Figure 14: Simulation Result Figure 15: Power Supply Overview Figure 17: Prototype and Design Comparison (2)

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2 Contents Introduction Needs Statement Objectives Statement Background Overview Technical Additional Description Marketing Requirements Objective Tree Table 1 Table 2 Figure 1 (Objective Tree Diagram) Requirement Specification Table 3 Table 4 Table 5 Table 6 Alternate Features Design Figure 2: Block Diagram of system. Figure 3: Detailed Block Diagram showing components. Mechanical Construction Figure 4: Mechanical CAD drawing of the air intake and fan enclosure. Figure 5: Back view of enclosure showing air intake. Figure 6: Side view of enclosure. Figure 7: Dowel rods at the top of each tube. Electrical Construction Figure 8: Basic electrical circuit for the switches and blowers. Figure 9: Four controllers with switched mounted. Figure 10: Board used for connections of blowers, switches, and resistors. Design for 12 Volt AC to DC wall outlet power supply Description of concept Circuit Design Figure 11: Power Supply Circuit Diagram Figure 12: Zener Diode Physics Explanation Requirements and Specifications for power supply Figure 13: Blower Power Consumption at 12V Table 7: Power Supply Requirements Circuit Simulation

3 Figure 14: Simulation Result Figure 15: Power Supply Overview Figure 16: Prototype and Design Comparison (1) Figure 17: Prototype and Design Comparison (2) Alternate Designs Lab Instruction Documentation Analysis and Applicability of Constraints Standards and Regulatory Issues Single Tube Prototype Figure 18: Single Tube prototype lifting pingpong ball Test Results Project Management Milestones Task List Gantt Chart Figure19: Gantt Chart (Red line represents today s date) Required Resources Table8: Cost of mechanical components used Table9: Cost of electrical components used Table10: Tools used to build the apparatus Table11: Total cost and budget Table12: cost for testing the apparatus Risks Challenges, issues, and problems encountered Conclusion

4 Introduction Needs Statement In the meeting that our team held with Professor Passino, he mentioned that...the current state of [electrical engineering] education in developing countries is governed by book-based learning. This method, while beneficial in its own right, needs to be accompanied by a hands-on, lab based approach for best results. Professor Anderson, who operates and designs experiments that K-12 students from around Columbus use, quoted a lab cost of a couple hundred dollars as an arbitrary experiment cost. This cost is reasonable for areas that have people with the resources to support both methods. It proves difficult, however, in lower income areas because of the costs of running appropriate labs. There needs to be alternative lower-cost labs that can be performed to help in the education process of these areas. In order to help reduce this cost, and as a means to provide alternatives for the learning process in low income areas, we need to make a feedback control lab that can be built, transported, performed, and maintained cheaply. Objectives Statement The team will design and build a low-cost, hands-on engineering laboratory experience based on a mechanical juggler that uses human as feedback control to manipulate ping pong balls inside four tubes. The lab will teach students the concepts of open loop and closed loop feedback control as well as team cooperation. Moreover the cost will be maintained under 85 U.S dollars as it will be constructed from plastic and portable. Background The Juggler also referred to as the balls-in-tubes experiment was created to be an inexpensive test experiment for dynamic resource allocation strategies that exploit information from the plant in feedback. The dynamic resource allocation involves the limit on the amount of air the whole system can use at a given time. The feedback involves the sensors used which will be mentioned later. There exists a larger model of the Juggler in the Distributed Dynamical Systems Laboratory in Dreese labs.

