Beach Wheelchair Project
Total Page：16
File Type：pdf, Size：1020Kb
Beach Wheelchair Project June 14, 2013 for Bridge II Sports Team SandCrawler Rory Aronson - [email protected] Joshua Marcum - [email protected] Sam Coyne - [email protected] Alex Hayes - [email protected] Alexa Colburn - [email protected] Max Hessel - [email protected] Benedikt Strauss - [email protected] Marvin Rimmele - [email protected] Marco Pietsch - [email protected] College of Engineering California Polytechnic State University, San Luis Obispo Munich University of Applied Sciences 2013 1 Statement of Disclaimer Since this project is a result of a class assignment, it has been graded and accepted as fulfillment of the course requirements. Acceptance does not imply technical accuracy or reliability. Any use of information in this report is done at the risk of the user. These risks may include catastrophic failure of the device or infringement of patent or copyright laws. California Polytechnic State University at San Luis Obispo and its staff cannot be held liable for any use or misuse of the project. 2 Table of Contents Statement of Disclaimer Table of Contents Table of Figures Table of Tables 1 - Executive Summary 2 - Introduction Design Challenge Background Research Manual Beach Wheelchair Notes Electric Beach Wheelchair Notes Objectives Customer Requirements Optional Features Design Development Management Plan Timetable Gantt Chart 3 - Conceptual Models Prototyping Lab 3 Wheeled Design Using Bike Wheels Using Hand Truck Wheels Scissor Lift Sliding Rear Assembly Internal Gear Hub Lever Drive 4 - Subsystem Pugh Matrices Collapsing and Disassembling Drive Systems Number and Size of Wheels Seat Adjustability Seat Raising Mechanism Gear Shifting Tire Selection Floating Water Propulsion 5 - Initial Whole Concepts Avila Wheelchair Designs Joshua Marcum’s Initial Whole Concept Sam Coyne’s Initial Whole Concept Benedikt Strauss’s Initial Whole Concept 3 Alex Hayes’s Initial Whole Concept Rory Aronson’s Initial Whole Concept Marco Pietsch’s Initial Whole Concept Marvin Rimmele’s Initial Whole Concept Max Hessel’s Initial Whole Concept Initial Whole Concept Matrix 6 - Iterated Whole Concepts Rory Aronson’s Iterated Whole Concept Marco Pietsch’s Iterated Whole Concept Final Selection Process 7 - The Final Concept Satisfying User Requirements Safety Considerations Gas Piston Frame Cranks Belts Hand Brake Headrest and Footrests Balloon Tires 8 - The Final Design Frame Construction Wheels Seat Construction Lower frame Upper frame Backrest Adjusting Mechanism Torsion spring system Linkages & bushing Textile meshing Safety Calculations Bolt Calculations Linkages bushings calculation Backrest adjusting mechanism - piston calculation Piston Hand Crank Components Construction Rear Pulley Construction Gear Ratio Calculations 4 Brake Construction Maintenance Cost Estimation Testing Plan Weight Capacity Floatability Speed and Ease of Maneuverability Size Disassembly Piston Stability Feedback from Potential Users 9 - Manufacturing Overview Main Frame Construction Cutting Materials Jigging Finishing Mini-frame Construction Cutting Materials Jigging Finish Work Push Handle Construction Rear Drive Hub Construction Cutting Materials Machining Round 1 Welding Machining Round 2 Tensioner Construction Cutting Materials Machining Welding Finishing Pin Disk Construction Crank Construction Axle Construction Rear Wheel Modification Final Assembly Seat Manufacturing 10 - Testing Crank Realignment Arm Maneuverability and Spacing Component Size, Weight and Transportability Ease of Assembly 5 Hand Force Requirements and Ramp Test Drivability in Different Conditions Floatation Stability Safety Braking Maintenance Engineering Specifications Client Testing 11 - Implemented and Proposed Design Changes Frame Wheels Belt Guard Crank Assembly Footrest Assembly Drive System Seat Brake Steerability 12 - Closing Remarks 13 - Appendices Appendix 1: Existing Beach Wheelchair Designs Appendix 2: Engineering Specifications List Appendix 3: Gantt Chart Appendix 4: Bill of Materials Appendix 5: Detailed Drawings Main Frame Crank Assembly Rear Hub Assembly Front Wheel Assembly Main Frame Front Wheel Frames Tensioner* Pin Disk Crank Arm Drive Hub Axle Push Handles Rear Drive Rod Appendix 6: Supporting Analysis Forces During Wheelchair and Hand cycle Use Wheelchair Force Testing Supporting Calculations for Load Analysis on Lower Member of Frame Seat Module Calculations Supporting Calculations for Force Loading Cases on Pin 6 Supporting Calculations for Forces on Crank arm Supporting Calculations for Force on Crankshaft Appendix 7: Team Contract Team Sandspitter Contract Member Roles and Responsibilities Commitment and Accountability Communication Pathways Conflict Resolution Project Room Civility Appendix 8: Anodization Forms Appendix 9: Instruction Manual Parts List 1 - Seatbelt Wheelchair Assembly Seat Raising Seat Lowering Water Operations Land Movement 7 Table of Figures Figure Title Page Number 1.1 The Cal Poly Wheelchair 15 1.2 The Munich