Final Week - Pictures!

I understand that we are not required to do our usual blog post this week, but check this out:


Our project is all over the Design Expo publications! Here are some more pictures from Facebook:

Final WEEK - Exciting findings

The most exciting finding of the entire project was that it worked!!! During the design expo we were able to proudly display our working prototype. In addition it actually worked at one point much better than we had anticipated. We got the motor to displace a charge onto the capacitors and then on to the phone's battery for 20 seconds without adding another pull! This was a huge surprise. Previous testing had shown that the displaced charge only would last a second or two after pulling.

Another great finding was that people were extremely satisfied with the weight of the case. While they did mention they didn't really like the bulkiness, they still loved the fact that it was about the same weight as current battery cases on the market, and that the projected cost was about a quarter of the cost of the battery cases.

Final WEEK! - Challanges

Having successfully designed, prototyped, and presented out product, "Clutch".
The only challenges left is to reflect and learn from this experience, and to determine whether or not to take the next step and make actually dive into the consumer market and attempt to find investors. However, to do this, more work and testing would need to be done on our current prototype.
Nonetheless, we have been able to meet all the previous challenges set before us, and have learned a great deal along the way!

Week 12 - What's Next

We have a few things to finish up before the design expo. First, the circuit board must be soldered together with a cell phone charger properly configured. Next, we should assemble our 3D printed case shell, create the handle and string mechanism and assemble the whole thing with the spring attached. We need to finish our poster by adding some validation data and the business plan, print everything and attach it to a piece of foam core. For the design expo, we will need to plan our demonstration and business pitch. It seems that everything is now coming together, but we need to put together a few more things in order to be sure that it runs smoothly.

Week 12 Team Update

This week, the team accomplished a lot in terms of productivity towards manufacturing. The team was able to finish machining several components in the student machine shop, and also able to test the functionality of the device. This was done by hooking the Pololu DC motor up to an oscilloscope to see if it produced enough voltage to feasibly charge a phone It was confirmed from testing that the motor could output much more than the needed voltage. Because many of the orders took several weeks to arrive, it was a slight rush to get the components to arrive on schedule and Also accomplished was the final submission of the case design to the 3D printer, which is on schedule to be completed before the Design Expo. The team is on task with the high probability of completing the project before the expo and having a working demo at the booth. Still to be done is make sure that the harnessed energy can actually charge an iPhone with a working charging circuit, and integrate all components (including circuit board and mount plate) into the 3D printed case.

week 12 -Eciting Findings

Although a stressful realization, it was still interesting to learn that to charge an iPhone, providing the right current and voltage is not really enough. A special circuit must be made so the iPhone realizes and accepts a charger.
Another exciting finding was that we were able to makes some of our parts even smaller, while machining them and still maintain our stress tolerances. More specifically, we were able to make the part that hols our clutch spring a little bit smaller, saving space, weight, and reducing the materials used!

Week 12-Challanges

Our biggest challenge now is to ensure that our device, the "Clutch" is assembled, tested, and ready to go in time for the design expo. Currently all of our parts are in, and most of the "Clutch" is assembled. However, it is still not 100% completed, and we also still have to get our 3D printed housing, and then lay carbon fiber over it. We also will have to test it and ensure that the iPhone accepts it as a charger, via circuits, and ensure that it successfully charges the iPhone.

Week 11 - Status

Design expo is scarily close, and while we are on track to finish I am still nervous about the timing. We still need to machine a few simple parts and are still waiting for our clutch bearing to come in. If that bearing isn't here on Monday we might be in trouble. However, the majority of the work left for the prototype is assembly, and we are signed up for machines on Monday and Tuesday. We also have all of the components we need for the circuit board except for the iPhone cable. I don't know if there is going to be a more complicated wiring system to connect the charging cable, but I intend to put together the rest of the circuit tomorrow.  The CAD of the case shell has been submitted to 3D print just a little while ago, and we were told that it should be done by the end of the week. Brian is working on the poster, and David has volunteered to handle our business plans. It seems that everything is on track to finish, but nothing has come together yet. Hopefully in a few days we will have a poster, a working prototype and a partial business plan for the final report!

Week 11 - What's Next

We are so close to design expo!!! We have all but one of our parts in, and this next week we need to assemble and test our prototype. I am concerned that we won't have very much time to fix things if they don't work on the first try, but Dr Luntz (who I spoke to on Friday) seems to think that our testing will run smoothly and that replacing parts should be easy if something breaks. We also need to get our poster together and printed. We seem to be right on track, but time is very tight.