5 The February 2005 issue of IEEE Control Systems Magazine, states the cost of this setup is around $200 plus the cost of the power supply and wires. The system allows for the use of feedback to be shown visually through the use of Devantech SRF04 ultrasonic sensors, Dynatron DF1209BB dc fans, and a DS1104 dspace card. An issue faced with this system that we could also face would be the fact that the time it takes for a ball to rise a fixed distance in a tube is generally greater than the time it takes the ball to drop the same distance. Another issue would be if 4 tubes are used, the two in the center tend to have greater airflow due to the input manifold being in the center of the model. Our group aims to recreate this setup in a cheaper form. This will be achieved by using human feedback instead of the sensors. The dynamic resource allocation strategies through juggling or balancing the balls forcing the users to cooperate with each other to complete the objective will still be implemented. The purpose of the Juggler Lab is to make sure students have interactive exposure to how electrical apparatus can teach you physical principles. The lab is designed in a manner to make the students understand feedback as well as cooperation. The lab aims to target these concepts by allowing the students themselves to be the feedback. This is achieved with the task of trying to balance the Ping-Pong ball at a certain height. The switches play as mode to allow the students to use their feedback response. Another concept the Juggler Lab teaches students is to act and perform the experiment as a team. This is incorporated by having 4 switches with 4 different people controlling them and the aim is to try and balance the balls at a specific height level while cooperating with other users of the apparatus. This makes the lab fun as well as intuitive. Overview The remainder of this document will give in detail the specifications and requirements that the juggler was designed to meet. Following this, we will present our final design as well as the iterations that we went through. Next, a report is given of testing and results showing how the design met the desired specifications. Finally, some project management considerations will be given such as design and implementation costs and issues faced.

6 Technical Additional Description A major factor in engineering is teamwork. The lab is designed to help with working together as a unit. This will be achieved through three factors of the lab: 1) Personal tasks, 2) The bigger picture and 3) Communication. On a team, each member has a job that they need to perform. For the juggler, each student must balance a ball in a given region. This mirrors the concept sufficiently. The second factor that must be realized is the big picture. Since the airflow into the device is finite, how an individual ball performs is dependent on the other tubes. It is designed to simulate the need for cooperation. Cooperation leads to communication. For a team to succeed a channel of communication must be opened. This will hopefully be a way to show the collaborative nature of engineering work. Marketing Requirements 1. The lab should be designed on a low cost budget. 2. The apparatus should be light-weight. 3. The apparatus should be compact to fit easily on a lab bench. 4. The product should be interactive. 5. The product must be challenging for the students to perform. 6. The lab should be usable in a reasonable classroom. 7. Easy manual and instruction set should be provided for the lab such that it can be understood in any country across the globe. The proposed requirements are to be able to market the product as a WeLab. The purposes of these labs are to make electrical engineering more accessible. This is especially true in under

7 developed countries. The lab should be low-cost. The lab is to be marketed as portable. The set-up should be light weight and useable in a reasonable classroom. Last the lab will be moderately fun. This is taken as interactive and challenging. A breakdown of these requirements is provided in the objective tree section. Table 1 shows how the group weighted each of these goals in reference to the final product. The main conflicting goals were between cost, interactivity, and challenge. Challenge was weighted as the most important at 65%. Interactivity and cost of production followed at 25 and 11 percent respectively. The items in table 2 were independent from those in table 1. Ease of manual is the most important here. Objective Tree Table 1 Low-Cost Interactive Challenging GMean Weight Low-Cost Interactive Challenging Table 2 Advanced application Easy manual GMean Weight Advanced application Easy manual

8 Figure 1 (Objective Tree Diagram) Requirement Specification Table 3 Engineering Requirements Marketing Requirements Engineering Requirements Justification 1 Total cost < $85 Developing countries may not have much money for lab equipment

9 1, 4, 5, 7 Controls with < 6 buttons 1, 2 Total weight < 50 lbs. 3, 6 Fit within a 1x1x1 meter box 6, 4, 7 Manual with pictures 2 Use of a 12V batteries To keep the use simple and interactive there should be a controller with minimal buttons Flights out of the country have a baggage weight limit of 50 pounds to keep from getting extra fees (1). To keep the size manageable for a lab bench To keep the manual simple as well as getting the point across To provide easy replacement of batteries. Batteries readily available in the respective country. Table 3 shows the requirements that were designed to meet. The price was kept under $85. This ideally would have been under $50. Due to some changes in design however the baseline price was increased. The other big change was the use of 12V batteries. A self-produced power supply was used instead. The implementation will still be functional with a battery source. The other requirements have not changed.

