1. Stair Caddy Sketch Model Review
Carries items up to 50 lbs up and downstairs
2.009 Blue B

2. Stair Caddy Design
For the 36+ million senior citizens

3. Existing Products
AATA International SR 450
AATA International SR 1750

4. Comparison SR 450 SR 1750 Stair Caddy Mass of Cart 49 kg 175 kg 25kg
Power
375 W
500 W
400 W
Battery
Life
3.5 hours
5 hours
Speed
.15 m/s
(7.9 in/s)
.05 m/s
(5.9 in/s)
.31 m/s
(12 in/s)

5. Testing for Consumer Needs
Safety - Slip
Not ruining floor material
Items not falling out
Items not squished
Storage

6. Other Issues Learned Need more testing with treads Turning Radius
Force applied to handle
Safety
Storage Size
Driving
Downstairs

7. Appendices

8. Additional Calculations
Total Steps
50 Steps
Total Operation Time
50 sec
Mass of Front Treads
3 kg
Ang Speed
.5 rad/sec
(~30 deg/sec)
Coefficient of Friction of Floor
.3-.5
Motor Torque for Main Treads
20 Nm

9. Size
Narrow Staircase
3 Contact Points
Staircase
30”
30”

10. Stair Data Building Codes (Public Areas) Measurements (Residential)
Tread length: 9”
Riser: 8.25”
Measurements (Residential)
Tread length: 7”
Riser: 8”