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Spring Final Review (SFR)

Geocentric Heliogyro Operational Solar-sail Technology (GHOST)

April 29th, 2014

Nicholas Busbey, Mark Dolezal, Casey Myers, Lauren Persons,

Emily Proano, Megan Scheele, Taylor Smith, Karynna Tuan

Presentation Sections

• Project Overview

• Design Solution

• Test Overview

• Test Results

• Systems Engineering

• Project Management

2

1 Overview Design Solution Test Overview Test Results Systems Eng. Project Mgmt.

Background - HELIOS

• Solar-sails use momentum transfer for

propellant-less propulsion

• High Performance Enabling Low-cost

Innovative Operational Solar Sail (HELIOS) NASA project of low-cost heliogyro flight demonstrations

Heliogyro sails (blades) are gyroscopically stiffened

No ground-based tests have been successfully performed

Main Objectives

Validate heliogyro deployment technologies

Show controlled heliogyro solar sail flight

Characteristic acceleration larger than 0.5 mm/s2

Validate structural dynamics

Determine orbit changing capabilities

• GHOST project is extension of HELIOS Concentrates mainly on CubeSat structural design

Main tests include deployment and pitching of solar-

sail blades in 1g environment

rotation

2

HELIOS Design

Overview Design Solution Test Overview Test Results Systems Eng. Project Mgmt.

1g controlled deployment of solar sails

• Suspend CubeSat in 1g environment

• Establish connection and initiate deployment

mechanism using motors

• Measure controlled sail deployment

Concept of Operations

GHOST project responsible for deployment and

pitching validation:

1) Controlled Solar Sail Deployment

2) Solar Sail Root Pitch Control

1g pitch control of blade reel module

• Establish connection to pitching mechanism

• Send appropriate pitch command

• Measure resulting pitch angle

Measure actual pitch angle and compare to

expected pitch angle


Project Purpose and Specific Objectives

• Purpose: Design, build, and test a heliogyro solar sail deployment and pitching mechanism housed in a 6U CubeSat to improve current technology

• Top Level Objectives and Requirements:

GHOST_001: Deploy a heliogyro solar sail in a 1g environment at a controlled rate between 1 and 10 cm/s

GHOST_002 : Pitch solar sail blades in a repeatable periodic motion within error margin of 5˚

GHOST_003: House adequate length of solar sail to achieve minimum characteristic acceleration of 0.1 mm/s2

GHOST_004: Withstand static loads experienced from contact points within the Canesterized Satellite Dispenser (CSD) during launch and ejection from CSD

GHOST_005: Deployment and pitching system shall not exceed 10W



• Project Overview • Design Solution

Functional Block Diagram

Mechanical

Electrical

Software

• Test Overview • Test Results • Systems Engineering • Project Management

6


Functional Block Diagram CubeSat Bus

CDH Pitch Servo

Motor

Gear

Blade Reel

Module

BPCS SSDM

Solar Sail

Pitch

VC

τM

τB

θ

Deployment

Stepper Motor

Shaft

Gear

System

τA

τC

τG

Solar

Blade

Power

Solar Sail

Deployment

Rea

lTer

m C

om

man

ds

Encoder

Angular Position

Step Pulse

Pitching

Software

Power

Ground Station

(User Input)

Deployment

Software

5 V Power Supply

EPS

3.5 V Power Supply

Direction and Rate

Overview Design Solution Test Overview Test Results Systems Eng. Project Mgmt. 6

Front View

C-Brackets Tip Mass

Top View Stepper Motor

Ball Bearing

Hub

Blade

Blade

Side View

Servo Motors/Encoders

Servo Motor

Clamps Motor Drivers

and PCB

“Launch Locks”

Mechanical Overview

Theoretical (kg) Measured

(kg)

BRM Total 2.062 2.012

CCM Total 1.694 + driver 1.490

CubeSat Total 3.756 + driver 3.502

Mass Summary

30 cm

Blade Reel

Module (BRM)

Central Control

Module (CCM)


Component Mass Summary

Theoretical (kg) Measured (kg)