10 Table 4 Table 5

11 Table 6 Tables 4, 5 and figure 6 show the feasibility analysis of the project. The house diagram in figure 6 wraps up the goals and how well they would work together. The positive 1 s show goals that can be performed simultaneously, negative 1 s are conflicting. It shows cost, total weight and total size all can be improved at once. It is interesting to note that reducing the number of buttons also reduces interactivity. Also, if the manual is too easy, then challenge is adversely affected. An easy manual is one that gives students the exact procedure to balance the balls. Alternate Features There were many possible features the team investigated. From electrical to mechanical options some we rejected immediately and others we tested and chose the best route based on our results. In terms of the electrical design we sketched up many different designs the for features we wanted. We contemplated adding an electrical feedback system incorporating sensors at the top of each tube similar to the original Juggler. This system would utilize a microcontroller to control each sensor. The team rejected this idea early due to the fact that we wanted the system to be interactive for the users and this was accomplished through the users being the mode for feedback which will be explained later. The group also investigated adding color L.E.D. to mark

12 each tube with a different color and the same color to mark each controller. This was rejected because it was easier to just number each tube and their corresponding controller. Another electrical feature of the system the group investigated involved adding a momentary switch instead of the normal flip switches. We rejected this in the beginning because we thought we would need a 3 state switch for high/low/off but ended up only using high and low power. In light of this using a momentary switch would have been a better option after testing. If the group had more time to work on the project we would have experimented with implementing this type of switch. As for the mechanical features, due to the fact that our design was based off a previously designed lab, the design of our apparatus was straightforward and therefore did not involve any extra features. Design The main concept that fueled the design of our teams project was feedback. The interaction of the user allows the juggling to occur. Figure 2 below details how the user input to the system affects the apparatus. Figure 3 below is a more detailed block diagram of the system showing the major components.

13 Figure 2: Block Diagram of system. Figure 3: Detailed Block Diagram showing components. Mechanical Construction The air intake and the enclosure that houses the fans was constructed with plexiglass and the CAD drawing displaying the measurements is shown below in Figure 4. We were aided in the cutting of the plexiglass by Mr. Thalgott in the basement shop. Once we acquired the needed

14 pieced we assembled the structure using PVC glue. The completed enclosure is shown below with fans inside in Figures 5 and 6.

15 Figure 4: Mechanical CAD drawing of the air intake and fan enclosure. Figure 5: Back view of enclosure showing air intake.

16 Figure 6: Side view of enclosure. The next step in the construction process was to attach the 4 tubes to the base which is also shown completed in Figures 5 and 6. Figure 7 display the tops of each tube. The team glued dowel rods on the bottom of each lid for the tubes. This prevents the ping pong balls from getting stuck in the tops of the tubes which was a problem we ran into. Figure 7: Dowel rods at the top of each tube. Electrical Construction The electrical construction involved the basic circuit below in Figure 8. The components were four blowers, four switches for low and high power mode, and four 50 ohm resistors. The

17 switches were mounted on their controller so the user could easily operate the switch displayed in Figure 9. Testing multiple resistances allowed us to choose 50 ohms as the best option. Figure 10 shows the board we used to construct the circuit with the big red and yellow connectors being the location where the power supply is connected. As can be seen in Figure 9, there is an enclosure on the side of the box which can be used to house the circuit board.

