/15/2015 4/16/2015 JW 0 0.5 0

17 Title Sheet 4/15/2015 4/16/2015 JW 0 0.5 0



20 Team Checkups Team 1.5 1


Total Hours 84.78% 213 159.5






HoursActualHours

March April

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----------------------------------------------------------------------------------------

---------------------------

----------------------------

JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

10

Justin

Typewriter

April 12, 2015


5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 Plan 3/5/2015 3/10/2015 JW 100 3 2




5 Mover 3/11/2015 3/29/2015 2,3,4 JH 100 25 22

6 Claw 3/18/2015 3/29/2015 2,3,4,5 SL 100 20 20

7 Control 3/11/2015 3/29/2015 2,3,4,6 TJ 100 20 16

8 Platform 3/18/2015 3/29/2015 2,3,4 JH 100 10 6

9 Testing 3/18/2015 4/12/2015 4,5,6,7,8 TJ,JW 100 40 46







16 Cover Sheet 4/15/2015 4/16/2015 JW 100 0.5 0.5

17 Title Sheet 4/15/2015 4/16/2015 JW 100 0.5 0.25





Total Hours 101.63% 213 198.5






HoursActualHours

March April

-------

----------------------------------------------------------------------------------------

---------------------------

----------------------------

JH = Jace Horak

TJ = Troy Johnson

SL = Sten Larson


Group 35 Project 2

11

Justin

Typewriter

April 16, 2015

Justin

Typewriter

Justin

Typewriter

Specification Development:

First as a group we came of with a list of requirements that could be required from our project, this list included:

Small starting size- The project must fit in the bounds.

Quick setup time- It must be set up in under 45 seconds.

Autonomous start- It must be able to start consistently with no input except from the movement of the starting bar.

Elevates over the barrier- device must in some way make it to the height of the barrier.

Releases ping pong ball- the device must release the ball in the target area to be successful.

Ping pong ball must stay in the target- To be successful the ball must also stay in the target area

Device must return to the start- After the device delivers the Ping-Pong ball it must get back to the starting area.

Lighter than 3 lbs. - the total device must weight less than 3 lbs.

Inexpensive- the device should be as inexpensive as possible to complete the tasks.

Simple design- The more simple the design the less is likely to go wrong and the more the customers will enjoy it.

Resets in less than 15 minutes- all repairs and resets must take place in under 15 minutes.

Non-hazardous- Our device must not cause any danger to us or any other, or their projects.

Does not damage fixture- Our device may not damage the fixture or leave any sort of residue.

Customers

We then took a look at our potential customers

Group 35(us) - The project must meet our requirements, since our grade requires it to do well and it must be something we as a group are proud of.

Bert and Bob- The objective was created by Bert and Bob so it is very important it meet their requirements, which prioritize safety, creativity, and ability to complete the given tasks.

Group 35 Project 2

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Customers vs. Requirements

We then took these requirement and customers and made a Customers vs. Requirements chart that shows the importance of certain requirements to specific customers.

Customers Vs. Requirements

Requirements Bert and Bob

Group 35 Total Normalized Total

Small Starting Size 7 6 13 6.5 Sets Up in under 45sec 8 9 17 8.5 Start Autonomously 12 12 24 12 Elevates over 2ft barrier 12 12 24 12 Releases Ping Pong Ball 8 7 15 7.5 Ping Pong Ball Stays In Target 8 7 15 7.5 Returns to Start 3 3 6 3 Under 3 lbs. 8 7 15 7.5 Inexpensive 5 8 13 6.5 Simple Design 3 5 8 4 Resets in under 15min 5 6 11 5.5 Non-hazardous 13 10 23 11.5 Does Not Damage Fixture 8 8 16 8

From the Chart we see that the most important requirement to Bert and Bob is that the device is non-hazardous. To Group 35 the most important requirements are that the device starts automatically and that the ball is elevated over the barrier. The overall most important customer requirements were also that the device starts automatically and makes it over the two foot barrier.

Group 35 Project 2

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What Vs How

These requirements were then made into engineering specifications and related in their importance to the original requirements in the What vs How chart shown below. There is mostly a one-to-one ratio of requirements to specifications, but overlaps were determined from this chart. Measurements were determined by finding values that could be compared to each other.

Group 35 Project 2

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The competition rules and our team goals were then looked and examined with the engineering specifications to create target and thresh holds for each of the engineering specifications. For most specifications the threshold was determined by the constraints of the competition while the target was the goal set by our team. For some specifications, such as amount of electrical parts, the threshold and target were determined solely by what our group thought would best accomplish the given task.

Final QFD

Last all the parts of the QFD were put together along with the How vs How section and this can be seen on the page below.

Group 35 Project 2

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After searching on the internet for a product that could perform the tasks required, competition was left off of the QFD. Even through their designs were not close enough to be considered competition, certain devices were looked at for for their potential strengths in completing certain requirements of the device. Examples of this include the Boy Craft Catapult wars (Amazon.com), a DYI catapult kit capable of launching the ball over the barrier and Lego Mindstorms (http://www.lego.com/en-us/mindstorms) , programmable Lego devices that could function like an Arduino board to program our device to complete the tasks. Overall certain portions of these devices gave us goals to try to achieve with our device, but were not specific enough to our given task to be defined as competitors.

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Engineering Analysis:

Optimal Trajectory Analysis

Due to the locations of the starting bar, the location of the capsule launcher is very

restricted as the launcher arm needs to have a decent amount of clearance from the bar to

ensure an unimpeded trajectory. From the dimensions of the competition fixture, primarily

the distance from the launcher to the license plate holder, an optimal trajectory was

calculated to give the capsule the best chance of landing in the license plate holder while

also clearing the wall. The most important part of this section of the analysis is the launch

angle. The optimal launch angle is the angle that gets the capsule over the wall consistently

(with some margin for error) while also launching the capsule as low as possible to lower

the amount of kinetic energy that needs to be dissipated as the capsule lands, lowering the

chance of the ping pong ball being thrown from the competition fixture. The calculated

optimal launch angle is 83 degrees from horizontal. This angle will allow the capsule to

land centered in the license plate holder and reach an optimal peak height of 78.7 cm. (See

following calculations) These calculations could be accomplished through use of equation

solving learned in dynamics.

Group 35 Project 2

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Group 35 Project 2

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Change in Launch Angle Analysis

The sensitivity of the system to flex and other variation is very important for a

consistent trajectory. One drawback of lightweight materials is that they tend not to be

extremely rigid. This lack of rigidity leads to flex in the launching system and a change in

the launch angle. Calculating the change in trajectory due to a small change in launch angle

(in this case 5 degrees) shows that the distance the capsule is launched is increased by

nearly 25 cm, enough to cause the capsule to miss the license plate holder all together.

Knowing this, tongue depressors were used to reinforce the base to reduce flex while also

keeping the overall weight of the device to a minimum. This analysis expanded on the

dynamics analysis used for the trajectory analysis.

Group 35 Project 2

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Group 35 Project 2

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Change in Capsule Mass Analysis

In order to land the capsule without it bouncing off target, some sort of energy

absorbing material needed to be implemented. Regardless of the type of material, the use

of any sort of energy absorbing device adds mass to the capsule, effecting its trajectory and

landing location. In general, the heavier the material (or an increase in the amount of

material) used is proportional to the energy absorbed by the material, but adding more

mass to the capsule will negatively affect the trajectory of the ball. By increasing the mass

of the capsule by 25%, the max height of the capsule drops 13.2 cm below optimal peak

height with a peak height of 66.5 cm, not enough to safely clear the wall. Knowing this, the

use of lightweight energy absorbing materials became a priority. This was a further

expansion of the previous analysis.

Group 35 Project 2

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Group 35 Project 2

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Material Analysis

As stated in section 8 of the rules, the device with the lowest weight will win the

heat by default if there is a tie or if all the devices in that heat fail. This puts weight high on

the list of design priorities. Materials such as metal and large amounts of dense wood were

immediately removed from designs and replaced with similar materials of lighter weight.

Initially plywood was used as a base for the device but was replaced with a sheet of

cardboard, drastically reducing weight of the device from 1.5 lbs (680g) to about 16 grams.

