A S S I S T R E K

Michael ElpersKyle FleegeKevin MasonMary Phillips

Theresa PolowskiMegan Schroeder

AMBULATORY ASSISTANCE SYSTEM

Critical Concept Design Review

Project Objective

• Design and prototype an ambulatory assistance device for a temporary injury

• Initial Concepts:

Design Selection

• Contacted medical professionals to discuss current rehabilitation devices

• Researched ADA requirements

• Tested various devices

• Tested and used crutches

• Prototyped and used a knee crutch

Crutches

- Large user energy input

- User’s arms and shoulders become sore after extended use

- Cheap (under $30)

Powered Wheelchairs

- Increased Mobility with minimum energy input

- Expensive (over $500)

Assistrek Design Objective

• User age: 16-50 years old• Healthy/strong enough to use crutches

• Single leg injury

• Meet ADA requirements

i. Width < 32 in.

ii. Length < 3 ft

iii. Able to complete a 180° turn in 5 ft wide space

• Motor powered movement• Ability to maneuver and turn

• Inclusion of crutches into design

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Final Concept Selection

•Key Features

• Motor powered

• Incorporates crutches

• 3 wheeled

• Back rest for user safety and support

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Final Design

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Final Design

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Design Rationale

vs.

Advantages to Standing Design:

- Easy on/off

- Incorporates crutches

- Helps maintain muscle of healthy leg

- Assists recovery

Technical Issues

• Issues Identified:

• Platform material and thickness

• Motor type and size

• Steering angle and radius

• Type of crutch locking device

• Axle diameter and material

• Back support material and size

Design Decisions

• ¾ in. HDPE platform

• Direct Current motor

• ½ in. steel axle

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Design Decisions

• 58° rotation of front wheel

• Spring force sufficient for crutch locks

• Black steel pipe, minimum 3/8 in. diameter for backrest

Issues Resolved

• Front steering systemIssue: Front wheel too wide for intended steering forkResult: Chose a four bar mechanism and castor wheel

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Issues Resolved

• Powering rear wheelsIssue: Both rear wheels powered inhibits turningResult: Powered one rear wheel and allowed other to spin freely

Free Spinning Wheel

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Issues Resolved

• Rear axle deflectionIssue: Rear axle diameter too small for torque applied by motorResult: Replaced deformed axle and installed bushings to support axle

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Feasibility of Design

Forward and reverse settings

Feasibility of Design

User can get on or off product in under 45 seconds

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Feasibility of Design

Able to complete a 180° turn within a 5 ft radius

Video

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Feasibility of Design

Budget:

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Feasibility of Design

Total weight less than 150 lbs

~ 100 lbs

3 wheels on ground at all times

Crutches maintain position within 10°

from vertical

Backrest deflection less than 5 in. under user weight

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Future Modifications

• CRUTCH LOCKING DEVICE

• Improve material

• Automate

• Recess into board

• Weatherproof design

• Redistribute weight on platform

•POWER SYSTEM

• Optimize power output and size

• Introduce variable speed control

• LCD user interface

• Brakes

Assistrek

Acknowledgements

-Mr. Greg Brownell

-Mr. Leon Hluchota

-AME40463 TA’s

Thank you to:

- Mr. Jim Russ, Notre Dame Head Football Trainer

- Mr. Ricardo Moreno, St. Mary’s High School Athletic Director

- Dr. Scott Kreiner, MD, Fellowship Director at Ahwatukee Sports and Spine

- Mr. Stacey Whiteside, Manager at Tempe CDC

-Dr. Stephen Batill

-Dr. John Renaud

-Dr. Michael Stanisic

Questions