BRM Walls 1.160 1.110

CCM Walls 0.980 0.923

Blade Stabilizers 0.080 0.062

Corner Cubes 0.140 0.216

Deployment Axle 0.026 0.027

Pitching Axle and Hub 0.116 0.094

Tip Mass 0.148 0.148

C-Brackets 0.024 0.022

Misc. screws/nuts 0.135 0.135

BRM Structural Total 1.829 1.759

CCM Structural Total 1.213 1.047

Structural Shell Theoretical (kg) Measured (kg)

BRM Structural Total 1.829 1.759

CCM Structural Total 1.213 1.047

Stepper Motor 0.090 0.083

Servo Motor/Encoder 0.120 0.075

Mylar Blade 0.016 0.018

PCB 0.110 0.080

Servo Driver -- 0.056

BRM Total 2.062 2.012

CCM Total 1.694 + driver 1.490

Total 3.735 + driver 3.481

Total CubeSat


Electronics Overview

Microcontroller PIC18F programmed

and used to control the

stepper and servo driver

Stepper Driver Used to control the

direction and step number

of the stepper motor

BLDC Motor Equipped with HALL

and digital feedback

RJ-12 PicKit Interface for

Programming of

PIC18 Stepper Motor Used for blade

deployment

Servo Driver Used to drive the BLDC

motor through direction

and velocity control


Microcontroller PIC18F programmed

and used to control the

stepper and servo driver

Stepper Driver Used to control the

direction and step number

of the stepper motor

BLDC Motor Equipped with HALL

and digital feedback

RJ-12 PicKit Interface for

Programming of

PIC18 Stepper Motor Used for blade

deployment

Servo Driver Used to drive the BLDC

motor through direction

and velocity control

8

DIR

Speed Control

DIR STEP


Electronics Overview

Deployment Software

• Calculation performed every 48 steps (1 rotation)

Every one rotation reduces diameter by 2 ∗ 𝑡𝑚𝑦𝑙𝑎𝑟

𝑡𝑚𝑦𝑙𝑎𝑟 = 2.5 𝜇𝑚

• Length deployed with each rotation is recalculated after every 48 steps


𝑑𝑒𝑙𝑎𝑦𝑇𝑖𝑚𝑒 =𝑙𝑒𝑛𝑔𝑡ℎ𝑆𝑡𝑒𝑝

2π ∗ 𝑑𝑒𝑝𝑙𝑜𝑦𝑅𝑎𝑡𝑒

Determine Current

Circumference from Diameter:

D

Calculate Length Deployed:

D

D = Diameter

C = Circumference

L = Length Deployed

48 Steps = 1 Rotation

Mylar Roll

L

Step Angle

Mylar Being Deployed

Calculate delayTime Between 48

Steps Before Next 48 Steps:

C

D

L

C

CCM

BRM

Pitching Software

12

Σ [𝐴𝑜 − 𝑘𝜃𝑒] 𝜃

𝐴

1

𝑆

Optical

Encoder

𝜃𝑐 𝜃𝑎 𝜃𝑒

-

𝐴

Servo and Driver

Motor System

𝜃 𝑐 𝜃 𝑎

A = Maximum Amplitude

𝜃 = 𝐴 sin2𝜋𝑡

𝑃

𝜃 =2𝜋

𝑃𝐴 cos

2𝜋𝑡

𝑃

𝜃𝑒 𝑡 = 𝜃𝑐 𝑡 − 𝜃𝑎(𝑡)

𝜃𝑐(𝑡)

ê1

ê2

𝜃𝑎(𝑡)

𝐴

𝜃𝑎= Actual Angular Position 𝜃 𝑎= Actual Angular Velocity

𝜃𝑐 = Actual Command Position

𝜃 𝑐 = Actual Command Velocity

• Controller inputs maximum

Angle A

Period of rotation P

• Angle and period may be changed

dynamically


Blade Pitching Video

Time (s)

An

gu

lar

Po

siti

on

[d

egre

es]

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

40

45

Pitching Control System Concept


𝐴0

1. Given a

perturbation

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

40

45

𝑡1

1. Given a

perturbation

𝐴1 = 𝐴0 + 𝑘𝑒1

𝐴0

An

gu

lar

Po

siti

on

[d

egre

es]

