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This report was prepared by students as part of a university course requirement. While considerable effort has been put into the project, it is not the work of licensed engineers and has not undergone the extensive verification that is common in the profession. The information, data, conclusions, and content of this report should not be relied on or utilized without thorough, independent testing and verification. University faculty members may have been associated with this project as advisors, sponsors, or course instructors, but as such they are not responsible for the accuracy of results or conclusions.

Table of Contents DISCLAIMER 2 1 BACKGROUND 1 1.1 Introduction 1 1.2 Project Description 1 2 REQUIREMENTS 2 2.1 Customer Requirements (CRs) 2 2.2 Engineering Requirements (ERs) 2 2.3 Testing Procedures (TP's) 3 2.3.1 Weight 3 2.3.2 Sharp Edges 3 2.3.3 Pinch Points 3 2.3.4 Mobility 3 2.3.5 Size 3 2.3.6 Power 3 2.3.7 Visual 3 2.4 Design Links (DL's) 3 2.4.1 Weight 3 2.4.2 Sharp Edges 3 2.4.3 Pinch Points 4 2.4.4 Mobility 4 2.4.5 Size 4 2.4.6 Power 4 2.4.7 Visual 4 2.5 House of Quality (HoQ) 5 3 EXISTING DESIGNS 6 3.1 Design Research 6 3.2 System Level 7 3.2.1 Existing Design #1: Robotic arm exhibit from Aliens and Androids 7 3.2.2 Existing Design #2: Circuit Puzzle from TMNT: Secrets of the Sewer 7 3.2.3 Existing Design #3: Kinetics Gallery 8 3.3 Subsystem Level 9 3.3.1 Subsystem #1: Gear and pulley display 9 3.3.2 Subsystem #2: Marble wall 9 3.3.3 Subsystem #3: Pulley Race 9 3.4 Functional Decomposition 9 4 DESIGNS CONSIDERED 11 4.1 Sound Disk 11 4.2 Air Rocket/Artillery 11 4.3 Magnet Car 12 4.4 Oil and Water 13 4.5 Weight Game 13 4.6 Magnet Pulley 14 4.7 Egg Helmet 15 4.8 Thermal Structure 16 4.9 Pulley Wall 16 4.10 Gear Reduction Box(es) 17 5 DESIGN SELECTED 18 5.1 Rationale for Design Selection 18 5.1.1 Brainstorming 18 5.1.2 Pugh Chart 18 5.1.3 Decision Matrix 18 5.2 Design Description 19 6 Proposed Design 22 6.1 Bill of Materials 22 6.2 Schedule 23 7 References 24

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The Wonder Factory is an up-and-coming community science center located in Flagstaff Arizona. The center is founded by Steve and Jackee Alston, a husband and wife who are locals in Flagstaff. Mr. and Mrs. Alston (having careers in the technical field) are passionate about fostering the interest of science, technology, engineering and math with the younger generation [1]. And what better way to do this, than with a science center in Flagstaff. Studies have shown that “visual and verbal elements complement each other and promote effective learning” [2]. The capstone team’s objective with the Wonder Factory is to create a variety of fun and innovative exhibit ideas for this new science center. The exhibit must portray one or more STEM centered subjects that integrate a fun and interesting learning aspect. Ultimately the team will fabricate a final design idea that not only follows the customer’s requirements, but an exhibit that is fully functional and ready to use for Wonder factory events.

The mission statement of this project is to create a fun and engaging exhibit that not only appeals to a younger audience, but sparks an interest in STEM centered subjects. The project itself is planned to take a duration of two semesters. The first semester’s goal is to create a proposal of a final idea that the capstone team decides upon. The second semester will include the actual construction of the final idea with a final presentation/demonstration of that idea. The STEM interactive display project description entails the requirements for this capstone team to follow. These requirements are laid out by the project supervisor (Dr. Willy) and the customers (Mr. and Mrs. Alston).

