Scooterizers Detailed Design Review

Scooterizers Detailed Design Review

“Making last-mile transportation safer, easier, and more efficient”1

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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

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.

Project Goals

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Project Specifications

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General Specific Acceptable RankingEfficiency Total system efficiency. > 51%. 2

Weight Must be lightweight; easy to carry. 20lbs.3

Human Input

Must have intuitive human input and control. Have both mechanical and regenerative brake controls.

Twist throttle and handbrakes.

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Total Scooter Cost Must be affordable. < $750. 1

Energy Storage/Propulsion Must store electrical energy.

Ultracapacitors provided by IVUS.

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Ease of Use

The scooter frame must be foldable, and the propulsion and regeneration systems should be transparent to the user.

Collapsible frame with brake regeneration.

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Project Budget

Project Risks

Project Schedule

Project Deliverables from First Semester

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1. Model the Electrical System2. 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

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Project Budget

Project Risks

Project Schedule

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.

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Project Budget

Project Risks

Project Schedule

Colin 10

Variable Throttle and Brake(Jet- Tread’s Choice)

Thumb throttle

Options

• Push Button• Linear Motion

Potentiometer• Rotational Motion

Potentiometer

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.

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Project Budget

Project Risks

Project Schedule

Clutch for the MotorReell 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 shock-absorbing device. These clutches drive in one direction only. Max. rpm is 1400. They operate on 24 VDC and include wire leads for hardwiring

Colin 14

Design Characteristics

Single Direction

Wrap spring clutches provide torque only in the direction in which they wrap down. This allows for overrunning.

Relative High Shock

Due to the EC30XP's rapid acceleration, system inertia effects can be significant. In some applications an in-line slip device may be used 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 oz-in) plus customer input bearing torque.

Technology Electromechanical wrap spring clutch

Low Wattage The EC30XP requires only 3.5 watts of power for engagement

High Torque, Small Package Size

The EC30XP provides 3.39 N-m (30 lb-in) of total load over a life of 1 million actuations with an outside diameter of 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 SourceAll Reell clutches operate on either filtered or unfiltered dc power. The use of filtered power is recommended for better life at high speed.

Application Considerations

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Project Budget

Project Risks

Project Schedule

Control and Electrical Introduction

• Lacked good voltage regulation• Lacked current limiting• No master control system

RESULT:Reliability and usability issues

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Project Budget

Project Risks

Project Schedule

Simplify Series-Parallel Switch

PROBLEM: Hard to use

Jet-Tread Series-Parallel Switch

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USAGE SCENARIOS

Regenerative Mode: • 2.7VdcDrive Mode:• 24.3Vdc (9*2.7Vdc)

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Design No. 1: SPDT Relay Design No. 1: SPST Relay

SPST SwitchSPDT Switch

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Design Choice: Design No. 1 (SPDT Relays)• Cheapest• Most Reliable• Fewest Points of Failure

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Project Budget

Project Risks

Project Schedule

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Circuit Protection Mechanisms

• Electrical Isolation• Voltage Regulation• Current Limitation

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Circuit Protection MechanismsElectrical Isolation

KISS: SPDT Relays!

SPDT Switch

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Circuit Protection MechanismsVoltage Regulation

Drive Mode• 12-24Vdc Input• 12Vdc Output

Regenerative Mode• 0-15Vdc Input• 2.7Vdc Output

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Custom Design: Best idea, but lacking time/expertiseCommercial Solution: EXPENSIVEInverter-Power Supply Combo: Best fit for this project

Drive Mode

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Inverter-Power Supply Combo: Best fit for this project

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Circuit Protection MechanismsVoltage RegulationRegenerative Mode

Circuit Protection MechanismsCurrent Limitation

Current Limiter: MOSFET + Microcontroller Solution

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Project Budget

Project Risks

Project Schedule

Combine the Control System

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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

Combine the Control System

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Project Budget

Project Risks

Project Schedule

Project BudgetWHAT SYSTEM COST24V NiMH 2000Ah Battery Control 34,9924V NiMH Battery Charger Control 29,995V Regulator Control 0ATMega48 Chip Control 2,8416 SPDT 40A Relays with 24V Coil UltracapCircuit 46,56ATMega48 Chip UltracapCircuit 2,843 Relay Driver ICs UltracapCircuit 1,25V Regulator UltracapCircuit 0150Watt 10 Ohm Resistor UltracapCircuit 105V Regulator ClutchCircuit 0ATMega48 Chip ClutchCircuit 2,84SPST 40A Relays with 24V Coil ClutchCircuit 2,91Relay Driver IC ClutchCircuit 0,45V Regulator MotorCircuit 0ATMega48 Chip MotorCircuit 2,843 SPDT 40A Relays with 24V Coil MotorCircuit 8,731 Relay Driver IC MotorCircuit 0,4LM7812C Voltage Regulator RegenCircuit 5Various Small Capacitors/Resistors RegenCircuit 103 TIP2955 Transistors RegenCircuit 105V Regulator RegenCircuit 0ATMega48 Chip RegenCircuit 2,84SPDT 40A Relays with 24V Coil RegenCircuit 2,91Relay Driver IC RegenCircuit 0,4Used Computer Power Supply DriveCircuit 524Vdc/240Vac Inverter DriveCircuit 40Power MOSFET DriveCircuit 55V Regulator DriveCircuit 0ATMega48 Chip DriveCircuit 2,84MOSFET Driver IC DriveCircuit 5Sense/Shunt Resistor DriveCircuit 23,95Shipping Costs ALL 40Manual PCB Costs ALL 30Wiring ALL 30Other Components ALL 50PCB Costs ALL 80

TOTAL 489,5

Electromechanical Clutch Motor 77,82Twist Throttle Machine Interface 31,94

TOTAL 109,8

COMBINED TOTAL 599,2

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Project Budget

Project Risks

Project Schedule

Project Risks and Scope

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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.

Future-Proof Designs: (Place Most Effort)

Modular Control SystemDurable Series-Parallel Switch DesignThrottle/Brake/Clutch ControlsSystem Modeling

Need Future Design Work:Drive-mode Power SupplyRegenerative-mode Power Supply (possibly)Motor (hub?)Frame

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Project Budget

Project Risks

Project Schedule

Project ScheduleDetailed Design Review [October 8]

Order Parts [Early October]

Individual Fabrication [Mid/Late October]Individual Assembly

Final Assembly [Early/Mid November]

Client Review [November 19]

Documentation [November/December]Knowledge Database

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Questions?

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Scooterizers Detailed Design Review

Documents

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