Time (s)

• Amplitude changed by error

A = [𝐴𝑜 + 𝑘𝜃𝑒]


𝑃

𝜃 =2𝜋

𝑃𝐴 cos

2𝜋𝑡

𝑃

2. Commanded

Amplitude changes

𝑘𝑒1



𝑒1

• Angular rate accounts for error

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

40

45

𝑡1

𝐴1 = 𝐴0 + 𝑘𝑒1

𝐴0

An

gu

lar

Po

siti

on

[d

egre

es]

Time (s)

2. Commanded

Amplitude changes

Δ𝑡

𝑒2

3. Decreasing the

amplitude of the error

𝑡2

Note: time step magnitude not reflective of actual time times

𝐴1 = 𝐴0 + 𝑘𝑒2



1. Given a

perturbation

𝑒1




𝑃

𝜃 =2𝜋

𝑃𝐴 cos

2𝜋𝑡

𝑃

• Angular rate accounts for error 𝑘𝑒2

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

40

45

𝑡1

𝐴1 = 𝐴0 + 𝑘𝑒1

𝐴0

An

gu

lar

Po

siti

on

[d

egre

es]

Time (s)

2. Commanded

Amplitude changes

Δ𝑡

3. Decreasing the

amplitude of the error

𝑡2

Note: time step magnitude not reflective of actual time times Δ𝑡

𝑡3

4. Error dampens to

infinitesimal limit

𝐴1 = 𝐴0 + 𝑘𝑒2






𝑃

𝜃 =2𝜋

𝑃𝐴 cos

2𝜋𝑡

𝑃

• Angular rate accounts for error

1. Given a

perturbation

𝑒1

𝑒2

Major Changes Since TRR

• LIN Protocol - Local Interconnect Network

Unable to find documentation regarding driver internal

MCU and LIN driver

Servo driver > 20 years old, not supported by ATMEL

Unable to set servo driver/motor resolution

• Unable to program PCB designed for system Fell back to PIC18F452

Not enough I/O ports for pitching and deployment together

Greater power usage

Focused on basic pitch and deployment requirements

• Cut out Triangles in CCM and BRM


1. Manufacturing the solar sail and

determining thickness around the roll

so deployment is within +/- 1 cm/s

2. Programming the servo motor

with use of DAC to convert analog

to voltage

3. Aligning the deployment axle

perpendicular to the pitching axle

axis with tolerance of ~3.8˚ to avoid

toppling of spacecraft


Servo driver Deployment axle alignment

Critical Project Elements

Rolled solar blade

15

3.8˚



• Design Solution

• Test Overview Deployment

Pitching

Deflection

• Test Results



20


Centripetal Acceleration

Rotation Rate Ω = 1 RPM

Orbital Trajectory

Vtip

Ω

Fg

Fc

Fg is negligible

Fc is centripetal force


Deployment

Length

(m)

Centripetal

Acceleration

(m/s2)

Sail

Mass

(kg)

Centripetal

Force

(N)

3.2 0.035 0.011 3.9×10-4

100 1.1 0.058 0.064

200 2.2 0.11 0.23

300 3.3 0.15 0.51

400 4.4 0.20 0.89

500 5.5 0.25 1.37

545 5.8 0.27 1.63

L

17

Space to Earth Comparison

CubeSat rotating at 1 RPM → centripetal acceleration → centrifugal tension

Blade is fully deployed → maximum centrifugal tension

Simulate same centrifugal tension blade would experience in space

Total blade mass of 18 g used in deployment test

mTotalSpace = 273.2 g

𝑭𝒕𝒊𝒑 = 1.63 N

mTotalEarth = 𝐹𝑡𝑖𝑝

𝑔 = 166.2 g

Space Application

Motor

CubeSat

rotating at

1 RPM

Blade

Tip mass

F

Top View

Tip mass trajectory

mTipMass = 148.2 g

F = mg

Ground Deployment

r

Mounted to

Scaffolding

Side View

Tip mass

Motor

Blade Front View


Blade

F = mg

Stabilizer

18

Deployment Test Overview

1. Command deployment at 5 cm/sec

2. Measure Deployment Rate

• Compare footage to expected rate

3. Repeated for variable rate testing

• Compare footage to predetermined

deployment profile


5V

Power

Supply

3.5V

Power

Supply

Testing Location: Fleming High Bay

1 m

2 m

3 m

Scaffolding

5 cm/s

CubeSat

Tape

Measure

Calibrate

camera to 3 m

window

Power on activates

holding torque

Remove tip

mass locks

Design Requirement: CubeSat shall demonstrate the capability to deploy a heliogyro solar sail in a 1g environment at a controlled, variable rate between 1-10 cm/s