In brainstorming for ideas, the team is required to generate up to 100 different ideas. Per the project description, these ideas can include existing, new, wacky and off the wall concepts [3]. The reason behind this is to gather as much inspiration and innovative concepts as possible, but keeping in mind that the exhibit must keep young kids engaged. After this, the team must glean the list of ideas and pick at least five plausible ideas. The team can hold focus groups or take surveys to decide on which idea would fit best for the Wonder Factory. Most importantly, the team will share their ideas with the customer before a final design is selected [3]. Safety will be a number one priority when deciding on a final idea. Next will be if the idea is fun and engaging. The idea must also portray one or more concepts that are easy for the user to understand and feel smart about understanding the concept. Lastly, multiple users must be able to interact with this exhibit. Once all of this is met, a final idea can be agreed upon.

Materials for the final design must be selected strategically. The capstone team has to work within the customer budget of $1,500. This budget has the potential to increase. The team can organize fundraising and aid in events with the client [3]. The Wonder Factory will eventually be founded by the city of Flagstaff with donations and grants, but until then the customers will need to fund it independently or through fundraising events.

In meeting with the customer, the design team acquired design parameters. These parameters will be used to help guide the design process in terms of customer satisfaction. From here the team can then formulate multiple ideas in brainstorming sessions. The customer requirements are as follows with weights of importance (1-5):

 Safety (5)

 Simple to operate and understand (4)

 Ensure user feels smart (4)

 Project themselves into the exhibit (4)

 Interactive (3)

 Mobility (3)

 Multiple users (2)

The customers insist that our exhibit is not only safe, but can be simple for users to operate. A complex display can inhibit users from learning the core concept. In doing this, the user also needs to feel smart when operating the exhibit. An important goal of the Wonder Factory is to foster the interest of STEM centered subjects. This can only be done if the user is engaged while playing with the exhibit. The exhibit also must be interactive for the user. This coincides with the user being able to project themselves into the exhibit. Mr. and Mrs. Alston were very keen on making sure that when a child uses the exhibit, he or she can “be” the engineer. They want a user to feel like they are in the position of a real-life scientist, doctor, engineer, etc.

Mobility of the exhibit is also important in terms of setting up and tearing down for future events and expos. The customers added this because they want an exhibit that can be moved from place to place while they are looking for a permanent location in Flagstaff. Mr. and Mrs. Alston also mentioned that they would like the exhibit to accommodate multiple users. They envision this science center accommodating a large volume of people. An exhibit that can integrate multiple users is ideal for this situation. Also, having an interactive display in which the user can experience the exhibit with multiple people seems beneficial in terms of connection.

The team's engineering requirements are a translation of the customers’ requirements. The team’s customer listed seven requirements that are imperative for the final design. Safety was the highest weighted requirement and the team projected two engineering requirements for these parameters accordingly. The first one being that the exhibit does not have any pinch points or sharp edges. Also, if the exhibit should use electrical power, the exhibit must not exceed more than 15 amps and 120 volts to avoid electric shock.

The weight of the design is important. The final design must be light enough so a couple individuals can lift the exhibit and move it. This coincides with the mobility of the exhibit. An ideal weight requirement for our final design must be less than 60 pounds.  This can be tested by physically weighing the design on a scale. Lifting the exhibit with two to three people can also be a good benchmarking test.  

Sharp corners on this exhibit can be a problem. One way to avoid this is to simply check the outside of the final design, by running a hand along the sides of the exhibit to find a sharp corner.  

To avoid a pinch point hazard, our final design must avoid the chance of a user pinching his or her self. This can be tested simply by interacting with the exhibit or by searching for potential hinge and clamp hazards.   

Mobility of, the exhibit must be easy to store in a truck, trailer, or van. The maximum dimensions of 60 by 60 by 60 inches correspond to the average van or trailer size. This can be completed by physically measuring the exhibit with a measuring tape when it is disassembled and ready for storage.  

Once the exhibit is fully set up, the size of its footprint is a big factor. The maximum dimensions for the setup should be 12 ft. by 12 ft. by 12 ft. This can be monitored by measuring the outside of the final design with a measuring tape.  