Wheelchair 15 2.1 The Natural Access Landeez™ manual beach wheelchair in Avila 17 Beach 2.2 Electric beach wheelchair in Avila Beach 18 2.3 Method of approach in order of timeline, with iteration illustrated as 20 backward lines 2.4 Project Gantt chart showing dependencies 22 3.1 Lego™ model 23 3.2 Floating Model 23 3.3 Wheel adjusting model 23 3.4 Tank tread model 23 3.5 Shock absorbing model 24 3.6 Hand crank model 24 3.7 The 3 wheeled conceptual model proved to be unstable 24 3.8 The 3 wheeled design with mountain bike tires proved to dig into the 25 sand 3.9 Go-kart tires sinking into the sand 26 3.10 Modified go-kart tires to have an increased and flatter contact surface 26 3.11 Scissor lift conceptual model made of a wooden camping chair 27 3.12 Sliding rear assembly concept in the raised position 27 3.13 Sliding rear assembly concept in the lowered position 27 3.14 Internal gear hub conceptual model using bicycle parts 28 3.15 Internal gear hub conceptual model close up 28 3.16 Lever drive conceptual model 29 8 3.17 Close up on lever drive conceptual model 29 5.1 Joshua’s initial whole concept 43 5.2 Sam’s initial whole concept 44 5.3 Bene’s initial whole concept 45 5.4 Bene’s initial whole concept 45 5.5 Bene’s initial whole concept 45 5.6 Alex’s initial whole concept 46 5.7 Exploded view of Alex’s concept 47 5.8 Side profile of concept showing the raising and lowering aspects 47 5.9 Rory’s initial whole concept 49 5.10 Marco’s individual whole concept 50 5.11 Marvin’s initial whole concept 50 5.12 Max’s initial whole concept 51 6.1 Rory’s iterated whole concept 55 6.2 Marco’s iterated whole concept 56 7.1 Final concept design sketch 58 7.2 CAD render of the final concept design in the driving position 58 7.3 CAD render of the final concept design in the transfer position 59 7.4 CAD render of the final concept design in the floating and sand exit 59 position 7.5 Gas piston sketches and rubber shielding 61 7.6 Piston lever system 62 7.7 Calculation of piston force based on geometry and user weight (Fy) 63 7.8 Detailed drawing of the frame. Member location and sizing subject to 63 change 7.9 Close up sketch of the handle, ratchet, crank, and pulley assembly 64 7.10 Sketch of the toothed belt and drive gears 65 7.11 Hand brake mechanism showing the locked “parking brake” mode 65 9 7.12 Close up of the hand brake mechanism 66 7.13 49cm diameter balloon tire from Wheeleez.com 66 8.0 The SandCrawler 68 8.1 Final frame design. Made of square and cylindrical aluminum tubing 70 8.2 Actual footrest being bought 71 8.3 Close up conceptual CAD of footrests 71 8.4 Rear wheel with modifications to hub 72 8.5 Front wheel assembly 73 8.6 Lower frame cross section 74 8.7 Lower frame and the links for the upper frame 75 8.8 Backrest Adjustment Mechanism 76 8.9 Torsion Spring 77 8.10 Linkages & bushing in exploded view 78 8.11 Textile meshing wrapped around the circular tubes 79 8.12 Piston Assembly along with hydraulic line and push button 81 8.13 Exploded view of the hand crank 82 8.14 Free Body Diagram of shaft with Adjustable Lengths 83 8.15 Force and Moment Relations 83 8.16 Diagram illustrating the shear and bending forces on the pin 84 8.17 Bending and shear relations used 84 8.18 Relations used to determine bearing stress load on pin disk 85 8.19 Exploded view of the rear pulley assembly 87 8.20 Force testing at Avila Beach 88 8.21 Brake assembly 89 9.1 Cutting square tubing with the horizontal band saw 93 9.2 Cutting square tubing with the horizontal band saw 93 9.3 Mainframe halve jig 94 10 9.4 Second mainframe jig 94 9.5 Torsion spring resting on Frankenstein nubs for positioning and cutting 94 length 9.6 Drilling the first holes in the frame using the mill 95 9.7 Miniframe Jig 1 96 9.8 Miniframe Jig 2 96 9.9 Caster mounting plate offset block 97 9.10 Prepared for welding push handle stock 98 9.11 Rear Drive Hub holes being machined with the rotary table 99 9.12 Rear Drive Hubs and a mill boring bar 99 9.13 Milling the circular grooves 100 9.14 Contact between the axle and plate 100 9.15 Final design of the brake/tensioner system 101 9.16 Pin Disk under construction with the drill press 101 9.17 Gates sprocket being mounted to pin disk. 101 9.18 Crank manufacturing in progress 102 9.19 Rear hub disassembled and ready to be drilled 103 9.20 The ‘merican way of squaring the seat 103 9.21 Perfect weld root 104 9.22 Tempering oven 105 9.23 Tungsten inert gas welding 105 10.1 The disassembled wheelchair in the back of a Subaru hatchback 107 10.2 Navigating the wheelchair ramp corner at Avila Beach 108 10.3 Sam operating the wheelchair on a 1:10 slope ramp 109 10.4 Operating the wheelchair on hard packed and wet sand 110 10.5 Operating the wheelchair in shallow water conditions 110 10.6 Operation in deep water conditions 111 11 10.7 Brake test at Avila 112 10.8 Rinsing off the wheelchair components with the beach shower 113 10.9 Robert approaching the sand at Avila 117 10.10 Robert in shallow water, enjoying himself 117 10.11 Robert and Cindy having fun on the beach.