Deployment Verification Tests

Test Design Requirement Objective

Deployment

System

Power

Check

• Deployment system

hardware does not

exceed 10W power

• Measure current and

voltage across

electrical components

individually

Variable

Deployment

Rate

• Deployment can be

stopped given user

command

• Deployment rate can be

changed given user

command

• Measure and compare

pulses of step output

pin using oscilloscope


Pitching Test Overview

Design Requirements: Blade Reel Modules shall pitch in a repeatable,

periodic motion and shall be theoretically capable of orbit changing, spin rate change, and attitude maneuvers within a 5˚ error

CubeSat software receives and responds to pitching maximum angle and period of motion from user


Testing Location: Aerospace

Instrumentation Shop

Angle Sensor

ADI516xxxIM4

(3 axis gyroscope)

5V

CubeSat

CCM

Plywood

Pitching Stand

BRM

1. Input predetermined pitch and period commands

via Realterm

2. Record data and compare to expected

performance and error tolerance

12V

Logic Power

Supply

Servo Motor

Power Supply

Pitching Verification Tests


Pitching

System Power

Check

• Pitching system does not

exceed 10W

• Measure current and

voltage across electrical

components individually

Variable Pitch

Period and

Amplitude

• Pitch profiles: collective,

1P, and ½P

• Pitching system capable

of rotating 180°

• Measure the angles rotated

by servo motor and

compare to predicted

models


Deflection Test

2. Add 169N (~38 lbs) to right BRM

• Worst case scenario from Planetary

Systems CSD launch specifications

3. Measure deflection of right BRM using

knee mill (measured at rightmost edge)

F

X-axis

F

d

Clamp left BRM to table

BRM BRM CCM

Pitching axle (gray) and

launch lock (purple)


Testing Location: Aerospace Machine Shop

24

Design Requirements: The CubeSat shall remain performance intact during the forces of launch in a standard CubeSat CSD

1. Measure zero point of right BRM using

manual knee mill

Deflection Verification Tests


Static Load CubeSat walls intact under

169N load

• Ensure that the structure

itself will not fail under

launch loads

Axial

Compression

CubeSat walls shall not fail

under a 44N compressive

force experienced by CSD

ejection

• CubeSat structure will

survive during CSD

ejection

BRM

Deflection

Blade reel modules shall

not deflect more than 0.3

inches during load of 169N

• The pitching axles will

not fail under worst case

scenario loads on BRM




• Design Solution

• Test Overview

• Test Results

Deployment

Pitching

Deflection



29

5 Overview Design Solution Test Overview Test Results Systems Eng. Project Mgmt. 26

Deployment Test Results

• Diameter of the blade decreases as

blade is deployed

Shorter length of blade is deployed

for each rotation

• Decreased delay time between steps

• RPM of stepper motor increases to

maintain constant deployment rate


# of Revolutions

Stepper Motor Spin Rate

Tim

e (s

)

27

Deployment Results

• Constant Average deployment rate (within 1 𝑐𝑚 𝑠 )

• Variable deployment rate capability

• Average deployment rate at 5 𝑐𝑚 𝑠

Deployment

Distance (cm)

Time (s) Desired

Rate (𝑐𝑚 𝑠 )

Average

Rate (𝑐𝑚 𝑠 )

210.82 75 2.5 2.8

205.74 44 5.0 4.7

180.34 34 6.0 5.3

Deployment Test Results



Deployment Validation

29

Deployment Test Velocity

Time (s)

Vel

oci

ty (

cm/s

)