An exhibit that runs on a low amount of power is ideal in terms of cost and in safety. To measure this, a voltmeter will be utilized to measure the amount of current and voltage is using. A voltmeter can also be used on the exhibit itself to detect potential electrical hazards. 

Visually seeing the exhibit is very important. If incased in a box, the user must be able to see how the display works. The visual aspect can be tested in focus groups were users can interact with it and can provide feedback. 

Weight will be controlled by using light materials such as plastics, wood or aluminum, as opposed to using heavy materials such as steel and glass. Parts will also be designed in such a way to reduce weight. When reducing weight on parts, the redesigned parts must keep their structural integrity. 

Young users will be using our exhibit, so it is important to cover all and or reduce all sharp corners or protruding objects. Padding will be installed on these hazards in the exhibit if they are not easily. An inexpensive foam material (like a pool noodle) can be used on edges to reduce the chances of unexpected injuries.  

Pinching hazards can be avoided by redesigning the component. For example: instead of a hinged door, the door can be removed and replaced with a curtain. If redesigning is not an option, then padding can be installed (inexpensive foam material). If a pinching hazard is present in the exhibit and is not essential to the user interaction, this hazard can be relocated on the exhibit itself so it can be inaccessible.  

The storage size of the exhibit can be controlled by designing the exhibit in a way that can be disassembled and reassembled when ready for use. Incorporating attachments and connecting parts can help reduce the storage footprint size. Scaling down dimensions is another alternative to reduce size. 

The full setup footprint can be controlled by scaling design dimensions down. Structural integrity must be considered as well when scaling down dimensions. This can also be monitored by setting up the exhibit in a room that is like the science museum location.  

In terms of voltage and current, the maximum amount we want is as follows: 5 mA and 120 V. A low voltage exhibit will reduce the chance of a user encountering an electrical hazard. Strategic electronic placement and proper insulation are other alternatives. 

For visuals (if incased), it should be easily seen. This can be accomplished by using clear Plexiglas or some sort of transparent material.

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The House of Quality (HoQ) is a brief overview of the customer requirements and their corresponding weights. These requirements are formulated from customer specifications and parameters that are needed. As see below, safety is a number one priority. The fact that the exhibit conveys a STEM topic to younger users in an engaging way is also a very important aspect that the customers want. As this capstone project progresses, these parameters will aid in guiding the group’s ideas.

Table 11 - House of Quality

Science is a very fundamental aspect of our economy. It is an effective way of exploring, engaging and understanding the world around us. Science, Technology, Engineering and Math (or STEM) is an education curriculum used to promote these subjects. The overall goal here is to promote these subjects to the younger generation so they have the desire and determination to achieve success in these fields of study. STEM is a program with the primary objective of gathering, evaluating and solving various problems faced by individuals who work in the field today. STEM mainly aims at enhancing the skills of students studying these subjects. The STEM program has ensured an increase in the number of students and teachers taking STEM subjects.

This exhibit should improve their skills and experiences in the subjects of science, technology and mathematics. Conveying information by teachers and professors plays a significant role in developing the quality of learning. STEM has improved the welfare of teachers and professors. The information they teach is of a higher caliber, and they are compensated for this [4]. Different students across the world face different challenges that obstruct them from achieving success. The study of technology and science improves the global economy by offering quality and active researchers, innovators, leaders and educators. STEM grants have the obligation of ensuring equitable distribution of learning resources to different regions to ensure appropriate development and research. STEM grants come from various agencies and education institutions. These funds are used to improve the level and distribution of federal investments, improving youth engagement in various science and technology programs and improving the quality of preschool learning with the use of technology and science.

Different designs have been researched to enhance the flexibility and efficiency of STEM programs. Research by the National Research Council of the United States has contributed to the efficient use of STEM programs. The study postulates that STEM has significantly increased per capita growth in the United States. The research also stipulates that STEM has developed the United States into one of the leading innovation leaders in the world [5]. The designs were investigated using qualitative and quantitative approaches to develop better applications of STEM. Research practices such as interdisciplinary project based learning and understanding of the real world have been used to produce striking designs used in STEM programs. Research on challenging objectives containing opportunities to improve learning for children has been used to create and facilitate the education process. Models for community partnerships were elaborated by the conducted research as having unearthed better and appropriate ways of promoting internship among the STEM learners and education trainers [5].

