CDR Geocentric Heliogyro Operational Solar-sail Technology (GHOST)

1
CDR
Geocentric Heliogyro Operational Solar-sail Technology (GHOST)
Nicholas Busbey, Mark Dolezal, Casey Myers, Lauren Persons,
Emily Proano, Megan Scheele, Taylor Smith, Karynna Tuan
2
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
2
Purpose and Objectives
3
Heliogyro Background
“Traditional” Solar Sail
• Solar-sails use momentum transfer for
propellant-less propulsion
• Heliogyro sails (blades) are gyroscopically
stiffened in place of structural support
• Greatly reduces mass of satellite, simple design
scales to a much larger conventional solar sail
• Blades must be extremely long to provide
Satellite bus
Heliogyro Solar Sail
adequate area for meaningful acceleration
• Presents a challenge to provide storage and
deployment of sails
rotation
rotation
• No ground demonstrations of systems
capable of packaging and deploying full
scale blades currently exist
Solar Sail Blades
3
Purpose and Objectives
4
Objective Statement
GHOST will design, build, and test a heliogyro solar sail deployment and
pitching mechanism packaged into a CubeSat of up to 12U and capable of
deploying and pitching adequately sized solar sail blades to provide a
characteristic acceleration of 0.1 mm/s2
• Design a storage system for two blades
• Build and test deployment mechanism for one solar sail
• Build and test coordinated pitching mechanism for two solar blades using blade-
equivalent masses
Purpose and Objectives
5
Specific Objectives
• Blades will deploy using motors aided by centrifugal tension
• Blades will deploy at a controlled rate of 1 – 10 cm/s
• Verified by deployment test in 1G environment
• Blade roots demonstrate coordinated pitching motion of 180º (± 90º)
• Verified by pitching test in 1G envornment
• Entire structure must be stowable within a 6U CubeSat
• System limited to 10 W of power
• Must show that structure can survive launch
Purpose and Objectives
6
Basics of CubeSat Design
Blade Modules
Center Module
Front View
Front View
Blade
Tip Mass
Top View
Launch Tabs
Brackets to Secure Blade
Deployment
Motor
Tip Mass
Pitching Motors
and Encoders
Top View
Blade
Hub to Attach
Center and
Blade Modules
Motor Drivers
and Electronics
Board
Brackets to Attach
Walls Together
Launch Locks
Purpose and Objectives
7
Deployment and Pitching
Deploying the Blades
Blade
Tip Mass
Pitching the Blade Modules
Purpose and Objectives
8
Concept of Operations (ConOps)
3.0
Controlled deployment of sails via motors
3.1 Suspend undeployed blade in 1G
3.2 Initiate deployment mechanism
3.3 Controlled sail deployment using motors
5.0
Pitch solar sail roots
5.1 Establish connection with
pitching mechanism
5.2 Send appropriate pitch command
5.3 Measure resulting pitch angle
5.3.1 Record actual pitch angle and
compare to expected pitch angle
5.3.2 Ensure both actuators are capable
of generating synchronized –
collective, ½ P, and 1P cyclic root
pitch deflections
Purpose and Objectives
9
Rideshare Opportunity
6U Heliogyro CubeSat has an opportunity to be a
Secondary Payload on Exploration Mission 1 (EM-1)
Orion Crew Module
Spacecraft Adapter (SA)
1st Launch of NASA’s Space
Launch System (SLS) Launch
Vehicle inserting the unmanned
Orion Multi-Purpose Crew
Vehicle (MPCV) into Lunar Orbit
• TBA ~ Dec, 2017
Orion SLS Configuration
See Appendix for CSD Configuration on SLS
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EM-1 Timeline
Lunar Flyby: Separation
of Orion from ICPS
SLS Launch
ICPS Disposal Burn
Moon
Earth
Injection of Secondary Payloads: GHOST
Low C3, Heliocentric Trajectory
Purpose and Objectives
11
Orbit Transfer Capability
𝑅
• Heliogyro architecture
• A component of thrust can be vectored into the
in-plane (𝑆) direction of a solar blade
• Allows for efficient orbit raising without having
to precess the momentum vector like a
conventional solar sail
Cyclic 1P Pitch Profile
Orbit Raising Pitch
Orientation Profile
θ = 35°
𝐹𝑛𝑒𝑡
Single Blade In-Plane Thrust vs. Blade Pitch
𝐹𝑊
θ = 0°
𝑆
θ = 0°
Ω
𝐹𝑠
𝑊
ℎ
ℎ𝑝𝑟𝑒𝑐𝑒𝑠𝑠
Sunlight
θ = -35°
12
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
GHOST Design Solution
13
Functional Block Diagram
GHOST Design Solution
14
Baseline Design
•
•
•
•
Constrained by 6U design
8 cm – 13 cm – 8 cm with ½ cm clearance
Blade Module
Deployment modules rotate ± 90 to pitch
Deployment
Each Blade Module holds rolled sail and Sanyo
(Stepper) Motor
Stepper motor
• Central Pitch Module holds 2 servo-motors/encoders,
Center Module
4 motor drivers, and 1 electronics board
Pitching
•Extra 2U for power source, communication
(Servo) Motor
systems, and scientific instruments
• Launch Tabs for CSD deployment
Stepper Motor Drivers
Blade
8 cm
½ cm
13 cm
½ cm
8 cm
Blade
Launch
Tabs
Electronics Board
Servo Motor Drivers
GHOST Design Solution
15
Baseline Design: Central Pitch Module
1. Servomotor stabilized to outer wall
1. Pitching Axle fed through hole in wall
2. Driven by servo for consistent, low-vibration inputs
Servo Motors
3. Powered by 5V battery
2. PIC receives input and interfaces with drivers
Encoders