This led to a rigidity issue that is discussed above in the Launch Angle Analysis. Another

large source of weight is the batteries that power the control circuit and motors. The

implementation of more power dense batteries would allow for a lighter batteries but at

the cost of being much more expensive. Instead, the control circuit was simplified in order

to use only a single 9v battery to power the both the starting motor as well as the winch

motor saving another 45 grams.

Group 35 Project 2

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Circuit Analysis

Both the mousetrap activation motor and the spooling motor are controlled by the

same circuit and are powered by a single 9V battery. These motors can be wired into the

circuit in either a series or parallel configuration. When the motors are wired in series,

both motors receive the same amount of current, but the 1st motor in the series will create

a voltage drop. This lowers the voltage across the second motor. In a parallel circuit, a

current divider is created, supplying each motor with the same voltage. This allows each

motor to spin at the same speed without drastically hindering the performance of either

motor. This could also be completed by using two separate circuits for each motor, but this

would increase complexity and part count as well as weight. This analysis was

accomplished from material learned in ECE 204.

Group 35 Project 2

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Series Circuit

Parallel Circuit

Group 35 Project 2

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Concept generation and concept selection:

Main Concept

To generate our main concept, our group got together and used our QFD chart and other research to brainstorm in an hour long session, recording all ideas as we went. After we brainstormed, every member of the group took a concept that we thought could work and was practical and refined it into a well thought out idea. We then met again and compared these thought out concepts to our QFD chart once again, made a decision matrix, and as a group decided on our design. Our final decision was to use a catapult and a delivery device. All the thought out devices compared to each other and there notes are below.

1) Catapult and delivery device. Original design includes a mousetrap as the catapult, a claw for the delivery device and an Arduino board to control the mousetrap launch, claw opening, and motor to pull the device back.

Pros Cons -inexpensive -easy to build -few electronic components -simple -small -light weight

-needs lots of calibration to make accurate -needs a way to break impact of the ball

Group 35 Project 2

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Group 35 Project 2

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2) Crane. A scissor lift would be used to raise the ball above the wall, then a tape measure would extend the ball over the wall and a string would have lowered it down into the license plate holder. Pros Cons -very accurate -would get over barrier consistently -ball placement would be exact

-expensive -time consuming to build -heavy

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3) Swinging arm device. A series of arms would unravel from the rest position by a motor and lock into a position that delivers the ball into the license plate holder. The motor would the reverse pulling all arms back into the starting position. Pros Cons -would get over barrier -places ball accurately

-hard to build -possibly expensive - might be too long for constraints

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4) Air cannon. Compressed air would provide the force to get the ball over the barrier, other than that it would be run about the same as the catapult. Pros Cons -light weight -small

-safety concern -possible inaccuracy -expensive to run -separate delivery system needed

5) Hooked crawler- A device that would crawl over the barrier using hooked arms,

place the ball, and then reverse and go back to the original time, would be controlled with an Arduino board. Pros Cons -ball delivered without any bounce -“Wow” for mechatronics

-very expensive to build -many electric parts -might have problems with getting back to start -if set incorrectly might not get over the barrier

After we chose the catapult as our system of choice, we began to develop concepts for how every piece of our device should be made and out of what materials. Our original design called for the use of a claw, three motors attached to an Arduino board, a base of wood, and a mousetrap to launch the claw over the barrier. Almost all of our original plans changed as time went on.

Launcher

The launcher was one of prototyped parts of our device, and four total launchers were created. The first launcher was made out of a mousetrap and was abandoned as its design didn’t allow the mousetrap to lock in place. The second was also made of a mousetrap and had a long lever arm. We ended up not using this one as it was too hard to fit in the height restraint and also launched too far. Next we made another launcher with a similar design to the second but with a shorter lever arm. This design was promising but we were unsure if it would fit in the height limit set in the QFD. Last a prototype was made with a rat trap, to try to get more power from a shorter device. This was abandoned as it was too strong and posed a safety concern with the force it swung. Therefore we chose our third device. Next we had to find a way to launch our carrier at the correct angle. We calculated the ideal angle (shown in the engineering analysis section) and used cut wood blocks to get the desired launch trajectory.

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Base

The base was originally prototyped with wood, but changed our design for two reasons. First, it was heavy and one our specifications was to keep our weight down to a minimal level. Second it also warped slightly, which was not conducive to keeping our launches consistent and our ability to land our device in the license plate. Our second and final prototype was made of cardboard which solves our problems since it is lighter than wood and can be lied flat easily. One of the downsides of cardboard is that it is less stiff than wood, which also caused our consistency to go down. To combat this we used Popsicle sticks to keep the base rigid as well as non-residue sticky tack to secure our base to the fixture for even more support.

Carrier

The carrier was originally designed to be a claw opened by a small motor activated by an Arduino board. Quickly we realized the weight of the claw may be an issue as well as the difficulty of launching a wire attached to the motor and the Arduino over the barrier. This related to our engineering specification for amount of electric parts. Therefore we decided to look for a low tech solution and while walking through Safeway around Easter saw plastic Easter eggs and thought we might be able to make our carrier open using impact like the Easter eggs. We then found soccer ball shaped Easter eggs that the Ping-Pong ball fit in nicely and began to experiment with different ways to minimize the impact the ball would feel while still opening up the egg. First cotton was used inside the ball to try to increase the time of the contact to decrease the force put on the Ping-Pong ball. This worked but did not stop the carrier from bouncing, so a sticky tack layer was added to the carrier. This damped the impact but not as much as desired. Because of this it was decided to create a new carrier. The new carrier has a net inside to stop the ball from bouncing after the carrier opens and, to stop the full carrier from bouncing, uses a part of a packet of mustard attached to the outside to soften the impact. This design has much more success in releasing the ball in the license plate and was used in our final design.

The string we used to connect the launcher to the device also changed from our original prototype. Originally we used dental floss because of its strength and light weight. Unfortunately during testing the dental floss frayed becoming a problem getting caught on the rest of our device. This increased the unreliability of the system due to tangling, and it had to be changed. To combat this we decided to use fishing line as it is strong and light like the dental floss but also does not fray.

Group 35 Project 2

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Device Description:

The device that our group has chosen to construct is a simple mousetrap

catapult. We have modified a capsule to hold the Ping-Pong ball and release it when

contacted with a surface. We have also put the mousetrap up at an angle so the

trajectory of the capsule, with ball inside, will clear the two-foot barrier and land in

the license plate holder. The entire system is self-automated with two small motors,

a switch and a 9V battery.

The overview of the device above consists of 13 major parts. The platform

(11) that holds all of the components is made out of cardboard. The cardboard

1

2

3

4

5 6 7 8

9

10

11

13 12

Group 35 Project 2

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rectangle is approximately 12 inches long by 10.5 inches wide. We put three dots of

sticky tack on the bottom of the cardboard for extra support to hold the entire

device down. The next major component is the mousetrap (2), which is restrained

by a zip tie and elevated at about a 60-degree angle by a wooden block (1). Mounted

on the arm of the mousetrap is a small motor (13) with a zip tie connected to it. The

target of this motor is to spin the zip tie into the arm of the mousetrap to set it off. At

the end of the arm of the mousetrap is a cup to hold our capsule device (3). The

capsule sits perfectly in the holder and has a string connected to it to pull the

capsule back after releasing the Ping-Pong ball. There is also a packet of viscous

liquid (4) connected to the capsule to control flight and dampen the landing so it can

stay within the license plate holder. All of this is connected to the cardboard with

hot glue and carries a lot of force when used. To counteract these forces we use

Popsicle sticks (5) as braces for the cardboard, mousetrap wedge and the switch

holder (7). The switch for the device is self automated by the starting gate. When the

starting gate is placed in its second position, the switch is activated by a 9V (6)

battery that is placed with copper wires (12) in parallel with the motor connected to

the mousetrap and the motor connected to a spool (8) to pull back the capsule from

the other side. Connected to the spool is eight-pound test fishing line (10) that is

long enough to get the capsule to the other side and have some room to spare. The

fishing line is pulled through two eyelets (9) as to prevent tangles. This is a quick

overview of the entire system. Here is more detail into each part.

