Spring Final Review (SFR) Geocentric Heliogyro Operational Solar-sail Technology (GHOST) April 29

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
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
1
Presentation Sections
• Project Overview
• Design Solution
• Test Overview
• Test Results
• Systems Engineering
• Project Management
2
Overview
Design Solution
Test Overview
Test Results
Background - HELIOS
Systems Eng.
Project Mgmt.
2
HELIOS Design
• 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
rotation
• GHOST project is extension of HELIOS
▫ Concentrates mainly on CubeSat structural design
▫ Main tests include deployment and pitching of solarsail blades in 1g environment
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
3
Concept of Operations
GHOST project responsible for deployment and
pitching validation:
1) Controlled Solar Sail Deployment
2) Solar Sail Root Pitch Control
1g controlled deployment of solar sails
• Suspend CubeSat in 1g environment
• Establish connection and initiate deployment
mechanism using motors
• Measure controlled sail deployment
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
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
4
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
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
5
Presentation Sections
• Project Overview
• Design Solution
▫ Functional Block Diagram
▫ Mechanical
▫ Electrical
▫ Software
• Test Overview
• Test Results
• Systems Engineering
• Project Management
6
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Functional Block Diagram
SSDM
CubeSat Bus
3.5 V Power Supply
Power
Deployment
Stepper Motor
BPCS
5 V Power Supply
Encoder
EPS
VC
Power
τA
Pitch Servo
Motor
CDH
Shaft
Angular Position
Deployment
Software
τC
Pitching
Software
Gear
System
Solar
Blade
Solar Sail
Deployment
Gear
Direction and Rate
τB
Step Pulse
RealTerm Commands
τG
τM
Ground Station
(User Input)
Blade Reel
Module
θ
Solar Sail
Pitch
6
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
7
Mechanical Overview
Side View
30 cm
Front View
Servo Motors/Encoders
Blade
C-Brackets
Stepper Motor
Tip Mass
Top View
Central Control
Module (CCM)
Blade Reel
Module (BRM)
“Launch Locks”
Servo Motor
Motor Drivers
Clamps
and PCB
Mass Summary
Theoretical (kg)
Measured
(kg)
BRM Total
2.062
2.012
CCM Total
1.694 + driver
1.490
CubeSat Total
3.756 + driver
3.502
Hub
Blade
Ball Bearing
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
8
Component Mass Summary
Total CubeSat
Structural Shell
Theoretical (kg) Measured (kg)
Theoretical (kg) Measured (kg)
BRM Structural Total
1.829
1.759
0.923
CCM Structural Total
1.213
1.047
0.080
0.062
Stepper Motor
0.090
0.083
Corner Cubes
0.140
0.216
Servo Motor/Encoder
0.120
0.075
Deployment Axle
0.026
0.027
Pitching Axle and Hub
0.116
0.094
Mylar Blade
0.016
0.018
Tip Mass
0.148
0.148
PCB
0.110
0.080
C-Brackets
0.024
0.022
Servo Driver
--
0.056
Misc. screws/nuts
0.135
0.135
BRM Total
2.062
2.012
BRM Structural Total
1.829
1.759
CCM Total
1.694 + driver
1.490
CCM Structural Total
1.213
1.047
Total
3.735 + driver
3.481
BRM Walls
1.160
1.110
CCM Walls
0.980
Blade Stabilizers
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Electronics Overview
BLDC Motor
Servo Driver
Used to drive the BLDC
motor through direction
and velocity control
RJ-12
PicKit Interface for
Programming of
PIC18
Equipped with HALL
and digital feedback
Stepper Driver
Used to control the
direction and step number