Launch Locks
3. 1/8 in. flat aluminum walls
1. Corner brackets to resist loads/resist vibration
4. Launch locks to reduce vibrational forces during launch
Pitching Axle
Servo Motor Drivers
Stepper Motor Drivers
Launch
Tabs
Electronics Board
with PIC
Corner Brackets
GHOST Design Solution
16
Baseline Design: Blade Deployment Modules
• Hub with set-screws to stabilize
Hub
and hold deployment axle
• Service loop to allow full ±90
degree motion
• S-brackets on sides to stabilize
deployment reel
Blade
• Non-motor side utilizes ball bearing
to assist with low-friction
deployment
• Axle stabilized by motor and
ball bearing
• Tip mass of sail held on a C-
bracket on the outer side of the
module
Ball Bearing
Service
Loop
S-brackets
Blade
• Held still by holding torque, C-
bracket, and stainless steel tape
measure material
C-brackets
GHOST Design Solution
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Baseline Design: Electronic System
Servo
Driver 1
Servo 1
DAC
Hall Sensor
Hall Sensor
Encoder
Servo
Driver 2
Servo 2
Encoder
MicroController
Stepper
Motor 1
Stepper
Driver 1
Stepper
Driver 2
Stepper
Motor 2
GHOST Design Solution
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Baseline Design: Software System
Emergency Stop
1
• Block Deploy/Pitch
• Wait for State 2
• StorePlace( )
N-1 = 1
Restart
2
CheckState( )
Deployment
3
N-1 != 1, N-2 = 3
• CheckDeployed( )
• Deploy( )
Pitching
4
Communications
ISR( )
N-1 != 1, N-2 = 4
Initialization
• Check two
previous states
• Adapt Algorithm( )
LEGEND
Emergency Stop
Restart
Deployment
Pitching
SpinUp
• CheckDeployed( )
• Pitch( )
SpinUp
5
• TapeDeploy()
• Pitch( )
• EndSpin()
6
Idle
• Idle( )
N-1 != 1, N-2 = 6
GHOST Design Solution
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Mass Budget
Attribute
Mass
[kg]
Mechanical
2.18
Electrical
0.429
Structural
0.265
Total
2.88
Total Limit
4.0
Available
1.12
Mechanical: CubeSat plates, axles, aluminized mylar,
stiff steel tip
Electrical: Servomotors, stepper motors, motor drivers,
wiring
Structural: Brackets, braces, stabilizers, hubs, screws
• If mass goes over-budget, triangles can be cut into non-load bearing sections of the CubeSat
• Reduces mass without compromising structural integrity
• Slight over-estimation: does not account for holes for screws/axles
GHOST Design Solution
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Power Budget: Individual Components
Mission Phase
Description
Power Budget
Total Power Used
Pre-deployment (1)
Stepper motor holds, Launch Locks initiate unlock
> 10 W
22.15 W
Initial Spin-Up (2)
Stepper releases 5m, stepper holds while pitching
10 W
9.1 W
Stepper motor rotates to deploy blade
10 W
7.15 W
Servomotor pitches blade root, Stepper motor holds
10 W
9.1 W
Deployment (3)
Pitch and Hold (4)
Power Usage
Number per
System
Supply Current
per System (A)
Supply
Voltage (V)
Power Subtotal
(maximum) (W)
Mission Phase
Launch Locks
2
--
28
15
1
PIC18F87K22
1
0.01
5
0.05
1, 2, 3, 4
Sanyo Stepper Motor
2
0.4
3.5
1.4
1, 2, 3, 4
Driver DRV8834
2
1/phase
5
5
1, 2, 3, 4
Servomotor
FAULHABER 2036
2
0.2
5
1.0
2, 4
Servomotor Driver
2
0.1
5
0.5
2,4
Encoder AUZSD1000A
2
0.04
5
0.95
2, 4
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Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
21
CPEs
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Critical Project Elements
• Mechanical
• Blade Deployment
• Blade Reel Module can store a sufficiently sized solar sail blade
• Sized such that will produce a minimum characteristic acceleration of 0.1 mm/s^2
• Motor fits in Blade Reel Module and is capable of a controlled deployment rate of 1 to 10 cm/s
• Pitch Actuation
• Motor can actuate the Blade Reel Module ± 90°
• Central Module allows for a minimum of 2U (200 cm^3) storage for COMM, EPS, and scientific
payload considerations
• Structural Integrity
• Structure can handle shear and tensile stresses present in space and 1G environment
• Mitigates vibration of external modules on pitch axle and motor
• Mass & Volume Budgets
• Mass and Volume limited by 6 kg and 6U (1 kg/U)
CPEs
23
Critical Project Elements
• Electrical
• Microcontroller/Driver/Motor Connection
• Functional and wiring sufficiently sized to carry necessary current
• Inter-module service loop connection
• Thermal Considerations
• Pitch motor and electronics are sufficiently insulated and/or heated by electrical coils
• Electrical heat dissipation does not overheat internal components
• Power Budget
• Power usage never exceeds 10 W
• Software
• Algorithms
• Integrated with electronics
• Language compatible with microcontroller
• Capable of producing relevant pitch profiles to be used by pitch motor
• Control initial deployment, deployment rate, and confirm deployment status
• Memory Concerns
• Bus has necessary memory storage on board
CPEs
24
Critical Project Elements
• Space Concerns
• Launch Vibrations & Survivability
• Structural integrity uncompromised due to launch conditions
• Launch Locks installed for launch vibration mitigation between external Blade Reel Modules and Internal