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This is the launching device made out of a simple mousetrap. The mousetrap

is connected to a wooden block (14) cut at a 60-degree angle as to elevate the lever

arm to release. This block was cut from a two by four on a miter saw. Between the

mousetrap base (16) and the block are shims (15) to create a little larger of an angle

to launch the ball higher. These shims were used because they are an easy way to

slightly change the angle, making testing more productive. The shims are made out

of the same Popsicle sticks that the supports are made out of. The mousetrap is

activated by a small motor (18) that is connected to the arm of the mousetrap. The

motor has a small shaft that spins; connected to the shaft is a zip tie that is hot glued

to it. When the 9V battery activates the motor, the shaft spins the zip tie to contact

an arm that holds the mousetrap spring in compression. This arm is pushed off its

support (17) and releases the mousetrap. The mousetrap rotates its lever arm until

it is stopped by a zip tie (23). This zip tie is approximately one inch long and

14

15 16 17 18 19 20

22 24 23

21

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connects the end of the mousetrap lever to the back of the mousetrap base. The

mousetrap lever arms (22) have three inch long Popsicle sticks duct taped to them.

These Popsicle sticks allow a platform to put the motor on and a platform to put the

capsule holder (19) onto. The capsule holder is centered and duct taped between

the two Popsicle stick lever arms of the mousetrap. The capsule holder is made out

of daily mini cups and has the bottom and side cut a little to save on space that the

capsule (20) does not touch while in it. The little motor has two wires (21)

connected to it. One wire is connected in parallel to the other motor being use while

the other wire is connected to the switch. All of the launching mechanism is

supported by Popsicle sticks (24). These are placed to brace the back and are placed

along the sides of the block to minimize flection in the cardboard base.

The capsule of the device is very simple. It has changed a lot from testing. We

used sticky tack to weight it, cotton balls to dampen the hit and Velcro strips. Those

were all tested and taken out as they failed to produce exactly what we wanted. The

25

26

27 28

29

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shell of the capsule (26) is an Easter egg holder that is used to put candy in and hide

it for Easter egg hunts. The objective with this type of capsule is for the impact of the

ground to break the egg open and place the Ping-Pong ball (27) inside the license

plate holder. We cut the edges of the Easter egg so that it releases easier. This

happens because the contacts points when the egg is snapped together are greatly

reduced when cut so the force to break open the egg is greatly diminished. Once the

egg is cracked open we have placed netting (29) to hold the ball in the egg casing so

it does not violently fling the ball when broken open. The last measure to help the

landing is a packet of viscous liquid (25). This packet adds controllability to the

flight and greatly dampens the landing so that everything can stay inside the license

plate holder. Finally, the two eggshells are connected to a string (28) on each side so

that it can be pulled back over the barrier after the Ping-Pong ball is released into

the license plate holder.

30

31 32

33

34 35

36

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The switch mechanism is what starts the entire device. We used a simple

switch (31) from RadioShack. The switch is activated when the starting bar is

pressed down on the switch arm (32). We modified the switch arm so that it is

longer and has more to be pressed. We did this by hot gluing a bent paper clip to the

original switch arm. We glued it so that the switch is very sensitive. With the paper

clip glued to it we get play within the height of the switch and play forward and

backward allowing for variability. The entire switch is connected to a base (36) to

elevate the switch to be in contact with the starting bar. The piece of wood is thin

and was cut to about three inches. The base for the switch is held up by Popsicle

stick supports (35) on each side. The switch is connected to the little motor on the

mousetrap (30), the motor that spools the fishing line (34), and to the 9V battery

(33). All of these connections are in the respective ports of the switch as explained

in the picture above.

37

38

39

40

41

42

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The motor assembly to pull the capsule back in is made out of a modified

motor (42). The motor spins a shaft that we extended with a mechanical pencil

casing (37). The longer shaft spins, allowing more room for the fishing line (38) to

spool onto. This takes away error in the spooling process. We also used the

mechanical pencil casing because the diameter is small, so it has to go through more

revolutions to spool up the fishing line. The more revolutions give us more time to

get the ball over and allow us to use less fishing line, which causes fewer tangles.

The motor is supported by Popsicle sticks (39) that have been broken in half. These

Popsicle sticks elevate the motor and stabilize it from moving. The motor has two

wires connecting the terminals to the switch (41) and connecting this motor in

parallel to the small motor that trips the mousetrap.

This part of the device is simply to help the fishing line (43) feed into the

spool that the motor is spinning. It is elevated two inches by a Popsicle stick (46).

43

44

45

46

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This elevation makes the angle into the spool straighter, creating less friction in the

line while it is being pulled. Less friction allows the motor to not work as hard while

spooling in the fishing line. The line is first pulled through a bent paper clip (44).

The paper clip makes a small loop with very little friction. This part takes out large

imperfections in the way the line is sitting. The second part is a sewing needle (45).

The line is pulled through that small hole which has more friction. The friction takes

out any more imperfections in the line and straightens the line as it is spooled onto

the mechanical pencil spool. The only function of this aspect of the device is to help

diminish errors while the fishing line is pulling the capsule back.

To create this device one needs a mousetrap, a 60 degree cut block of wood,

scrap wood, a simple switch, copper wire, two small motors, two zip ties, fifteen

popsicle sticks, cardboard, small cup, screws, Easter egg, netting, fishing line, liquid

packet (mustard packet), paper clip, sewing needle, mechanical pencil and a 9V

battery. The tools that are needed are a hot glue gun, soldering iron, scissors and a

saw. First the base must be made. Cut the cardboard down to a 10.5-inch by 12

inches. Then cut a square that is two inches by two inches in size. The square should

be place five inches back from the front edge and two inches to the left of the right

edge. This is a place for the end of the catapult to sit so that it may stay underneath

the 3.5 inches of available space. For the mousetrap, two, three inch Popsicle sticks

must be taped to the arms and the a popsicle stick is taped to the two ends of the

popsicle sticks on the arms for support and a place to put the small cup to hold the

capsule. All of this must be securely duct taped to the lever arm of the mousetrap. It

is very important that the lever arm to set the mousetrap goes between the small

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cup and the end of the mousetrap lever arm. This is also where a zip tie is placed,

connecting the end of the lever arm of the mousetrap to the bottom of the

mousetrap. The zip tie stops the mousetrap from swinging creating the catapult.

Finally a small motor is placed on the left arm of the mousetrap catapult. This is how

the mousetrap will be tripped. A second zip tie is hot glued to the shaft of the motor

so that part hits the mousetrap mechanism to set the mousetrap off. All of the

mousetrap and everything connected to it is screwed to the 60-degree block. This is

to elevate the launch angle so more height is achievable. The block of wood, with the

mousetrap, are then trimmed down using the saw. Cut off the top portion of the

mousetrap and block so that it fits under the 3.5-inch max. This includes the metal

arm used for tripping the mousetrap. The 60-degree block is then glued to the

cardboard base so that the cup lines up with the square cut out while the trap is set.

Use eight Popsicle sticks to support the cardboard form flexing and the bock from

moving. Refer to the first picture for placing of the Popsicle sticks to best support

the device. The simple switch is then glued to the scrap wood so that it is elevated

3.5 inches in the air. A paper clip is then bent out and glued to lengthen the switch

arm and sensibility of the switch. The switch stand is then glued two inches from the

back piece of cardboard and supported by two Popsicle stick wedges on each side.

The next motor is placed right to the left of the switch. A stand is made out of a

Popsicle stick to elevate the motor. The casing of a mechanical pencil is cut to a two-

inch length and glued to the shaft of the motor to increase the length that can spool

up the fishing line. The guide for the line is placed two inches down from the spool

connected to the motor. The guide consists of a two-inch Popsicle stick with a paper

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clip bent into a loop at the far end of the Popsicle stick and sewing needle connected

to the close end of the Popsicle stick. For placement specifics please visit the

pictures above. The fishing line is rapped around the mechanical pencil holder and

through the sewing needle and paper clip. The line is then connected to the Easter

egg capsule. The Easter egg capsule consists of a net inside to keep the Ping-Pong

ball from bouncing out too violently. A liquid pack is also glued to the side of the

Easter egg so that it has some control in flight and the landing is dampened. Finally

the two motors are hooked up in series to the switch and 9V battery. The wires are

soldered so that they will be stable and not fall apart. For any questions on how the

device is put together please view the pictures above for clarification.

