P15007: Anti-Rollback Wheelchair Jessica Jeffrey (ISE) Jacob McCarthy (ME) Warren Roser (ME) John Sweet (ME) Faculty Guide: Edward Hanzlik Customers: Dr. Elizabeth DeBartolo & Jack Cholette

Agenda  Problem Definition  Alpha Prototype  Requirements  Design Concepts  Analysis  System Architecture  Final Design Summary  System Testing Results  Final Prototype  Project Evaluation  Future Opportunities

Problem Definition Users of manual wheelchairs encounter difficulties when traversing an incline or decline

Alpha Prototype Pros  Fully functional “hill holding” device  Fully functioning brake assist  Reassuring functional sound Cons  Heavy (~22 lbs)  Not easily adaptable  Custom components  Wheelchair not revertible

Requirements  Low Cost  Light Weight  Adaptable  Retain Original Functionality *Highest Importance (9) – Lowest Importance (1)

Design Concepts Retain Ratchet and Pawl Concept  Enclosed vs Exposed  1 pawl vs 3 pawls  Control locations, locking ability, and type Braking System  Locking Brake Handles  1 vs 2 Independent Inputs

Analysis  Shaft Material Selection  90/10 Use Scenario Estimation that system will be engaged 10% of the time

System Architecture Use Scenarios  Client/aid reaches incline and engages anti-rollback  Client/aid reaches decline and engages brakes

Final Design Summary

System Testing Results Pawls  Over 150,000 cycles  Life expectancy 5+ years under 10% utilization scenario Ratchet  Over 280,000 cycles  Exceeds life expectancy of pawls Enclosed Pawls Test Fixture

Final Prototype Final System Installed on Wheelchair Final Controls Positioning

Project Evaluation  On time  Overall customer satisfaction  Over budget by $100 *Highest Importance (9) – Lowest Importance (1)

Future Opportunities  Maintain quick-release functionality  Review design to reduce variation in size and length of fasteners  Weight reduction through component design  Material selection  Alert system to ensure client is aware of system reaching end of life

Acknowledgements Edward Hanzlik, Faculty Guide Dr. Elizabeth Debartolo, Customer Jack Cholette, Customer Machine Shop: Dave Hathaway Jan Maneti Rob Kraynik Brinkman Lab: John Bonzo

Questions? Thank You!