Central Module
• Launch Lock design for support of sail blade tip
• Canisterized Satellite Dispenser (CSD)
• CubeSat meets specifications for use in dispenser
• Initial Spin-Up
• CubeSat induces rotation of its own accord
• Use of stainless-steel reinforced sail material at blade tip
CPEs
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Critical Project Elements
• Manufacturing and Assembly
• Order of Manufacturing
• Construction from outside-in
• Wall Construction
• Thickness sufficient for structural needs and use of fasteners
• Solar Sail
• Attachment to deployment axle in Blade Reel Module
• Bonding of stainless-steel supports to sail material
• Pitching Axle
• Connection between pitch motor and external Blade Reel Module
• Satisfies tensile and shear stress concerns
• Minimizes vibration between interfaces
• Bearings
• CSD Tabs
• Tabs implemented into construction to allow use in satellite dispenser
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Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronic/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Controlled Deployment Rate
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Initial Spin-Up
Steel Spine
• Problem: Initially deploy solar sail straight without
aid in centripetal forces
• Hardened stainless-steel support attached along
middle of last 5 m of Sail Membrane and acts as a
“tape-measure”
• Properties of “tape measure”:
Solar Blade
CubeSat
• Dim: 5m x 2cm x 12.7μm
• ρ = 7860 kg/m3
• m = 9.98 g
F = 3.5 μN
• A maximum torque of 0.147 mN·m required by
deployment motor
• Conditions to reach Ω = 1 RPM:
• 𝜃𝑝𝑖𝑡𝑐ℎ = 35°
• ∆𝑡𝑠𝑝𝑖𝑛 𝑢𝑝 = 1.84 days
Rinitial = 5 m
Ω = 1 RPM
Controlled Deployment Rate
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Centripetal Acceleration
Deployment
Length
(m)
Centripetal
Acceleration
(m/s2)
Sail
Mass
(kg)
Centripetal
Force (N)
5
0.055
0.014
7.4×10-5
100
1.1
0.080
0.088
Orbital Trajectory
Vtip
200
2.2
0.15
0.33
300
3.3
0.22
0.72
400
4.4
0.29
1.27
500
5.5
0.36
1.97
545
5.8
0.38
2.17
Ω
Fc
Fg
Fg is negligible
Rotation Rate Ω = 1 RPM
Controlled Deployment Rate
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Space to Earth Comparison
CubeSat rotating at 1 RPM → centripetal acceleration → centrifugal tension
Space Application
Ground Deployment
Motor/Bus
Interface
Motor
r
Tip mass trajectory
Side View
CubeSat
rotating at 1
RPM
Blade
Blade
Mounted to Table
Tip mass
F = mg
Front View
Tip
mass
F
Motor
Top View
Blade is fully deployed → maximum centrifugal tension
mTotalSpace = 377.5 g
F = 2.17 N
Simulate same centrifugal tension the blade would experience in space
Total mass of 36 g used in the deployment test
mTotalEarth =
𝐹
𝑔
= 221.5 g
mTM = 207.0 g
The holding torque of the motor used must be able to withstand this force
τ=r×F
τ = 0.011 N·m
Controlled Deployment Rate
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Deployment Parts List: Electronics
Part
Voltage (V)
Current (A)
Interface
Dimensions (mm)
Cost ($)
Sanyo Stepper Motor
3.5
0.3
Input: 4 (bipolar)
42×42×11
60
DRV8834 Low-Voltage
Stepper Motor Driver
2.5-10.8
0.5/phase
Output: 4
Input: 8 (7 I/O, 1 CCP)
Power: 2 (motor and logic)
Ground: 2 (motor and logic)
15×20
10
Stepper Motor Driver
Stepper Motor
Controlled Deployment Rate
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Software: Prototype
Deployment
Algorithm
Calculate new
Rotation Rate
Set Initial Diameter
and Circumference;
Calculate Rotation
Rate
Time Step Passes
Find Rotations
Made in Time Step
• Written in MATLAB
to prove concept of
deployment
• Need to maintain
constant deployment
rate
Find new
Diameter and
Circumference
Calculate Length
Deployed
32
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronic/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Pitching
33
The Need for ± 90° Range of Pitch
Blade
Pitch θ
Condition (Profile, Description)
0°
Max Thrust (Collective, Blade Surface
Normal to Sunlight)
± 35°
Max Torque (Collective) or Max In-Plane
Thrust (1P Cyclic)
± 90°
No Thrust (Collective, Blades Edge on to
Solar Wind)
 Full 180° range of motion for blade pitch necessary for spacecraft to have full capabilities of
controlling the thrust vector. See Appendix for further information
Pitching
34
Pitching Parts List: Electronics
Part
Voltage (V)
Current (A)
Interface
Dimensions (mm)
Cost ($)
FAULHABER 2036
BLDC Motor
5
0.2
Input: 3 phase
Sensors: 3 HALL
Power: 1
36×20 (diameter)
230
Atmel ATA6832-DK
Brushless DC Motor
Controller
5
0.1
Output: 3 phase
Input: 1 Serial, 2 I/O
45×45
208
2 Channel IE2-1024
Encoder
5
0.4
Output: 4 I/0
Power: 1
16.5×15 (diameter)
225
2036 BLDC Motor
Pitching
35
Servo Controller
• Bypass LIN input for direct interface with potentiometer
(Serial input: use DAC from microcontroller)
Pitching
36
Pitching Software
Pitch Profile
Command Sent
Find
corresponding
sinusoid equation
for pitching
Given a pitch profile, the software will
• Find the corresponding sinusoid command for the
servos
• Step through those angles over the time period
• Compare commanded angle to encoder feedback
• Adjust for accuracy.