18 Figure 8: Basic electrical circuit for the switches and blowers.

19 Figure 9: Four controllers with switched mounted.

20 Figure 10: Board used for connections of blowers, switches, and resistors. Design for 12 Volt AC to DC wall outlet power supply Description of concept As team members realized using 1.5V batteries in series to provide 12V DC power would not be practical. In addition for the sake of increasing design complexity and reliability, team members decided to adapt an AC/DC converter design that outputs 12V DC power for four blowers team acquired. Circuit Design In order to achieve the goal of providing 12V DC voltage, design below is considered. Figure 11: Power Supply Circuit Diagram

21 The ultimate goal of the power supply is to provide 12V DC voltage for the sub circuit of the design. To accomplish our goal we first use a transformer to stepdown AC voltage from 110V to roughly 30V. Follow by Diode Bridge, negative voltage cycle will be folded to positive region. After adding a capacitor, Voltage ripple will be smoothed out dramatically. At last a 12V Zener diode regulator design will be utilized in order to achieve a 12V DC output. A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. When operating at reverse bias, voltage across diode will be 12V. Figure below explains the physics of Zener Diode. Figure 12: Zener Diode Physics Explanation Requirements and Specifications for power supply Since the purpose of the power supply is to provide reliable power source for four blowers solely to lift ping pong balls, the power supply is required being able to output 12V DC voltage. In addition, as tested in the lab each fan will consumed 0.17A current at 12V (shown below). Therefore, the power supply will also be able to provide a minimum current at 0.68A.

22 Figure 13: Blower Power Consumption at 12V Engineering requirements Justification Power Supply Output 12V DC & Minimum 0.68A 0.68A is the nominal current consumption of all four fans and 12V is fan's operating voltage Capacitor Being able to handle up to 36V Transformer outputs 36V Voltage Pull up resistor 20ohms & being able to handle up to 6.8W All current will flow through the pull up resistor. W=I*R=0.68A*10ohms=6.8W Zener Diode Being able to handle up to 0.68A Nominal current flowing through will be 0.68A

23 Table 7: Power Supply Requirements Circuit Simulation Before construction team member ran software simulations for the sake of circuit reliability and being able to fully understand the circuit. Below is the simulation result. Figure 14: Simulation Result Red line presented in the graph represents input AC voltage. Voltage across capacitor is being presented by blue line. At last, green line is the output voltage of the power supply

24 Figure 15: Power Supply Overview

25 Figure 16: Prototype and Design Comparison (1) Figure 17: Prototype and Design Comparison (2) Alternate Designs Throughout the design of our project the team ran into many problem we had to work though in order to get to our final successful design. The first problem we ran into was both mechanical and electrical. The team had difficulty implementing our initial design for the prototype and successfully lifting the ping pong ball. This was due to the fact that the first set of fans we purchased were 4.7 in length and we used a pyramid design for the base. Due to both the mechanical design of the base and the size of the fan, there was not enough force at the bottom of the tube to lift the ball. The team realized we needed to reject both the large computer fans and the pyramid base design. The teams solution to this problem was to change from using a computer fan to a blowers. We got our idea to experiment with a blower from research on the internet. The blower was a positive addition to our apparatus because it applied its entire output force at the base of the tube so lifting the ball was much easier. Additionally it was much smaller in size than the previous fans, so this allowed for a much smaller rectangular design for our base. This made it much more structurally sound by decreasing the overall size of the base and gluing

26 together a rectangular box was much easier than the previous pyramid design. In addition the change made the apparatus cheaper which was a requirement of our project. The second problem was the fact that our choice of power for the system was not sufficient for the force we needed to come out of the fans. After testing the eight D batteries, which was our original idea, the team decided to build the power supply mentioned above and this was a much better solution than the batteries. First because is supplied then additional power needed to keep the balls lifted and second it was a reusable source that did not need to be replaced like the batteries. Lab Instruction Documentation The WeLab will also come with instructions similar to those given in a class period. The proposed lab procedure is defined in a stand alone document that is included with the lab. The purpose is to allow them to be posted separately from the machine itself. This will allow the most people to view and use the product. Structurally the instructions are divided into two parts: A teacher s manual, and a student version. The teachers manual outlines the purpose of the lab. It will give what concepts are being taught and how. Additionally, the teacher version contains a parts list as well as details on constructing a juggler. This is to allow multiple people to build a cost effective lab. Finally the teacher version will give several troubleshooting tips. The student portion gives a walkthrough on how to perform the lab. Analysis and Applicability of Constraints Economical: The lab is designed to be less than $80 to provide a cheap, but also provide an intuitive lab experience for students in developing countries. This economical lab explains the different concepts by providing the students with hands-on experience. Environmental: The materials used for the lab are environment safe. The tubes are made from recyclable plastic. The ping pong balls are also biodegradable and can be disposed of easily

