This document summarizes a student project to design a powered wheelchair trainer. A team of students worked on revisions to create a device that attaches to manual wheelchairs to allow users to practice with powered wheelchairs. The final design was tested but had some issues with batteries, size for transportation, and traction on carpet. Recommendations included further engineering work, market studies, and pursuing a patent.

1. Eric Domke
Drew Pretzer
Brandon Rood
Karl Hiedemann
Powered Wheelchair Trainer Design Project
Fall Semester - 2008
“The ability to move is the first foundation
stone in building personal dignity.”
- D. Linda Bidabe
Grand Valley State University Fall 2008

2. Introduction
● Project Description
● Customer Needs
● Specifications
● Design Evolution
● Demonstration & Evaluation of Prototype
● Recommendations
Grand Valley State University Fall 2008

3. Problem Description
● Must pass test to get
money from insurance
company
● Not enough practice
● Powered chairs are
expensive
● Goal: Build
"inexpensive" device
which attaches to
manual wheelchairs.
Grand Valley State University Fall 2008

4. Target Market
Grand Valley State University Fall 2008

5. Customer Needs - Interviews
● Fit through a standard door
● Change between different wheelchairs quickly
● Easily transportable between different buildings.
● Good battery life.
Grand Valley State University Fall 2008

6. Product Specifications
● Switch Users in Under 5 Minutes
● Accommodate Different Sized Wheelchairs
● Widths of 20-25 inches
● Lengths of 32-50 inches
● Wheelbase of 16-32 inches
● Fit Through a Standard Door
● Width is under 32 inches
● Mimic a Powered Wheelchair
Grand Valley State University Fall 2008

7. Revision A
● Motor Calculations
Torque 480.98 In-lb 54.31 N-m
(Driving)
Torque 209.49 In-lb 23.65 N-m
(Steering)
● Support Bar Calculations
● 0.065" Wall Thickness for Steel Tube
● Force to Load Calculation
● 170 lbs
● Tipping Calculation
● Need to move > 9.33" off center
Grand Valley State University Fall 2008

8. Revision B
Front of
Trainer
1 2 3
Grand Valley State University Fall 2008

9. Revision C
● Motor Testing
● Cordless motors possible, but
durability and brake concerns
● Frictional Force Experiment
● Approx. 300 lbf to get a 4"
dia. wheel over a 0.75" ledge
Grand Valley State University Fall 2008

10. Revision D
● Finite Element Analysis
● Need multiple gussets to
minimize deflection
● Frame Design Analysis
● Tube frame is stronger and
more cost effective
Grand Valley State University Fall 2008

11. Revision E
● Site Visit to LDC #2
Motors
● Motors cannot go between
Batteries
wheelchair wheels.
● Traction Analysis
● Issues with traction,
especially on carpet.
Grand Valley State University Fall 2008

12. Final Design
Grand Valley State University Fall 2008

13. LDC – Final Visit
Grand Valley State University Fall 2008

14. Loading
Goal : "Not Strenuous" Actual : Very Easy PASS
● Improvements: None
Grand Valley State University Fall 2008

15. Locking
Goal : < 5 minutes Actual : < 1 minutes PASS
● Improvements: None
Grand Valley State University Fall 2008

16. Maneuverability
Goal : Similar to powered Actual : Some minor PASS
wheelchair deviations
● Improvements: Tweak the controls algorithms
and deal with traction issues.
Grand Valley State University Fall 2008

17. Fits Through a Door
30"
Goal : Width < 32" Actual : Width = 30" PASS
● Improvements: None
Grand Valley State University Fall 2008

18. Batteries
Goal : Discharge > 16 hr Actual : Discharge >20 hr (BORDERLINE) FAIL
(1.4 A Draw)
Charge < 8 hr Charge > 10 hr
● Improvements: Better compromise between
price, weight, and electrical capacity.
Grand Valley State University Fall 2008

19. Transportation
Goal: Can fit in trunk Actual: Length and FAIL
height are too large
● Improvements: Make the trainer "collapsible"
into two or more pieces.
● Aluminum Frame
Grand Valley State University Fall 2008

20. General Concerns
● Joystick
● Loses calibration resulting in unexpected motion of
the trainer
● Looser spring and better mounting system
● Traction: Cannot turn easily on carpet
● Over-Heating: Look at controls system
● Battery-Level Reading: Calibration could be off
Grand Valley State University Fall 2008

21. Proposed New Features
● Attendant Control
● "E-Stop" Bumper
● Joystick:
"Backwards
Mode"
● Multiple control
interfaces
Grand Valley State University Fall 2008

22. Budget
Part Supplier Supplier Number Cost Qty Total Cost
Motor NPC NPC-B81, -B82 $339.00 2 $678.00
Charger McMaster-Carr 7558K68 $299.03 1 $299.03
Batteries Digi-Key 522-1015-ND $82.51 2 $165.02
Acrylic for Joystick McMaster-Carr 8774K43 $134.82 1 $134.82
and Controls
Motor Driver Dimension Sabertooth 2x25 $124.99 1 $124.99
Engineering
Subtotal $1,952.89
+20% (Shipping, tax) $390.58
Total $2,343.47
Grand Valley State University Fall 2008

23. Recommendations
● Patentable?
● Continue engineering design work
● Perform market studies
Grand Valley State University Fall 2008

24. Our Role
● Troubleshooting existing features and making
recommendations on design changes
● Website: http://sites.google.com/site/pwtgvsu/
● E-mail: pwt.gvsu@gmail.com
Grand Valley State University Fall 2008

25. Special Thanks
● D. Linda Bidabe
● Founder of Move International
● Cathy Ripmaster
● Lincoln Development Center
● Karen Gora
● Mary Free Bed Rehabilitation Hospital
● Engineering Faculty and Staff
Grand Valley State University Fall 2008

26. Grand Valley State University Fall 2008