Command servo to
turn to angle in
pitching sinusoid
Compare to
Encoder Angle
37
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronic/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Survive Launch
38
Canisterized Satellite Dispenser: CSD
• 6U fits into CSD during launch
• Gives extra clearance on each side
• Allows for locking mechanism outside the 6U
• Available with Alum 6061
• Pushed into orbit on “Tab” structure
• Additional tabs added below CubeSat base
• Able to separate tabs for each separate section
Survive Launch
39
Structural Integrity of Pitching Axle and Selection of
Material
• Aluminum 6061
• Lightweight (density of 2.7g/cc)
• Very strong
• Inexpensive
• Pitching Axle – rod 1 cm in diameter
• If made of Aluminum 6061:
• Can withstand shear force of 16.2 kN (~3600 lbs)
• Does not take into account ability of motor to withstand torque
τ
F
(from Solar
Sail)
Pitching Axle
Survive Launch
40
Launch Locks
SP-5025
• Sierra Nevada SP-5025 pin puller
Deployed
• 350 lbf (1500 N) of shear load
• Powered by a single timed power pulse to one of
the redundant heater circuits
• SP -5025 greatly exceeds budget, so manual
screw and bolt sized appropriately simulate
launch locks in the prototype
SP-5025
Simulated
Launch Locks
Stowed
Credit to SNC
Survive Launch
41
Secure Blade Tip Mass
• C-brackets attached to exterior walls stabilize tip mass
vertically and horizontally
• Cylindrical tip mass fits securely in brackets on both sides
• Holding torque of stepper motor and tape-measure
material holds tip mass in towards rolled blade
• Within outer limit required by CSD
1.6 cm
0.75 cm
2 cm
42
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronics/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Electronics/Software Integration
43
Service Loop
Power and input wires needed in for stepper
motor in deployment module
• 4 1.2A rated wires: AWG 21, D = 0.73 mm
• Full loop around pitching axle to allow for
±90° rotational freedom
• 1 cm diameter hole through each plate
• Current must run throughout launch to
keep holding torque.
• Need not worry about freezing later in mission
Wires (red) exit opening in wall, loops around
pitching axle, enters opening in opposite wall
Electronics/Software Integration
44
Electrical Block Diagram
D3
D4
C0
(Speed Set)
GND
VoutA SCLK
CS
DIN
VoutB VDD
Servo
Driver 1
C0
(Speed Set)
B5 B4
5V GND U V W C2 C3 C4
3.5 V Supply
5 V Supply
DAC
Servo
Driver 2
VDD GND
D3
D4
5V GND U V W C2 C3 C4
P G A B C
P G A B C
Servo 1
Servo 2
GND VDD
A3
A7
A4
B6
B7
Microcontroller
H4
H5
H3
H6
E1
H0
E2
E0
M0
M1
ENABLE
CONFIG
SLEEP
FAULT
STEP
DIR
VMOT GND
Stepper
Driver
B2
B1
A1
A2
J2 J3 J4 J5 J6 J7 TX RX
Key
Encoder
Encoder
VDC G A B C
VDC G A B C
Tin Rout
Vin GND
RS 232
I/O
CCP
Power
Serial
GND
Sensor
Stepper
Motor
Electronics/Software Integration
Microcontroller
Board Requirements:
• Serial output for communication with computer
and servomotor controller
• DAC used for servomotor communication
• I/0 ports for stepper driver interface
• CCP port for stepper driver interface
• Header pins for the encoder interface
Total:
18 I/O
1 CCP
1 TX/RX
• Would need more I/O and CCP ports for a second
stepper motor driver
• Unused ports: 37 I/O and 10 CCP/ECCP
PIC18F87K22
Electronics/Software Integration
PCB Design
• 2 Layer Board
• FR4 material
Incompatible Industrial Boards
EasyPIC PRO
v7 Pinout
• 1 oz Copper traces
• Estimated Dimension = 5×5 cm
80 Pin Development
Board
• (See Appendix for Electrical Schematic)
47
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronics/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Manufacturing the CubeSat
48
Manufacturing In-House vs. Purchasing
Part
In-House
Purchase
Details
CubeSat walls
Aluminum will be purchased with correct thickness and
manufactured to needed dimensions
Blade and pitching axle
Axles can be cut down to needed length
Corner brackets
Brackets can be altered to fit needed dimensions
S-brackets and C-brackets
Will have to be machined to fit strict dimensions
Tip mass
Tip mass can be cut down to needed length
Tape-measure material
Purchased from McMaster-Carr
Solar sail blade material
Blade material is provided for free by NASA LaRC
Launch Locks
Launch locks we will use are a screw and bolt
Launch Tabs for CSD
Tabs must meet strict dimensions to fit into CSD from
Planetary Systems Corporation
Hub to attach pitching axle to blade module
Will have to be machined to meet needed dimensions
Screws/nuts/bolts
All can be purchased in various sizes and lengths
Motors/encoders and motor drivers
All purchased to meet necessary requirements
Electronics board
Will have to be made to accommodate needed electronics
Stabilizers to hold pitching motors
Will have to be machined to properly fit around motors
Manufacturing the CubeSat
