2014 Frankie Wiggins Alex Seitz Justin Bautista [email protected] Mechanical Engineering California Polytechnic State University, San Luis Obispo [TEAM NATHAN SUSPENSION] THURSDAY, OCTOBER 16, 2014 The purpose of this document is to define our design solution to the current problems with the Standing Dani™ mobility device as well as provide relevant background information. This document also outlines the process by which we validated our design, manufactured and tested it, and the costs associated with it. 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. i ii TABLE OF CONTENTS Table of Contents ................................................................................................................................... iii List of Figures ......................................................................................................................................... vi List of Tables .......................................................................................................................................... ix Abstract ................................................................................................................................................ 10 Chapter 1: Introduction ......................................................................................................................... 11 Client Background and Needs ............................................................................................................ 12 Nathan and the Coopers ................................................................................................................ 12 Spinal Muscular Atrophy ................................................................................................................ 12 Benefits of Standing ....................................................................................................................... 13 Formal Problem Definition ................................................................................................................. 13 Objective & Specification Development ............................................................................................. 13 Objective Descriptions ................................................................................................................... 14 Project Management ......................................................................................................................... 15 Project Milestones ......................................................................................................................... 15 Responsibilities .............................................................................................................................. 16 Chapter 2: Background .......................................................................................................................... 18 Exisiting Products ............................................................................................................................... 18 LEVO® Combi Jr.............................................................................................................................. 18 Go-Bot ........................................................................................................................................... 18 Strider 1 & 2 .................................................................................................................................. 19 Alber Adventure ............................................................................................................................ 19 Twell Airless Tires .......................................................................................................................... 20 Current State of the Art: The Standing Dani™ ..................................................................................... 20 Chapter 3: Design Development ............................................................................................................ 21 Methods of Idea Generation .............................................................................................................. 21 Discussion of Conceptual Designs....................................................................................................... 22 Low Pressure Tires ......................................................................................................................... 22 Twin A-Arm.................................................................................................................................... 22 Rear Trailing Arm ........................................................................................................................... 23 Cantilever with Spring .................................................................................................................... 23 Concept Selection .............................................................................................................................. 24 Chapter 4: Description of the Final Design ............................................................................................. 26 iii Overall Description and Solid Model .................................................................................................. 26 Detailed Design Description ............................................................................................................... 27 Front Caster ................................................................................................................................... 27 Frame Design ................................................................................................................................. 28 Suspension Linkages ...................................................................................................................... 29 Attachment Assembly .................................................................................................................... 29 Arm Rest ........................................................................................................................................ 30 Wheelie Bars ................................................................................................................................. 30 Shocks ........................................................................................................................................... 31 Analysis Results.................................................................................................................................. 32 Static Deflection ............................................................................................................................ 32 Stress in Trailing Arm ..................................................................................................................... 33 Titltover Angle ............................................................................................................................... 33 Suspension Natural Frequency ....................................................................................................... 33 Manufacturing Drawings .................................................................................................................... 33 Safety Considerations ........................................................................................................................ 33 Procurement & Cost Analysis ............................................................................................................. 33 Maintenance and Repair Considerations ............................................................................................ 36 Chapter 5: Product Realization .............................................................................................................. 37 Manufacturing Processed Employed .................................................................................................. 37 Fabrication Methods .......................................................................................................................... 37 Manufacturing Resources .................................................................................................................. 38 Outsourced Manufacturing ................................................................................................................ 38 Manufacturing Flow Diagram ............................................................................................................. 42 Recommendations for Future Manufacturing..................................................................................... 42 Chapter 6: Design Verification Plan (Testing) ......................................................................................... 43 Test Descriptions ............................................................................................................................... 43 Preparation ..................................................................................................................................