scooterizers detailed design review

Scooterizers Detailed Design Review

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

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Review of Project Goals and Specs

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 Breakdown

Project Risks and Problems

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 Schedule


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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.6. Add a Clutch to the current Motor System

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Project Schedule

Model the Electrical System

What has been done ?• We came up with simply circuits to test each

component separately• Fortunately, all work GREAT• Each component will be connected to other

components with confidence• Will be completely done by the time of

submitting the final report

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Project Schedule

Variable Throttle and Brake(Scooterizers’ Choice)

Twist throttle

Specifications

• Item Code: Throttle-ES (Hole Effect Type)

• Price: $ 24.99 + tax• Supply Voltage: 5Vdc • Voltage on Full: 4.27Vdc• Voltage on Zero: 827milivolts • Green wire voltage increases as the

throttle is turned• 6mA maximum current

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Project Schedule

Clutch for the Motor

Miniature Electromechanical Clutch

From Reell Precision Manufacturing

Pros:•Lightweight•Small•Easy to integrate into existing design•Works well with this scooter’s various user scenarios

Cons:•Requires 24 Volts to function•Needs a human interface or remote sensor to activate•Electronic Leads must be securely fastened to avoid damaging the clutch

Fabrication and Integration• Mill a new mounting plate

for the motor and drive train

• Manufacture a new input shaft adapter for the clutch

• Securing the wire leads

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Project Schedule

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Project Schedule

Simplify Series-Parallel SwitchJet-Tread Series-Parallel Switch

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Simplify Series-Parallel Switch

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SPDT Relay

SPDT Switch

• 12 Relays• 30 Amps Current• 15ms Switch Time• 2.7Vdc Parallel Mode• 13.5Vdc Drive Mode

Simplify Series-Parallel Switch

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• Preliminary tests using batteries indicates an extremely low or nil voltage drop through the system.

• Testing with Ultracapacitors is needed• Testing in regen mode with the motor is needed

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Project Schedule

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Circuit Protection Mechanisms

• Electrical Isolation• Voltage Regulation• Current Limitation

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Circuit Protection MechanismsRelay Circuit 1:Prevent ESC Destruction when in Regen mode

Status: Partially assembled (to be finished soon)

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Circuit Protection MechanismsRelay Circuit 2:Prevent damage to Ultracapacitors when in Regen mode

Status: Partially assembled (to be finished soon)

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Project Schedule

Combine the Control System

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Modularity = Future Usability

Have several minor control systems under the direction of master control system

• Regen Control System• Clutch Control System• Master Control System• Ultracapacitor Control System• Motor Control System


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Regenerative Control System• ADC hardware to sense Ultracapacitor circuit voltage


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Regenerative Control System• Analog comparitor to sense if H-bridge voltage ever goes

higher than 2.7Vdc while in regen mode


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Clutch Control System• Receives signal from Master Control System when throttle is

sensed, and activates the clutch


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Master Control System• Interprets signal from throttle and regen brake button, then

sends commands to other control system circuits.

No Throttle1ms Pulse

Full Throttle2ms Pulse


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Master Control System – Interface with ESCRequired extensive reverse-engineering

No Throttle1ms Pulse

Full Throttle2ms Pulse


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Ultracapacitor Control System• Receives signal from Master Control System when throttle is

sensed, and activates drive or regen configuration on UCB relays

• Assembly completed this weekend

Motor Control System• Receives signal from Master Control System when throttle is

sensed, and activates drive or regen configuration on UCB relays

• Assembly will be completed this weekend

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Project Schedule

Current Bill of Materials (BoM)

Purchased Items:Electromechanical Clutch

Twist Throttle

NiMH 24V Battery Pack

Battery Pack Charger

Shunt Resistor

Atmel ATMega48 Chip (8)

Relays (21)

Relay Drivers (8)

Additional Materials Acquired: Electrical Wiring

Chip Sockets

Aluminum Sheet Metal Stock Brass

Stock

Project Budget

McMaster CC Z0729924 $ (82.52)Scooter Catalog CC $ (31.94)McMaster CC Z0729924 $ (82.49) credit $ 82.52 Digikey CC $ (15.76)Allied CC $ (20.52)All Battery CC $ (74.17)RC Electronics CC $ (35.40)Digikey Colin $ (109.67)

-369.95

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Project Schedule

Project Risks and Scope

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Systems we will not be able to deliver:• DC/DC1 Power Supply• Current Limiter• DC/DC2 Power Supply


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DC/DC1 Power Supply

• Idea was tested• Voltage level on DC/AC inverter did not act as expected• Finding: Oscillators controlling AC output shut down abruptly

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Current Limiter

• Idea has been evaluated by EE grad student• Current limiter would need a prohibitively large heatsink• Not enough time resources


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DC/DC2 Power Supply (control voltage level during regen)

• Not enough time to implement• Voltage control is managed by regen circuit microcontroller

Previous Project Risks and Scope

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Perceived Risks:• Unexpected problems with the Electronic Speed Controller means

that we will have to shift focus to getting it to work.• This will use a lot of extra time resources.

Need Future Design Work:Drive-mode and Regenerative Mode Power Supplies (EE Oriented)Custom-Built Electronic Speed Controller (CompE, EE Oriented)

Future-Proof Designs: (Place Most Effort)Modular Control SystemDurable Series-Parallel Switch DesignThrottle/Brake/Clutch ControlsSystem ModelingClutch for Motor

THESE ARE STILL ON TRACK TO BE DONE ON TIME!

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Project Schedule

Project Schedule

Client Review [November 19 (Today)]

Finish Assembly [November 19-November 29]

Final Testing [November 29-December 3]

Documentation [December 3-December 9]Knowledge Database

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Questions?

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scooterizers detailed design review

Documents

project goals3

project deliverables6model

project learning

review of project goals

problems project schedule

specs project deliverables

seriesparallel circuit

fragmented control system