49
Assembly Procedure
Manufacturing the CubeSat
50
Bonding Mylar to Spool and Stiff Material
• Loctite Super Glue Professional
Blade
¼ of roll glued
• Shear strength of 0.1 N/mm2
• Cross-Sectional Area = 6575 mm2
• Shear Stress = 3.3e-4 N/mm2
• Blade will retain 4 rolls around axle at
final length
• Loctite to bond stainless steel stiff
material to Mylar and to spool
F = mg = 2.17 N
Motor
Manufacturing the CubeSat
51
Fixing Deployment Motor to S-Bracket
• Deployment stepper motor is attached to S-bracket
• S-bracket stabilized to back of blade deployment
module and vertical CubeSat walls
• Motor is capable of being screwed directly to S-bracket
• S-bracket has thickness of 1/8 inch
Holes for screws to
stabilize S-bracket
Holes to screw motor
to S-bracket
Hole for motor shaft
or press-fit ball
bearing to attach to
blade axle
Manufacturing the CubeSat
52
Pitching Axle Interfaces
• Pitching axle to motor axle
• Motor axle (smaller) fits into pitching
axle (larger) using set-screws
• Pitching Axle to Blade Reel
Module
• Axle fixed by set screws inside a hub
Motor Axle
Hub
4 Set Screws
Pitching Axle
53
Presentation Sections
• Purpose and Objectives
• GHOST design solution
• Critical Project Elements
• Requirement Satisfaction
• Controlled Deployment Rate
• Pitching
• Survive Launch
• Electronic/Software Integration
• Manufacturing the CubeSat
• Summary
• Remaining Risks and Mitigations
• Verification and Validation of Design
• Schedule and remaining work
Summary
54
Requirements Satisfaction
Aspect
Requirement
GHOST Specification
Mass
1 kg/U
2.88 kg
Volume
<= 12U
6U
Life Span
4 months
Greater than 4 months
Space Applicable
While design does not need to be
space worthy, it should be applicable
to being used in space
All components are picked for
realistic use in space with minimal
cost parts and increased life span
Summary
55
Requirements Satisfaction
Aspect
Requirement
GHOST Specification
Characteristic Acceleration
ac ≥ 0.1 mm/s2
ac = 0.3868 mm/s2
Sail Aspect Ratio
AR ≥ 100:1
AR = 3893:1
Sail Deployment Speed
1 cm/s ≤ 10cm/s
~5 cm/s
Pitching Range
Ability to pitch blades ± 90°
Ability to pitch blades ± 90°
Pitching Coordination
Multiple blade coordination when
pitching
Can pitch both blades at once: either to
same angle, or opposite angles
56
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Remaining Risks
57
Design Risks
Severity
Likelihood
Often
Occasional
Improbable
Marginal
Major
Pitch angle error, root not
following tip
Power loss, COMM loss
Small tear in Mylar
Structural survivability,
pitching motor failure
Deploy too fast, stowage
and deployment of Mylar
Axle failure,
launch fail,
space dust,
deployment motor failure
Remaining Risks
58
Logistical Risks
Severity
Likelihood
Minor
Often
Parts delayed due to U.S.
Postal Service
Occasional
Structural consultation
unavailable
Improbable
No time for pitching test
Marginal
Major
Ball vibrations test is not
available, machine parts
not done on schedule
Government shutdown and
we can’t get Mylar or help
from NASA
High Bay in Fleming is
unavailable, motors don’t
show up
Remaining Risks
59
Financial Risks
Severity
Likelihood
Minor
Often
Repurchase parts
Occasional
Motor breaks
Improbable
Marginal
Major
Price of shake table
Hyper inflation
60
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Verification and Validation
61
Verification and Validation
Deployment System
Validate that the blade is deployed at a
constant rate of 1-10 cm/s in a high bay
room
Validate that the blade can successfully
deploy a blade with tape measure
material at a constant rate along ground
Verify that the motor can deploy at
constant rate
Verify with demonstration that the tape
measure material can extend length of
blade
Verify with test that the deployment
system does not use more than the
maximum power available of 10W
Verification and Validation
62
Blade Deployment
•
•
•
•
Testing Information
Location: Prof. Frew’s High Bay Lab
Scheduled: March/April with late night access to avoid
scheduling conflicts
Measurement: Tape measure for distance and video
camera for time
Power Delivered: 6253A Dual DC Power Supply
delivers 0-20 V and 0-3A
Wire
CubeSat
Power Supply
Tape measure
marking
distance up
wall
Kinematic Model
• Torque from motor drives a constant velocity deployment
𝜏𝑚𝑜𝑡𝑜𝑟 = 𝜏𝑟𝑜𝑙𝑙 + 𝜏𝑝𝑢𝑠ℎ𝑖𝑛𝑔 𝑇𝑀 − 𝜏𝑔𝑟𝑎𝑣𝑖𝑡𝑦 𝑇𝑀
𝑑𝐼𝑟𝑜𝑙𝑙
𝑑𝜔𝑟𝑜𝑙𝑙
𝜏𝑟𝑜𝑙𝑙 =
𝜔𝑟𝑜𝑙𝑙 + 𝐼𝑟𝑜𝑙𝑙
𝑑𝑡
𝑑𝑡
𝑑𝑚𝑒𝑥𝑡
𝑑𝑟𝑟𝑜𝑙𝑙
𝜏𝑝𝑢𝑠ℎ𝑖𝑛𝑔 𝑇𝑀 =
𝑟 𝑣 + 𝑚𝑒𝑥𝑡
𝑣
𝑑𝑡 𝑟𝑜𝑙𝑙
𝑑𝑡
𝜏𝑔𝑟𝑎𝑣𝑖𝑡𝑦 𝑇𝑀 = 𝑚𝑒𝑥𝑡 𝑟𝑟𝑜𝑙𝑙 𝑔
• 𝝉𝒉𝒐𝒍𝒅𝒊𝒏𝒈 = 𝟎. 𝟎𝟖𝟓 N∙m 𝝉𝒎𝒐𝒅𝒆𝒍,𝒎𝒂𝒙 = 𝟎. 𝟎𝟎𝟕 N∙m
Verification and Validation
63
Verification and Validation
Pitching System
Validate that the blade reel modules
experience coordinated pitching
Verify that one blade reel
module experiences periodic
motion
Verify that the
blade reel module
rotates to 0° upon
initialization