Enough evidence exists that indicates the effectiveness of the STEM program. Different journals, catalogues and publications have been developed to show the effects of STEM. The census bureau, national center for education and statistics, and the Institute of Education Science and Technology in the United States are examples of organizations that have developed publications that record the practical measures of STEM in the country. The Journal of Research in Science and Teaching by Bell, Blair and Crawford (2003) stipulates the effectiveness of STEM programs. The journal of interactive learning Research by Schallert and Liu (2006) also contains clear evidence of the flexibility and importance of STEM policies [5].

The benchmarking process of STEM concentrates on efforts to improve the applicability and flexibility of STEM to all students. It involves the use of impact data collected from learning institutions. The benchmarking data set for STEM uses a broad definition of STEM. It comprises different fields such as economics, architecture, health science and economics. The benchmarking also uses a dashboard that gives a complete data set. The benchmarking process involves visiting learning institutions, interviewing students on the impacts of STEM and observing the effects of STEM on students.

STEM is a very significant program that should be developed in every part of the world to enhance the application of science and technology in students. It improves equitable distribution of learning resources that leads to equitable economic development and research.

The exhibit in Figure 1 shows a robotic arm display from the Aliens and Androids traveling exhibition. This exhibit shows how a robotic arm works to pick up blocks and place them in the correct cut outs. This exhibit shows from a basic level what a robot can do with a vision system. The requirements for this capstone project is to design and build an interactive exhibit for the Wonder Factory.

Figure 1 - Robotic Arm [6]

The exhibit shown in Figure 2 is from the Teenage Mutant Ninja Turtle: Secrets of the Sewer exhibit that is currently at the Discovery Cube in Orange County. This exhibit has two different puzzles. Both puzzles use a battery and other electrical components that a child uses to complete a circuit to either turn on a sign or a fan [7]. This exhibit allows the children to become an electrical engineer by creating an actual circuit.

Figure 2 - Circuit Puzzle [8]

Figure 3 shows an exhibit at the Discovery Science Place in Texas. This exhibit has two separate areas where children can learn about the concept of kinetics. One portion is a prebuilt exhibit where objects move on a specified track. On the other portion of this exhibit, a child can build a track that a ball can travel through using different configurations of pipes.

Figure 3 - Buford Kinetics Gallery [9]

This display would have a small gear box with an output shaft attached to a handle, and an input shaft attached to a pulley. As the pulley on the output shaft turns it will take up a rope that is used to lift a weighted bag. This system would show the children how pulleys and gears can be used to reduce the amount of force that is required to lift an object.

This display would show the differences in potential energy. With different tubes placed at different heights a child would set a marble onto a ledge then push it into a tube. As the marble travels down the tube it would be launched and they would be able to see how far it travels. The height of the start locations and the exit angle can be changed so that the child could see the differences in landing locations.

This display would show the differences in pulley systems and the ease of lifting an object. The object would have the same mass for all the pulley systems. One system would be a 1:1, another system would be a 2:1. This will show the differences in speed and the amount of work needed to lift the same object.

A functional decomposition is a well-structured diagram of a walkthrough of the team’s design requirements and process (diagram 1). The team will use this as a guide to shape the overall product. It is imperative that the team follows these design restrictions. These will not only shape the design process, but will shape the overall outcome of the design.

Diagram 1 - Functional Decomposition

This concept generation was an idea based off sound waves and how they can be channeled and amplified. The apparatus consists of a large concave disk about eight feet in diameter and about a half a foot to a foot deep for the concave. The disk would be large and deep enough for a small user to stand back inside the concave. The large disk could then be mounted on a swivel that could be rotated by a user. When the user is in the back of the concave disk, the sound will be amplified. The disk channels the sound emitted from the surrounding area to the user, like a giant megaphone.