The device we created is very simple to set up. All of the components are hot

glued to the cardboard, which is used for positioning. To place the device, we line up

the back left corner of the cardboard with the back left corner of the lane. This

positions the mousetrap launcher in the front right of the cardboard. Once lined up,

we push down on the cardboard to set the sticky tack. After the device is set in the

right position, the Ping-Pong ball must be placed in the net, inside the capsule. Next,

the capsule must be closed till it clicks just like closing an Easter egg. Once the ball is

ready, all of the fishing line must be pulled out of the spool and set right in front of

the guide paperclip and sewing needle. Now that the capsule and line retraction

system are ready the mousetrap must be set. This is exactly the same as setting a

normal mousetrap. Once that is set the zip tie on the motor on the mousetrap must

be spun to the outside position, allowing for maximum movement before hitting the

mousetrap lever arm. Finally the ball must be set in the mousetrap catapult so that

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the glue dot on the capsule touches the front of the capsule holder, the glue dot is

just for positioning purposes. Once all of this is set up the device is ready to start.

The starting bar will push down on the switch when it is moved to its second

position. The switch will start both motors that will trip the mousetrap and start

pulling in the line. There is enough line out that the capsule will be able to reach the

other side without being pulled back before it strikes the ground. The mousetrap

will throw the capsule, containing the Ping-Pong ball, over the wall and into the

license plate holder where it will break open. Once it breaks open it will sit there till

the motor retracting the line gains tension and pulls the capsule back over the wall,

leaving the Ping-Pong ball in the license plate. Once the ball is back to the other side

all of the steps will be completed.

Some elements that have been put into this device to make it work well and

reliable are mostly the support systems. The sticky tack on the bottom of the

cardboard keeps the entire device from jumping up when the catapult is fired. The

Popsicle sticks reduce the flection in the cardboard when the catapult is fired. The

main goal for the supports was to stop the device base from moving when the

catapult is fired. Another element that is critical to our success is the 60-degree

block. This angle change allows the mousetrap to open further which creates more

power. This power makes getting over the barrier easy and attainable on almost

every trial we have run. These are just some of the parts of our system that keep our

device working and working reliably, but we put thought and engineering into every

part of our device.

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While making this device we changed things several times until we got

something that worked consistently through the tests. One thing that we came up

with that is very unique is our release capsule. It is an Easter egg that cracks open

when it impacts the ground. This is unique because we don’t need any electrical

component to open the capsule. It is also unique because it is seasonal for Easter

eggs, so we were lucky to take this class in the spring semester when Easter eggs are

readily available. The Easter egg varies from other designs because it harnesses the

force of the impact to crack the capsule. So where a lot of teams will not like the

force of landing, we are using it to our advantage.

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Bill of Materials

Item Description Material Where Purchased Quantity Cost Incurred

Cost of Parts

1 Fixture 1.1 License Plate Holder Steel Ace Hardware 1 11.27 N/A 1.2 Base OSB N/A 2 N/A N/A 1.3 Sides 2"x4" Fir N/A 2 N/A N/A 1.4 Ball Plastic N/A 2 N/A N/A 1.5 Gate Plastic N/A 1 N/A N/A 2 Claw

2.1 Egg ABS Plastic Safeway 8 2 0.25 2.2 String Fishing Line N/A 20 yards N/A 0.15 2.3 Net Plastic Netting N/A 6in x 6in N/A 0.15 2.4 Cushion Mustard Packet N/A 1 N/A 0.1 3 Mover

3.1 Mousetrap Pine, Steel Ace Hardware 4 3 0.75 3.2 Hobby Sticks Pine Safeway 75 3 0.3 3.3 Duct Tape Cloth + Plastic N/A 2 rolls N/A 0.1 3.4 Cup Plastic Safeway 50 3 0.06 3.5 Ziptie ABS Plastic N/A 1 N/A 0.01 3.6 Ramp 2"x4" Fir N/A 4in x 4in N/A 0.15 4 Base

4.1 Baseplate Cardboard N/A 18in x 11in N/A 0 4.2 Switch Stand Pine N/A 3/8in x 4in N/A 0.2 4.3 Glue Hot Glue Ace Hardware 24 7.89 0.33 5 Control System

5.1 Switch ABS Plastic RadioShack 1 3 3 5.2 Small Motor Steel N/A 1 N/A 1.95 5.3 Large Motor Steel N/A 1 N/A 1.95 5.4 Wiring Copper RadioShack 6 ft 2.5 0.5 5.5 Paperclip Steel N/A 2 N/A 0.01 5.6 Ziptie ABS Plastic N/A 2 N/A 0.02 5.7 Spool Plastic N/A 1 N/A 0.2 5.8 Battery 9V Safeway 5 12.5 2.5 5.9 Battery Terminal Steel RadioShack 1 0.67 0.67 5.1 Needle Steel N/A 1 N/A 0.05 6 Test Parts (unused)

6.1 String Dental Floss Safeway 100 yards 2 N/A 6.2 String Thread N/A 5 ft N/A N/A 6.3 Rattrap Mixed Home Depot 1 2 N/A 6.4 Cushion Funtak Safeway 2 N/A 6.5 Electric Terminal Plastic N/A 1 N/A N/A 6.6 Padding Cotton Balls Safeway 70 1.5 N/A 6.7 Battery AA Safeway 2 0.5 N/A

Total Incurred Cost 56.33

Device Cost 13.4

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Testing:

Testing procedures:

Placement:

Measured Value: Could the device be placed in 45 seconds or less?

Details: This test is to determine if the device could be set-up and placed correctly in

the 45 seconds the team has in order to compete. The test will determine the time from

receiving a ping pongball to device placement. This tests task 1. This test was not run as

other testing took longer than anticipated and was more pressing. Observations during

other trails showed that the device could be placed in approximately 30 seconds and the

group decided that it would be better to spend time testing other parameters.

Sub-measurements:

Time to place ball in capsule?

Time to align base with fixture?

Time to set switch and mousetrap?

Sizing:

Measured Value: Does the length, width, and height of the device fit inside the 18”,

11”, and 3.5” dimensions?

Details: The device is measured at every feature to determine if it can fit inside these dimensions. The results are either pass or fail as there is no benefit to being

less than required.

Starting mechanism:

Measured Value: Did catapult start autonomously?

Details: The test is started by moving a bar from the front position to the rear position on a test fixture without the bar contacting any part of the device except for the

starting switch when the bar is in the rear position. The device must then activate the small

motor, which must rotate and hit the mousetrap, causing it to release. This corresponds to

task 3 of the project requirements.

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Sub-measurements:

Does the starting bar contact the switch?

Does the switch cause the small motor to rotate?

Does the small motor contact the mousetrap and cause it to release?

Does the mousetrap release fully?

Capsule Height:

Measured Value: Does the capsule make it over the central barrier to the other side

of the fixture?

Details: The capsule must make it over the barrier and into the far side of the fixture. This test can be run and recorded with measurements of how far the capsule is over the

barrier in order to determine not only the reliability, but also the trajectory. In order to run

more trials, precise measurements were not taken regularly.

Capsule delivery:

Measured value: Does the capsule land in the license plate fixture and successfully

release the ping pong ball into the license plate holder?

Details: For this test the capsule must land in the license plate holder without

leaving the lane and break open. The test also includes the process of the initial pull-back

for the capsule. The test requires that the ping pong ball remain in the license plate holder

after it leaves the capsule and that the capsule doesn’t go outside our lane before being

pulled into the air. This test measures the results of task 5.

Sub-measurements:

Does the capsule land in the license plate holder?

Does the ping pong ball fall into the license plate holder?

Does the ping pong ball remain in the holder?

Does the capsule go outside the lane at any point?

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Capsule recovery;

Measure value: Does the capsule return to the starting area?

Details: This test starts as soon as the capsule is lifted off the fixture base. The test runs until the device moves no more. The test requires that the capsule stay in the lane

during the entire recovery process. This test measures task 6.

Sub-measurements:

Does the capsule go outside the lane on the far side?

Does the capsule return to the near side?