Verify that the
blade pitches to a
given command
angle
Verify that the
motor/encoder system
does not exceed power
available
Verification and Validation
64
Verify Pitching Angle
Experiment Set-Up
Experiment Equipment and Specs
• Use R60D RVIT (Rotary Variable Inductance
Transducer) sensor to measure angles, attaches to pin
(red) in line with pitching axis
•
•
•
•
•
Measures ranges of ±60° rotation
Input Voltage = ±15 V
Output Voltage = ±7.5 V
Resolution = 0.125 V/°
𝑓𝑚𝑎𝑥 = 20 Hz
AD524
R60D RVIT
• Use AD524 Precision Amplifier Instrumentation for
signal conditioning
• Input Voltage: ±10 V
• Output Voltage: ±10V
• Requires Supply Voltage: ±15
• Use NI 9201
• Input Voltage: ±10 V
• Has a USB output that can connect to a computer where vi
program records
PC via USB
NI 9201
Verification and Validation
65
Verify Periodic Motion
Experiment
• Using the R60D RVIT set-up to measure deflection angles
• With data of the angle deflection 𝜃, angular velocity 𝜔 and angular acceleration 𝛼 can be measured
• Motor restriction: 𝜏𝑚𝑎𝑥 = 0.32 N·m
• Model restriction: 𝜔𝑚𝑎𝑥 = Ω 2 if Ω = 2rpm, 𝜔𝑚𝑎𝑥 = 0.2094 rad/s
Validation Model
• R60D RVIT measures ±60° deflection angles
• Critical condition: blade reel module pitches ±90°, Ω=2rpm
• 𝛼𝑐 = 0.0172 rad/s2 and 𝜔𝑚 = 0.164 rad/s thus 𝜏𝑚 = 0.083 mN·m (𝐼𝑚𝑜𝑑 = 0.0048 kg·m2)
𝜃 𝑡
𝜔 𝑡
𝛼 𝑡
Verification and Validation
66
Verification and Validation
Structural System
Validate that the final design can
survive launch by using a shake
table
Verify the structural
integrity by demonstrating
that all stationary parts are
static
Verification and Validation
67
Trade Study: FEM vs. Vibration Table
Cost
Time
Experience
Similar to
Actual
Launch
F.E.M.
4
1
1
3
4
2.15
Vibration
Table
2
3
4
4
2
3.2
Weight (%)
5
30
25
20
20
100
Guaranteed Can
Do
Total
See Appendix for Full Trade Study
Verification and Validation
68
Validate Structural Stability
• Will use a shaker table from Ball Aerospace
• Cost = $250/hr
• Schedule: Time to be determined in April
• Specifications: Peak vibration occurs with 34g at
frequency of 16 Hz (Saturn V)
• Will be verified by examining the structural integrity
of the manufacturing
Shake Table
CubeSat
69
Presentation Sections
• Purpose and Objectives
• GHOST Design Solution
• Critical Project Elements
• Requirement Satisfaction
• Remaining Risks
• Verification and Validation of Design
• Project Planning
Project Planning
70
Organizational Chart
Mark
Dolezal
Emily
Proano
Lauren
Persons
Casey
Myers
Nicholas
Busbey
Taylor
Smith
Karynna
Tuan
Megan
Scheele
Project
Manager
Software
Lead
Electrical
Lead
Systems
Test and
Safety
Manufacturing
Lead
Mechanics
Lead
C.F.O. and
Materials
Lead
Perform
and Plan
tests
Manufacture
all in-house
parts
SolidWorks
Organizing
team
meetings
Supporting
other leads
Non C.P.E.
Tasks
Pitching
Control
Deployment
Control
Motors and
Electronics
Power
Integrate
all system
Specific
System
Requirements
CubeSat
Assembly
Keep track
of financial
spending
Right
materials
are being
utilized
Project Planning
71
Work Breakdown Structure (WBS)
GHOST
Materials
Mechanical
Electrical
Software
Documents
Thermodynamic
Analysis of
Electronic System
Mechanical
Layout
Power Budget
Pitch Control
Algorithm
CDR
Mass Budget
Shake Table
Vibration
Analysis
SolidWorks
Model
Prototype of
CubeSat Bus
Mylar from
NASA
Electrical
Wiring Layout
Motor
Subsystem
PCB Design
FFR
Deployment
Rate Control
Algorithm
Financial
Budget
Spin Up
Algorithm
Spring
Schedule
Emergency
Stop/Restart System
Spring
Documents
Project Planning
72
Electronic
integration
Purchase
motors/drivers
GHOST Spring Schedule
Electronics/code
interface
Deployment test
Preliminary code
Pitching test
Tasks
Test code
Vibration test
Manufacture
remaining parts
Purchase
raw materials
Integrate system
Assemble bus
Key
Manufacture frame
1/13
1/20 1/27
2/03 2/10
MSR
Planned
2/17
2/24
3/03
TRR
3/10
Time (date)
3/17
3/24
3/31
4/07
4/14
Uncertainty
4/21
SFR
4/28
PFR
Project Planning
73
Test Plan
Test
Scheduled
Facility
Verify Pitch Angle
3/17
ITLL
R60D RVIT, NI 9201, AD524, Oscilloscope, bench
power source
Zero Pitch Angle
3/17
ITLL
R60D RVIT, NI 9201, AD524, Oscilloscope, bench
power source
Measure power used in
pitch/deployment
3/17
ITLL
Ammeter, voltmeter, bench power source
Verify constant deployment
3/24
ITLL
Firewire camera, bench power source,
ASEN2003BallTracker.vi
Verify periodic motion
3/24
ITLL
R60D RVIT, NI 9201, AD524, Oscilloscope, bench
power source
Validate tape measure ground
deployment
3/31
ITLL
Bench power source, tape measure, stop watch, rollers
for tip mass
Validate coordinated pitching
3/31
ITLL
R60D RVIT, NI 9201, AD524, oscilloscope, bench
power source
Validate 1g blade deployment
3/31-4/14
Prof. Frew
high bay
Portable 6253A Dual DC Power Supply, ladder, tape
measure, video camera
4/14
Ball Aero.
