Scooterizers
Detailed Design Review
“Making last-mile transportation safer, easier, and more efficient”
1
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
2
Project Goals
The goals of this project are twofold:
• Produce a prototype scooter that is lightweight
and foldable, easy to use, and provides an
electronic boost for uphill travel.
• Provide future design teams with a database of
knowledge, so that they can benefit from our
project learning and experience.
3
Project Specifications
General
Specific
Acceptable Ranking
Efficiency
Total system efficiency.
> 51%.
2
3
Weight
Human Input
Must be lightweight; easy to carry.
Must have intuitive human input and
control. Have both mechanical and
regenerative brake controls.
< $750.
Ultracapacitors
provided by
Energy
IVUS.
Storage/Propulsion Must store electrical energy.
Collapsible
The scooter frame must be foldable, and frame with
the propulsion and regeneration systems brake
should be transparent to the user.
regeneration.
Ease of Use
Total Scooter Cost
Must be affordable.
20lbs.
Twist throttle
and
handbrakes.
2
1
2
3
4
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
5
Project Deliverables from First Semester
1. Model the Electrical System
2. Improve Voltage Regulation / Protection Circuits.
3. Add Parallel-Series Ultra-Capacitor Switching Circuit.
4. Combine the Fragmented Control System.
5. Add Variable Throttle / Regenerative Brake Control.
6. Add a Clutch to the current Motor System
6
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
7
Model the Electrical System
Why:
• To make the project well documented.
• To make it easy to test, assemble and validate.
What do we mean?
Any diagram, circuit, chart or graph has to be:
• Clear.
• Well explained.
• Tested.
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
9
Variable Throttle and Brake
(Jet- Tread’s Choice)
Thumb throttle
Options
• Push Button
• Linear Motion
Potentiometer
• Rotational Motion
Potentiometer
Colin
10
Variable Throttle and Brake
(Scooterizers’ Choice)
Twist throttle
Specifications
•
•
•
•
•
•
•
•
•
Item Code: Throttle-ES (Hole Effect Type)
Price: $ 24.99 + tax
Supply Voltage: 12v
Return Voltage: 4v
Handle Bar Diameter: (approx) 22mm /
7/8"
Three wires red, green, black
The supply voltage = red and black
wires.
Green wire voltage increases as the
throttle is turned.
Fits 24 and 48v scooters.
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
12
Clutch for the Motor
Reell Precision Manufacturing
Miniature Electromechanical Clutch
Model: EC30XP
Cost: $77.82
Accelerate loads from zero to full speed
in less than three milliseconds. Apply
electricity and these clutches rapidly
engage; turn off the power, and they
instantly disengage. Due to the rapid
acceleration and nonslip design of these
clutches, some applications may need a
slip clutch, coupling, or other shockabsorbing device. These clutches drive in
one direction only. Max. rpm is 1400.
They operate on 24 VDC and include wire
leads for hardwiring
Design Characteristics
Technology
Application Considerations
Electromechanical wrap spring clutch
Single
Direction
Low Wattage
The EC30XP requires only 3.5 watts of
power for engagement
The EC30XP provides 3.39 N-m (30 lbHigh Torque,
in) of total load over a life of 1 million
Small Package actuations with an outside diameter of
Size
about 33mm (1.3 inches), and a shaft
length of about 27mm (1 inch).
Rapid
Acceleration
After spring wrap-down, the EC30XP
will accelerate loads from zero to full
speed in less than 3 milliseconds.
Consistent
Performance
Engagement is made with virtually no
slippage and disengagement is almost
instantaneous.
Power Source
All Reell clutches operate on either
filtered or unfiltered dc power. The use
of filtered power is recommended for
better life at high speed.
Wrap spring clutches provide torque only in the
direction in which they wrap down. This allows
for overrunning.
Due to the EC30XP's rapid acceleration, system
inertia effects can be significant. In some
Relative High applications an in-line slip device may be used
Shock
for shock absorption. Please contact a Reell Sales
Representative for more information regarding
this option.
Engagement
Relative to
Speed
The EC30XP relies on relative motion between
the input and output for engagement. Thus, the
slower the speed, the longer the time until
engagement.
Operating
Parameters
EC30XP performance is best within the following
conditions:
•0°- 40° C (32°-104° F)
•100-800 rpm typical, 1400 rpm max.
•Minimum load friction torque 0.05 N-m (6.0 ozin) plus customer input bearing torque.