of the stepper motor
Stepper Motor
Used for blade
deployment
Microcontroller
PIC18F programmed
and used to control the
stepper and servo driver
9
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.8
10
Electronics Overview
BLDC Motor
Servo Driver
Used to drive the BLDC
motor through direction
and velocity control
DIR
RJ-12
PicKit Interface for
Programming of
PIC18
Equipped with HALL
and digital feedback
Speed Control
Stepper Driver
Used to control the
direction and step number
of the stepper motor
DIR
STEP
Stepper Motor
Used for blade
deployment
Microcontroller
PIC18F programmed
and used to control the
stepper and servo driver
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
11
Deployment Software
CCM
Determine Current
Circumference from Diameter:
Calculate Length Deployed:
Step Angle
D
𝑑𝑒𝑙𝑎𝑦𝑇𝑖𝑚𝑒 =
D
C
C
BRM
D
Mylar Roll
Calculate delayTime Between 48
Steps Before Next 48 Steps:
𝑙𝑒𝑛𝑔𝑡ℎ𝑆𝑡𝑒𝑝
2π ∗ 𝑑𝑒𝑝𝑙𝑜𝑦𝑅𝑎𝑡𝑒
L
Mylar Being Deployed
D = Diameter
C = Circumference
L = Length Deployed
48 Steps = 1 Rotation
• Calculation performed every 48 steps (1 rotation)
L
▫ Every one rotation reduces diameter by 2 ∗ 𝑡𝑚𝑦𝑙𝑎𝑟
▫ 𝑡𝑚𝑦𝑙𝑎𝑟 = 2.5 𝜇𝑚
• Length deployed with each rotation is recalculated after every 48 steps
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
Pitching Software
𝜃𝑐
𝐴
𝜃𝑒
Σ
-
ê1
[𝐴𝑜 − 𝑘𝜃𝑒 ]
𝐴
𝜃
𝐴
𝜃𝑐
Optical
Encoder
𝜃𝑐 (𝑡)
𝜃𝑎 (𝑡)
𝜃𝑎
▫ Angle A
▫ Period of rotation P
• Angle and period may be changed
dynamically
𝜃𝑎 = Actual Angular Position
𝜃𝑎 = Actual Angular Velocity
𝜃𝑐 = Actual Command Position
𝜃𝑐 = Actual Command Velocity
A = Maximum Amplitude
2𝜋𝑡
𝜃 = 𝐴 sin
𝑃
2𝜋
2𝜋𝑡
𝜃=
𝐴 cos
𝑃
𝑃
𝜃𝑒 𝑡 = 𝜃𝑐 𝑡 − 𝜃𝑎 (𝑡)
𝜃𝑎
Servo and Driver
Motor System
• Controller inputs maximum
ê2
1
𝑆
Blade Pitching Video
12
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
13
Pitching Control System Concept
45
40
𝐴0
Angular Position [degrees]
35
30
25
1. Given a
perturbation
20
15
10
5
0
0
10
20
30
40
Time (s)
50
60
70
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
13
Pitching Control System Concept
45
2. Commanded
Amplitude changes
𝐴1 = 𝐴0 + 𝑘𝑒1
A = [𝐴𝑜 + 𝑘𝜃𝑒 ]
• Amplitude changed by error
40
𝑘𝑒1
𝜃 = 𝐴 sin
𝐴0
35
2𝜋𝑡
𝑃
Angular Position [degrees]
• Angular rate accounts for error
30
𝜃=
2𝜋
2𝜋𝑡
𝐴 cos
𝑃
𝑃
𝑒1
25
1. Given a
perturbation
20
15
10
5
0
0
10
𝑡1
20
30
40
Time (s)
50
60
70
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
13
Pitching Control System Concept
45
2. Commanded
Amplitude changes
𝐴1 = 𝐴0 + 𝑘𝑒1
A = [𝐴𝑜 + 𝑘𝜃𝑒 ]
• Amplitude changed by error
40
3. Decreasing the
amplitude of the error
𝐴0
𝜃 = 𝐴 sin
35
𝑘𝑒2
Angular Position [degrees]
𝐴1 = 𝐴0 + 𝑘𝑒2
2𝜋𝑡
𝑃
• Angular rate accounts for error
𝑒2
30
𝜃=
2𝜋
2𝜋𝑡
𝐴 cos
𝑃
𝑃
𝑒1
25
1. Given a
perturbation
20
15
10
5
Δ𝑡
0
0
10
𝑡1
20
Note: time step magnitude not reflective of actual time times
𝑡2
30
40
Time (s)
50
60
70
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
13
Pitching Control System Concept
45
2. Commanded
Amplitude changes
𝐴1 = 𝐴0 + 𝑘𝑒1
A = [𝐴𝑜 + 𝑘𝜃𝑒 ]
• Amplitude changed by error
40
3. Decreasing the
amplitude of the error
𝐴0
𝜃 = 𝐴 sin
35
Angular Position [degrees]
𝐴1 = 𝐴0 + 𝑘𝑒2
2𝜋𝑡
𝑃
• Angular rate accounts for error
𝑒2
30
𝜃=
4. Error dampens to
infinitesimal limit
𝑒1
25
2𝜋
2𝜋𝑡
𝐴 cos
𝑃
𝑃
1. Given a
perturbation
20
15
10
5
Δ𝑡
Δ𝑡
0
0
10
𝑡1
20
𝑡2
Note: time step magnitude not reflective of actual time times
𝑡3
30
40
Time (s)
50
60
70
Overview
Design Solution
Test Overview
Test Results
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
Systems Eng.