This concept is relatively small, so the footprint size in the science center isn’t an issue. The design can even be retrofitted to be broken down for transportation purposes. This is a big requirement for the client. The exhibit itself (if designed right) is free of high voltage danger, pinch points and sharp corners. So in this case, this is a relatively save exhibit. The problem with this exhibit is the fact that the design is limited to only one user. This is a parameter violation. The customer clearly stated that that they want the exhibit to allow for multiple users. Also, the materials for this design are costly. Relatively light weight sheet metal that is non-corrosive may be expensive. Fabrication for this design is also an issue. Forming that concave shape may be challenging and welding may be needed. But most importantly, this exhibit isn’t all that engaging to a younger user. When users are engaged in an activity or with an exhibit, they feel connected and can learn an important concept.

Figure 4 - Sound Disk

This idea was generated off the concept of the game of Battleship. A user would be able to launch a foam air rocket from an apparatus that utilizes pressure, angle of launch and trajectory from left to right. A user can add pressure for the launch with a bike air pump. Once a pressure the desired pressure is reached, he or she can change the direction of the launch from left to right and the launch angle. The user will then fire the rocket and try to aim it over a wall in front of them to hit a target on the other side. The capstone team was thinking that two users could be firing rockets on opposite ends of the wall at targets. Each side would also have a spotter that would tell the user firing the rocket to change angle, pressure or position. In this case the first user to hit the target on the opponent’s side wins.

This idea is relatively small when broken down for storage and movement. The wall would be constructed of foldable beams and panels. Or the wall could be made of a foldable sheet for ease of setting up and braking down. This idea is also safe. The team could add padding on the bike pump to reduce pinch points and even install a safety relief valve so the tank can’t reach dangerous levels of pressure. This idea is also cheap. Materials for the wall, launch apparatus and targets can be made of wood, aluminum and PVC piping. Also, the fact that the exhibit can accommodate for more than one user, is an important customer requirement that this exhibit reaches. The best aspect of this idea is that it can engage these users. In working in teams, the users can feel smart in problem solving to achieve a goal.

There are some drawbacks to this design. The full setup of this design would have a large footprint. The design would have to be scales down to fit customer dimensions. Also, this exhibit in some ways could be dangerous. An individual could aim a rocket at another user and could seriously hurt them. If the capstone team chooses this idea, they would have to design trajectory restrictions on the apparatus and make the rockets lightweight. A rough rendering of this design can be seen below in figure 8.

Figure 5 - Air Rocket

The capstone team generated a concept called the Magnet car, which is basically a multi-track system which allow multiple users to race a slot car. Each car has a magnet attach to it. Behind each car, a user can choose to add one or multiple magnets. The polarity for the car magnets and the magnets behind the cars should be facing the same polarity. This will cause the magnets to repel. In front of the cars, there is a removable wall which prevent the cars from moving forward. When the wall is removed, the cars will move toward due to the repealing power. In this case, this exhibit is a game. Whoever can make their car move forward the furthest will be the winner. This concept utilizes visual learning. A user will see that the stronger magnetic field comes from adding magnets. Therefore, the car will move forward more with a strong field behind it.

We have five customer requirements and this design meets most of the requirement. The dimensions for this design don't exceed the parameters of a 12-cubic foot footprint. Also, it will be more mobile than most of our other designs. The track table could have caster wheels fitted on the bottom so the table could be easily moved. The best parameter that this design meets is the fact that kids will feel smart during this exhibit. They will be able to figure out the more magnets you have, the stranger the repelling polarity. And therefore, the car will move farther. They can see themselves as an engineer while they are trying to race with another user. Moreover, they will have fun at the same time while they play. A figure of this design can be seen below in figure 9.

Figure 6 - Magnet Car

This design is basically allowing a user to separate an amount of oil from a given volume of water. The water is housed in a glass container, along with the oil layered on top. The user will then be presented with several methods of removing the oil. It is up to them to figure out the best way. They are provided with a spoon, a coffee filter and some ice for chilling the water and oil. This exhibit is more like a puzzle that a user should figure out.