Success

Level Design Requirement Achieved

1 CubeSat shall deploy heliogyro sail in a 1g

environment at a controlled, variable rate. Yes

2 CubeSat shall maintain blade tip velocity

within 1 cm/s from user defined set rate Yes

2 CubeSat shall reverse blade tip velocity to

reel in blade Yes

2 Tip mass shall successfully deploy 3 m at

a constant rate in 1g environment No

Pitching Model Simulation

• A Simulink model was produced and analyzed to validate GHOST pitching capabilities*

• Simulated 1P Pitch Profile: A = 35°, ϕ = 0°, P = 1 min

Used initial -0.5° amplitude offset to display control capabilities

• Error peaks at -0.8° initially, oscillates to about zero within the range of ± 0.4°

• Validates control algorithm to be well within tolerances


* See Appendix

Pitching Test Results

31

Pitching Test Results

• Expected peak deflection angle from model is ± 35°

• Testing showed deflection angles of ± 31.5°

• Experimental angle is within requirement of a 5° error

Solar Sail Blade Pitching Video


Pitching Test

Success


1 BRM will pitch in a periodic, sinusoidal motion with error tolerance of 5° Yes

2 BRM shall be capable of collective maneuvers within error tolerance Yes

2 BRM shall be capable of 1 P maneuvers within error tolerance Yes

2 BRM shall be capable of ½ P maneuvers within error tolerance No


Collective Pitch Maneuver

Deflection Test

36 Testing Location: Aerospace Machine Shop

Predicted Results

Force

(N)

Predicted

Deflection

(m)

Predicted

Stress in axle

(MPa)

Yield Stress of

axle (MPa)

169 1.21×10−6 0.027 276


Success


1 CubeSat walls shall not break in shear stress

under loads of 169N Yes

1 CubeSat walls shall not fail under a 44N

compressive force experienced by CSD ejection Yes

2

Blade reel modules shall not deflect more than

0.3 inches during load of 169N experienced

under 100 g’s

No

33

CubeSat modeled as equivalent cantilever beam

• Aluminum beams (purple)

• Unbendable rigid sections (orange)

F

axle and

launch locks

modules

Power Budget

Component Voltage (V) Current (A) Power (W)

Board and PIC Logic 5 0.015 0.05

Stepper Driver 5 0.001 0.005

Stepper Motor 3.5 1.35 4.73

Servo Driver 12 0.05 0.6

Servo Motor (driver) - -

• Deployment Power

Components: Board, Stepper Driver

(x2), Stepper Motor (x2)

Total Power Consumption: 9.52 W

• Pitching Power

Components: Board, Servo Driver

(x2), Servo Motor (x2)

Total Power Consumption: 1.25 W

• Underusing pitching system potential

(different driver setting could fix RPM and

allow for high speed precision control)

Success Level Design Requirement Achieved?

1 CubeSat heliogyro system shall use no

more than 10W during operation Yes




• Design Solution

• Test Overview

• Test Results



38


Systems Engineering Approach

• Mechanical

CubeSat Manufacturing

Mechanical/Electrical interfaces

• Electrical

PCB design

I/O interfacing

Power requirement

Motor/Driver Testing

• Software

Software method development

Pitching control system

Deployment rate control method

Embedded SW development - C

SW validation models (MatLab/Simulink)

Objective Top Level Requirement

Deployment “Capable of deploying sail in a 1g environment at

controlled variable rate…”

Pitching “Blade reel modules pitch in a repeatable, periodic

motion…”

Sizing Theoretically capable of achieving a minimum

characteristic acceleration of 0.1 mm/s2

Power Uses no more than 10W during operation

Integration Software, Electronic, and Mechanical systems are

integrated together

Subsystem Organization


Mechanical Integration Issues

Subsystem Issues Lessons Learned

Manufacturing

• “Small” tolerance issues propagated

throughout mechanical system

• Unorganized production schedule

• Interface compliance document (ICD) to

define tolerances

• Create and enforce responsibilities chart

and manufacturing schedule

Software

• Interface issues with new

microcontroller/board

• Unorganized development process

• Software development schedule

• SW method development (flowchart)

• SW validation models (MatLab/Simulink)

• Embedded system design (C)