Project Mgmt.
14
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
15
Critical Project Elements
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
3.8˚
Rolled solar blade
Servo driver
Deployment axle alignment
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
16
Presentation Sections
• Project Overview
• Design Solution
• Test Overview
▫ Deployment
▫ Pitching
▫ Deflection
• Test Results
• Systems Engineering
• Project Management
20
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Centripetal Acceleration
Orbital Trajectory
Vtip
Ω
L
Fc
Fg
Fg is negligible
Fc is centripetal force
Rotation Rate Ω = 1 RPM
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
17
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
Space to Earth Comparison
CubeSat rotating at 1 RPM → centripetal acceleration → centrifugal tension
Space Application
Ground Deployment
Motor
Tip mass trajectory
Stabilizer
r
Blade
Side View
Front View
Mounted to
Scaffolding
CubeSat
rotating at
1 RPM
Blade
Tip mass
Blade
F = mg
Top View
Blade is fully deployed → maximum centrifugal tension
𝑭𝒕𝒊𝒑 = 1.63 N
F = mg
F
Motor
mTotalSpace = 273.2 g
Tip mass
Simulate same centrifugal tension blade would experience in space
Total blade mass of 18 g used in deployment test
mTotalEarth =
𝐹𝑡𝑖𝑝
𝑔
= 166.2 g
mTipMass = 148.2 g
18
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
19
Deployment Test Overview
Testing Location: Fleming High Bay
Power on activates
holding torque
CubeSat
5V
Power
Supply
3.5V
Power
Supply
Remove tip
mass locks
Scaffolding
Tape
Measure
5 cm/s
3m
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
1. Command deployment at 5 cm/sec
2. Measure Deployment Rate
• Compare footage to expected rate
1m
2m
Design Requirement:
Calibrate
camera to 3 m
window
3. Repeated for variable rate testing
• Compare footage to predetermined
deployment profile
Overview
Design Solution
Test Overview
Test Results
Deployment Verification Tests
Test
Design Requirement
Objective
Deployment
• Deployment system
System
hardware does not
Power
exceed 10W power
Check
• Measure current and
voltage across
electrical components
individually
• Deployment can be
stopped given user
Variable
command
Deployment
• Deployment rate can be
Rate
changed given user
command
• Measure and compare
pulses of step output
pin using oscilloscope
Systems Eng.
Project Mgmt.
20
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
22
Pitching Test Overview
Testing Location: Aerospace
Instrumentation Shop
Servo Motor
Power Supply
12V
Logic Power
Supply
5V
CubeSat
CCM
Plywood
Pitching Stand
BRM
Angle Sensor
ADI516xxxIM4
(3 axis gyroscope)
1. Input predetermined pitch and period commands
via Realterm
2. Record data and compare to expected
performance and error tolerance
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
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Pitching Verification Tests
Test
Design Requirement
Objective
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
Project Mgmt.
23
Overview
Design Solution
Test Overview
Test Results
Deflection Test
CCM
Project Mgmt.
24
Design Requirements:
The CubeSat shall remain performance intact
during the forces of launch in a standard
CubeSat CSD
Testing Location: Aerospace Machine Shop
BRM
Systems Eng.
BRM
1. Measure zero point of right BRM using
manual knee mill
X-axis
d
2. Add 169N (~38 lbs) to right BRM
• Worst case scenario from Planetary
Systems CSD launch specifications
Clamp left BRM to table
F
Pitching axle (gray) and
launch lock (purple)
3. Measure deflection of right BRM using
knee mill (measured at rightmost edge)
Overview
Design Solution
Test Overview
Test Results
Deflection Verification Tests
Test
Static Load
Design Requirement
Objective
CubeSat walls intact under
169N load
• Ensure that the structure
itself will not fail under
launch loads
CubeSat walls shall not fail
• CubeSat structure will
Axial
under a 44N compressive
survive during CSD
Compression force experienced by CSD
ejection
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
Systems Eng.
