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Detailed Design Review MSD P14045 12/5/13

Detailed Design Review MSD P14045 12/5/13. Emily Courtney, John Daley, Alex Hebert, Greg Roeth, Martha Vargas. Agenda. Addressing Previous Concerns Engineering Requirements Feasibility of Critical Areas Wheel Adapter Tray Packaging Electrical Systems Bill Of Materials Electrical

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Detailed Design Review MSD P14045 12/5/13

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  1. Detailed Design Review MSD P14045 12/5/13 Emily Courtney, John Daley, Alex Hebert, Greg Roeth, Martha Vargas

  2. Agenda • Addressing Previous Concerns • Engineering Requirements • Feasibility of Critical Areas • Wheel Adapter • Tray • Packaging • Electrical Systems • Bill Of Materials • Electrical • Mechanical • Totals • 7. Risk Assessment • 8. Test Plan • 9. MSD II Plan 2 14045 Detailed Design Review – 12/5/13

  3. Addressing Previous Concerns • LEGO Tray • Contacted LEGO, ok to use as long as we do not profit. • iPad • Dropped due to complexity/time constraints. • May include a recommendation for future generations. • Actuator • Cost too high • Could not determine a viable solution within allotted time • Changed to a Manually operated tray folding mechanism. • Acceleration/Deceleration • Ramp-up mechanism included in software. • Straight Travel (tires/wheel similarity) • Added encoder functionality to motorized wheels in order to create a feedback system. • Sensitivity tests added to the test plan. 3 14045 Detailed Design Review – 12/5/13

  4. Engineering Requirements Go to the Document! 4 14045 Detailed Design Review – 12/5/13

  5. Feasibility of Critical Areas • Wheel Adapter • Demonstration of Tray • Demonstration of Battery Box 5 14045 Detailed Design Review – 12/5/13

  6. Wheel Adapter 6 14045 Detailed Design Review – 12/5/13

  7. Critical areas turned out to be the top and bottom of the fillet near the step. Stress on critical locations converged to within 6% of calculated values. 7 14045 Detailed Design Review – 12/5/13

  8. ANSYS Results - in Detail Maximum Stresses: • Blue Stander: 12,905 psi • Red Stander: 12,374 psi Issues: • If we 3D print these parts, this stress exceeds the maximum tensile stress of ABS Plus (5300 psi) • Impact force greatly varies with impact time. These values based off an impact lasting 0.05 sec. 8 14045 Detailed Design Review – 12/5/13

  9. Impact Analysis I will need to determine the actual impact time for dropping the stander to properly estimate stress. However, this is all academic because... 9 14045 Detailed Design Review – 12/5/13

  10. Cost Analysis The Cost of creating the four required parts makes manufacturing infeasible. • 3D printing all parts @ $15/in3 = $457.50 • CNC is $95/hr • Rate is for both programming and machine run time • Does NOT include material cost • Time for 4 parts and the necessary programming would easily make the cost meet or exceed the break-even point with 3D printing. Best option: • Contact R82 (stander manufacturer) and get replacement adapters. • Do a better job machining the parts to fit the current setup. • Keep this design as a theory for the kit we would make. 10 14045 Detailed Design Review – 12/5/13

  11. Tipping Analysis • Updated 13045 Results • 2 Dimensional Analysis Assumptions: no slipping 11 14045 Detailed Design Review – 12/5/13

  12. Case 1 12 14045 Detailed Design Review – 12/5/13

  13. Case 2 13 14045 Detailed Design Review – 12/5/13

  14. Demonstration of Tray 14 14045 Detailed Design Review – 12/5/13

  15. Demonstration of Tray 15 14045 Detailed Design Review – 12/5/13

  16. New attachment piece: Tray Mounting System Current attachment: * Fits snuggly inside the slot for greater stability and adjustability * Thumb screws will anchor outer bracket through this piece to center top view 16 14045 Detailed Design Review – 12/5/13 side view

  17. Tray Bracket side view front view 17 14045 Detailed Design Review – 12/5/13 http://www.adjustablelockingtech.com/products_variloc_stainless_mounting-flange_dimensions.php

  18. Tray Deflection Analyzing the tray as a beam in bending, we calculated a maximum expected deflection for the end of the tray. The maximum expected deflection is 0.044 inches if the tray is pushed down by a force of 110 lbf. 18 14045 Detailed Design Review – 12/5/13

  19. Demonstration of Battery Box Total Area = 252.75 in2 19 14045 Detailed Design Review – 12/5/13

  20. Battery Box We are still working to determine the material for the box • Most likely a plastic We are also unsure on manufacturing • Make it ourselves? • Outsource? • Need to analyze cost & labor 20 14045 Detailed Design Review – 12/5/13

  21. Electrical System 21 14045 Detailed Design Review – 12/5/13

  22. Schematic 22 14045 Detailed Design Review – 12/5/13

  23. Power • 12V battery • Launchpad takes +5v through USB micro B • Gives output of 3.3V • Each Launchpad takes .9A • Each HB-25 can take 25A continuous • 3.3 V - Quadrature Encoders, HB-25, Temperature Switch, Bump Sensor • 5V - Launchpad • 12V - HB-25 (motor voltage) • Worst Case Power: 325W • (With a current draw of 12A in each motor) 23 14045 Detailed Design Review – 12/5/13

  24. Processors • Original Project used Stellaris Development board • turned into the stellaris launchpad • turned into the Tiva C launchpad • Same RAM and Flash memory • Has plenty of GPIO channels, 2 QEI modules, 2+ UART, 3+ GP timers, 24 14045 Detailed Design Review – 12/5/13

  25. Software • Written in C • Monolithic loop • Uses Tivaware extensively • Will require rewriting portions of the code • syntax not algorithm • Codebase was cluttered 25 14045 Detailed Design Review – 12/5/13

  26. Software Flowchart 26 14045 Detailed Design Review – 12/5/13

  27. Controls • Addition of Quadrature Encoders • Position capture • Enabled by Tivaware • Master Wheel Speed • Incremented or Decremented each update by a standard acceleration • Set Slave wheel speed • Straight: • SlaveSpeedOffset= k(Pm-Ps) • Turning: • SSO= k(Pm-(Ps-Of) • Of=Of-1+tr 27 14045 Detailed Design Review – 12/5/13

  28. Motor Drivers • Kit from Parallax • HB-25 takes servo motor controls • Pulse width determines position • Uses PWM6 and PWM7 • 100ms period • Digital power off 3.3V from launchpad *image from www.parallax.com 28 14045 Detailed Design Review – 12/5/13

  29. Communication • Considered • Bluetooth - Bluegig wt12 • dropped due to complexity and cost, and drop of iPad functionality, requires a breakout board • Electric Imp • dropped because overkill and dependance on wifi • Xbee • dropped requires a breakout board • RC transmitter and receiver • separate module, stands alone, does some self sanitising inputs • requires interpretation 29 14045 Detailed Design Review – 12/5/13

  30. B.O.M. for Electrical 30 14045 Detailed Design Review – 12/5/13

  31. B.O.M. for Mechanical 31 14045 Detailed Design Review – 12/5/13

  32. B.O.M. Totals 32 14045 Detailed Design Review – 12/5/13

  33. Risk Assessment Go to the Document! 33 14045 Detailed Design Review – 12/5/13

  34. Test Plan Go to the Document! 34 14045 Detailed Design Review – 12/5/13

  35. MSD II Plan Go to the Document! 35 14045 Detailed Design Review – 12/5/13

  36. Questions? 36 14045 Detailed Design Review – 12/5/13

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