Solar Elevator Subsystem
Oct 19, 2015
Solar Elevator Subsystem: Tether GuidesName: Vipin Kannampuzha
Student Number: z3461814
A.2 Rationale
1. Problem statement: A tether guide should be built in place with its function to assist the elevator in moving up the tether. It must be lightweight, up to 15 grams, and look aesthetic. Furthermore it should also ensure that the tether is secured in between the wheel system such that the elevator remains on the tether for the duration of the test
2. Design Goals: 1. To ensure the material used be lightweight (Max of up to 10 grams) This was to ensure that no addition weight was added to the elevator2. Does not interfere with the wheels If the tether guides interfered with the wheels then some of the output power would have been lost, hence less torque 3. Assists the tether in staying secured between the wheels If the tether slipped of the wheels then the whole elevator would fall down
3. Creative Development1: There were several ideas that were generated for the construction of the tether guides, as shown in appendix 1A. One such idea was to melt plastic and mold it into a circular disk. This circular disk would then be placed in front of the wheels to ensure the tether is secured firmly next to the wheel. This idea, albeit suitable to the situation, would have required us to melt and mold plastic, which would have not only been tedious but also quite dangerous. Another idea was to join all 3 of the wheels with a rubber band or string that would grip tether in between the wheels. This was a great idea, however we decided to use this as our final resort simply because it increased the amount of tension between the tether and the wheels. Our final idea was the implementation of a material, such as a metal piece, behind and in front of the wheel system so as to ensure the tether does not slip back or slip in front. We finally decided to this idea simply because it seemed to work, theoretically, and there would have been no excessive weight added.
4. Decision Process2:We decided to use skewers as our tether guide and placed them behind and in front of the wheel system. We decided not to use the circular plastic disks simply because it would have to be placed on the wheels, hence interfering with the wheel system, which went against our design goals. Furthermore we decided to use skewers not metal because skewers were easier to handle and they weighed lighter than metals, weighing in around 0.40 grams. This clearly satisfied our criteria and hence it was decided that skewers would be used. However our initial prototype failed because we used only 1 skewer at the back and front of the wheel system, as per Appendix 1A, image 3. The tether kept on slipping off the wheels, which did not satisfy our design goals nor did it address the problem statement. Thus we hypothesized that more skewers would help; more support in keeping the tether in place, as shown in appendix 1B, image 5. This did work and still altogether weighed 2.40 grams, which satisfactorily met our design goals.
1 Refer to Appendix 1A2 Refer to Appendix 1B
10
9
5. Estimation:
Table 1: Test data collected from various design ideas
Material for Tether GuideWeight (approx.)OutcomeDid it meet Design Goals
Circular disksDid not MeasureDid not work as it interfered with the wheel system.
Stainless Steel 1.80 gramsNot only was it too heavy but it was hard to mold and hence was very crooked
Cheaper form of steel wire1.00 gramsThis was too malleable and was too weak hence did not secure the tether in place
Skewer sticks0.40 gramsThis was great not only because it was strong but also because it kept the tether in place.
A.3 Implementation
1. Basics:
The tether guide, as shown in Image 1, works in a simple manner. 3 skewers are placed behind the wheel system placed evenly apart and 3 skewers are placed in front of the wheel system. The skewers are placed at a distance so as to not interfere with the wheels but to also ensure that if the tether does not completely slip of the wheel. Our idea for the tether guide completely addressed the problem statement adequately; the skewers assisted the elevator in moving up, it was lightweight (weighing in at 0.40 grams each) and it ensured that the tether did not slip off the wheels.Image 1: 3 skewers placed in front and at the back of the wheel system, which not only secures the tether in place but also helps the elevator in going up.
Image modeled by group and edited on Photoshop. [20/05/2013]
2. Materials: Initially the material we decided to use was a cheaper form of steel wire. This however, though malleable, was completely ineffective as it was very weak and did not support the tether. We then decided to use stainless steel, obtain from a metal coat hanger. This however, though it was strong and supported the tether, was extremely hard to bend and hence was crooked. Finally we decided to use wood. The long, strong cellulose fibres ensure that wood is a strong material [Chemistry 2, Geoffrey Thicket]. Hence wood was use and it proved to be effective as it was lightweight and was strong enough to hold the tether in its place and thus was selected because it addressed our design goals.
3. Techniques3: The construction of the tether guide was quite simple. It required a hole to be cut, using a pocketknife, on both sides of the elevator. The skewers were then place into these holes. Hot glue was then used to secure the skewers at the back however the front was left removable so that the tether may be placed between the wheels when needed. This is demonstrated in Appendix 1B, image 7.