Week 11: Exciting Findings

The biggest development this week was finding out just how small some of our parts were. It was a definite concern for us that, if the parts we ordered turned out to not really work with the dimensions we needed, we would have to reorder and wait for everything to show up again. However, we were pleasantly surprised by the size of the motors, but even more so by the Zener diodes, which were much smaller than we anticipated. This helps us because with our size restrictions limited to the size of a standard phone case without becoming cumbersome, the smaller the parts, the better. The challenge of it is being able to assemble it all without breaking anything.

Week 11-Challanges

Rolling through week 11, our biggest challenge is now assembling and testing our product in time for the deign expo! As we begin this process we are finding that assembling our spring system, designed to ensure that after the user pulls on our string connected  to the motor shaft, the string is retracted back in to the case. However, this is proving to be harder than anticipated due to space, time and the type of springs we can use in our system. Another challenge is going to be to test our electronics. Due to our teams lack of experience in circuits this may prove to be more time consuming and harder than we anticipated. We are still optimistic, and hope that this will not take too much time. Nonetheless, ensuring that we obtain he most efficient system, mechanically and electronically is not going to be easy!

Week 10 -What's Next

The next week will be used to manufacture and assemble the components of our device. The machine shop will be used to mill the base plate, pillow blocks and motor mounts. The electronic circuit that will be used in the device must also be configured. Then the transmission, motor and electronics can all be assembled after all the necessary components arrive. Hopefully there will be time this week to also test each part of the device to ensure it functions properly. While this is being done a member of our group will also be working on the business plan and financial analysis before completing the conjoint analysis.

Week 10 Exciting Findings!

As we prepared for GR3, and surveyed which colors people liked and found reliable or fun, we found that mot people found black to be the most reliable. We also found that engineers found the carbon fiber print to be the most reliable. Nonetheless, it was interesting to see a correlation between the color and reliability, instead of material and reliability.
Another interesting finding was how well we anticipated our needed space inside the phone case! While designing the CAD it was nice to see that we did not need to redesign to many things in order to accommodate  all the internal components.

Week 10: Project Status Update

The team has passed Gate Review 3 and is now ready to begin construction. A design for the case shell has been designed and CAD, and further manufacturing process development is underway. It was decided that the best option for manufacturing the case will be a rapid-prototyped ABS part via 3D printing, and then capped with carbon fiber for rigidity. Because the device will see up to 25 lbs of force distributed over where the motor is mounted, basic FEA analysis has been done on the case shell to ensure it will not suffer from fracture or yield during normal use. The carbon fiber cap also makes sure of this. 

Part orders have been placed from Mouser Electronics, Pololu, and McMaster. Upon arrival of these components, the team can get in the machine shop and begin manufacturing the parts needed to conduct testing on the motor setup. Manufacturing plans and diagrams have been developed for quick manufacturing in the ME student shop, which will decrease time required in the shop. The team also scoured for materials that can be used to build the case this week in and around the ME X50 assembly room area. 

Currently being worked on is cost analysis,conjoint analysis to choose the best consumer preferences for the device, and the business plan.

Week 10 - Challenges

Now that we have been approved to order parts and begin building, it looks like the biggest challenge that we face is the time constraint. There are a few bugs in our design that can only be worked out by testing, and hopefully everything can be solved in the next few weeks. I'm sure that we could make our design better if we had another semester instead of only a month, but we have to get enough done to be satisfied with our working prototype. We will have to create a schedule and stick to it and should divide up the work into sub-systems that can be verified independently. Another challenge relating to time constraints is shipping times. While shipping is relatively fast when parts are made in the US, shipping from Asia takes 1-2 weeks. If something breaks at the last minute, it will be impossible to reorder parts from overseas, and we may have to pay very high overnight shipping fees even if the parts come form within the US. It will be better to begin building early so that we have enough time to make mistakes and don't run into these problems.

Week 9 - Project Status

This weekend we are working hard to complete Gate Review 3. As of this writing, the pieces are coming together nicely, and I expect to be able to submit the report to Professor Brei by the end of the day tomorrow. Gate Review 3 is quite involved though, and it has taken a lot of diligence to move it forward so quickly. While we were given plenty of time to complete it, we got very stuck on motor selection and were unable to move forward until the end of last week. After extensive office hours with Dr Luntz, we were finally able to choose a motor and find suitable transmission parts to begin the CAD. A detailed analysis of the motor and transmission have now been done for the Gate Review, and Nick has been hard at work on the CAD model. We were pleasantly surprised that one of the most readily available motors happens to produce exactly the power that we need and is very compact (only 0.4" in height)! It also turned out that the clutch bearing that we were looking at can provide the remaining gear ratio that we needed on top of the motor, and that we won't need to add any extra transmission components. This greatly reduces the size of the device.