Does the capsule go outside the lane on the near side?

Does the device stop moving?

These tests are run as listed because they measure the main functions of the device without

discriminating on the failure mode. Finer test results would have produced too much data

for our team to process in the limited amount of time we had for this project. Additionally, the team did not complete all the test as we had planned as it would have made for a worse

device due to these time constraints. Our position for this decision was that since the

project was only ours (and only ever would be), the collected data would not be useful for any other reason than to put in the report. The data was in our heads and proved useful in

changing the capsule to improve reliability in task 5, though it was probably too little too

late. Ideally, for future projects, we would like to start component testing earlier in the

design cycle in order to have more data for when system testing is done.

Further requirement tests were done; however, they were not done in a systematic way as

they best fit a pass/fail model. Results are recorded in the test status chart.

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Final Test Status:

Group Number: 35 Group Members: Justin Weinmeister, Jace Horak, Sten larson, Troy Johnson Project: Ram lander

Specification description, direction & measure Targets How it will be tested Target Date Owner Status

Want Must Dimensions (sq. in) with lower is better 198 198 Measuring tape 4/1/2015 JH

Steps to set up (#) lower is better 2 5 Number of items on checklist 4/12/2015 SL Reliability of start (%) high is better 100 90 % starts out of 100 final trials 4/12/2015 SL

Height (in) lower is better 3.5 3.5 Measuring Tape 4/1/2015 JH Ball Release Reliability (%) higher is better 100 75 % release out of 100 final trials 4/12/2015 TJ Ball Release Speed (m/s) higher is better 1 3 Kinetic equations 4/5/2015 TJ Steps to pull back in (#) lower is better 1 4 Number on Checklist 4/12/2015 SL

Weight (lb) lower is better 1 3 Place Device on scale 4/1/2015 JH Cost ($) lower is better 20 50 Bill of Materials 4/12/2015 JW

Number of Parts (#) lower is better 20 50 Bill of Materials 4/12/2015 JW Number of Electric parts (#) lower is better 1 10 Bill of Materials 4/12/2015 JW

Steps to Return to "ready" (#) lower is better 1 5 Number on Checklist 4/12/2015 SL Hazards (#) lower is better 0 0 Safety Analysis 4/1/2015 JW

Possible Fixture Damage (#) lower is better 0 0 Safety Analysis 4/1/2015 JW

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Key areas of Variability:

To create a Mean Time between Failures chart specific goals were created for our device that correlate with success in the competition. We then tested our device 82 times, stopping whenever the device failed a task. The breakdown of our goals and their success percentage were then compiled into the chart below.

Fires successfully

Makes it over barrier Lands in

license plate Ball stays in license plate

Device gets back over barrier Total

Tries 82 82 72 60 21 82 Completes task 82 72 60 21 16 % Complete 100 87.80487805 83.33333333 35 76.19047619 19.5

This chart shows out of the 82 test runs the device completed every task 16 times for an overall reliability of 19.5%. This means the device will fail slightly more than 4 out of 5 cycles. Most of the failures happened during later tasks, which is much better than early tasks failing. This chart helps us realize key areas of variability in our device. The first mentioning is that it makes it over the barrier 87.8 percent of the time. The ball landing in the plate is also an area of variability as our device does not succeed in this area 100 percent of the time. The main area of variability in our device is that the ball only stays in the license plate through the whole cycle 35% of the time our device lands in the license plate. The last area of variability is that our device only makes it back to the starting side 76% of the time it gets that far in the cycle. To try to minimize this variability we analyzed it using a Failure Modes and Effect Analysis chart.

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Failure Modes and Effect Analysis

Function Affected Importance Out of 5 (5 is very important, 1 is not important)

Test results Failure Mode Failure Effect

Ball makes it over barrier

5 Occasionally does not make it over

Set up error

Device fails to make it past step 4 of the competition

Ball lands inside of license plate

4 Sometimes lands outside or on the edge of the license plate

Set up error Ball could bounce out of competition setup and we will be disqualified

Ball stays in license plate

3 Carrier either does not open Or opens too violently and the ball comes out

Carrier design Device does not complete all the steps Or The ball falls of the competition setup and our device is disqualified from the round

Device returns to starting side

1 Motor fails at drawing the carrier to the starting side

Battery design or carrier design

Device does not complete all of its tasks and could possibly damage the motor

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Function Affected Failure cause Corrective action Ball makes it over barrier Angle of carrier in catapult is

off Make sure carrier is lined up with mark Realign the base

Ball lands inside of license plate

Angle of base on the setup is off

Realign the base with the side of the competition fixture Push down on edges of base to make sure the base will not move during firing

Ball stays in license plate The ball lands at an angle where the pressure isn’t sufficient to open Or carrier does not land on cushion and too much force launches the ball out

Detailed under chart

Device returns to starting side

Battery is too low and does not provide the energy required Or The carrier gets tangled on part of the barrier

Use new batteries every 2 to 3 rounds Make sure the motor is capable of pulling the weight required

Extended Analysis

Ball makes it over barrier- We classified this as very important as it is an early step for the device in the competition and also it is worth 2 points in the project. After doing a session of testing we realized that how the carrier sits in the catapult before launch affects the flight path of the carrier. To fix this problem we made marks on the carrier to help line it up as well as practiced loading the ball in the carrier more to get a feel for where the carrier needs to be placed.

Ball lands in license plate- This is a 4 on importance since the ball landing on the license plate significantly raises our chance of the Ping-Pong ball leaving the fixture, which would disqualify our device. We realized that the accuracy of our device has a lot to do with the base not moving during the firing of the catapult so to improve on the ball landing in the license plate, we put Popsicle stick supports on the base and used a non-residue sticky tack to better secure the base to the fixture.

Ball stays in license plate- This function is slightly less important, rated at a 3, because its failure could lead to disqualification but it has already completed all the parts required to improve our grade on the project. The ball staying in is the most inconsistent

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part of our design, which is made clear from the testing. Because of this it’s hard to come up with a concrete cause of failure so the fault tree analysis below was created.

In the chart above, 4 possible problems with the function “Balls stays in the license plate” were identified and now possible solutions for each problem will be explored.

Problem 1- Since the carrier is too rigid we can remove some of the material in place to keep the carrier from opening up. Another solution would be to launch the ball with a higher trajectory to increase the impact on the ball. The solution we decided to use was to remove some of the material holding the carrier together.

Problem 2- There are two solutions we came up with for this problem. The first is to adjust the position of the carrier in the license plate to give consistency to the carrier landing on the crease. The second solution is to put a mass near the crease that will weight the carrier in a way to where it consistently lands near the crease. We decided to use a half of a mustard packet to do this, as well as for a solution for problem 3.

Ball Stays in license plate

Ball does not leave carrier

Carrier opens and ball exits with too much force

1. Carrier is too rigid and cannot open from the impact

2. Carrier lands at an angle too far away from the crease and does not

3. Carrier design does not increase the time of impact long enough to lower force on ball

4. Carrier opens partially in the air and does not damp the impact

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Problem 3- To solve problem 3 we needed a solution that would lower the force on the ball by increasing the time of the impact from the carrier to the fixture. We tried to do this multiple times, (the prototypes of this are listed in the concept generation section) but eventually settled on using a mustard packet. The packet had some air in it and was not over inflated and this increased the time of impact enough to stop the ball from flying out as well as still having enough force to open the carrier.

Problem 4- This problem is the inverse of problem 1 and was a direct effect of taking too much material used to keep the ball closed. This problem was solved by making a new carrier and removing material slowly, then testing it, and repeating that cycle until the correct amount of material held the carrier together.

Using these solutions we were able increase our success at keeping the ball in license plate, but unfortunately were not able to get our success to a high percentage (over 50%) for this function.

Device returns to original side- This function often failed as a result of the battery not having enough energy. When we use a fresh battery this problem doesn’t occur, but we realized we only get about 5 full tests in before the battery becomes too weak. The easy solution to this problem is to change the batteries every couple runs but we could have also found a different energy source than a 9 volt battery that could last longer. The other way we could fail at getting the device back to the original side is if it gets tangled in the fixture on the way back over. Unfortunately this problem was realized too late to properly fix but it could have been fixed if we were able to change the shape of the carrier to something less likely to get stuck on the barrier.

