EVS Sports Knee Brace Testing Machine Final Design Report Sponsored by: EVS Team: CSN June 14, 2013 Team Member Names: Silvia Aguilar [email protected] Nick Mattison [email protected] Chris McCarthy [email protected] Sponsor Contact Information: Murali Sreeramagiri EVS Sports Head of Design T: 310.637.5000 x .122 E: [email protected] California Polytechnic State University Mechanical Engineering Department San Luis Obispo June 14, 2013 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, students and its staff cannot be held liable for any use or misuse of the project. Executive Summary The purpose of this document is to report on the development of a test machine for EVS’ Web and Axis knee braces. Between September 2012 and June 2013, Team CSN, comprising of Nick Mattison, Silvia Aguilar, and Chris McCarthy, have methodically planned, designed, built, and tested this machine. The overarching goal of this unique machine is to address the need for both hyperextension and fatigue testing. From here on out this report dives into details of the machine with an Appendix C reporting testing results of said knee braces. Table of Contents List of Tables ............................................................................................................................................................... 1 List of Figures ............................................................................................................................................................. 2 Chapter 1: Introduction ......................................................................................................................................... 4 Sponsor Background and Needs .................................................................................................................... 4 Formal Product Definition ............................................................................................................................... 4 Objectives ................................................................................................................................................................ 5 Management Plan: ............................................................................................................................................... 8 Chapter 2: Background ........................................................................................................................................... 9 Mechanical Actuators ...................................................................................................................................... 10 Hydraulic and Pneumatic Actuators ......................................................................................................... 10 Electric Actuator................................................................................................................................................ 10 PLC (Programmable Logic Controller) .................................................................................................... 11 Load Cells ............................................................................................................................................................. 12 Safety ...................................................................................................................................................................... 12 Chapter 3: Design Development ...................................................................................................................... 13 Method of Approach ........................................................................................................................................ 13 Initial ideation .................................................................................................................................................... 14 Step 1: Component Ideation .................................................................................................................... 14 Step 2: System Ideation ............................................................................................................................. 18 Step 3: Feasible System Ideation ........................................................................................................... 19 Final Two Concepts .......................................................................................................................................... 21 Concept 1: ........................................................................................................................................................ 21 Concept 2: ........................................................................................................................................................ 24 Changes from Conceptual Design Review .............................................................................................. 28 Solution Considered .................................................................................................................................... 28 Final Solution ................................................................................................................................................. 29 Chapter 4: Final Design ....................................................................................................................................... 30 Overview: ............................................................................................................................................................. 30 Motor and Worm Gear Box ........................................................................................................................... 31 Variable Frequency Drive .............................................................................................................................. 32 Electricity ............................................................................................................................................................. 32 Power Transmission System ........................................................................................................................ 35 Linkage System .................................................................................................................................................. 36 Torque Arm to Linkage Connection ..................................................................................................... 37 Linkage to Arm Connection ..................................................................................................................... 38 Machine Arms ..................................................................................................................................................... 39 Gripping System ................................................................................................................................................ 40 Fixed Clamp .................................................................................................................................................... 41 Free clamp ....................................................................................................................................................... 42 Hyperextension Testing ................................................................................................................................. 44 Force Transducer .............................................................................................................................................. 45 Arduino ................................................................................................................................................................. 45 Wheatstone Bridge Pseudo-Code: ......................................................................................................... 45 SD Card Pseudo Code: ................................................................................................................................ 48 Communication Pseudo Code: ................................................................................................................ 50 Special Safety Considerations ...................................................................................................................... 50 Prototype Cost Breakdown ........................................................................................................................... 51 Raw Material Costs: $2,896 .......................................................................................................................... 53 Budget.................................................................................................................................................................... 54 Maintenance Considerations ........................................................................................................................ 55 Engineering Analysis ......................................................................................................................................