So far, everything looks pretty good. Realistically however, I know that not everything that we have planned will work the first time, and that we will probably have to make changes to the design. I am anxious to order parts and start building so that we can begin to work out the bugs!

Week 9: What's Next

As we move on through Gate Review 3, our next step is to develop and complete a business plan, approaching the Design Expo. We have complete material research and component research, as well as a final design, so our next task involves figuring out manufacturing costs and production costs for the product. In order to develop a coherent business plan, we are also looking into different production methods so that we are pursuing the most efficient and cost-friendly method of production. We have to consider the other aesthetics involved in the design that are geared more towards production, such as color. These have been resolved using the Kansei method of selection, and will be taken into consideration as part of the business model.

Week 9 - Exciting Findings

While deciding ways to transfer the power generated from the DC motor to the actual Iphone, we were continually bouncing back and forth between using a battery or a set of capacitors. We ended up finding that we could actually use two super capacitors instead of two heavy batteries, to collect and dissipate charge between the DC-motor and the Iphone. We also found that this saved space and weight, which was extremely important as continue to determine the best way to manufacture a housing that will also serve as a case for the Iphone. We also found that due to the size of the one direction ball bearing we will be using with our DC motor, on its  shaft, we may not need to have a gear train to increase the gear ratio. This again, saves space, weight, and more importantly, reduces chances for losses in efficiency!

Week 9: Challanges

As we are preparing for gateway review 3, we are finding that our next biggest challenge will be fitting all of our components needed for completing our circuit and generator, all inside our iPhone case. We are also a little concerned with how we will make the plastic component of our iPhone case that will also hold all of the components. If we decide to use injection molding, manufacturing the mold case will be be both difficult and expensive. we will have to make the mold out of a single piece of aluminum and this could also result in insufficient tolerances and precision. Our other option is to 3-D print the part. However, this could result in an unreliable and imprecise case. Nonetheless, manufacturing our housing, and ensuring that all of our components fit inside of it, will be a big challenge, but critical to the success of our project. 

Week 8 - Our Project Status

In the last week we have looked further into our design specifications. We calculated the power that the motor must be rated for and did an extensive search for motors that fit this requirement and were small enough to fit into our design. We then found the specific parameters of the motor by looking up information on the data sheet of each potential motor. This allowed us to start modeling the system and to figure out the optimal motor for use in our application. We then looked into potential gearing as well as a clutch system that would work with these motors. The information gathered will be related to what must be done for the gate review. Other aspects of the gate review were also considered when choosing the design. However, more work must be done in the following week to complete the necessary tasks for the design and review.

Week 8 - Exciting Findings

This week we are excited to solidify the design for our product. Gate review 3 is just around the corner, and we need to select a motor and transmission so that we can move forward. This is the part of the design process that everyone has been looking forward to as engineers, and hopefully we will be able put this enthusiasm to good use.
Last week, we got some good input from Dr Luntz about modeling our power system, and our preliminary findings show we will definitely be able to find a motor that fits our needs. While we are still looking to reduce size and weight, there is a motor available that is only 10mm in thickness and can handle twice the power that we need. We are still looking for other smaller versions, but this first one would be suitable and can make our design possible.

Week 8: Challenges

Our biggest challenge right now is finding a motor that will be able to take our input torque and convert it to the necessary output voltage, while maintaining the smallest size possible. Using our known input and needed output combined with dc motor performance calculations, we plan to test different motors and their motor constants to determine which mote will be the best for our application. We also are working on the best way to position a clutch mechanism with the dc motor to ensure the transfer of a continuously inputted force is converted to electrical energy in the most efficient manner possible. In addition, we are determining what kind of materials to use in our case, as it has to be able to hold all of our components under the high torque inputed by the potential user.

Week 8 - Whats next

Our next step is to determine what kind of motor to use as well as what qualities the motor needs to have. While we know what our input torque will be and what our output voltage needs to be, we need to find a motor that can take the input toque and convert it into the needed output voltage, while still being small enough to fit within our desired dimensions. We also need to begin constructing a 3-d CAD model of our design, and considering what materials we will use in our design.

Week 7: Team Update

Heading into week 8, the team has several tasks that we will need to complete to stay on track. After speaking with Professor Brei, the team gained some pointers on how to start modeling our system. She suggested that we first go online and find companies that make motor/generator systems. This will give us a good sense of what's available and what companies make them. We will need some reliable suppliers with good spec sheets, also making sure that the components these companies make are small enough for our application.