4. Estimates/Measurements:
Image 2: Dimensions of Skewer (Picture self drawn. 07/06/2013)5. Methods: As concurrent engineering suggests, design decisions can strongly influence many factors [Dr Evatt Hawkes Lecture notes]. Hence these factors were considered during the design of the tether guides. We initially used the DFX (design for x) method to attain guidelines for developing a concept for the tether guides [Dr Evatt Hawkes Lecture notes]. The guidelines included Recyclability, Performance and Reliability and in following these guidelines the skewer design promoted our implementation. However it was these guidelines that restricted our ideas and designs. Several ideas that we had, such as the circular disks, were not only innovative but also practical. However it failed to satisfy the criteria and our initial design goals
A.4 TestingThe Uplifters performed brilliantly during the scrutineering. Our aesthetically built design elevated our stature not only because it looked cool but also because of the colour scheme we chose to employ. Our elevator was structurally built and this was tested through the shake test, during the scrutineering. The balance of the elevator was perfect, demonstrated in the time trials as the elevator moved up the tether in a uniform manner. During the time trial the subsystem, the tether guides, performed brilliantly. The elevator remained on the tether throughout the course of the race and our use of skewers actually supported the elevator throughout the race. However, the power output provided by the solar panels werent sufficient to move the elevator up and so it was run on batteries. Regardless we were extremely happy with the outcome and the tether guides worked exceptionally well.
3 Refer to Appendix 1B
Appendix 1AImage 2: Circular disks in front of the wheels to ensure tether stays in between the wheels
Image modeled by group and edited on Photoshop. [20/05/2013]
Image 3: String or rubber band connecting all three wheels together and effectively keeping the tether in between them
Image modeled by group and edited on Photoshop. [20/05/2013]
Image 4: A metal piece attached to the back and in front of the wheel system to ensure the tether cannot move out of the wheels.
Image modeled by group and edited on Photoshop. [20/05/2013]
Appendix 1BImage 5: 3 skewers are placed at the front and back of the wheel system. This helps the elevator to lift up while keeping the tether between the wheels.
Image taken by group. [30/05/2013]
Image 6: Technique of making the tether guide
Image taken by group. [30/05/2013]
2. The skewers were then placed in the holes3. Hot glue was then used to secure the skewers at the back however the front was left removable so that the tether may be placed between the wheels when needed. 1. Holes were first cut from the sides.
ReflectionB.1 If I knew then what I know nowOne thing I learnt was that time management can be the difference in having a great, working result and having a non-working result. 1 thing I wished I knew already was the importance of prioritizing my tasks; doing the important things first and the unimportant things last so as to focus my energy to attain important goals. 10 words of advice to next years class Tic. Tok. Tic. Tok. Beware. Time is a silent killer
B.2 Plan for Procrastination At the beginning of the course, I was slow to do work, possibly because I just returned from a large break, and this influenced the outcome of our design as we had very little time to generate a design that might actually work. Hence rather than having countless designs, we had one design that we ad to work on. This also impacted our testing, as we had no room for failure as we had no alternate design. However, I was extremely satisfied in the way both the team and I went in the course and I believe my efforts towards the end paid off.
B.3 Design for SuccessNext time, on my great big engineering project, I would approach the project through the simple act of planning; defining purpose and principles, envisioning the end product and brainstorming countless ideas. I thought the team did exceptionally well in combining our strengths together to attain a common goal however what we did poorly was lose motivation during the project and reduced our efforts. I think I did great in help generating ideas however I thought the way I approached my ideas to the ideas was poor.
B.4 Your ExpectationsThis course exceeded my expectations; originally I thought this was a simple project just to introduce us to the world of engineering, but in fact it was a project to introduce us to the world! It required us to gain social skills, time management skills and practical skills. I thought I met the expectations for the course in teams of gaining social skills, conversing not only with my group but with other groups from different engineering projects as well.
B.5 Your FeedbackFirstly I thought the Calibrated Peer Review was great in terms of allowing us to experience first-hand how our texts would be marked and the criteria for the marks. However marks are based on a persons judgement, which may conflict with the judgement of other people. Further more, I think the amount of CPR task should be reduced, as it soon became a nuisance towards the end; spending 15-20 minutes marking each text was time not spent well. In terms of Team based projects, I think it is a great idea that instigates social skills among people. However I think teams should be chosen based on skills of each person; each team should have someone interested in electrical components etc.
B.6 Contributions I contributed to the team through my ideas for the chassis of the elevator and the tether guides. I also, in my humble opinion, provided an optimistic charisma to the group, which helped in working on the project. Wilson Song was vital to our group as he contributed by doing all the wiring and the connections to the switch. One member who pulled her weight was Hannah Cox. She was instrumental to the team as she was the one who ensured we remained focused throughout the entirety of the project, encouraging us to always do what we can.