Mechanical Integration Issues

Subsystem Issues Lessons Learned

Electronics

• Unable to communicate with original PCB

• Unable to calibrate servo driver to needed

precision, LIN communication protocol issues

• More preliminary research on board configuration

• More detailed research into driver/motor

capabilities, interfaces and producer support

Motor/Driver

Testing • Too much weight/torque on pitching sensor

caused inaccurate data acquisition • Research into mechanical limitations of sensors

Mechanical/

Electrical

Interfacing

• Tolerance issues with servo motor mounting:

Datasheet sizes inaccurate

• Lack of communication regarding changes

• 9 pin RS-232 wiring outdated

• ICD to define tolerances

• Continual validation tests with

electrical/mechanical interfaces

• Note interface feasibility


Alternate Servo Driver

• SC2084 from Micromo

Up: 5 V DC power

Umot: 0.3-5 V (analog)

• Optimize

FG and DIR used for Tx and

RX via FAULHABER Motion

Manager

Can control RPM direction

through input command field

Alternately, the velocity and

position ranges can be set




• Design Solution

• Test Overview

• Test Results



43


Project Management

• PM Approach Assign leads to each group member

Define responsibilities for each lead

Set a schedule with deadlines for key tasks

Set times each week where everyone can meet and update teams on tasks

• Key Management Successes Team meetings allowed for everyone to obtain required

information from other leads

Splitting up tasks allowed everything to be completed on time

• Difficulties Encountered Key tasks sometimes missed deadlines

Leads were sometimes confused by responsibilities assigned

• Lessons Learned Ensure group members completely understand responsibilities

and assignments

Set deadlines for key tasks a week earlier


Project Budget

Projected Budget Actual Budget

$2337.43 $2031.25

• Remaining Projected budget was for

second servo driver never acquired

• Electronics largest expense

• Structural expense low because most

components were manufactured in

house

• Projected costs are printing costs for

final deliverables Structural Testing

Printing &

Presentation Projected Electronics

$428 $47 $105 $95 $1346

Structural

21%

Electronics

67%

Printing &

Presentation

5%

Projected

5% Testing

2%

BUDGET BREAK DOWN


HOW MUCH EFFORT?

• $65,000 for 2,080 hours worked (average engineer)

• Overhead rate of 200%

• Each member worked an average of 16 hours a week for 32 weeks

8 group members ∗ 32 𝑤𝑒𝑒𝑘𝑠 ∗16 ℎ𝑜𝑢𝑟𝑠

𝑤𝑒𝑒𝑘= 𝟒, 𝟎𝟗𝟔 𝒉𝒐𝒖𝒓𝒔

Total cost = 4,096 hours worked ∗$65,000

2,080 ℎ𝑜𝑢𝑟𝑠 𝑤𝑜𝑟𝑘𝑒𝑑= $128,000

• $16,000 per person

• 𝐼𝑛𝑑𝑢𝑠𝑡𝑟𝑦 𝐶𝑜𝑠𝑡 = 𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 ∗ 𝑂𝑣𝑒𝑟ℎ𝑒𝑎𝑑 𝑟𝑎𝑡𝑒 = $𝟐𝟓𝟔, 𝟎𝟎𝟎


Thank you!

Questions?

47


Pitching Capabilities: Collective

• Collective pitch profile

• Produces a constant moment M1 about the gyro rotational axis

• Used to provide maximum torque on spacecraft for spin-up or

spin-down

• Also can be used for max normal thrust or zero thrust

45 Appendix

• Cyclic 1P pitch profile

• Provides a net in-plane thrust F1

• Used to perform orbit raising and lowering maneuvers

Pitching Capabilities: 1P Cyclic

46 Appendix

• hP pitch profile

• Produces a net moment M2 about spacecraft

• Used to process the spacecraft angular momentum vector and

reorient the gyro rotational axis

Pitching Capabilities: hP

47 Appendix

The Need for ± 35° Range of Pitch

Blade

Pitch θ Condition (Profile, Description)

0° Max Normal Thrust (Collective, Blade Surface Normal to Sunlight)

± 35° Max Torque (Collective) or Max In-Plane Thrust (1P Cyclic)

± 90° No Thrust (Collective, Blades Edge on to Solar Wind)