In the meantime, we have begun to draw the system out in detail and come up with a gear-train design that will actually work. It was recommended that we find a motor first and then figure out what kind of transmission we need based on the gear ratio. The input power must be estimated to then find a motor that can accommodate it within a factor of safety. Once we've chosen a motor, we can use motor calculations and data from the spec sheets to figure out the optimal motor torque and speed and the gear ratio. This process will involve a lot of tweaking though, and we will probably have to it more than once.

It was implied that eventually we would model the entire system and solve it as a whole to find optimum values. How we plan on doing that is somewhat ambiguous, but the lectures helped the team at least gain insight as to how optimization can be used as a helpful design tool when dealing with problems that are unclear where to start from (like our gear-train/motor problem).

The modeling process is going to involve a lot of repetitive and confusing math, but where to start is outlined above. We have divided into sub-teams so that two group members can just focus on modeling, and the others can worry about the administrative/gate review 3 tasks. We are looking at a very busy week next week.

Week 7 - What's Next

Gate review 3 is due in a few weeks, and we still have a lot of work to do before we get there. Finishing our mathematical model is key to being able to move on to the next step of creating a detailed CAD model. We were given some more specific instructions about modeling in office hours with Professor Brei, but are not yet satisfied with the one we have created. It will take several iterations and adjustments before we can feel that we have adequately considered all aspects of the design. 

In addition to designing for engineering, it is important to consider product aesthetics and ergonomics in the next stage as well. We will need to consider how the user interacts with the product, how it will fit in their hand and how they intend to carry it. It will be interesting to see what Sou says about these topics in her lecture next week. 

Week 7: Challenges

Challenges that our team is going to face in the coming week will be creating a model of our dynamic pulley-string-generator system and then solving it to find the optimum values that would maximize efficiency. Setting up an optimizer in Excel will also require a strong set of analytical skills, since nobody on the team has much experience with optimization tools. With Gate Review 3 over our shoulders, staying on track time-wise is going to be difficult due to the solid effort the team needs to put into the design in the mean-time. Updating the Gantt chart will help gauge how we are managing our time, but that is another task in itself. Selecting a drivetrain that can transmit the power from the pulley in a compact/efficient package is a challenge because we cannot drive the DC motor with a worm gear on the shaft as originally thought, and requires more volume.

Week 7: Interesting / Exciting Findings

This past week, after learning about optimization, our team worked a lot on the different constraints of our design. Working with our alpha prototype, we discussed what our limitations were and where we could be more lenient. Right away, we had many constraints that were non-negotiable, such as the size of the motor housing needing to be less than or equal to the width of the phone case. Furthermore, we needed to constrain the total size of the case so that it would fit a majority of phones. Since we decided to prototype for an iPhone, that was a constraint we couldn't be lenient with because it the case could not exceed the size of a phone. However, the most interesting findings that we had are the aspects of the design that we could be lenient with, such as the length of the string/cord, and more of the aesthetic aspects of the design. Overall, this step in design was something our team had not previously thought about and therefore discovered a whole new collection of design details we could change.

Week 6: Team Project Update

This week the team used down-selection matrices to make a final decision on the product we are going to design. After conducting feasibility calculations for the work output and time/effort required, the team figures it can design a pull-string device that will be able to charge a smartphone in a reasonable amount of time. One pull should provide around 8 Joules, taking into account inefficiencies in the drivetrain and motor. The total charge time is estimated to be around 5 hours, but the team is striving to lower this time by keeping the total system efficiency higher than 20%.

Essentially, the device will be a case that attaches to the back of an iPhone and features a pull-string handle that the user tugs on. The force of the user pulling outputs a torque to the pulley, which will transmit that torque through an optimized gear-train and to a DC electric motor (acting as a generator). The generator converts the mechanical energy to electrical, and from here the energy will be stored in a large capacitor or small buffer battery. This energy will then be output at 5V to a charge port on the phone and hence will charge the phone battery.

We delivered a solid presentation Thursday for Gate Review 2 that really emphasized the feasibility of our product. The alpha prototype was demonstrated in class that was made from cardboard and a small-tape measure to show the retracting motion. All in all, it was quite a busy yet productive week and the team is looking forward to begin designing the physical product!

Week 6: Exciting / Interesting Findings

By making the alpha prototype this past week, one of the most interesting findings that our team discovered was the placement of every mechanic within our product, and just how much where each component is placed can affect the overall efficiency and design of the phone case. Previously, we had talked about getting it as compact as possible—even the possibility of making it an attachment rather than an entire phone case. However, after various design choices, we ultimately decided that making an entire case actually wouldn't be as bad as we thought. Most of all, we really learned this week how difficult it is to mesh aesthetic design with mechanical design. Furthermore, we discovered that if we assume a 20% motor efficiency, which is not very good, we can still achieve a certain level of feasibility. We calculated that although it takes about 5 hours of pulling to get a full charge on a smartphone battery, about 30 seconds of pulling will get a minute of talk time. Overall, although we hope to increase the efficiency, the results we currently have are not terrible.

