A S S I S T R E K

1
A S S I S T R E K
AMBULATORY ASSISTANCE SYSTEM
Critical Concept Design Review

• Michael Elpers
• Kyle Fleege
• Kevin Mason
• Mary Phillips
• Theresa Polowski
• Megan Schroeder

2
Project Objective

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

3
Design Selection

• Contacted medical professionals to discuss
  current rehabilitation devices

• Crutches
• - Large user energy input
• Users arms and shoulders become sore after
  extended use
• - Cheap (under 30)

• Powered Wheelchairs
• Increased Mobility with minimum energy input
• Expensive (over 500)

• Tested various devices
• Tested and used crutches
• Prototyped and used a knee crutch

• Researched ADA requirements

4
Assistrek Design Objective

• User age 16-50 years old
• Healthy/strong enough to use crutches
• Single leg injury
• Meet ADA requirements
• Width lt 32 in.
• Length lt 3 ft
• Able to complete a 180 turn in 5 ft wide space
• Motor powered movement
• Ability to maneuver and turn
• Inclusion of crutches into design

5
Final Concept Selection

• Key Features
• Motor powered
• Incorporates crutches
• 3 wheeled
• Back rest for user safety and support

6
Final Design
7
Final Design
8
Design Rationale

• Advantages to Standing Design
• - Easy on/off
• Incorporates crutches
• Helps maintain muscle of healthy leg
• Assists recovery

vs.
9
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

10
Design Decisions

• ¾ in. HDPE platform
• Direct Current motor
• ½ in. steel axle

11
Design Decisions

• 58 rotation of front wheel
• Spring force sufficient for crutch locks
• Black steel pipe, minimum 3/8 in. diameter for
  backrest

12
Issues Resolved

• Front steering system
• Issue Front wheel too wide for intended steering
  fork
• Result Chose a four bar mechanism and castor
  wheel

13
Issues Resolved

• Powering rear wheels
• Issue Both rear wheels powered inhibits turning
• Result Powered one rear wheel and allowed other
  to spin freely

Free Spinning Wheel
14
Issues Resolved

• Rear axle deflection
• Issue Rear axle diameter too small for torque
  applied by motor
• Result Replaced deformed axle and installed
  bushings to support axle

15
Feasibility of Design

• Forward and reverse settings

16
Feasibility of Design

• User can get on or off product in under 45
  seconds

17
Feasibility of Design

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

Video
18
Feasibility of Design

• Budget

19
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

20
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

21
Acknowledgements
Thank you to - Mr. Jim Russ, Notre Dame Head
Football Trainer - Mr. Ricardo Moreno, St.
Marys 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
-Mr. Greg Brownell -Mr. Leon
Hluchota -AME40463 TAs
22
Questions