Project Mgmt.
25
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.5
26
Presentation Sections
• Project Overview
• Design Solution
• Test Overview
• Test Results
▫ Deployment
▫ Pitching
▫ Deflection
• Systems Engineering
• Project Management
29
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Deployment Test Results
Stepper Motor Spin Rate
▫ Shorter length of blade is deployed
for each rotation
• Decreased delay time between steps
• RPM of stepper motor increases to
maintain constant deployment rate
Time (s)
• Diameter of the blade decreases as
blade is deployed
# of Revolutions
27
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Deployment Results
Deployment Test Results
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
• Constant Average deployment rate (within 1 𝑐𝑚 𝑠)
• Variable deployment rate capability
• Average deployment rate at 5 𝑐𝑚 𝑠
Project Mgmt.
28
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Deployment Validation
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
Velocity (cm/s)
Deployment Test Velocity
Time (s)
29
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
30
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
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
Pitching Test Results
Pitching Test Results
Solar Sail Blade Pitching Video
• Expected peak deflection angle from
model is ± 35°
• Testing showed deflection angles of
± 31.5°
• Experimental angle is within
requirement of a 5° error
31
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Pitching Test
Project Mgmt.
32
Collective Pitch Maneuver
Success
Level
Design Requirement
Achieved
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
Overview
Design Solution
Test Overview
Test Results
Deflection Test
Success
Level
axle and
launch locks
Project Mgmt.
Design Requirement
33
Achieved
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
F
modules
Systems Eng.
CubeSat modeled as equivalent cantilever beam
• Aluminum beams (purple)
• Unbendable rigid sections (orange)
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
Testing Location: Aerospace Machine Shop
36
Overview
Design Solution
Test Overview
Test Results
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)
-
-
Success Level
1
Design Requirement
CubeSat heliogyro system shall use no
more than 10W during operation
Achieved?
Yes
Systems Eng.
Project Mgmt.
34
• 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)
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.38
35
Presentation Sections
• Project Overview
• Design Solution
• Test Overview
• Test Results
• Systems Engineering
• Project Management
38
Overview
Design Solution
Test Overview
Systems Eng.
Test Results
Project Mgmt.
36
Systems Engineering Approach
Subsystem Organization
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
• 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)
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
37
Mechanical Integration Issues
Subsystem
Manufacturing
Issues
Lessons Learned
• “Small” tolerance issues propagated
throughout mechanical system
• Interface compliance document (ICD) to
define tolerances
• Unorganized production schedule
• Create and enforce responsibilities chart
and manufacturing schedule
• Software development schedule
Software
• Interface issues with new
microcontroller/board
• Unorganized development process
• SW method development (flowchart)
• SW validation models (MatLab/Simulink)
• Embedded system design (C)
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
38
Mechanical Integration Issues
Subsystem
Issues
Lessons Learned
• Unable to communicate with original PCB
• More preliminary research on board configuration
Electronics
• Unable to calibrate servo driver to needed
precision, LIN communication protocol issues
• 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
• ICD to define tolerances
• Lack of communication regarding changes
• Continual validation tests with
electrical/mechanical interfaces
• 9 pin RS-232 wiring outdated
• Note interface feasibility
Overview
Design Solution
Test Overview
Test Results
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
Systems Eng.
Project Mgmt.
39
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.43
40
Presentation Sections
• Project Overview
• Design Solution
• Test Overview
• Test Results
• Systems Engineering
• Project Management
43
Overview
Design Solution
Test Overview
Test Results
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
Systems Eng.
Project Mgmt.
