1. Electrically assisted human powered vehicle

2. Configuration Specifications
Specification Param. Name Value Unit
Number and 2+1
configuration
Wheelbase a+b 1.5 m
Track t 1.0 m
Height h_cg 0.4 m
Distance from front a 0.5 m
wheels
Overall Mass M 200 kg
Ground clearance h_ground 0.1 m
Wheel size OD D_wheel 0.66 m
(all)

3. Performance Specifications
Specification Param. Name Value Unit
Maximum lateral a_lat_max 7.8 m/s^2
acceleration
Maximum d_max 7.8 m/s^2
deceleration
Maximum a_max 3.3 m/s^2
acceleration
Deceleration for d_max_tip 8.4 m/s^2
'header'
Lateral a_lat_tip 9.3 m/s^2
acceleration
at tip over
Maximum speed V_max_brake 54 kph
for braking
Minimum turning R_turn 3.0 m
radius

4. Key Specifications
Specification Param. Name Value Unit
Ride frequency f_ride 2 Hz
Motion ratio (front) MR_front 1 -
Motion ratio (rear) MR_rear 0.53 -
Suspension K_susp_front 10150 N/m
stiffness
(front)
Suspension K_susp_rear 11012 N/m
stiffness
(rear)
Suspension c_front 404 N-s/m
damping
(front)
Suspension c_rear 417 N-s/m
damping
(rear)
Wheel travel (front) travel_front +/- 50 mm
Wheel travel (rear) travel_rear +/- 43 mm

5. Rear Suspension Details
CG height 0.4 m
Ground Clearance 0.1 m
Pivot radii 0.01905 m
Max Acceleration 3.924 m^2/sec
Length of swing arm 0.458 m
Vehicle mass 200 kg
Force accel 784.8 N
Pivot Height 0.14 m
Moment (Pivot) 109.872 N m
Force (wheel- Vertical) 239.8951965 N
Stiffness of the wheel (K) 11012 N/m
Squat 0.021784889 m
Wheel radius 0.33 m
Force Lateral 523.2 N
Hub width 0.1 m
Force (arm) 1726.56 N
Axle Diameter 20 mm
Motion Ratio
Motion Ratio of Rear Suspension 0.53
Wheel Location from Pivot 0.3929 m
Shock Location from Pivot 0.208237 m

6. Decision Matrix Summary
Oil/ Helical
Air shock Leaf spring spring
Satisfaction 452 305 383
Bicycle Motorcycle Car
Satisfaction 472 377 318
Twin Shock Single Pivot Multi Link Fork Style
Satisfaction 374 348 292

7. Rear Suspension CAD Models
Wheel Rear Swing Arm
Rear suspension Assembly Rear Axle

8. Steering CAD Models
Center Pivot
Steering Assy. Tie rod

9. Steering Details
Description Specifications
Steering bar length 0.6m
Grip Length 0.12m
Grip Diameter .03m
Maximum Steering Bar angle + 45 degree to – 45 degree
Steering ratio Hand: Wheel 1.6:1
Steering input force 67 N
Maximum aligning torque from tires 125 N-m
Wheel angles (inside/outside) 43/28 deg.
Track Width 1.0 m
Lateral Forces on one corner 522.66N
Steering Torque on one corner 62.72N*m
Load on Tie Rod 448N
Actual Torque on Steering Column 40.32N*m
Steering Arm Length 0.14m
Steering Pivot length (Base of Column) 0.09m
Steering Shaft Dia 0.015m
Steering Shaft Length 0.6 to 0.7m
Dia of Tie rod 0.00952m
Length of Tie rods (Tublar) Chrome Plated light weight 0.177 to 0.60