This idea met some of the team’s engineering requirements. This exhibit falls within the budget, it’s safe and the footprint size of this design is small for mobility purposes. However, it doesn’t meet the client’s requirements in regards to engagement and allowing multiple users. The exhibit is small and can only allow for one user at a time. The customer was adamant about the exhibit accommodating for multiple people. Also, the exhibit isn’t all that engaging. A user could lose interest in trying to problem solve with no end goal that is entertaining. A sketch of this idea can be seen in figure 10 below.

This design would teach children how to balance two objects that have different weights as seen in Figure 6 - Weight Game below. This design incorporates a seesaw and some weights. The user’s mission in this exhibit would be to balance the seesaw by adding weights to either side. If the total of weight on one side of the seesaw is greater than the other side, the side with the more weight will be misbalanced and will tilt more. The concept behind this exhibit is to teach users mass balance.

This design is relatively small and therefore is mobile for the customer. The weight of this exhibit really depends on the amount of weights the team will utilize. Medium sized weights varying from 1 to 5 pounds would allow for more weights for this exhibit without exceeding the 60-pound limit. This exhibit is also very visual. He or she can see the weights being added to both sides and can see the variation in position of the seesaw. The user then can correct the tilt by either adding or subtracting weights form a side. However, there are some problems to this design. This design is not very engaging. Users are just balancing weights and are not learning anything from this exhibit other than that equal weight amounts balance the seesaw. When there is not engagement involved, an interest in the concept is not achieved. The one big requirement for the team’s final design is that the exhibit engages a user and strikes their interest.

This design integrates magnetic fields and adds a games aspect to it. For this idea, a magnet is hanging by a cord at the bottom of a clear cylinder. A user can rotate a crank to raise up the magnet at the bottom. To add complexity to this, strong magnets are placed in slots around the outside of the cylinder. The magnets on the outside will try the pull the hanging magnet to the side of the cylinder and prevent it from reaching the top. Another user will try to flip the magnets on the side of the cylinder to repel the hanging magnet. The team was thinking of incorporating multiple apparatuses to race one another to add the game aspect to this exhibit idea.

This design is engaging to users because it has the gamming element behind it. Users can compete with one another by problem solving and racing to the top of the cylinder. This reaches the customers number one requirement in terms of being fun and engaging. This exhibit also includes multiple users, which was another big requirement for the customers. This idea also uses very few materials, so the cost of this design is low. The size however could be a problem along with the weight. Multiple magnet pulley apparatuses are needed for this exhibit for the game aspect. This could be a problem in terms of mobility.

Figure 9 - Magnet Pulley

The egg helmet idea is the simplest idea in the team's Pugh chart. The idea consists of a protective shell in the shape of an egg that a user will construct with given material. An egg will then be placed inside this protective shell to help protect the egg when the user throws or drops it. The user will be provided with a variety of cheap material like paper, cotton, cardboard and bubble wrap to help add protection to the helmet. The goal of this exhibit is to protect the egg from breaking when the user release it from a certain height.

This idea meets a lot of customer requirements. It is simple to understand and therefore can spark an interest with a user. A user can perform trial and error to construct a protective helmet for their egg. Here they can visually learn that these simple materials act as a cushion to protect the egg. This exhibit would also allow for multiple people to use (a big requirement for the customer). The idea is also very small and mobile. Being way less than the size parameters, this allows for an easy set and storage.

This idea does have some drawbacks. Integrating an egg can be very messy. The egg could be replaced with an accelerometer to simulate an egg breaking. This however might cost a lot of money for multiple accelerometers and the programming for the fictional egg breaking may be labor intensive. A rendering of this design can be seen below (figure 10).

Figure 10 - Egg Helmet

The concept of a thermal structure is more complicated than the other ideas that were generated and there for would be recommended for children between the ages of 8-15. This concept would entail the child to build a structure like a building. A light bulb would then be placed inside and a thermal camera would be used to observe if there were any the thermal energy leaking from the structure. A device that could be attached to a mobile device could be used in place of an expensive industrial thermal camera.     

