2. Team Members
2
Iatchi Sin
(MEM)
Mechanism
Design and
Prototype
Product Design
and Development
Denzel Golay
(ECE)
Circuit board
design and
Programming
Electronic
Troubleshooting
Bin Li
(MEM)
Components
sourcing and
load calculation
Plumbing, Fire
protection drafting
Yadira Mejia
(MEM)
CAD prototype
simulation and
project
management
HVAC Drafting
Abou. D Kouyate
(MEM)
Hardware
selection and
structure design
Structural
Engineer
4. 4
Fall Term
Goal:
Design, fabricate, test, and validate a device attached to a wheelchair to
ascend and descend staircases
Research Existing Models:
iBOT B-Free Chair
6. 6
Fall Term
Prototype:
Geometry of wheels
Size requirement
Stability
Power requirement
F
T
Rear Wheel FBD
M: T = F x r = 188Nm = 138.66 lbft
Rotation speed = 40rpm
Power = 138.66 x 40 / 5252 = 1.06 hp
Calculation:
7. Components Overview
Bearing pillow block (x4) Shaft coupling (x4) Electric Jack (x2)
Aluminum welded
wheel and shaft (x4)
Aluminum alloy
Gearbox (x1) Motor (x1) Battery (x1) Motor (x2)
10. Outline
Previous Term
Improved Design Solution
10
Concerns Posed by
Committee from Winter Term
Final CAD Model
村 Scale Prototype
Prototype Demonstration
11. Concerns Posed by Committee from
Winter Term
The platform is too steep for wheelchair to go up.
The ADA standard
slope ratio is 1:12
Too Steep!
12. Reverse ramp ascent by wheelchair
Three ratios (1:12, 1:8, 1:6)
5 times for each angle and take the average
3 different body types (weight, height, gender, age)
12
12
1
8
1
6
1
Slope Experiment
ADA Standard
15. Independent Variables:
Steps height
Angle of the steps
Friction of the wheels
Length of the carriage
Weight of the wheelchair and user
15
Concerns Posed by Committee from
Winter Term
17. Friction
Stairs
17
The stairs without carpet has
small friction and wheelchair is
hard to climb
The stairs with carpet has
increased friction and
wheelchair is easy to climb stair
18. Slope and length change of the model
Decrease the slope to
accordingly to the result of the
experiment
Increase the distance between the
wheels to enable 90 degree turn
after landing
18
Final CAD Model
23. The toy wheelchair used is close to 村 of a
standard wheelchair
23
Why 村 Scale?
24. Main Components Overview
Battery Box Holder (x5) Recharge Batteries (x20) Toy Wheelchair
Motor Shaft Coupling
Joint
Bearing Pillow
(x4)
Wheel Materials
Mini Motor ( x2)
Open Beam
Plywood
25. 25
Purchased items Quantity Cost
Battery Charger and Batteries 2 $72.05
Motor 1 $63.99
Coupling 2 $13.06
Wheel Material 1 $19.92
plywood for steps model 1 $24.25
stepper motor for scissor and lock 4 $56.95
Bearing Pillow 2 $11.96
switches 1 $10.00
gyroscope 1 $7.01
stepper motor for hinge 1 $14.90
battery holder 1 $26.81
beam for wheel 1 $40.00
Open beams, screws and nuts 1 $48.61
H-Bridge 1 $11.42
Hinge 1 $4.70
wood for staircase box 1 $54.06
Total cost $479.69
Total Expense
32. Calculation at instant of climbing up a step (max torque required)
Rear wheel drive, 80% of total weight at rear wheel
W = total weight x 80% = 185kg x 80% =148kg
r = 0.13m
Fy: F = W
M: T = F x r = 188Nm = 138.66 lbft
Rotation speed = 40rpm
Power = 138.66 x 40 / 5252 = 1.06 hp
32
W
F
T
Specification requirement for motor and gearbox
Rear Wheel FBD