Power Generation System for the Better Water Maker

1. Detailed Design Review Power Generation System for the Better Water Maker By P14418 on December 10, 2013

2. Objective To provide a low cost, efficient power generation system for the Better Water Maker that does not easily tire the user, while still being fun and easy to use. Scope The power generation portion of the Better Water Maker.

3. Concept Selection • The selection of a recumbent seating redesign was chosen in the interest of increasing the efficiency through leg power and a higher gear ratio. • Pugh analysis, pros vs. cons, and group discussion concluded this decision • The higher gear ratio was chosen to increase the RPM at the motor in order to increase motor efficiency • This was later modified to 1:28 due to the motor’s inertial effects that would be translated to user • Decrease the motors to 3 to reduce torque, trade-off in higher RPM

4. Engineering Requirements

5. Project Plan

6. Project Plan

7. Seating and Adjustable Track

9. Track Analysis • The positions for the gearbox were based on the length of the legs of our expected users • Statistics on leg lengths for children and women were obtained for all the countries in which the BWM is currently used • Census data • www.disabled-world.com • Developed 13 positions for the gearbox along the adjustable track

10. Ergonomics Research

11. Ergonomics Research • We obtained the average height statistics and from there used the averages to calculate the hip to ground height to help us design the track

12. SIDE VIEW OF GEARBOX AND TRACK

13. drawings of track and dimensions go here

16. Seat Design and Mitigation Plan • Makes use of a bucket support insert that consists of two plywood sheets and a 2”x4” • Same as current but allows for additional room at the bottom of the bucket for inserting the track • 135 degree angle with the bucket lid • To reduce costs, more ergonomic options were not viable • Prototyping, user testing, and final cost will play a part in whether or not more ergonomic options are revisited

19. Testing Plans • Test for Ease of Assembly • Provide volunteers with a user manual • Discretely time volunteers to avoid any pressure regarding assembly time • Ask volunteers to rate the clarity of the user manual and difficulty of assembly • Test for Ease of Gearbox Repositioning • Have volunteers change the current position of the gearbox to the position that fits them • Ask volunteer to rate the difficulty

20. Testing Plans III. Test for Ease of Power Generation • Ask users to power the device by pedaling for 5 minutes, if volunteers cannot sustain this after three attempts, make note otherwise measure the level of water sanitized • Ask users to rate the difficulty of use IV. Test for Comfort • After using the device for an extended period of time, ask volunteers to rate the comfort of the seat and the positioning of their body during use

21. Electronics

22. Generator Circuit • 2 stages • Regulation • LEDs

24. Regulator Stage

25. LED Circuit

26. Gearbox

27. Gearing Decisions Original Design • Original 1:72 gear ratio deemed unreasonable • Modeling of system proved difficult • Final decision to increase ratio slightly from original product (1:28) using a symbolic analysis of the inertia

28. Case • Made of ¼” PVC sheets • Cost • Wood not viable • Weight

29. Pedal Interface • OTS crank arm considered • ½” aluminum stock due to cost • Keyed shaft for power transmission

30. Tolerancing Stack • Bearings have a light press fitting with the PVC housing • Shafts have a close fit with the bore of the bearings

31. Gearbox Test Plans • Motor Testing • User Testing • Height, weight, and age • Survey users • VO2 Testing • Verify effort required

32. Stress Analysis of Gearbox • Shaft Bending Analysis

33. Bill of Materials/Drawings • BOM • Drawings

34. Gearbox Assembly Process • Gearbox Assembly • Gearbox Sub-Assembly

37. Assembly Process

38. Estimate of Assembly Time

39. Labor Costs • Estimated manufacturing costs for the parts in the gearbox and the woodworking • High estimate of labor rate • Used DFA assembly time estimation methods • Currently working on ways to further reduce assembly time and cost

40. Cost Analysis

41. Prototype Budget

42. Risk Assessment Risk Assessment

43. Project Plan for MSD II

44. Project Plan for MSD II • We recognize that we only have approximately 3 days of slack for the next semester

45. Lessons Learned • Actions-Issues-Decisions log rather than simply action items list • Track risk and manage risk carefully to ensure that every step of the process is eliminating risk and not creating more • Project Plan Adhesion • Review each sub-committee’s work as a team to identify risks-QA/QC • Itemize action items by person and date • Seek advice of faculty early on in process

46. Suggestions for MSD I Program • Quicker assignment of individual projects so we can become familiar with them • The first few classes should be exercises to get to know our teammates. A good time for the (very successful) Team Values and Norms exercise • There should be a better explanation of how to use EDGE (Maybe a technical support team) • A better explanation of what to do with our notebooks • Online lecture more effective than 3-hour in class lectures

47. Questions

48. Backup slides

49. Pool noodle section Wooden dowel (same diameter as a broomstick) 2” x 4” 5-gallon bucket