This would satisfy the customer requirements for size, safety, and easy to use. This concept could be built on top of most tables and portable devices are also small enough to use with a single hand. Since the light bulb would only be turned on after the structure is built and then be covered, it would be difficult for someone to get burned. One thing that might deter the build of this concept would be the cost of the thermal camera. Industrial cameras are expensive and would exceed the budget for this project. This concept is also not simple due to the involvement of thermal devices camera, and having to build the structure to test.

There are many concepts that could be taught from this idea. One of them is introducing the user to how heat can transfer through different materials. It will also show them the effects of bad design for insulation and how it will result energy loss. The user also will discover which materials work better as a thermal insulator.

Figure 11 - The Thermal Structure

This design will show the children how pulleys can be used to reduce the about of force supplied by a person to lift an object. The display would consist of two different pulley configurations as seen in Figure 10 - Pulley Wall below. One configuration would be with one pulley. This configuration would require an equal amount of force that is applied to lift the objects weight i.e.-a five-pound object would require five pounds of force to lift. The second configuration would have multiple pulleys that would be set up in a way that would reduce the amount of force needed by at least have i.e. – a five-pound object would require at most two and a half pounds of applied force to lift the object.

There are both pros and cons to this idea. Some of the pros would include: this display would be easy for multiple people to use, the concepts are easy to understand, and it would be easy to set up and take down. Some of the cons for this idea would be: could be heavy and bulky which would make it hard to transport because of the ropes in-between the different pulleys which could get tangled during transportation.

This design would focus on the concepts of gear reduction as seen if Figure 13 - Gear Box below. Overall this would be like the pulley wall in regards to being able to visually see that is happening and also there would be multiple gear boxes with different ratios. Each box would have a clear cover or the entire box would be made with a translucent material like acrylic or polycarbonate. With being able to see inside of the gear the child would be able to see how using different ratios, the output shaft rotational speed would differ from the input shaft rotational speed.

Some of the pros for this design include: portability, ease of use. For this design, there are many cons. That cost of materials would be higher, the weight of the gearboxes could be high due to the material and size of the gears. It would also be harder for multiple people to use the gearboxes due to the size being small.

To generate as many ideas as possible, the team held several brainstorming sessions. These sessions utilized two different techniques of brainstorming: C-Sketching and Standard Brainstorming session. C-Sketching was the most useful way to generate many ideas. Each team member had multiple turns to go up to a whiteboard and sketch a concept. With the rough rendering on the board, another team member would explain their concept. Then the rest of the team would critique the concept and add to it in order to improve it. Between the two different brainstorming techniques, the team generated 40 concepts.

The top ideas from the Pugh chart process were entered in a decision matrix. This design matrix aided the team in narrowing the top concepts down to three. The top five concepts were rated on a scale of 1 to 10, with 10 being the highest to each of the customer requirements. The results of the design matrix can be seen in Table 3 -Decision Matrix. The egg helmet scored the highest with 180 points because it satisfies the customer requirements. It's small, light, mobile and safe. The Rocket/Artillery idea scored the lowest with a score of 118. This is due to the design size, weight, and safety.

Figure 14 – Pulley

This exhibit will utilize four different configurations to explain the concept of how pulleys can reduce the amount of work to lift an object with mechanical advantage. The Single Fixed Pulley will be the first configuration on the pulley wall (figure 15). This is a 1:1 ratio of pulling, where the pulling force by the user on the rope (the red arrow) is proportional to the weight (the blue arrow) of the object being lifted. In this case, the user will be feeling the full force of the ten-pound weight.

Figure 15 – Single Fixed Pulley [10]

The second configuration is known as a Single Flowing Pulley (figure 16). This configuration is a 2:1 pulling ratio, were the pulling force is split between the two sides of the line. Here, a user can feel the mechanical advantage of the mechanism when compared to the single fixed pulley system. The weight is cut in half, thus making it easier to pull the weight up. The downside to this configuration, is that a user is restricted to pull from above to lift the weight.

