P14042: Una-Crutch Right Move, Right Place, Right Time Subsystems Design Review Ana Allen Joanna Dzionara-Norsen Beverly Liriano Dan Sawicki DAN QUESTIONS TO ANSWER IN SYSTEM DESIGN REVIEW •Do requirements "flow down" to functions, and are all requirements addressed? •Do your functions map to the physical architecture? •What analysis have you done to support decisions about critical technologies and selected concepts? •What are the performance limits? •How are you going to test that requirements are met? •Do you have the capabilities and resources to realize your design? •What are the major risks (technology, project)? Do you have mitigation plans? •Has you design been adequately reviewed?

Agenda Review (Weeks 1-6) Identifying Critical Subsystems Background Problem Definition Additional Project Deliverables Identifying Critical Subsystems Engineering Requirements Risk Assessment Functional Decomposition System Architecture Proof Of Concept Overview of Prototypes / Prototype Test Plan User Feedback Second- Order Analysis Feasibility Manufacturing Analysis Detailed Design Preview (Weeks 10-12) DAN ***Do requirements “flow down” to subsystems & are all requirements addressed? •Have you demonstrated “proof-of-concept”? What analysis/prototyping have you done to demonstrate feasibility of critical subsystems? Prototypes created ***How are you going to test that requirements are met? •Has your design been adequately reviewed? Analysis: Focus Group, Second Order Analysis

Review (weeks 1-6) JOANNA

Many designs all revolving around two SEPERATE crutches. Current Product Many designs all revolving around two SEPERATE crutches. Una-Crutch is a design that can combine from 2 separate pieces into 1 universal device JOANNA

P14042 Problem Statement Current State Standard axilla crutches A prototype was developed by Kyra, but the product is non-load bearing and has no effective connective mechanism Desired State A functional product which is ergonomically friendly, has a quick and intuitive method of connection, and can be marketed to companies Project Goals Perform analysis of standard axilla crutches, crutch patents, and assistive technologies used specifically for lower body injuries Constraints Consider Intellectual Property for the connective mechanism JOANNA The Una-Crutch is an assistive technology which supports and allows mobility for any user who has a lower body injury.  The device is a two-crutch design which snaps together to form one crutch when needed, thus eliminating the burden of handling an unused crutch.  The standard two-crutch design is not comfortable for the user and does not have any connective mechanism.  A current prototype of the Una-Crutch is not designed with load-bearing capabilities or cheap mass production, and refinement is required in ergonomics, comfort, and the connective mechanism. The goals of this project are to analyze the current Una-Crutch prototype and identify opportunities to improve the comfort of the design, the adjustability, ease of use, and the production costs, while maintaining the functionality of a standard crutch.  The final result will be a functional prototype which will be manufactured for market production.

Additional Project Deliverables Functional prototype which will be targeted towards the majority of crutch users and will be available as a household item. The product will have an aesthetic appeal and will have the potential to be manufactured right away. Patent Documentation Logbook Prove the concept – prototyping Protection of Intellectual Property Conduction of market research JOANNA Consistent, thorough, and chronological logbook notes and documentation http://www.dimwit.com/ShowArticle.aspx?ID=33&AspxAutoDetectCookieSupport=1 Design with manufacturing process identified Testing / Analysis with ‘x’ number of people to demonstrate functionality Exploration in materials Design drivers: innovative design that is completely new

Prototypes Introduced Week 6 A B C D E F JOANNA

Identifying Critical Subsystems ANA •Consider your risk list –Highest technical risks: review with team •Consider your functional decomposition –Most challenging technically: review with team •Consider your engineering requirements –Most important 4-8 system level requirements •Consider the required system-level behavior –Most important behaviors •Other considerations??

Risk Assessment ANA

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg ANA

Functional Decomposition Support independent user with lower extremity injury walking from point A to point B in multiple types of environments. Position Crutches Access crutch assembly Permit height adjustment Permit connective versatility Transport User Support user weight Maintain contact with the ground Stabilize user in vertical position Mobilizes user Release User Disengage from crutch-user interface ANA

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility ANA

Engineering Requirements ANA

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility Engineering Requirements Do not fracture or break under user load on double crutch or ½ user load on one crutch User will be able to use the Una-Crutch without compromising comfort Interfacing mechanism does not unlock due to user weight Appealing to the majority ANA

System Architecture ANA

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility Engineering Requirements Do not fracture or break under user load on double crutch or ½ user load on one crutch User will be able to use the Una-Crutch without compromising comfort Interfacing mechanism does not unlock due to user weight Appealing to the majority System Architecture User Interface Height Adjustment Connective Mechanism ANA

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility Engineering Requirements Do not fracture or break under user load on double crutch or ½ user load on one crutch User will be able to use the Una-Crutch without compromising comfort Interfacing mechanism does not unlock due to user weight Appealing to the majority System Architecture User Interface Height Adjustment Connective Mechanism ANA Connective Mechanism

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility Engineering Requirements Do not fracture or break under user load on double crutch or ½ user load on one crutch User will be able to use the Una-Crutch without compromising comfort Interfacing mechanism does not unlock due to user weight Appealing to the majority System Architecture User Interface Height Adjustment Connective Mechanism ANA Connective Mechanism Axilla Pad/ Handles

Identifying Critical Sub Systems Risk Assessment Connective Mechanism Failure User treats crutch as toy User Cannot connect the crutches while immobilized on one leg Functional Decomposition Permit height adjustment Permit connective versatility Engineering Requirements Do not fracture or break under user load on double crutch or ½ user load on one crutch User will be able to use the Una-Crutch without compromising comfort Interfacing mechanism does not unlock due to user weight Appealing to the majority System Architecture User Interface Height Adjustment Connective Mechanism ANA Connective Mechanism Axilla Pad/ Handles Frame