10. Schematic Diagram
http://www.shakyparts.com/steering_parts.html

11. Steering Geometry Check

12. Data for Longitudinal Acceleration and Braking
0.45 LIMITATIONS FOR UPHILL MOTION AT CONSTANT SPEED
0.4
0.35 •Constant Velocity of 19.5 km/h at 3:
0.3
0.25
•Constant Velocity of 11 km/h at 6:
5⁰ Acceleration (g) •Constant Velocity of 4.3 km/h at 15:
0.2
0.15 •Constant Velocity of 2.8 km/h at 20: - Maximum Slope at μ=0.8
0.1 0⁰ Acceleration (g)
0.05 (beyond this slope, vehicle will begin to lose speed)
0 -5⁰ Acceleration
15
6
1.5
2
8
10
0.05
1
3
12
4
Velocity(m/s)
(g)
ASSUMPTIONS
MAXIMUM ACCELERATION ON DIFFERENT SLOPES
•Coefficient of friction = 0.8
CONSIDERING AERODYNAMIC DRAG •Wheelbase = 1.5m
•Three wheels, (2) in front, (1) drive
LIMITATIONS FOR DOWNHILL BRAKING wheel at rear.
•CG is located 0.4m above ground and
•For 10:1 motor/wheel gear ratio, vehicle speed = 17 m/s 0.47m from front axle or datum
•0: - 11.5: slope, minimum stopping distance = 18.4m •Wheels – Standard, 26” dia. X 1 ¼”
@0.8g (skidding will occur at steeper slopes unless dec. •Braking discs – 8” front and rear
rate is reduced) •Coefficient of Drag – 0.5 (Chassis
•0: - 21: slope, minimum stopping distance = 25.5 m @0.6g Team)
(skidding will occur at steeper slopes unless dec. rate is •Frontal Area – 0.39 m^2 (Chassis
reduced) Team)
•For induced velocity of 40 m/s (5: slope), minimum stopping distance = 102 m •Motor Power Rear Wheel = 500W
•For induced velocity of 54 m/s (10: slope), minimum stopping distance = 186 m •Motor RPM – 5000
•Human Power = 75 – 200W
•N.B: THESE STOPPING DISTANCES ARE ALL BASED ON A DECELERATION OF
0.8g UNLESS STATED OTHERWISE
THESE DATA WERE PREPARED BASED ON DATA FROM
THE SPREADSHEET ‘Brake Calculation Sheet.xls’

13. Power and Gearing Requirements
Rear Velocity POWER AT CONSTANT SPEED (W)
Motor/wheel Pedal/wheel
RPM ratio RPM ratio RPM (m/s) 0: 3: 6: 15: 20:
Front wheel diameter d_fw 0.66 m
Rear wheel diameter d_rw 0.66 m
Pedal RPM 50 rpm
Motor RPM RPM_m 5000 rpm
Gear Ratio 10 GR_10 10/1 1/10 500 17.2783 772
Gear Ratio 9 GR_9 11/1 1/9.1 454.5 15.71 606
Gear Ratio 8 GR_8 16/1 1/6.25 312.5 10.7989 253
Gear Ratio 7 GR_7 20/1 1/5 250 8.63913 160
Gear Ratio 6 GR_6 24/1 1/4.2 208.3 7.19812 114
Gear Ratio 5 GR_5 28/1 1/3.57 178.571 6.1708 89 717
Gear Ratio 4 GR_4 32/1 1/3.13 156.25 5.39945 67 622 1171
Gear Ratio 3 GR_3 56/1 1/1.79 89.2857 3.0854 34 349 662
Gear Ratio 2 GR_2 110/1 1/0.91 45.4545 1.57075 16 176 336 800 1052
Gear Ratio 1 GR_1 220/1 1/0.46 22.7273 0.78538 8 88 168 400 526
RED OUT OF RANGE
GREEN HUMAN + ELECTRIC
BLACK ELECTRIC ONLY
According to the US Road Design Manual,
• The maximum slope over an unlimited distance corresponds to 3⁰
•The maximum slope over 150m corresponds to 6⁰
•http://www.dot.state.mn.us/tecsup/rdm/english/3e.pdf (Road Design Manual)

14. Longitudinal Dimensions  The wheelbase and CG height
were selected based on the
following limiting
conditions:
 The maximum
deceleration attainable
would be 0.8g.
 The maximum slope to be
encountered would be
20% or 11⁰ on roadways.
At these conditions, the
vehicle would tend to skid
before flipping over the
front axle. If the CG height
is increased to 0.5m, the
vehicle would flip at these
conditions. Therefore,
considering safety, these
parameters were selected.
FINAL SPECIFICATIONS
1.Maximum speed on level ground – 56 km/h
2.Maximum speed on 3: uphill (this is the maximum slope over an unlimited distance for access roads) – 19.5 km/h
3.Maximum speed on 6: uphill (this is the maximum slope over 150m for access roads) – 11 km/h
4.Maximum acceleration on level ground – 0.34g
5.Maximum braking deceleration – 0.8g

15. Vehicle Cornering Stability
.
X  V cos(   )

.
Y  V sin(   )
l f tan  r  l r tan  f
  tan ( 1
)
l f  lr
 o  i L
 
2 R
Fig. : Kinematics of Lateral Vehicle Motion
[Rajmani, R., 2006, “Vehicle Dynamics and Control”

16. Vehicle Cornering Stability
L
  f r
R
2
L mf mr V x
 (  )
R 2Cf 2Cr R
L
  Kvay
R
Cornering force F  C * 
Cornering stiffness is a function
of:
• Inflation pressure
• Percent of rated load
Fig.: Steering Angle for High Speed Cornering • Vertical load
[Rajmani, R., 2006, “Vehicle Dynamics and Control”
• Size and shape of the tire