Figure 16 – Single Floating Pulley [10]

The third configuration is called a Double Pulley system. As seen in figure 17 below, this system is a hybrid between the Single Fixed Pulley and the single Floating Pulley. This system creates a 2:1 ratio, just like the Single Floating Pulley. The tension in the line and the mechanical advantage is also the same as well. But rather than a user pulling from above, he or she can pull from bellow in this configuration. Here, a user can learn that this combination of systems allows for easier access of the rope, as well as a mechanical advantage.

Figure 17 – Double Pulley [10]

The last pulley configuration is known as the Block and Tackle. This is a very common pulley configuration that is used on ships and even on cranes. This system is comparable to the double pulley but it has the ability to reduce tension significantly by utilizing two double pulleys. The system consists of a four-line configuration that yields a mechanical advantage of 4 (4:1 ratio). More pulleys can be added to this to further increase the mechanical advantage. A user can pull on this rope and see that this is the best pulley configuration.

Figure 18 – Block and Tackle [10]

For the team’s final design, a prototype will be constructed first before construction of the actual design. This prototype will be a proof of concept prototype. It will have the esthetics of the final design and will show the basic overall structure and function of the exhibit. With the use of a three-dimensional rendering of the final design in SolidWorks, a prototype can be 3D printed in the MakerBot lab at the Cline Library on campus. This is done by saving the SolidWorks file as a “.stl”. The file is then sent via work order to the Maker Bot staff on campus at the library, where it will be printed and ready for pickup within 2-3 business days.

The prototype is essential for concaving the team’s overall vision of the final product. This prototype will also be shown to the customer to help them visualize the esthetics and mechanics in the exhibit. For the pulley wall, the prototype will consist of fixed pulleys on vertical plane. Fishing line or cheap cord can be used to simulate rope acting on the pulleys. The motions of the line sliding on the fixed pulleys will help visualize the different configurations. The prototype will also show that the pulley wall has two sides with different configurations on each side. This visually shows that the exhibit can be used with multiple users.

After a small prototype is constructed, a larger full scale model can be rendered. This model will strictly be a visual aid in terms of footprint size, not a functional prototype. This can be constructed out of plywood and cardboard to show the size of the real exhibit. The model will show pulley placements, along with the height, width and length of the board. This method of prototyping will not only help the customer, but will aid the team to visualize and construct the final product.

Materials, material sourcing and a cost analysis are crucial to constructing the final product. Estimates can be seen below in table 4. The framing selected for this design will be aluminum members for the base, upright and cross members. This material is not only strong, but will be lightweight for the customer to aid in mobility. The vertical panel will be constructed out of plywood. This is to reduce cost and weight. There will be a total of six pulleys in this exhibit: one hanging double pulley, one fixed double pulley, two hanging single pulley and two fixed single pulleys. Strategically placed rulers and tensile force gauges are factored into the cost as well, along with plenty of Nylon rope for the pulleys and a plywood wall for the pulleys to by mounted on. The total comes out to $827.79, which is well under the $1,500 budget limit.

Table 4 – Bill of Materials

When the full-scale prototype is presented and evaluated, planning and setting a schedule for the construction of the final design can commence. Figure 19 below is a screenshot of the schedule. The dates are a layout of when prototypes need to be done and when orders need to be sent out. The purple bars represent the prototyping phase. This is estimated to take about a week. This entails two 3D printed pulleys (see figure 14) for a proof of concept and a full-scale model that will show a footprint size of the exhibit. A CAD rendering of this can be seen figures 20 and 21, a front view and an exploded view.

The light blue is a scheduled customer meeting. This is just to touch base with the client and present the 3D printed prototype. The orange bar represents the start of construction of the final design. This will be the first round of construction. The blue bars represent ordering of parts. These are estimates of time for a part to be ordered and the received. The green bar at the bottom of the figure represents testing. This will entail physical trials of the exhibit, along with focus group testing with users. This schedule is subject to change. In terms of parts, they could be out of stock at the time or delivery time could extend. This can cause the start and end date of construction to change as well. Testing will dictate weather the final product is ready or not. Mechanisms could malfunction or focus group participants could provide input about the exhibit in terms of changing or adding a feature.

Figure 19 – Schedule

Figure 20 – Pulley Wall Figure 21 – Pulley Wall Exploded view

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