Week 6 - Challenges

Making the device as efficient as possible will be our main challenge as we move forward. If the device isn't efficient enough the design may become less comfortable and the product could fail. In order to ensure that this doesn't happen, the areas where losses may occur have to be carefully analyzed. Measurements must be taken to ensure that the electronics are configured and working properly. The device will also have to be tested over and over again. Faculty will also be consulted to help make sure the device is as efficient as possible.

Additionally, we will have the challenge of figuring out what materials will be included in the final design and how they will be set up. The right type of string to pull the gears must be found. Also we will need to figure out the correct type of gears to use. We must also find the right electronics to use. 

Week 6 - What's Next

Now that we've finished Gate Review 2, it's time to start the physical design of our product! We know that it needs a retractable cord, torsion spring, transmission, electric motor and a super capacitor, but we have yet to figure out how to fit it all together. Next week we will begin to model each system and begin to select the components needed for our prototype. We will have to begin our engineering drawings and will need to meet with Dr. Luntz for advice about electronics and how to minimize losses. We should try to build a first version of our prototype as soon as possible so that we can refine it and fix and bugs. It would be great if we could build a second prototype after the first to ensure higher quality.

Week 5 - Project Status

Gate review 2 is in less than a week, and we are working hard on our conceptualization and downselection processes! After an initial roadblock with our original design idea, we are now considering a much wider range of energy gathering methods that will likely lead to something better and more interesting than what we originally thought of. We have been meeting with Dr. Luntz frequently to help us with design ideas and feasibility calculations, and we are making good headway.

Though our downselection process is not finished yet, it looks like we are narrowing our product down to a device that is powered by deliberate human motion that can be worn or incorporated into a cell phone case. Harnessing energy from large, deliberate motions (such as stepping or cranking) will be much easier than capturing wasted energy from vibrations and oscillatory motion because deliberate motions are more predictable and constant. This still solves the problem of convenient and portable power because the device can be used anywhere and requires only your body to generate energy. While several products similar to this exist (there are a lot of cranks on the market), our product will be more convenient and easier to use because it will harness larger body movements than a small hand crank will. To do this, we are thinking of making a device that gathers energy from the motion of the user pulling on a retractable tape. From our preliminary calculations, it is possible to generate a significant amount of energy in a short time, and could be made to be very compact.

Week 5: Exciting / Interesting Findings

As we talked a lot about feasibility this week, our most interesting find was that of different solutions for our original problem statement. After determining that a mechanism involving a coil that was small enough to be portable, yet powerful and efficient enough to generate enough energy was just not possible, our task lied in finding a different approach to the problem. As such, we continued to put more details into our conceptualization tree and coming up with new ideas, no matter how far-fetched until we were satisfied with a more feasible solution. We came up with a crank design, and are interested in implementing different methods of energy generation. This was interesting because it forced us to think in more unconventional methods to come up with something that still contained the same focus we originally began with, but approached it from a different angle. We were surprised by how many mechanisms others have tried already, as well as the sheer number of possible other solutions, no matter how inefficient or unfeasible they were.

Week 5 Whats next

The next step is for our group to start downslecting our deisng choices. After having met with Dr. Luntz and researched more design solutions we have found that feasibility has been the major issue with finding a solution to providing energy that originates from kinetic energy. But to keep our options open we have also been looking at other areas such as environmental sources, or heat, or solar as a solution to providing portable energy. Nonethless as we contineu to weigh and compare our options, we are keeping in mind the feasibility of each option as well as which method can provide the most energy the quickest and in a manner that suits our market.

Week 5: Challenges

We ran into some issues this week when double-checking if our design for a magnet and coil device is feasible. It was determined that to have a device approximately the same size and weight of the average smartphone, it was be impossible to charge a phone in a reasonable amount of time using magnetic induction in a reasonable amount of time. This was estimated to be around 100 hours give or take, accounting for inefficiencies in the device. This is unacceptable, and so we have to come up with another similar device that accomplishes the same goals for the same target audience, but perhaps uses a different method for harnessing energy. We could still stick with magnetic induction, but we would need to make the device larger or heavier. Another challenge will be creating a feasible mechanical charging device that hasn’t already been made, which is difficult to do in today’s electronics market.