Shake Table
Validate launch ready
Specialized Equipment
Project Planning
74
Cost Table – Structural Components
Part
Price per
part
# Needed/Volume Needed
Total Price
Supplier
Aluminum 6061 Sheet
(1/8” thick)
$ 89.76
2ft × 2ft × 1/8 in
$ 89.76
The Metals Depot
Aluminum 6061 rod
(1/4 in diameter)
$2.80
2 ft
$2.80
The Metals Depot
Aluminum6061 rod
(7/16 in diameter)
$4.94
2 ft
$4.94
The Metals Depot
Steel Corner Brackets
(3/4” × 1/2”)
$1.97 / 4
braces
16
$7.88
Home Depot
Hardened 302 Stainless
Steel
$33.00
2 cm × 5 m × 12.7 µm
$33.00
McMaster-Carr
Total
$118.34
Project Planning
75
Cost Table – Electrical Components
Part
Price per
part
# Needed
Total Price
Supplier
Sanyo Stepper Motor
$ 59.95
2
$119.90
Pololu Electronics and Robotics
DRV8834 Low-Voltage Stepper
Motor Driver
$9.95
2
$19.90
Pololu Electronics and Robotics
FAULHABER 2036 BLDC
Servo Motor
$230.00
2
$460.00
MicroMo: Micro Motion Solutions
Atmel ATA6832-DK Brushless
DC Motor Controller
$208.00
2
$416.00
Atmel
Encoder AU-ZSD1000A
$225.00
2
$450.00
MicroMo: Micro Motion Solutions
PIC18F87K22 Microcontroller
$5.00
1
$5.00
Microchip
AD-524 Signal Converter
$17.67
1
$17.67
Agilent
Total
$1488.47
76
Questions?
77
References
• www.loctiteproducts.com
• Vallado, D. A., Fundamentals of Astrodynamics and Applications
• Guerrant, D., Lawrence, D., Heaton, A., Earth Escape Capabilities of the Heliogyro Sail.
•
•
•
•
•
•
•
•
AIAA Paper.
www.spaceflightnow.com
Guerrant, D., HGVizGui.m. MATLAB Program.
http://www.micromo.com/brushless-dc-motors.aspx
http://www.faulhaber.com/servlet/com.itmr.waw.servlet.Anzeige?fremdaufruf=ja&kdid=4092
9&sprachid=1&htdigurl=/n169933/i95222.html
http://www.pololu.com/
http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061t6
http://www.ruag.com/thermal/Space_Thermal_Hardware/Multi_Layer_Insulation
Helgesen, Bryan, Sierra Nevada Corporation
Appendix
78
GyroSail: Launch Configuration and Deployment Sequence
1. Launch configuration (6U)
2. Blade reel modules pitch to zero
Fits within a 6U or 12U dispenser.
Other array configurations are possible.
3. PV arrays deploy
NASA PREDECISIONAL - FOR DISCUSSION PURPOSES ONLY
78
[email protected]
Appendix
79
GyroSail: Primary Bus Systems
Based on modified JPL/U. Mich/UCLA/Cal Poly/UT INSPIRE bus *
0.5U COTS star tracker/imager, ADC (BCT); sail
module processor (CU).
0.5U cold gas thruster ACS for detumbling
and initial spin-up
(http://www.austinsat.net)
0.5U EPS, battery, C&DH, UHF backup
comms (U. Mich)
0.5U DSN-compatible X-band
communications (JPL)
* Klesh, A., et al. 2013. “INSPIRE: Interplanetary NanoSpacecraft Pathfinder In Relevant Environment,” Proceedings of the AIAA/USU Conference on Small Satellites, Around the Corner, SSC13XI-8, http://digitalcommons.usu.edu/smallsat/2013/all2013/127/.
NASA PREDECISIONAL - FOR DISCUSSION PURPOSES ONLY
[email protected]
Appendix
80
COMM Subsystem
• 18 m Ka-band antennas at White
Sands, New Mexico
• Goddard Space Flight Center,
Greebelt, Maryland, USA,
supplied the Mulemba Space
Center in Angola
Appendix
81
Secondary Payload Attachment to SLS
Orion Crew
Module
Spacecraft
Adapter
Interim Cryogenic Propulsion
Stage (ICPS)
ESPA Ring
The SLS design is currently going through CDR. An ESPA
ring is not currently in place but is mentioned in the SLS
CONOPS in order to accommodate secondary payloads.
6U Canisterized Satellite
Dispenser (CSD)
Appendix
82
Max Thrust Condition
 Collective 90° pitch profile
 Max thrust normal to orbital plane
(Halo orbits, orbital plane rotation, i.e.
inclination change)
Credit to Dan Guerrant
Appendix
83
Max Thrust Condition
F vs β
M vs β
Credit to Dan Guerrant
Appendix
84
No Thrust Condition
 Collective 0° pitch profile
 Zero thrust
Credit to Dan Guerrant
Appendix
85
No Thrust Condition
F vs β
M vs β
Credit to Dan Guerrant
Appendix
86
Max Torque Condition
 Collective 35° pitch profile
 Max torque used for spinning up s/c
(opposite orientation for despinning)
Credit to Dan Guerrant
Appendix
87
Max Torque Condition
F vs β
M vs β
Credit to Dan Guerrant
Appendix
88
Max In-Plane Thrust Condition
 Cyclic 35° pitch profile
 Max thrust in in-plane (d2) direction for orbit raising
Credit to Dan Guerrant
Appendix
89
Max In-Plane Thrust Condition
F vs β
M vs β
Credit to Dan Guerrant
Appendix
90
Orbit Raising
F
Appendix
91
Thermal Space Concerns
• Material Concerns:
• Aluminum 6061: -196 °C to 160° C
• Electronics Concerns
• Typical Operating Temperature: -55 to 80 °C
• Countermeasures:
• Multi-layer Insulation: AAErotherm S10-190
• (0.005 – 0.035 W/m2K)
• Battery operated heaters for pre-sail deployment
Multi-layer Insulation
Layer 1: 1 x Outer layer
Layer 2: 8 x 0.3 mil VDA/Polyimide/VDA, perf.
