Brian Saghy (CE) - Team Leader

Alejandro Lam (EE)

Gaurav Patel (ME)

Brian Payant (EE)

Nathan Pendleton (EE)

Multidisciplinary Engineering

Senior Design - Project 05400

Sustainable Platform Development for Self-positioning Microsystems

Utilizing Magnetic Field Propulsion

Critical Design ReviewNov 11, 2005

Coordinator:

Dr. Edward Hensel

Team Mentor & Sponsor:

Paul Stiebitz

Presentation Overview

• Introduction

• Process Overview

• Design & Testing Details

• Budget Report

• Project Schedule

• Future Recommendations

• Conclusion

• Questions

Project Introduction and History

Swarms of small, intelligent objects can form a seemingly larger shape.

Future MEMS technology could make for microscopic robot.

Review of SD1

Previous Work

Does not work due to lack of static friction in fluid, and symmetric design.

Inertial DriveMagnetic Field

Propulsion

3D control issues

Non-robust design

Review of SD1

Magnetic Field Propulsion

•Tank has six high power magnetic coils on each side

•Chunxil drives itself by turning on internal coils to attract it to the desired wall

•Chunxil is able to determine location in tank by the strength of the EMF fields induced by the external coils

Review of SD1

Timing Diagram

N S E W F B N S E W F B W

N S E W F B N N S E W F B B N

S E W F B E N S E W F B S N S

E W F B F N S E W F B N N S E

Wake Up Signal Post Wake Up Delay Sleep Timer Running

North AC Signal Asserts Interrupt

DC Period

Sleep Delay

Review of SD1

SD2 Focus and Objectives

•Primary goals include assembly ease, modularity, re-programmability and charging ease.•Scalable mechanical and electrical engineering model which could be implemented using current & future small-scale technologies.•Utilize improvements over the last few years in microcontrollers and batteries•Start with small steps, rather than trying to tackle the whole project at once.

Process Overview

• Concept Development of Magnetics & Chunxil Design. Brainstorming (SD1)

• Feasibility Assessment of individual components (SD1)

• Analysis of Components (SD1/2)

• Engineering Model (SD2)

Desired Outcomes

• Ability to recharge the battery without opening the Chunxil

• Ability to change the Chunxil's control software without having to open/rebuild the Chunxil

• Ability to attach a debugger to the Chunxil while in operation

• Easier physical modification of Chunxil coils and battery, if necessary.

• Positioning control within a limited 1-dimension in the tank

Mechanical Design

Tank Design

Chunxil Axis Limiter

Chunxil Cube

Chunxil Assembly

Charging/Programming Station

Software & Microcontroller

Design and Testing

Microcontroller Requirements

Desired Traits:

•Reprogrammable

•Low Power

•Backward compatible with current code

•High Resolution A-D Converter

•Programmable in-circuit

FeaturesPIC

16LC716[Previous

Generation]

PIC 16F88[Current

Generation]

In-CircuitRe-

Programmable

No[single use]

Yes

RAM 128 Bytes 368 Bytes

Flash DataMemory

[holds dataduring power

loss]

No 256 Bytes

A/D precision 8 bits 10 bits[4x more

data]Software

Debugging No YesInstructionMemory

2048words

4096words

Low Poweroperation No YesI/O pins 13 16

Microcontroller Upgrade

PIC Pinout

PIC Engineering Model

Chunxil Software Flowchart

Chunxil Electronics

 

Chunxil PCB Design

Coil Design

AC Position Sensing

+/-4.5mV Corner of Coil6"

+/- 58mV Corner of Coil0.25"

+/- 6mV Center of Coil6"

+/- 68mV Center of Coil0.25"

InducedVoltage Alignment

Distance fromTank Coil

Voltage Regulator

PCB Layout

Component Packages

Assembly

Power, Programming, Debugging,& Charging

Power & Programming Requirements

• A Chunxil must be able to make 3 trips across the tank.

• The battery must be rechargeable, & able to recharge in less than 5 hours.

• A Chunxil shall be recharged, reprogrammed & debugged without being disassembled.

• All Chunxils must conform to a common interface standard, such that a universal reprogramming, recharging, and debugging method can easily be used for all Chunxils.

Deliverables

• A power source (battery) capable of providing ample power.

• A recharging method which is auto-controlled and easy to use.

• A reprogramming dock which allows data, debug, and power access to the microcontroller without opening the Chunxil case.