Colin
14
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
15
Control and Electrical Introduction
• Lacked good voltage regulation
• Lacked current limiting
• No master control system
RESULT:
Reliability and usability issues
16
17
18
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
19
Simplify Series-Parallel Switch
Jet-Tread Series-Parallel Switch
PROBLEM: Hard to use
20
Simplify Series-Parallel Switch
USAGE SCENARIOS
Regenerative Mode:
• 2.7Vdc
Drive Mode:
• 24.3Vdc (9*2.7Vdc)
21
Simplify Series-Parallel Switch
Design No. 1: SPDT Relay
Design No. 1: SPST Relay
SPST Switch
SPDT Switch
22
Simplify Series-Parallel Switch
Design Choice: Design No. 1 (SPDT Relays)
• Cheapest
• Most Reliable
• Fewest Points of Failure
23
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
24
Circuit Protection Mechanisms
• Electrical Isolation
• Voltage Regulation
• Current Limitation
25
Circuit Protection Mechanisms
Electrical Isolation
KISS: SPDT Relays!
SPDT Switch
26
Circuit Protection Mechanisms
Voltage Regulation
Drive Mode
• 12-24Vdc Input
• 12Vdc Output
Regenerative Mode
• 0-15Vdc Input
• 2.7Vdc Output
27
Circuit Protection Mechanisms
Voltage Regulation
Drive Mode
Custom Design: Best idea, but lacking time/expertise
Commercial Solution: EXPENSIVE
Inverter-Power Supply Combo: Best fit for this project
28
Circuit Protection Mechanisms
Voltage Regulation
+
Inverter-Power Supply Combo: Best fit for this project
29
Circuit Protection Mechanisms
Voltage Regulation
Regenerative Mode
30
Circuit Protection Mechanisms
Current Limitation
Current Limiter: MOSFET + Microcontroller Solution
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
32
Combine the Control System
Modularity = Future Usability
SOLUTION: Have several minor control systems under
the direction of master control system
Utilize ATMega48 Chips
• Very cheap ($2)
• 21 I/O Points
• PWM
• ADCs
• Expandable
33
Combine the Control System
34
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
35
Project Budget
WHAT
24V NiMH 2000Ah Battery
24V NiMH Battery Charger
5V Regulator
ATMega48 Chip
16 SPDT 40A Relays with 24V Coil
ATMega48 Chip
3 Relay Driver ICs
5V Regulator
150Watt 10 Ohm Resistor
5V Regulator
ATMega48 Chip
SPST 40A Relays with 24V Coil
Relay Driver IC
5V Regulator
ATMega48 Chip
3 SPDT 40A Relays with 24V Coil
1 Relay Driver IC
LM7812C Voltage Regulator
Various Small Capacitors/Resistors
3 TIP2955 Transistors
5V Regulator
ATMega48 Chip
SPDT 40A Relays with 24V Coil
Relay Driver IC
Used Computer Power Supply
24Vdc/240Vac Inverter
Power MOSFET
5V Regulator
ATMega48 Chip
MOSFET Driver IC
Sense/Shunt Resistor
Shipping Costs
Manual PCB Costs
Wiring
Other Components
PCB Costs
SYSTEM
Control
Control
Control
Control
UltracapCircuit
UltracapCircuit
UltracapCircuit
UltracapCircuit
UltracapCircuit
ClutchCircuit
ClutchCircuit
ClutchCircuit
ClutchCircuit
MotorCircuit
MotorCircuit
MotorCircuit
MotorCircuit
RegenCircuit
RegenCircuit
RegenCircuit
RegenCircuit
RegenCircuit
RegenCircuit
RegenCircuit
DriveCircuit
DriveCircuit
DriveCircuit
DriveCircuit
DriveCircuit
DriveCircuit
DriveCircuit
ALL
ALL
ALL
ALL
ALL
TOTAL
Electromechanical Clutch
Twist Throttle
COST
34,99
29,99
0
2,84
46,56
2,84
1,2
0
10
0
2,84
2,91
0,4
0
2,84
8,73
0,4
5
10
10
0
2,84
2,91
0,4
5
40
5
0
2,84
5
23,95
40
30
30
50
80
489,5
Motor
Machine Interface
77,82
31,94
TOTAL
109,8
COMBINED TOTAL
599,2
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
37
Project Risks and Scope
Future-Proof Designs: (Place Most Effort)
Modular Control System
Durable Series-Parallel Switch Design
Throttle/Brake/Clutch Controls
System Modeling
Need Future Design Work:
Drive-mode Power Supply
Regenerative-mode Power Supply (possibly)
Motor (hub?)
Frame
Risk: Variable Regenerative Brake
The regenerative break itself will be implemented. However, we may
not have time to make it variable. This will be done given enough time.
38
Review of First Semester
Project Deliverables
1. Model the Electrical System
2. Variable Throttle and Brake
3. Clutch for the Motor
Control/Electrical Overview
4. Simplify Series-Parallel Circuit
5. Circuit Protection Mechanisms
6. Combine the Control System
Project Budget
Project Risks
Project Schedule
39
Project Schedule
Detailed Design Review
[October 8]
Order Parts
[Early October]
Individual Fabrication
Individual Assembly
[Mid/Late October]
Final Assembly
[Early/Mid November]
Client Review
[November 19]
Documentation
Knowledge Database
[November/December]
40
Questions?
41