List of Improvements-

To finish here is the final list of improvements made due to our testing and analysis.

- Mustard packet attached to carrier to stop the carrier from bouncing on impact - Popsicle sticks used to reinforce base - Sticky tack used to hold base of device to fixture through cycle - Material removed from carrier to allow it to open with less force - Using new batteries every couple cycles - Using a net on the inside of the carrier to keep the Ping-Pong ball from bouncing

through the impact. - Knowledge of how to set up the device to maximize the devices rate of success

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Safety Analysis:

Risk Areas:

1. Fire a. Electronic fires- This is the risk of fires starting from excessive

current in a circuit. b. Flammability- The cardboard and wood on the fixture are

moderately flammable along with other components at higher temperatures.

2. Electric Shock a. Wiring- Exposed wiring could result in electric shock to users.

3. Pinch Points a. Mousetrap- Mousetraps are pinching devices and can cause pain

and possible broken fingers to users. b. Thread Spool-Rotational movement of spool can pinch against

stationary parts. c. Support Structures- These static structures are arranged in a way

that could cause pinching to users. 4. Possible cutting areas

a. Support Structures- Some structures have sharp corners. b. Needle- The working end of the needle is very sharp. c. Mousetrap- Cut trigger lever is somewhat sharp and can cut users.

5. Inappropriate Uses a. No obvious inappropriate uses for device other than launching

small projectiles.

Risk Assessment: (using MIL-STD 882D)

1. Fire a. Electronic fires- The device uses only a 9V battery as its power

source and cannot produce enough energy to start a fire. Frequency of occurrence is improbable (E) with a mishap severity of marginal (3) giving a risk hazard of 17 which is acceptable with review.

b. Flammability- The device should not be used near or around fires or heat sources and has no foreseen inappropriate use either. Frequency of occurrence is improbable (E) with a mishap severity of marginal (3) giving a risk hazard of 17 which is acceptable with review.

2. Electric Shock a. Wiring- The wiring is exposed in soldered areas where

connections are made. The shock resulting from a 9V battery is minor and can cause no harm even to users with electronic

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medical hardware. Frequency of occurrence is occasional (C) with a mishap severity of negligible (4) giving a risk hazard of 18 which is acceptable without review.

3. Pinch Points a. Mousetrap- the mousetrap is restrained with a ziptie that has

100% proficiency. Additionally, if the ziptie were to fail, there is no reason to expect a person’s body to be in the path of the device and the additional attachments reduce the applied force of the spring. Frequency of occurrence is improbable (E) with a mishap severity of negligible (4) giving a risk hazard of 20 which is acceptable without review.

b. Thread Spool- The thread spool can cause a pinch; however, the low torque of the motor at its power rating cannot produce significant force. Frequency of occurrence is remote (D) with a mishap severity of negligible (4) giving a risk hazard of 19 which is acceptable without review.

c. Support structures- These structures are secured and should not move. The user must directly interact with these structures and they cannot produce significant force if they were to deflect. Frequency of occurrence is improbable (E) with a mishap severity of negligible (3) giving a risk hazard of 20 which is acceptable without review.

4. Possible cutting areas a. Support structures- These structures have some sharp corners

that could cause minor cuts to the user. Frequency of occurrence is occasional (C) with a mishap severity of marginal (3) giving a risk hazard of 11 which is acceptable with review.

b. Needle- The sharp end of the needle is secured within a glue structure and should not become exposed in its lifetime. The other end of the needle could cause a puncture wound if hit with significant force. Frequency of occurrence is remote (D) with a mishap severity of marginal (3) giving a risk hazard of 14 which is acceptable with review.

c. Mousetrap- The trigger lever is only moderately sharp after cutting and can only produce cuts with directed and significant force. Frequency of occurrence is improbable (E) with a mishap severity of marginal (3) giving a risk hazard of 17 which is acceptable with review.

5. Inappropriate uses a. The device can be expected to be used to launch small projectiles

that are not the ball designed for the system. These uses would not produce a dangerous situation as the launch force is very low and

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cannot produce large velocities. Additionally, the trajectory of the device is limited to a high arc that will not hit bystanders. Other inappropriate uses cannot be foreseen at this time. Additionally, the device will be in the care of either one of the design team members or the professors at all times. These responsible parties are unlikely to inappropriately use the device. Frequency of occurrence is occasional (C) with a mishap severity of negligible (4) giving a risk hazard of 18 which is acceptable without review.

Actions Taken

1. Fire a. Electronic fires- These fires would be caused by bad connections.

Off the shelf components are considered safe without inspections. Soldered connections made by our team will be double checked before competition.

b. Flammability- The materials are common in life and are safe to use in applications similar to this device.

2. Electric Shock a. Wiring- Acceptable without review

3. Pinch Points

a. Mousetrap- Acceptable without review b. Thread spool- Acceptable without review c. Support structures- Acceptable without review

4. Possible cutting areas a. Support structures- All structures will be looked over upon

completion of the device and sharp corners covered or eliminated from the device.

b. Needle- The needle will be checked for being well secured and its sharpness on the back end can’t be reduced due to its small cross sectional area.

c. Mousetrap- The mousetrap trigger lever will be filed down to remove sharp burrs from the end.

5. Inappropriate uses- Acceptable without review

Assembly dangers:

Most parts in the device were constructed with hand tools including knives and scissors. These tools were generally safe to use following good practice. Knives could have caused lacerations; however, they were handled with care. The only other dangerous step in assembly was the use of a circular saw and a miter box saw for the construction of the wood ramp and fixture. These devices can cause serious

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injury to the user and proper safety practices were used. The only necessary safety equipment needed was safety glasses.

Overall the device is inherently safe due to power and weight constraints that make the entire device low energy.

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Service and Support Plan:

Troubleshooting chart:

Error Check Status Fix Device fails to start 1. Does the switch activate small motor? No Check contacts

a. Are contacts soldered to wires? No Re-solder b. Are contacts soldered to wires? Yes Replace Switch 2. Does the switch contact the starting bar? No Raise contact arm 3. Does the small motor rotate? No Re-solder motor contacts 3. Does the small motor rotate? Yes Check impact a. Does the motor contact the retaining arm? No Move motor b. Does the motor contact the retaining arm? Yes Check starting position

Ball launch height insufficient 1. Is the mousetrap fully open? No Adjust ziptie 2. Is there any obstruction? Yes Move it 3. Was the ball's cushion in the correct spot? No Align cushion

Capsule doesn't open 1. Was it closed properly? No Seat ridge well

2. Did the ball land on its cushion? No Adjust starting orientation

3. Is there sufficient force from cotton padding? No Add padding Capsule does not return 1. Did the large motor start? No Check contacts

2. Did the string break? Yes Replace string 3. Did the string tangle? Yes Check un-tangler 4. Did the string not wrap? Yes Check un-tangler 5. Did the motor not have enough power? Yes Replace battery

Repair Items Needed: Number/Amount Needed:

1. Duct tape 2 ft

2. Zipties 2

3. Mousetrap 1

4. Tongue Depressors 4

5. Needle 1

6. Paper clip 1

7. 9V battery 5

8. Wires 1 ft

9. Electric Switch 1

10. DC Motor (large) 1

11. DC Motor (small) 1

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12. Eggshell 1

13. Mustard Packet 1

14. Cotton balls 2

15. Netting 2in x 3in

16. Fishing Line 6 ft

Tools Needed: Number/ Amount Needed:

1. Hot Glue Gun 1

2. Hot Glue Sticks 4

3. Needle nose pliers 1

4. Soldering Iron 1

5. Solder 6 in

6. Wire Strippers 1

7. Knife 1

8. Scissors 1

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Teamwork Analysis:

Contract 61

Meeting Minutes 62-74

Team Health Assessments 75-84

Experience Reviews 85-86

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1. Get all assignments done by deadlines in Gantt charts.2. Have all members participate equally.3. Collaborate on all major decisions.4. Meet all criteria for A quality projects.5. Have all componenets manufactured with quality.6. Begin testing of components by spring break

1. JW2. SL3. JH4. JW5. TJ6. JH

1. Have everyone produce A-quality work by introducing "wow" factors.2. Have everyone understand each product's full operation.3. Have e veryone able t o u se assembly tools to create project.4. All team members meet deadlines for projects listed in Gantt charts.5. Be open to other's ideas by listening to ideas before decisions.6. Have at least 1 team meeting a week with full attendance.