Collective Pitch Maneuver

21 Appendix

Electronics Functional Block Diagram

Microcontroller (PIC)

Pitching

Motor (BLDC Motor)

Pitching

Driver

(Servo Driver)

Deployment

Motor (Stepper)

Deployment

Driver (Stepper)

Serial

Communication (RealTerm via RS-232)

HALL

Encoder

Digital

Encoder

DAC

Direction

Digital

Signal

Direction

Step

Voltage

Angular

Speed

Internal Position

Feedback

Position

Feedback

48 Appendix


A Simulink model was produced and analyzed to validate GHOST pitching capabilities

49 Appendix


• Simulated 1P Pitch Profile: A = 35°, ϕ = 0°, P = 1 min

• Expected error peaks at ~0.55°

• Validates software/hardware output to be well within tolerances

50 Appendix

Pitching Simulation Results

Deployment Test Considerations

Remove Screws and Washers from

Tip Mass for Deployment

Tip mass is secured with washers and screws to

C-brackets for ease of transfer

Both screws and washers will be removed during

testing so blade and tip mass can deploy correctly

51 Appendix

Tolerance of Blade Axle Stabilizers

• For solar blade to deploy smoothly and avoid ripping, Mylar blade must not contact front face plates of Blade Reel Module: Due to geometric constraints, this leaves a

tolerance of ~3.8˚ in the horizontal alignment of the blade deployment axle and stabilizers

• Significant to make sure the deployment axle and stabilizer arrangement is not vertically tilted as to impart a significant torque on the spacecraft due to the misalignment of the deployed blades Assuming a restriction of erroneous torque being

less than ~3% of the maximum torque, the tolerance of the alignment vertical tilt is ~0.66˚

Key: Perfect Alignment

Absolute Tolerance

θmax = 3.8˚ (horizontal),

0.66˚ (vertical)

52 Appendix

Pitching Test Considerations

Remove Screws and Nuts from inside CCM for Pitching

Screw and nut hold the BRM to the CCM for

ease of transfers, simulated “launch locks”

Top wall of CCM must be unscrewed to remove

“launch locks” and replaced

Tool will be inserted into front of BRM to hold

nut while screw is taken out

53 Appendix

Drawing Tree – Parts List

Appendix

Part Name Part Number Distributor Quantity Stock Stock Quantity Ordered? Completed? Total Cost Theoretical Mass Measured Mass Notes

BRM Side Wall

S318T6 Metals Depot

4

1/8" Thick Aluminum 2 Y

Y

$105.84

0.062 0.060 May want to cut out triangles

BRM Back Wall 2 Y 0.168 0.160

BRM Top and Bottom Wall 4 Y 0.132 0.130

BRM Left Front Wall 2 Y 0.0245 0.020

BRM Right Front Wall 2 Y 0.0245 0.020

CCM Side Wall 2 Y 0.0964 0.100 May want to cut out triangles

CCM Front and Back Wall 2 Y 0.15 0.160

CCM Top and Bottom Wall 2 Y 0.215 0.230 May want to cut out triangles

Left Blade Stabilizer 2 Y 0.023 0.023

Right Blade Stabilizer 2 Y 0.018 0.017

Corner Cube 99108A130 McMaster 24 5/8 x 5/8 x 12" Aluminum Key Stock 2 Y Y $22.86 0.009 0.010

Blade Deployment Axle R314 Metals Depot 2 1/4 x 24" Aluminum Axle 1 Y Y $1.96 0.0136 0.013 Needs to be press fit onto stepper motor

Pitching Axle R3716 Metals Depot

2 7/16 x 24" Aluminum Axle 1 Y

Y $4.94

0.0059 0.010 Needs to be press fit onto servo motor

Tip Mass 2 N 0.046

Hub N/A Matt Rhode 2 3/2 x 3/4" Aluminum Cylinder 2 N/A Y $0.00 0.041 0.043

C-Brackets N/A Matt Rhode 4 4 x 3/4 x 3/10" Aluminum Block 1 N/A N $0.00 0.0056

Servo Motor Clamps N/A Matt Rhode 4 1 x 1/2 x 1/2" Aluminum Block 1 N/A N $0.00 0.0033