27 without harming the environment. The case that is used to enclose the apparatus is made out of plexiglass and is a material that are also biodegradable. The power supply is the only part of the apparatus that could harm the environment if disposed of incorrectly. Social: The lab is designed in a way to provide a very social experience to all the users that perform the lab. The users have to communicate with each other in an interactive manner to balance the Ping-Pong balls inside the tubes. The users each have access to each of the switches on the apparatus that controls the fan in each of the tube. Thus, this lab provides a really social and team based experience which helps the students learn more about team coordination and communication skills. Health and safety: Since the lab is targeted to the students the health and safety has been the number one priority in designing the lab. The tubes are made up of plastic instead of using glass to make sure no one gets injured in case the apparatus was to break. The wires and the circuitry of the apparatus are not easily accessible to ensure none of the students get injured by a shock. The apparatus is designed in a way such that it has a lower center of gravity and thus making it hard for it to topple over and hurting some students foot. Sustainability: The tubes and the fans in the apparatus are designed and placed in a way such that they are easily replaceable in case they go defective. The ping pong balls can also be replaced easily. In addition the power supply should last a very long time are the parts are rated for long term use. Standards and Regulatory Issues Safety standard: Occupational Safety and Health Standards (f) Power Supply Standard: IEC/TS Ed. 1.0 en:2014

28 IEC TS 62700:2014(E) states the minimum requirements for DC power supply for notebook computers. Specifically, it gives an electrical specification (performance characteristics), an ID pin method and a connector for DC power output. Lab standard: IEC / IEC The IEC / IEC Electrical Equipment Package provides safety and EMC requirements for electrical equipment in a laboratory setting. It also provides general requirements for electrical test and measurement equipment, electrical industrial process-control equipment and electrical laboratory equipment. The IEC / IEC Electrical Equipment Package includes: IEC Ed. 3.0 b:2010 IEC Ed. 2.0 b:2012 All designs team used will follow standards listed above to comply our safety and voltage supply requirement. Single Tube Prototype Our prototype although successful, opened our eyes to a lot of issues our system had that through changes allowed us to have a better final product. The ultimate goal of our single-tube prototype was to successfully lift the pingpong ball. We accomplished this and our prototype is shown in Figure 10 below lifting the ball. Our prototype was built using the larger fans mentioned earlier that were later replaced with blowers. This is when the team first realized that a smaller solution was needed. In addition the base for the tube and enclosure for the fan was constructed in a pyramid design out of plexiglass, which was very hard to construct and keep stable. This was mentioned earlier when talking about changes the team made in design. The use of blowers allowed for a square base. With our prototype we also tested the use of eight D batteries and this

29 also failed so we ended up using a power supply in the lab for the prototype and decided to build our own for the final system. Figure 18: Single Tube prototype lifting pingpong ball