Critical Subsystems Defined Connective Mechanism Frame Axilla Pad/ Handles ANA

Proof-of-Concept DAN Technical feasibility: –Analysis (what questions are you answering?) •Simple models first to get approximate magnitudes •Estimate complexity to answer key questions •Several analyses to answer all key questions –Demonstration or prototyping (what behaviors are you trying to show?) •Functional demonstration (cause-effect) that proposal should work •Physical mock-up –Experimentation (what questions are you answering?) •Controlled and measured to quantify feasibility –Description of system behavior (what behaviors are you describing?) •Logic based flow charts •Feature descriptions, use cases, operating modes

Prototypes Introduced Week 6 A B C D E F DAN

Prototypes Introduced Week 6 A B C D E F DAN REVISED

Prototype G Pros: Cons: Compact Design Usable for all ages Stable Male/female mold Pros: Compact Design Usable for all ages Stable Cons: Not necessarily aesthetically pleasing Two separate bases Pad is in contact with the ground Pin DAN

Prototype H Pros: Cons: Lightweight Easy to manufacture Sliding button Pros: Lightweight Easy to manufacture Sliding button connective mechanism Cons: Design resembles standard axilla crutch DAN

1. Axilla Pads and Handles 2. Frames and Connective Mechanisms Prototypes to Create 1. Axilla Pads and Handles 2. Frames and Connective Mechanisms B C G H DAN

Axilla Pads and Handles Prototypes Created BEV

Frames and Connective Mechanisms Prototype B and C BEV C

Frames and Connective Mechanisms Prototype G BEV G

Frames and Connective Mechanisms Prototype H BEV Symmetric VS. Assymetric

Prototype Test Plan BEVERLY

User Feedback Axilla Pads and Handles BEV

User Feedback Axilla Pads and Handles BEV

User Feedback Frames and Connective Mechanisms BEV

Second-Order Analysis Magnetic Analysis Bike Clamp Analysis Connective Mechanism Analysis CAD Model Spring Analysis Deflection Analysis B/C Prototype Analysis BEV

Magnetic Analysis Two configurations: Two shapes: Magnet to Magnet Magnet to Plate Two shapes: Square/ Rectangular Cylindrical/ Disk Analyzing Grade 42 magnets Engineering Requirement S5: Interfacing mechanism does not unlock due to user weight. Ideal value: 3 lbs. Marginal Value: 5 lbs. DAN

Magnetic Analysis Magnetism Physics on a Crutch DAN Pull Force: quantity required to separate two attracting magnets. Pull Force Equations: The Lorentz Equations Pull Force Increases as Area Increases. Pull Force Decreases as Distance Increases.

Magnetic Analysis Configurations Analyzed Square Magnets Chosen Easier to embed in material. Proper amount of Pull Force. DAN

Prototype Design Tested Magnet Overview DAN Prototype Design Tested Note: If used in final design, magnets will have a small distance separating them.

Bike Clamp Analysis Split-Ring Clamp Type Shaft Collar Analysis: Torque necessary to achieve pre-load Axial holding force of seat post collar Hoop Tension in collar JOANNA

Bike Clamp Analysis Torque in Cap Screw Assume: Cap screw is coarse pitch Low or medium carbon Non-permanent connection Screw diameter = 6 mm Torque = 6.11 Nm JOANNA

Bike Clamp Analysis Axial Holding Force Assume: Coefficient of friction = 0.61 Fx = 13,000 N JOANNA

Bike Clamp Analysis Hoop Tension Assume: Collar width = 12 mm Internal radius 6.35 mm Internal pressure = 7.08 MPa Fh = 540 Pa JOANNA

CAD Model: B/C Prototype Cheetah Leg Connection Mechanism Grip Connection Mechanism

Spring Analysis N Analyzing Spring at Base of Crutch. Normal Force = Spring Force N = user load Two Stresses on Spring: Torsion Shear Stress Direct Shear Stress DAN N

Spring Analysis Results DAN Stress absorbed by the springs results in a large stress. May give user more endurance to use crutches longer.

Deflection of Cheetah Leg Base R2 Assume: Carbon fiber material Circular cross-section r = 0.75in = 1.91x10-2m R2 = 0.3 m Deflection = 0.08in = 0.002m P JOANNA M D P P

Feasibility BEV

Manufacturing Processes BEV Summary •What questions do you need to answer to demonstrate feasibility of your critical subsystems? What are the most efficient and effective means to answer questions? •Add-up key contributors to critical system requirements. Can system requirements be achieved thru your critical subsystems? •Iterate and converge as needed •Update your risk assessment

Brinkman Lab Resources 3D Printing (Connective Mechanisms) Water Jet (Frames) RTV Mold (Axilla Pads/ Hand grips) ANA

Detailed Design Preview ANA

Detailed Design Phase (Weeks 10-12) ANA

Detailed Design Phase (Weeks 10-12) Cost and Material Analysis (Friction Analysis) Connective Mechanism Prototypes from Brinkman Lab Focus Group for New Prototypes FEA and Detailed Design Analysis Bill of Materials ANA

Questions? Thank you! DAN Focus on areas with greatest impact (or risk) to success, and invite “critics” to challenge your assumptions & decisions Show evidence (analysis) used to support key decisions Follow agenda – if more time needed, schedule follow-up Thank you!

Backup Slides

Customer Requirements BEV

Final Product Test Plan