Stepper Motor SS2421-5011 Polulu 1 N/A N/A Y N/A $59.95 0.07 0.073

Servo Motor 2036U012BK312+OPEC05 Micromo

2 N/A N/A Y N/A $372.10

0.05 0.080 Encoder and motor ordered together, company interfaced them for us

Encoder HEDM5500J06 2 N/A N/A Y N/A 0.085

Rolled Blade N/A NASA LaRC 2 N/A N/A Y N $0.00 0.393 Theoretical mass based off entire blade length

Kapton Tape Unline 1 1 roll, 3/4" wide 1 Y Y $25.00

PIC 18F87K22 Mouser 1 N/A N/A Y N/A $5.29 0.006667

0.080 DAQ MAS522CPA Mouser 2 N/A N/A Y N/A $12.02

Sipex chip SP232EEP Mouser 1 N/A N/A Y N/A $1.05

PCB Board Advanced Circuits 1 N/A N/A Y N $33.00 0.034

Stepper Motor Driver DRV8834 Polulu 2 N/A N/A Y N/A $9.95 None 0.070

Servo Motor Driver ATA6832-DK Atmel 2 N/A N/A Need 1 N/A None Currently only have 1 because of supply shortage with distributor

Misc. Electronics parts N/A JB Saunders N/A N/A N/A N N ~$50.00 Wires, resistors, capacitors, etc…

Flathead Torx 92703A207 McMaster 72 4-40 x 5/16" 2 Y Y $15.20 0.00045 0.00040 Connecting all walls to cubes

Friction-Resistant Shoulder 95446A652 McMaster 2 10-32 x 1/4 x 7/16" 2 Y Y $5.76 0.00770 Launch Locks

Flathead Phillips 91771A053 McMaster 20 0-80 x 5/32" 1 Y Y $8.62 0.00013 Connecting stabillizers to walls

Flathead Phillips 91771A170 McMaster 20 1-72 x 1/2" 1 N N $13.93 0.00026 Connecting tip mass to walls

Hex Nut 90545A111 McMaster 2 10-32 x 3/8 W x 1/8" H 2 N N $5.26 0.00363 Launch Lock Nuts

Set Screw 92313A109 McMaster 8 4-40 x 1/2" 1 N N $10.00 0.00064 Securing pitching axle into hub

Flathead Phillips 91771A168 McMaster 8 1-72 x 3/8" 1 N N $12.78 0.00026 Connecting servo motor clamps to walls

Flathead Phillips 91771A175 McMaster 4 1-72 x 1" 1 N N $9.64 0.00026 Connecting servo motor clamps together

Hex Nut 90480A002 McMaster 12 1-72 x 5/32 x 3/64" 1 N N $2.92 0.00013 Nuts for connecting servo motor clamps to walls and together

Washer 90107A003 McMaster 4 1/8 ID x 1/4" OD 1 N N $2.64 0.00013

54

Electronics Testing Overview

• Design Requirement 10 Watt power constraint

• Objective Control pitching and deployment

system independently to alleviate power draw

• Testing Strategy Test pitching and deployment

system components power independently

Calibrate servo motor voltage input Compare measured voltage and

current across all subsystems to expected amount

Micro-

controller

+5V +3.5V

DAC

Stepper

Driver

(Deploy

ment)

Stepper Motor

Res

Servo

Driver

(Pitching)

Servo Motor

Encoder

Logic Supply

Logic Supply

Logic Supply

Motor

Supply

Motor

Supply Encoder Supply

55 Appendix

Software Testing Overview

• Objective Command pitching and deployment systems Be able to change pitching and deployment information Stop functions at any time

• Testing Strategy Test code on computer for expected behavior before integration Run individual functions on hardware to debug Run full system checks

56 Appendix

Critical Project Elements

• Cut, attach, and roll the

aluminized mylar solar sail and

maintaining a straight blade

• Integration between the

software and the servomotor

• Manufacturing and aligning the

deployment axle and stepper

motor within alignment of 4°

• Manufacturing and aligning the

pitching axles with servo

motors within alignment of 1°

57 Appendix

DAC Output Signal

58 Appendix

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