30 Test Results During the time of building this lab design, the team encountered many problems. To make sure the design can run correctly, the team did following tests and experiments. 1. Power Supply: The team planned to use D-batteries as the power supply before the team decided to use blowers instead of regular computer fans. But after the testing, the D-batteries did not give the computer fans enough power to lift the ping pong balls. So the team decided to use the in-wall power supply. Since voltage from the in-wall power supply is 110V, the team also design a AC-DC step-down converter circuit. After testing, the team converted the 110V AC voltage into a 12V DC voltage. 2. Fan Experiment: When the team built the single tube prototype, the regular computer fans did not work very well. They did not have enough concentrated strength to lift the balls under the 12V DC voltage. Instead of using the regular computer fans, the team decided to use the more powerful blowers. The blowers can easily lift the balls under 12V DC voltage. 3. Resistor Experiment: In order to create the low power settings, which makes the balls drop very slow, the team did the voltage experiment first and found the acceptable voltage range for the design was between 6.5V to 7.5V. After series of calculations, the team found the demand resistance - 50Ω. In case the resistor might burn, the team decided to use a 50Ω resistor with a higher rating. 4. Single Tube Prototype Experiment After all the above experiments, the team decided to put all the parts together and make a single tube prototype. The purpose of this experiment is to test whether each part of this design can work well together. During this experiment, the design easily lifted the ping pong balls. Under the low power setting the ping pong ball can drop down very slow. So single tube prototype work pretty well. 5. Final testing Based on the single tube prototype, the team built the final design. In the final design, there are four tubes and four blowers, and each of them has the high mode and low mode. They are constructed in parallel as the team planned. Before the team sealed all the pieces of the design, the team did the

31 final testing. Before turning on the master switch, all the blowers were set to default mode, which is high mode. After turning on the master switch, all the ping pong balls were successfully lifted up and hit the top. The the team tested the low mode for each blower, and they all worked correctly. Under the low mode, all the ping pong balls drop down very slow. So the final testing was very successful. Project Management Milestones To keep the project organized and finish it in a timely order. These milestones were chosen: 1. Completing the electrical blueprint for four multiple speed fans. 2. Prototype for a single tube completed. To make sure hardware setup is feasible 3. Full system prototype completed. This will be the finished product completion Task List Each of the milestones had tasks and subtasks under it. 1) Electrical Power Distribution Circuit a) Design i) Layout ii) Calculations b) Purchase Components i) List ii) Place the order c) Construct/Test 2) Single Tube Prototype a) Mechanical Design/Construction b) Electrical Construction For Single Tube c) Testing 3) Full System Prototype a) Construction i) Electrical

32 ii) Mechanical iii) Air-manifold b) Testing i) Safety ii) Stability iii) Performance Gantt Chart

33 Required Resources Figure19: Gantt Chart (Red line represents today s date) Mechanical Construction Item Price Plexi Glass $8.32 Tubes $5.00 4, Pingpong Balls $1.00 ea. Glue Varies (According to use) 4, Blowers $8.56 ea. 4, Nuts and Screws: $0.25 ea Electrical Components Table8: Cost of mechanical components used Item Price 5, Switches $1.00 ea. Bridge-Diode $0.62 ea. 12 Volt Zeiner Diode $0.54 Step-Down Transformer $ , 20-Ohm Resistors $0.64 ea. 4, 50 ohm Resistor $1.72 ea. 50 Volt Capacitor $0.90 Power Adapter Varies (Any power adapter works)

34 Table9: Cost of electrical components used Tools Item Sodder Multimeter Wire-cutters/Wire-strippers Band-saw 6, Circuit Boards Wire to connect Table10: Tools used to build the apparatus Total cost of apparatus $79.15 Requirement cost estimation $85.00 (We Lab) Total Budget for the project $ Table11: Total cost and budget Cost for testing(not used in the final apparatus): Item Price Boost, Flyback, SEPIC and Inverting Controller $ V N-Channel MOSFET $ , D-batteries $8.39 4, computer super quiet Fans $5.00 ea 4, computer fans $2.38 ea. Plexiglass $2.45