8 x Woven Polyester netting
Layer 3: 1 x Outer layer
Layer 4: 1 x Woven Polyester netting
Appendix
92
Rolled Up Blade Reel Calculation
Optimal Sail Length
545 m – Sail chord of 14 cm
Max Diameter of Spool
5.98 cm
Diameter of Axle
0.5 cm
Length of Stiff Material
Dimension of Stiff Material
5m
5 m × 2 cm × 12.7 µm
Appendix
93
Torque calculation
• Note: current calculated via T=kI (where T is torque, I is amp, k is the torque
constant specific to the motor)
T = kI
(k = 0.05 Nm/A)
Appendix
94
Servo Controller
Appendix
95
Encoder Dimensions and Interface
• FAULHABER IE2-1024
Appendix
96
Stepper Motor Torque
Appendix
97
Motor Phases (Stepper)
Appendix
98
Appendix
99
Appendix
100
Appendix
101
Appendix
102
Microcontroller
Appendix
103
ATA6832 Phase Output Chip
Appendix
104
ATA6624 Bypassed Chip
• Bypassed chip
on servo controller
Appendix
105
Power Budget
Appendix
106
Wire Gauge
Voltage Drop (%)
AWG Max Gauge
0.01
5
0.1
15
1
25
5
32
• Stepper Motor: 26AWG (0.4 mm diameter)
• Servomotor: 24 AWG (0.51 mm diameter)
• Encoder: 24 AWG
NOTE: Voltage drop calculated at 1A and 40 cm of wire
24 AWG Wire
Appendix
107
Trade Study – FEM vs. Vibration Table
Scoring
Factor
4
3
2
1
Cost
No money
0 > C > $100
$100 > C > $300
$300 < C
Time
0 min < T < 30 min
30 min < T < 2 hrs
2 hrs < T < 1 day
1day < T
Experience
Everyone has
experience
A couple people
know how to
1 person has
experience
No one has
experience
Similar To Actual
Launch
Simulate real launch
Doesn’t have all
variables experienced
Has only a couple
similarities
No similarities to
launch
Guaranteed Can Do
Don’t need any
outside equipment or
help
Need outside
equipment, but
guaranteed use
Need outside
equipment, but own
work at higher
priority
Need outside
equipment, but can’t
use
Appendix
108
Weighting
Weight (%)
Category
Reasoning
5
Cost
Have a lot of extra $ in the budget.
30
Time
Have a strict schedule, but not a main focus of the
project.
25
Experience
If no one has experience, it will take a lot of time.
20
Similar to Actual Launch
Needs to be like actual launch.
20
Guaranteed Can Do
Needs to be able to accomplish, but not the most
important focus.
Appendix
109
Finite Element Method (FEM)
Objectives
Description
Pro/Con
Cost
No money because one of us
would do it
Pro
Time
A lot of time to learn and then
perform F.E.M.
Con
Experience
No one in group has F.E.M.
experience
Con
Similar to Actual Launch
Very similar to actual launch
Pro
Guaranteed Can Do
All we need is paper, pen, and
theory to do
Pro
Appendix
110
Vibration Table
Objective
Description
Pro/Cons
Cost
$250/hr
Con
Time
A hour on the table should simulate
launch
Pro
Experience
Don’t need experience to run
vibration table
Pro
Similar to Actual Launch
Actually putting our system through
vibration stress
Pro
Guaranteed Can Do
No guarantee, but most likely can
Con
Appendix
111
SpinUp State
1.
Check value of SpinUp to see if satellite is already spun up
• Continue if satellite is not already spun-up
2.
Deploy the tape stiffened length of the blade
3.
Pitch to the spin up angle
4.
Wait until characteristic angular velocity is reached
5.
Pitch to pre-deployment position
6.
Save SpinUp as completed
Appendix
112
Deployment State
1. Check if satellite has been spun up yet
• Continue if it has
2. Check if blades are already deployed
• Continue if they haven’t
3. Run deploy algorithm until blades are fully deployed
4. Save value saying blades have been deployed
Appendix
113
Pitching State
1.
Check if satellite has been spun up
• Continue if satellite has been spun up
2.
Check if blades have been deployed
• Continue if blades have been deployed
3.
Look at commanded pitch profile
4.
Find correlated sinusoid command
5.
Command servo to pitch angle for the time in the orbit
6.
Continue until given a new pitch command
Appendix
114
Emergency Stop
Restart
1. Save which state was interrupted
1. Check two previous states to see
2. Save last position in interrupted
what is being restarted
2. Look at saved last position in
state being restarted
3. Adapt the algorithm of the state
to continue where left off
state
3. Wait until Restart command is
received
Appendix
115
Comparison with Previous Heliogyro Concepts
MIT (1989)
Total sail craft mass (kg)
18
NASA (2011)
8.4
GHOST
2.88 (6)
Characteristic acceleration, ac
(mm/s2)
Sail reflective area (m2)
Non-sail mass (kg)
0.6
1.0
0.3868 (0.1854)
1200
5
960
5
152.6
--
Number of sail blades
Blade chord (m)
Blade length (m)
Rotational period (minutes)
Blade root stress (Pa)
Blade root allowable stress (Pa)
8
1.5
100
3
8650
55 M
6
0.8
200
3
34000
55 M
2
0.14
545
1
---
Blade root tension load (N)
0.1
0.07
--