Pneumatic Museum Display

The following design is my senior capstone (E SC 497B) project. My team was assigned to design and construct a working prototype of a pneumatic tubing exhibit for Discovery Space of Central Pennsylvania Museum. The secondary objective was for the team to make recommendations to improve performance, reliability, and robustness for a follow-on capstone design project that would construct a full-scale exhibit in the children’s museum.

Attached is the final design report of the project, clearly depicting the various steps to acquire customer needs, engineering specifications, necessary calculations, and instructions for complete manufacturing, as well as documentation for improvements for the follow-on senior capstone project.

Here is a quick summary of the following design process:

1. Analyze: The first step in this process was to understand the project assignment. The team and I went to the Discovery Space Museum in downtown State College to ask our sponsor the objectives. Originally, they wanted documentation for the next semester senior design group to build off for a full-scale exhibit; however, our team felt it was optimal to build a smaller prototype that would serve as a model so the research we would conduct could be validated. The prototype they required wanted to be safe, durable, and functioning, but small enough to be transportable to various fairs and showcases (in order to promote the museum). Discovery Space relies on donations and they wanted a way for customers to donate to the museum via pneumatic tubing; however, they also wanted a way for kids to put in other small objects to stimulate their curiosity in science and spark imagination.

2. Design: The next step was establishing design specifications. From the previous step, it was determined that the customer needs included the prototype being safe, functional, portable, durable, entertaining, ergonomic, and replicable. With those needs in minds, engineering specifications were set as fan power, fan durability, transportability, actuator speed, microcontroller options, and tube quality. After running through concept screening and concept generation charts, the team and I decided that a design using a linear actuator between two separate tracks would be best. The two tracks allowed the money and other objects (whether they be scarves or ping pong balls) to be separate. The user would push a button for the actuator to switch the tube from the fan to different tracks, hence having one track active with continuous airflow from the fan and the other track dormant. One of my specific roles was to model the different parts of the prototype in SolidWorks and made specific drawings. Shown below are some of the preliminary models and drawings of the diverter box (shown in Figure 1 and 2), the electronic circuitry box (shown in Figure 3 and 4), and a SolidWorks 3D model of the linear actuator used (shown in Figure 5).

Figure 1: Diverter Box Model

Figure 2: Diverter Box Drawing

Figure 3: Electronic Box Model

Figure 4: Electronic Box Drawing

Figure 5: Linear Actuator Model

3. Develop: For the following weeks into the end of the semester, the team and I physically constructed the prototype. The below figures will show various stages of construction progress. The frame for the design was built from rigid PVC tubing. The other two large components were the diverter box, where the linear actuator and flexible tubing was built to control the airflow from one track to the other, and the electronic circuitry box, where the electrical engineers in the team would program custom coding for the microcontroller used and wire the two user inputs with the linear actuator. The flexible 20’ tubing tracks were cut into 4’ sections for easy disassembly and troubleshooting, and then molded into two tracks around the rigid PVC frame. One track launched the ping pong balls/other objects out up top while the other track landed the donations into a secure clear box. Check the below figures for pictures on this construction process.

Figure 6: Preliminary Construction on October 11^th, 2012

Figure 7: Team Constructing Diverter Box on October 16^th, 2012

Figure 8: PVC Frame Support Construction on October 18^th, 2012

Figure 9: Fan Construction Completed on November 1^st, 2012

Figure 10: Austin Sanding Edges on November 1^st, 2012

Figure 11: Austin Turning Out Couplings for Track on November 5^th, 2012

Figure 12: Assembly of Diverter Box on November 15^th, 2012

Figure 13: Wiring of User Inputs on November 15^th, 2012

Figure 14: Track Construction on November 29^th, 2012

Figure 15: Near Completed Assembly of Diverter Box on December 4^th, 2012

4. Test: The prototype was sent to the Discovery Space Museum to see how both the museum clerks and kids interacted with the exhibit prototype. MORE TO BE ADDED.

5. Improve: The purpose of this project is to be able to find rooms for improvement on this design; after all, it is only a prototype for the full-scale exhibit. One thing that stands out is that the actuator is slow to move from one track to the other; a transformer with a lower step-down that can send more voltage to the actuator would fix this problem. However, due to budget, that was not possible for this project. Another problem that the full-scale exhibit might face is head loss; within the flexible tubing track, there is loss in airflow velocity due to the friction in the track as well as the bends in the path. The fan was powerful enough to push small objects and money through the 20’ tracks, but for tracks that extend all throughout the exhibit, a more powerful fan is needed. One of my roles in this project was to calculate head loss; the output air speed from the fan was about 20 m/s, and at the end of each track, the air speed averaged about 10 m/s. However, 10 m/s was still good enough to push small objects and donations through the track. When the tubing was 40’, another test of air speed was conducted, and the exit air speed was about 6 m/s. With more track comes more head loss, so the next capstone group needs to take that in account when designing the exhibit.

Conclusion

Overall, this project got me familiarized with physical construction, using workshop tools, and analyzing project with a very different mindset – how will young kids interact with this product? The design had to be very visually appealing, but also had to be childproof. Safety was an obvious priority, but what could go wrong? When dealing with adults as consumers, the designer can make more assumptions that an adult would be able to use a product correctly; but with children, they always find ways to push the product to its limits. This project had the team and I really focus on how children would interact with this product – are the edges rounded? Is the diverter box and electronic box sealed? Is the frame and track firmly held together? If kids pull on the pipe, will it break or be able to hold on its own? These questions had to be addressed, and by going through this process, it helped assure that our product would be successful.

For a closer look on how the system was made, please check out the small documentary video project I made to compliment our prototype. Use the password "esc497b" (all lower case and without the quotations) to unlock the video.