35 tubes $2.50 2, 20 Volt Zeiner diode $0.54 ea. Table12: cost for testing the apparatus Risks 1. Durability: Since the apparatus is going to be used by students, the apparatus must be durable. The team faced several design problems to make the apparatus durable and reusable by the students. One of the key design changes that the team used to resolve this issue was to have a separate panel for the implementation of the switches. This would not only allow easy access to the switches but will also refrain the students from touching the circuit board. 2. Resistor getting hot: The power going through the resistor was very high. This caused the resistor to become very hot. Since the apparatus had to be safe to use the team had to tackle this problem and make it safe to use. Thus, the team decided to add another 20-ohm resistor in parallel. This reduced the load on each of the resistor and thereby made them less hot. 3. The diode: During testing the final apparatus, the team realized that the diode being used is of low rating. This meant that it is not capable of allowing or handling a lot of power. The team decided that the problem wasn't very severe and need not be resolved. Challenges, issues, and problems encountered The semester went as well as one might expect. We feel like our intended goal was met. There were, however, several issues that came up. The issues ranged from circuit problems to construction issues. The circuit challenges were fairly few. The first issue encountered was determining the resistance values for LOW power mode. This was determined through performance testing and was resolved. The next distinct problem we faced was complexity. This design is culminating from our collegiate experience. The original circuit that was proposed was too trivial. This was a

36 problem because it didn t show what was learned through school. To combat this, the group produced a working power supply to accompany the juggler. Adding the power supply gave rise to a final issue. Some components initially had too much power going across them. To resolve this two methods were employed. The first was to order better rated components. The second was to put devices in parallel to reduce the current flow through an individual device. All the construction issues were due to the fact that our group was all electrical engineers. Actual physical system tasks were not as practiced as the electrical ones. The first issue was how to actually build the parts. This was resolved thanks to Mr. Thalgott who machined all of our pieces. In the talks with Thalgott, it was discovered that some dimensions on the initial design were off. He helped us rectify this. Once everything was cut the group had to construct the final prototype. We did not want to drill any holes in the plexiglass. The risk of breaking a piece was too high. To combat this, we screwed the blowers directly together instead of attaching them to a wall. The result was the same. We then used the pieces for stabilizing the tubes. Conclusion To conclude, the team builds an apparatus called the juggler that helps schools in developing countries to have inexpensive interactive labs. The juggler is an apparatus that uses human as feedback control to manipulate ping pongs balls inside tubes. The lab will teach students about the concepts of open loop and close loop feedback control as well as team cooperation. The apparatus also teaches the students a handful of different concepts that help them develop skills like problem solving, communication, co-ordination with the team members, etc. The project is designed to be economical, safe for students, intuitive, social, sustainable and environmentally safe. This is achieved by using different design techniques to build the juggler. The problem that developing countries currently have is that they cannot afford to conduct labs that are intuitive enough to make the students understand abstract concepts by providing students with a hands on experience on these abstract concepts. The labs are generally really

37 expensive and thus, the school decides not to hold labs for the students. This makes it harder for students to understand the concepts. The solution that the team provides is an affordable apparatus that is sustainable and can be used multiple times in a year. The apparatus called the juggler provides the schools a lab and benefits the students to learn and understand the different concepts that the apparatus teaches. This experience of the juggler can be enhanced in a lot of ways. Firstly, the juggler s control feedback mechanism can completely be completely automated. This would be achieved by adding laser sensors on the top of each of the tubes to find out the level at which the Ping-Pong ball is floating. These sensors can in turn send data to a microcontroller that controls the speed of the fan and thereby keeping all four balls at the same level. The second enhancement that can be done on this apparatus is, by adding Ping-Pong balls of different weights. This makes it more challenging for the students to maintain the balls at the same level. Another enhancement that can be done in this apparatus is to have different strength fans. This has the same benefits as the previous enhancement and causes more communication and coordination among the users who serve as a control mechanism for the apparatus. Overall, this project includes many techniques, some of them are what we have learned from classes, and some of them are from online resources. During the time of building this design, every team member learned how to cooperate as a team. Although, sometimes team members had some disagreements about some problem, we could always find the best solution. From this project, the team gained experience about how to finish a real life project as a professional engineer. The team also learned the most valuable lesson about how to work as a team.