Weekly Progress

 

Week 8 (5/21/15-5/28/15)

As of week 8, we have collected all materials and are starting construction. The acrylic we purchased to make the back panel has arrived, and we are in the process of making coils for our generator. Pictures will be posted as the prototype is built.

 

 

Week 7 (5/14/15-5/21/15)

During week seven we encountered an issue with the materials in our project. Last week we decided to use polycarbonate sheet instead of 3D printed plastic for the structural components of our design. This was done to reduce the amount of  3D printed parts needed, in an effort to stay within the allowed amounts. Only after buying the sheet and submitting the proposal did we learn that the laser cutter cannot work with polycarbonate, and we would have to purchase acrylic. This will set us back a few days as the new material takes time to ship. Apart from this, we now have all the components we need for our project, we are just waiting for our order from the 3D printer. During this week we finalized our design of our regulator circuit and created a diagram. Additionally, we created a software to calculate the theoretical maximum voltage based on multiple input variables.

Week 6 (5/7/15-5/14/15)

This week in lab we made key decisions about the future of of our project. With the new constraint allowing only 8 cubic inches of 3D printed material per group, we had to cut back our print volume drastically. The first and most obvious change was to construct the structural components of the legs out of layers of acrylic or polycarbonate cut using a laser. To make this possible, we had to prepare the layers as a 2D drawing using AutoCAD. This was ultimately not enough, so we had to "shell" the generator components and perforate the gears. After this we were able to meet the limit on 3D printing. Additionally, we were able finish our gear assembly design and integrate it with the rest of the model. A large part of our time this week was spent on our final report draft.

 

Week 5 (4/30/15-5/7/15)

During week five, we made significant progress on the CAD design with respect to the gear assembly. We also altered our initial design for the shape of the support, because it needs to be robust enough to support multiple gears and a generator. We also followed through with our plan to purchase a voltage regulator, as well as many of the other necessary electronic components. At this point, we have all parts necessary to build the electrical system of the generator. All we need to do is purchase a spool of copper magnet wire to make the coils for the generator. We transferred our flowchart to an electronic medium, and uploaded it to the blog. For the next week, we plan to prototype our electrical system using a breadboard, and make the coils for our generator. We also plan to complete our CAD design and 3D print our mechanical parts.

     

Week 4 (4/23/15-4/30/15)

During week four, we continued working on the CAD model of our device. We also began sketching out the electrical diagram for the generator. We decided to make a full-wave rectifier circuit using diodes, to convert the alternating current (AC) generated to direct current (DC). We decided against purchasing a power regulator, as we do not know whether we will be modifying a motor to act as a generator or purchasing a prefabricated one. We plan on buying one in the next week, so that we can test the generator's electronics before assembling the device completely.

Week 3 (4/16/15-4/23/15)

During week three, we finalized our research on mechanical design and specified where, and how, we will mount the completed device on the knee. We also consulted previously implemented designs to further refine our own device. One idea we adopted was the use of gears to increase the mechanical energy generated by each step[1]. We also referred to these designs to determine the ideal placement and orientation of our magnets. From there, we decided on on the rudimentary layout of the various generator components, namely the magnets, gears, and ball bearing assembly. We chose to mount the generator on the outside of the leg brace, with the magnet assembly placed farther up the thigh, to create space for the gearbox, and make the device more comfortable for the user. For next week, we will start making specific CAD design, so that we can begin prototyping with the 3D printer. We will also continue our research into the electrical systems of the generator in greater depth, and attempt to create a basic example of the generators internal circuitry within the next 2 weeks.

Week 2 (4/09/15-4/16/15) :

This past week, our main objective was to was to finalize our design concept. We chose on which method of power generation we will use for our design. From there, we started thinking about how the apparatus would be mounted to the knee. We decided on using on using an average knee brace as the base structure of the device. We also chose what kind of batteries to use for the generator, and got a general idea of where we will mount them. From here, our next step is to fully plan out the device's design and begin  building the prototype. During the next few weeks, we plan to have a CAD drawing of the device's casing and non-electrical components completed. 

 

Week 1 (4/02/15-4/09/15) :

We began our class time musing on what our project would be. After our initial idea of building a solar powered Tesla Model S transformer was shot down, we began to think seriously about what we would make. The general consensus seemed to be that it would have something to do with electricity. As we proceeded, we tried to link electricity with the theme of sustainability, and agreed that our project would somehow generate electricity. We finally landed on the idea of generating electricity from human motion. This idea seemed especially great considering Drexel's urban setting, where walking is the primary method of transportation. From here on, we will research different methods of generating power, and find the one most suitable for our device.