17. Vehicle Cornering Stability
t
WL t  W ( )  WAY h
2
Fc
A W WAY h
CG O
WA WL  
2 t
W
W WAY h
P
1.8 W  WL  
M 2 t
N
C
D Assumptions:
B
Wc 1.25
WB
• Wheel base: 1.5m
Front
• Track width: 1.0m
• CG height: 0.4m
Fig.: Cornering stability analysis
• Coefficient of friction: 0.8
• Two wheels at the front and
one at the rear
• Front wheels are steered

18. Vehicle Cornering Stability
Track Width for Lateral Stability
800
700
Total Weight Transfer (N)
600
500
400
300 Front Corner Static Load
200 Total Weight Transfer
100
0
25
23
21
19
17
15
13
11
09
07
05
03
01
99
97
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
0.
0.
Track Width (m)

19. Vehicle Cornering Stability
CG Height for Lateral Stability
800
Total Weight Transfer (m)
700
600
500
400
Front Corner Static Weight
300
Total Weight Transfer
200
100
0
0.4 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.5 0.51
CG Height (m)

20. Vehicle Cornering Stability
Coefficient of Friction for Lateral Stability
800
700
Total Weight Transfer (N)
600
500
400
Front Corner Static Weight
300 Total Weight Transfer
200
100
0
0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 1.02
Coefficient of Friction

21. Vehicle Cornering Stability
Road Camber for Lateral Stability
660
640
Total Weight Transfer (N)
620
600
580
Front Corner Static Weight
560
Total Weight Transfer
540
520
15 16 17 18 19 20 21 22 23 24
Camber Angle (degree)

22. Merits and Demerits of Different Braking
Methods
P ros C ons
perform equally well in all c onditions more s tres s on a wheel's s pokes
Dis k B rake inc luding water, mud and s now. T he des ign and pos itioning of dis c brakes prec ludes
offer better modulation of braking power the us e of mos t types of pannier-rac k
s tandard parts and eas y to get
c heap, light, and very powerful perform poorly in wet weather when the rims are wet
R im B rake mec hanic ally s imple, eas y to maintain wear down quic kly, over longer time and us e, rims bec ome worn
heat the rim, bec aus e the brake
c onverts kinetic energy into thermal energy
us eful for wet or dirty c onditions heavier, more c omplic ated
Drum B rake les s maintenanc e and are les s affec ted frequently weaker than rim brakes
by road c onditions Intended to s low down the bike on long downhills rather than s top it

23. Braking Methods Decision Matrix
Alternative
C riteria Importanc e D is c B rake R im B rake D rum B rake
E as y to opetate 10 0.8 0.85 0.8
E as y to maintain 8 0.75 0.8 0.51
E as y to ajus t 6 0.82 0.83 0.62
E as y to as s embly 6 0.8 0.86 0.48
wear 7 0.78 0.52 0.61
W eight 5 0.8 0.85 0.56
F amiliar to c us tomer 9 0.82 0.84 0.65
P erform in all c onditions 12 0.89 0.45 0.51
O verall s afty 15 0.91 0.75 0.65
S atis fac tion 82% 75% 60%

24. Concept Selection Process and key Specification
Braking method: ISO standard (1996):
 By comparing Kinetic Energy with mountain  Disk withstands force: 2300 N [1]
bike, we decided to select braking method of
mountain bike.
Key specification::
 By comparing typical braking methods of  Force:
mountain bike, we thought that disk brake is  The force exerted on front disk: 1870 N
feasible for our project.  The force exerted on rear disk: 935 N
Disk dimensions:  Torque:
 The torque exerted on front disk:367 Nm
 Diameter: 8” (200mm)
 The torque exerted on rear disk:168 Nm
 Thickness: 0.07”(1.8mm)
 Material: Stainless Steel Marketing specification:[2]
*Hayes Disc Brakes HFX 9 HD V8
Limitations of disk brake:
*Rotor: 203mm
 Vehicle maximum speed: 40 km/h
*Weight: 520g
 Total weight: 200 kg
*Cable Length Front: 850mm
 Kinetic energy distribution:
*Cable Length Rear: 1400mm
80%--Front two wheels
*Includes: Rotor, Hardware, Pads,
20%--Rear wheel
and Pre-Bled Caliper and Lever

25. CAD Models of Brake Concept
40% Brake 40% Brake Brake
Force Force Pad
Hydraulic
distributor Brake
Disc
Wheel
Handle
Bar
Parking
Brake
20% Brake
Force

26. Isometric View

27. Side View

28. Front View

29. Top View