JWJHTJSL

1. Bi-weekly meetings for clarity and team performance assessment.2. Discuss all major decisions to hear all views and build consensus. (Tie-breaker by team coordinator)3. Discuss issues that come up, and do not hold in any unresolved issues.4. Use independent moderator (Bob) for unresolved issues.5. If all else fails, bare knuckle boxing...

35 3/10//2015

Justin Weinmeister

Justin Weinmeister Coordinator, organizational reports JW 970-631-7348 [email protected]

Troy Johnson Eletronics, assembler TJ 970-218-0464 [email protected]

Jace Horak Tester, hardware JH 970-218-1338 [email protected]

Sten Larson Innovator, editor SL 303-910-3567 [email protected]

7. Add wow factors to work when it is appropriate. 7. SL

7. All members actively check their "buddy's" work weekly.

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Team Meeting Minutes: Group 35 Date: 3/8/2015

Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Identify project 2 requirements 2. Create project plan 3. Brainstorm ideas based on specifications 4. Assign tasks

Discussions:

Meeting lasted 2 hours and discussed the project ahead. The group decided that the project would be difficult to solve and decided to follow Bert’s advice to brainstorm ideas after specifications were developed. Unfortunately, due to time constraints, we had to brainstorm with only specification development ideas and not the full chart developed.

Decisions:

1. Agreed to project plan 2. Assigned brainstorming tasks for refinement

Actions Required: Resource Deadline

Refine brainstorming ideas JH, JW, SL, TJ 3/11/2015

Finish specification chart SL 3/11/2015

Next meeting:

3/11/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Discussed refined ideas 2. Assign values for brainstormed ideas to specification chart 3. Choose ideas with most promise 4. Choose course of action

Discussions:

Meeting lasted 2 hours and discussed the options available to the group. The group had been leaning towards the mousetrap idea originally as many individuals thought that it provided the best solution for time cost. The debate then caused most people to side with the idea that a crane was the correct device to create due to its reliability. The group then decided to test the mousetrap for reliability in landing area before deciding which device to complete actions with. This would involve testing a simple mousetrap for feasibility before deciding next action.

Decisions:

1. Agreed to contract rules on conflict resolution 2. Assigned Justin Weinmeister as project leader


Test mousetrap feasibility JH 3/18/2015

Research further ideas SL, JW 3/18/2015

Create test fixture JW 3/13/2015

Next meeting:

3/18/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Discuss feasibility of mousetrap 2. Choose device 3. Develop device refinements 4. Assign refinements

Discussions:

Meeting lasted 3 hours and decided the final device plan for the project. The group decided that after initial testing the mousetrap looked to be a promising candidate for the device. The mousetrap was refined by adding additional sub-systems to the device after getting further materials. The group was able to create a device that launched an Easter egg successfully.

Decisions:

1. Agreed mousetrap was correct device to refine 2. Assigned refine projects to group members


Develop capsule SL 3/19/2015

Develop launch control system TJ 3/19/2015

Next meeting:

3/19/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Discuss current state of device 2. Collaborate on device refinement 3. Assign further tasks

Discussions:

Meeting lasted 4 hours and successfully gave the group a device that we were confident was close to being ready for testing. The group had found a reliable capsule design that simply needed improvements in landing repeatability as the variation in openings was still inconsistent. The device needed a fully developed base in order to start true testing of the device. The fixture also needed notched cut for a starting bar.

Decisions:

1. Egg capsule would work as delivery method 2. Base needed refinement before further testing


Create base JW, TJ 3/22/2015

Refine capsule SL 3/22/2015

Refine control System TJ 3/22/2015

Next meeting:

3/22/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Finish individual assignments for assignment 2 2. Collaborate on Russian Moon Team Health Assessment 3. Develop team contract 4. Assign project leader

Discussions:

Meeting lasted 1.5 hours and refined the device and assigned report tasks to individuals. The group decided that the base was unsatisfactory at its current arrangement because of its high weight. Additional work was done on refining the capsule and the launcher for the final device. Time has started to slip for the group with the start of classes tomorrow.

Decisions:

1. Agreed that base was unsatisfactory at current weight. 2. Assigned report work for upcoming meeting with Bob


Refine specification development charts SL 3/23/2015

Change base material TJ, JW 3/29/2015

Next meeting:

3/29/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Refine launcher

Discussions:

Meeting lasted 2 hours. The group decided that the device was still deficient for full system testing as the spool return system was creating difficulties with the string getting tangled. Additionally, the control system layout needed changing. Finally, the capsule needed further refinement in order to achieve consistent opening upon impact. The capsule also landed with significant force and caused the ping pong ball to bonce excessively.

Decisions:

1. Assigned further refinement targets to individuals


Work on spool for return system JW 4/52015

Adjust control system TJ 4/5/2015

Work on capsule SL 4/5/2015

Next meeting:

4/5/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Agenda:

1. Refine device

Discussions:

Meeting lasted 4 hours and was missing Sten as he was out on school activities. The group struggled to refine the capsule’s landing force as the device continued to be very unreliable in getting the ping pong ball to stay inside the license plate holder.

Decisions:

1. Capsule cushioning needed changing to sauce packet 2. Keep on refining project


Get additional sauce packets JH 4/8/2015

Next meeting:

4/8/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Refine sauce packet landing method

Discussions:

Meeting lasted 2 hours. Sten was surprised by sauce packet method, but the idea seems to have held up over additional trials. The group tried to refine the project more, but progress got stalled. The group became frustrated with progress and agreed to meet the following day.

Decisions:

1. Agreed to meet tomorrow in order to continue refinement


Continue work on report sections JH, TJ, SL, JW 4/12/2015

Next meeting:

4/9/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Refine project

Discussions:

Meeting lasted 3 hours and was able to refine the project significantly. Progress was made on being able to get the capsule to land in the same area with similar energy. There is still needed refinement on being able to land the ping pong ball without significant force.

Decisions:

1. Agreed to contract rules on conflict resolution 2. Assigned Justin Weinmeister as project leader


Continue work on report sections JH, SL, TJ, JW 4/12/2015

Next meeting:

4/12/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Start final testing 2. Start assembly of report

Discussions:

Meeting lasted 4 hours. The device developed troubles with being able to get the capsule over the barrier, and then after improvements, the capsule could no longer land reliably. Time was spent getting the device back to its performance level from the previous week.

Decisions:

1. Agreed to finish report sections 2. Agreed to meet the following day


Complete report JH, SL, TJ, JW 4/14/2015

Next meeting:

4/13/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Conduct final testing

Discussions:

Meeting lasted 4 hours as further problems were encountered with being able to get the capsule to land reliably. The group was able to conduct significant testing; however, everyone was displeased with the results. The group decided to meet the following day (minus Sten) in order to continue device refinement. There seems to be an error in the way the capsule lands as it varies significantly with how much force the ball is ejected with.

Decisions:

1. Agreed to meet the following day


Complete report sections JH, TJ, SL, JW 4/14/2015

Next meeting:

4/14/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Agenda:

1. Refine device 2. Start report assembly

Discussions:

The group worked on the ping pong ball release reliability. The issue could not be resolved despite multiple iterations of “improvements”. The meeting lasted 3 hours and involved a trip to buy supplies. It was decided that no further work could be done on the capsule until the full team was able to meet. Some work was done on the report, but it was delayed with the excessive work required on the capsule.

Decisions:

1. Agreed to meet tomorrow and decide whether or not 5 tasks could be completed


None

Next meeting:

4/15/2015

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Attendance:

Justin Weinmeister

Jace Horak

Troy Johnson

Sten Larson

Agenda:

1. Finish project minus proofreading.

Discussions:

Meeting lasted 3 hours and accomplished little of what we had hoped. We were unable to fully refine the landing of the ping pong ball and realized we were unlikely to complete the 5 tasks in the project due to the unreliable nature of the capsule. The team was unable to meet the following night as three of the group members would be traveling for the CSU track team. This created difficulty as it would have been good to have a final refinement meeting the night before the competition. The team was still in good spirits as the team agreed on all the tasks that needed to be done.