Power Consumption

ComponentMaximum

Current (mA)Expected

Time On (%)Net Power Usage(mA x 3V= mW)

Micro-controller 1 100% 3

Op-amps 1 x4 Op-Amps 70% 8.4

Transistor Base 2.6 50% 4

Chunxil Coil 90 50% 135

MiscellaneousLoss

3 100% 9

Voltage Regula-tor

1 100% 3

Total Power Consumed 162.4

Battery Specifications

• LiR2032 Rechargeable Li-Ion coin cell• 3.6 V nominal voltage• 35mAh nominal capacity• 70mA Max. drain current• Dimensions: 20mm dia. x 3.2mm thick• Mass: 3.0 grams• Unit price: $1.26 per cell

Recharging Parameters

• The LiR-2032 can be recharged at 17mA per cell [constant current].

• A stand-alone Li-Ion charging microchip was found to be a good solution.

• The Linear Technologies LTC1733 is capable of providing 1A of constant current, and does not require an external MOSFET or current sensing resistor.

Connector Port Parameters

• The PIC 16F88 requires five (5) lines for programming [+3V, GND, PgC, Pgd, MCLR]

• Two (2) lines are needed for charging [Bat_Plus, GND]

• The GND line is shared for charging & programming.

• The Chunxil dock connector was chosen to be 8 pins, to allow for future expansion & keyed operation.

Docking Station

• [get mechanical drawing or actual picture of drawing station.]

Tank ElectronicsRedesign

Tank Electronics

• Power controls where modified to allow polarity change, which implies a direction change of the magnetic field.

• General testing was performed on the tank power supply system. Yielding a need to replace a faulty power supply.

• Unreliable wiring was replaced using proper wiring techniques.

• Safety concerns where addressed with respect to protecting the electronics and the user

Tank Electronics Schematic

AC or DC

5Vdc

5Vdc

5Vdc

CTRL2

CTRL1

CTRL3

+

-

Tank Controls Layout

Tank Electronics Hardware

Budget Report

Schedule at Beginning of Quarter

Actual Schedule Followed

Future Recommendations & Ideas

•Wait to decrease size until after controls in 3D completed

•Increase size of tank coils for better multi-dimensional control

•Switch to using hall-effect sensors for position measurement, eliminate AC cycle

•Recharging and Programming using only inductors (No physical Connection)

• Wireless control of the Chunxil

• Use of multicolor LED’s inside, for color replications. Will add realism to the shape formed

Conclusion

● Proved to be very a challenging project

● Were able to overcome several obstacles

● Design should allow for easier transition of new groups to this project.

● Though we fell somewhat behind schedule, a working model is expected by the time of the demo in one week.

Questions?

Thank You

Sneaker Slides

PIC Feasibility AssessmentEvaluate each additional concept against

the baseline, score each attribute as: 1

= much worse than baseline concept 2 =

worse than baseline 3 = same as

baseline 4 = better than baseline 5=

much better than baseline

Cur

rent

( P

IC16

C17

6)

PIC 1

6F819

Pic

16F88

Pic

18F13

20

TI

MS

P430F11

3

Rel

ativ

e W

eigh

t

Suffi cient Student Skills? 3.0 3.0 3.0 3.0 1.0 2%

Size/ Weight/ Nano-Feasibility 3.0 3.0 3.0 2.0 1.0 13%

Cost of Chips 3.0 3.0 3.0 2.0 3.0 8%

Cost of Programmer,Burner, and Sof tware 3.0 3.0 3.0 3.0 1.0 3%

Compatible I SA 3.0 2.0 2.0 1.0 1.0 10%

Compatible Pin Layout/ Voltages 3.0 2.0 2.0 2.0 1.0 5%

Memory (Flash, Ram) 3.0 4.0 5.0 5.0 5.0 13%

Program in-circuit 3.0 5.0 5.0 5.0 5.0 12%

Suffi cient bit-ADC 3.0 4.0 4.0 4.0 4.0 18%

Power Usage 3.0 5.0 5.0 4.0 1.0 15%

Hardware Multiplier 3.0 3.0 3.0 5.0 5.0 3%

Low-Power Programming 3.0 5.0 5.0 3.0 5.0 5%

Weighted Score 3.3 4.1 4.2 3.7 3.1

Normalized Score 77.7% 96.8% 100.0% 88.0% 74.9%

Cube Feasibility Assessment*Evaluate each additional concept against

the baseline, score each attribute as: 1

= much worse than baseline concept 2 =

worse than baseline 3 = same as baseline

4 = better than baseline 5= much better

than baseline

Cur

rent

Chu

nxel

Cub

e (6

Sep

arat

e

Sid

es)

Prot

otyp

e 1:

Tw

o

shel

ls p

ut t

ogue

ther

Prot

otyp

e 2: U

se o

f

Exi

stin

g

Com

mer

cial

ly

Ava

ilable

1*1

*1 inc

h

Rel

ativ

e W

eigh

t

Chunxil Cube Size 3.0 1 5 25%

I nner Space for other components 3.0 2 4 21%

Waterproofi ng Capabilities 3.0 3 3 18%

Cost of Purchased Components? 3.0 4 2 4%

Ease of Assembly of a Full Chunxil

Everything I nside 3.0 2 4 7%

Modularity of Physical Parameter 3.0 3 3 7%

Nesting Ability 3.0 4 2 4%

Charging and Programming I nterface 3.0 5 1 14%

Weighted Score 3.0 2.6 3.4

Normalized Score 87.5% 75.0% 100.0%

Stabilization of Chunxil AxesFeasibility Assessment

Battery Feasibility Assessment

78.2%89.1%89.1%100.0%83.2%Normalized ScoreNormalized Score

2.83.23.23.63.0Weighted ScoreWeighted Score

       

7% 45553.0Price ($)Price ($)

4% 33333.0Average Lifespan (cycles)Average Lifespan (cycles)

0% 55443.0Internal Impedance (ohms)Internal Impedance (ohms)

21% 55443.0Max. Discharge rate [continuous] (mA)Max. Discharge rate [continuous] (mA)

18% 32113.0Normal Capacity (mAh)Normal Capacity (mAh)

11% 44443.0Voltage (v)Voltage (v)

25% 13453.0Size (mm)Size (mm)

14% 11233.0Weight / Mass (grams)Weight / Mass (grams)

Rela

tive W

eig

ht

Rela

tive W

eig

ht

  LIR2477LIR2477LIR2450LIR2450LIR2430LIR2430LIR2032LIR2032

[Presumed][Presumed]SanyoSanyo

CR-1/3NCR-1/3N

Evaluate each additional concept against

the baseline, score each attribute as:

1 = much worse than baseline concept2 = worse than baseline3 = same as baseline4 = better than baseline5 = much better than baseline

Coil Winding

Stabilization of Chunxil Axes

1) Widen Tank CoilsAdvantages:

Straighten Field Lines Inside Tank.

Increase Visibility

Disadvantages:

Physical Modification of Tank

Invalidate Past EMF Values

Wiki

•Online Collaboration

•Easy to edit

•Accessible from Anywhere

2 Coil Chunxil Model

Stabilization of Chunxil Axes

2) Simultaneous Activation of Opposite Coils Inside Chunxil

Advantages:

Greater Resistance to Spin

Opposing Field Directions on Opposite Chunxil Faces

Disadvantages:

Greater Power Consumption in Chunxil

More Complex Circuitry

More Complex Mathematical Model

1 Coil Chunxil Model

2 Coil Chunxil Model

Stabilization of Chunxil Axes

2) Simultaneous Activation of Opposite Coils Inside Chunxil

Advantages:

Greater Resistance to Spin

Opposing Field Directions on Opposite Chunxil Faces

Disadvantages:

Greater Power Consumption in Chunxil

More Complex Circuitry

More Complex Mathematical Model

Stabilization of Chunxil Axes

3) Simultaneous Activation of Opposite Coils On Tank

Advantages:

Straightens Field Lines Inside Tank

Disadvantages:

Needs Two Coils Inside Coil Activated

Greater Chance of Chunxil Spinning on “Pushing” Half of the Tank

More Complex Tank Circuitry

More Complex Mathematical Model

Stabilization of Chunxil AxesHybrid Model

Movement Cycle External InternalE W E W

West to East - West Side of Tank 1a + On On1b + - Off Off

West to East - East Side of Tank 1a + On On1b + - On On

+ = “Pulls Toward”

- = “ Pushes Away”

Velocity Control

• Increase Tank Coil Diameters

• Decrease Current

• Lessen # of Turns on Coil

• Pulse Coils

Proteus Gen 1B Navigation ControlDifference = North Voltage – South Voltage

NO

RT

H C

OIL

SO

UT

H C

OIL

X Position

50mV

40mV

30mV

20mV

10mV

Target: Difference=30mV

D=20mV

D=0mV

D=40mV

D=30mV

Review of SD1

Initial Battery saver circuit

Re-Designed Op-Amp circuit

Other Improvements

Coil Control Circuit

Tank Electronics

AC or DC

5Vdc

5Vdc

5Vdc

CTRL2

CTRL1

CTRL3

+

-