Decisions:

1. This project task was impossible to complete


Competition SL 4/17/2015

Report Submission JW 4/16/2015

Next meeting:

N/A

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Team Health Assessment Your assessment team members:

SA= Strongly Agree A = Agree N = Neutral

D = Disagree SD = Strongly Disagree NA = Not applicable

Measure SA A N D SD NA1

4

5

7

8 ✔

9

10 The team took time to develop consensus by discussing the concerns of all members to arrive at an acceptable solution.

11

12

16

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Remedies for improving the Neutral (N), Disagree (D) and Strongly Disagree (SD) responses:

Based on page 77 of The Mechanical Design Process (4th edition) By Professor David G. Ullman © 2008, McGraw-Hill

Justin WeinmeisterTroy JohnsonJace HorakSten Larson

Date of assessment:

3/2/2015

✔

✔

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9. Conflicts need to be aired faster.11. Ask for others opinions before making important decisions.

Justin Weinmeister, Sten Larson, Jace Horak, Troy Johnson

Group 35 Project 2

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Date of assessment:

3/2/2015

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10. time was an issue for mostly everyone. with the different schedules it was hard tocommunicate effectively. a better communication system would have helped

Jace Horak

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Date of assessment:

3/2/2015

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9. Each member should voice any problems that they are having so other membershave the chance to offer assistance.16. Start tasks on the date shown in the Gantt chart and no later.

Troy Johnson

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Date of assessment:

3/2/2015

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12. Coming in not knowing everyone, i don't really know everyones strengths andweaknesses and seeing everyone more will help me feel more comfortable.16. I feel like everyones personal parts are done except i still need to finish up mywork, as well as the style we want to put everything together in should have beentalked about from the start, and talking about that at our next meeting should help.

Sten Larson

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Date of assessment:

3/2/2015

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9. Some conflicts have been avoided rather than confronted.16. The team ended up far behind schedule, most likely my fault.18. People will get their work done, but the work may be rushed at the last minute.Additionally, some of the work has not lived up to the A standard in the contract.19. No team members have been especially vocal about helping others, though we dotry when possible.20. Everyone works hard, but they may not be putting enough care into the work.

Justin Weinmeister

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Date of assessment:

4/5/2015

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16. Neutral. Our group believed that we were well prepared and worked well in orderto get the project done. Progress slowed at the end of the project due to an inability toget further work done as testing could not be resolved.

Troy Johnson, Sten Larson, Jace Horak, Justin Weinmeister

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Date of assessment:

4/14/2015

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Our team worked well together. We have grown in our team work since the firstproject. We all got along very well each had an equal opinion on how to build andrevise this project.

Jace Horak

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Date of assessment:

4/14/2015

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The teams works very well together and any individual issues a brought to the teamfor discussion.

Troy Johnson

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Date of assessment:

4/16/15

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I am happy with how this project has gone, and feel like we have improved as agroup from the last project.

Sten Larson

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Date of assessment:

4/14/2015

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The team has done very well for the second project.

Justin Weinmeister

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84

Justin: I enjoyed the opportunity to build a project in a class this early. Talking to my

brother, who is an ME at Mines, it sounds like many other programs do not have this

opportunity. I did feel like it was hard to apply what we have learned so far to the project, but I believe that is more a lack of experience than the actual courses. I learned from this

project that it is important to have good planning and accountability procedures in place in

order to have success. With previous group projects I have participated in, the list of

requirements was low enough that it was not difficult to keep track of tasks. I found with

these projects that the tasks could be hard to keep track of if there was not an organized

checklist and periodic check-ups by teammates. Finally, it was great to have a group that

worked well together and all had a good work ethic in order to get all the work done on

time.

Troy: Although aggravating at times, getting to compete against my peers in an engineering

competition is quite enjoyable. Due to the short time period that we are given to complete

this project it is difficult to apply all of the design strategies that we are learning in lecture

but I have seen connections to many of these strategies while working as an intern with

Woodward, as well as how these strategies can fail. This is the first project where I have

taken an idea all the way through the design and building phases and actually had a chance

to implement the end product. While a project like this is hard to complete with very little

previous experience with a group it gives me an insight on what an engineer in industry

does everyday. I have really enjoyed working with my group members and I look forward

to working with them throughout the remainder of my time at CSU.

Jace: This class made me thankful I am only taking 12 credits. The work load has been

larger than any class I have ever taken. That being said, working on this project has made

me appreciate engineering. The amount of detail and testing we have put into this project

shows how hard we will have to work in the real world. Real world experiences such as

working in groups, being innovative, meeting deadlines and many other life long attributes

we have learned through this project. Even though the time commitment was very large, I enjoyed being hands on and building a device. This is the first project I have thought

through all of the design stages and followed a full plan. So far this is the best device I have

ever been apart of building with guys who work hard and expect excellence. This project is

definitely one of the best parts of my college career so far and will remain one of my most

favorite accomplishments.

Group 35 Project 2

85

Sten: This class overall taught me a lot about the design process and convinced me I want

to be involved with product design in my future career. That being said I was not able to

put as much time as I would have liked into this class because of my course load and

amount of work at my job, and this has definitely affected my ability to do as well as I

would have liked. For the projects I was put into where I did not know any other members,

and I am happy at this point that we are all friends and are able to joke around with each

other and have fun while still getting our work done. Overall, this class has been a positive

experience, I am happy with how our projects turned out, and I am happy with the

relationships formed in our group.

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86

Additional Work:

The Lone Wolf:

Our team knew at the beginning of the project that there was a possibility of having only Sten be present at the competition due to the rest of us having an out-of-state track and field meet on the day of the competition. Two of us (Jace and Justin) were on the injured list and were unsure of whether we would be travelling, but we did hope we would. Due to this constraint, we had to design our project to be very simple. The device would have to be able to be set-up by one person and the entire device would have to be easily repaired with only one person. Additional considerations were that Sten would have to be very familiar with every single system of the device, but we had to manage his hours so that he was not overwhelmed by the amount of work. We believed we accomplished these feats very well. (Also, Sten was able to get help at the competition we learned.)

Sauce Packet Analysis (decision matrix): This decision matrix was adapted from The Mechanical Design Process by Ullman. We were partial to the taco bell sauce, as it helped fuel us for the project, but the mustard was better. The honey was also fun, but it created a sticky mess on our test fixture (tasted good, though).

Qualities Weight

Baseline (Funtak and cotton balls) Mayonnaise Ketchup Mustard

Taco Bell Sauce Honey

Weight 4 + + + - Viscosity 5 + + + ++ Coverage 3 - - - - - Durability 1 + - Launch-ability 2 + + + + +

Total: 2 1 3 1 0

Weighted Total: 8 4 9 3 4

Home Build Effort:

Our project was designed to be built of materials that could be found in every single home. Additionally, we focused on using simple solutions to out challenges. The device was made of the following common materials; cardboard, popsicle sticks, duct tape, hot glue, mousetrap, small plastic cup, wires, zipties, paperclips, a needle, Easter egg, sauce packet, fishing line, netting, and wood scrap. These materials were found in all out homes. We

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ended up purchasing hot glue, popsicle sticks, mousetraps, small cups, and Easter eggs, but we did not need to. The Easter eggs were purchased because a round container gave us more consistent landings than an original egg shape. The other materials were purchased because we went through more material than we had in our houses as we tested multiple prototypes. The two less obvious materials were the switch and motors. The switch could be replace as a common light switch; however, we used a lighter version in order to save weight for competitive purposes only. The motors could be found in toys or old electronics. Our motors actually came from an old camera and toy hat, and most family’s have these disposable goods. Our final product would have been made with no purchased goods if we had not gone through as many prototypes as we ended up using.

Device Cost:

Based on data from the lecture, our device cost the least based on calculated costs. It came in at $13.40. Our group did not spend the least; however, that was due to fixture costs and the cost of batteries which we did not steal from each other’s homes.

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Mech 202 Project 2 Report

Documents

Transcript of Mech 202 Project 2 Report