41
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
42
Project Budget
BUDGET BREAK DOWN
Printing &
Presentation
5%
Projected
5%
Testing
2%
Projected Budget
Structural
21%
$2337.43
Actual Budget
$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
Electronics
67%
Structural
Testing
Printing &
Presentation
Projected
Electronics
$428
$47
$105
$95
$1346
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
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 ∗
Total cost = 4,096 hours worked ∗
16 ℎ𝑜𝑢𝑟𝑠
𝑤𝑒𝑒𝑘
= 𝟒, 𝟎𝟗𝟔 𝒉𝒐𝒖𝒓𝒔
$65,000
2,080 ℎ𝑜𝑢𝑟𝑠 𝑤𝑜𝑟𝑘𝑒𝑑
= $128,000
• $16,000 per person
• 𝐼𝑛𝑑𝑢𝑠𝑡𝑟𝑦 𝐶𝑜𝑠𝑡 = 𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 ∗ 𝑂𝑣𝑒𝑟ℎ𝑒𝑎𝑑 𝑟𝑎𝑡𝑒 = $𝟐𝟓𝟔, 𝟎𝟎𝟎
Project Mgmt.
43
Overview
Design Solution
Test Overview
Test Results
Systems Eng.
Project Mgmt.
44
Thank you!
Questions?
47
Appendix
45
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
Appendix
46
Pitching Capabilities: 1P Cyclic
• Cyclic 1P pitch profile
• Provides a net in-plane thrust F1
• Used to perform orbit raising and lowering maneuvers
Appendix
47
Pitching Capabilities: hP
• hP pitch profile
• Produces a net moment M2 about spacecraft
• Used to process the spacecraft angular momentum vector and
reorient the gyro rotational axis
Appendix
21
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
Appendix
48
Electronics Functional Block Diagram
Direction
Step
Serial
Communication
(RealTerm via RS-232)
Deployment
Driver
Deployment
Motor
(Stepper)
(Stepper)
Direction
Microcontroller
(PIC)
Position
Feedback
Digital
Encoder
Digital
Signal
DAC
Voltage
Pitching
Driver
(Servo Driver)
Internal Position
Feedback
Angular
Speed
Pitching
Motor
(BLDC Motor)
HALL
Encoder
Appendix
49
Pitching Model Simulation
A Simulink model was produced and analyzed to validate GHOST pitching capabilities
Appendix
50
Pitching Simulation Results
Pitching Model Simulation
• 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
Appendix
51
Deployment Test Considerations
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
Remove Screws and Washers from
Tip Mass for Deployment
Appendix
52
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)
Appendix
53
Pitching Test Considerations
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
Remove Screws and Nuts from inside CCM for Pitching
Appendix
54
Drawing Tree – Parts List
Part Name
BRM Side Wall
BRM Back Wall
BRM Top and Bottom Wall
BRM Left Front Wall
BRM Right Front Wall
CCM Side Wall
CCM Front and Back Wall
CCM Top and Bottom Wall
Left Blade Stabilizer
Right Blade Stabilizer
Corner Cube
Blade Deployment Axle
Pitching Axle
Tip Mass
Hub
C-Brackets
Servo Motor Clamps
Part Number
S318T6
Distributor
Stock Quantity Ordered? Completed?
Total Cost
7/16 x 24" Aluminum Axle
1
Y
3/2 x 3/4" Aluminum Cylinder
4 x 3/4 x 3/10" Aluminum Block
1 x 1/2 x 1/2" Aluminum Block
2
1
1
N/A
N/A
N/A
1
2
2
2
1
N/A
N/A
N/A
N/A
1 roll, 3/4" wide
N/A
N/A
N/A
N/A
1
Y
Y
Y
Y
Y
N/A
N/A
N/A
N
Y
Mouser
1
N/A
N/A
Y
N/A
$5.29
Mouser
2
N/A
N/A
Y
N/A
$12.02
Metals Depot
McMaster
Metals Depot
R3716
Metals Depot
N/A
N/A
N/A
Matt Rhode
Matt Rhode
Matt Rhode
Stepper Motor
Servo Motor
Encoder
Rolled Blade
Kapton Tape
SS2421-5011
2036U012BK312+OPEC05
HEDM5500J06
N/A
Polulu
PIC
18F87K22
Micromo
NASA LaRC
Unline
4
2
4
2
2
2
2
2
2
2
24
2
2
2
2
4
4
Stock
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
Y
N
N
99108A130
R314
DAQ MAS522CPA
Quantity
1/8" Thick Aluminum
5/8 x 5/8 x 12" Aluminum Key Stock
1/4 x 24" Aluminum Axle
2
2
1
Y
Y
Y
$105.84
$22.86
$1.96
$4.94
$0.00
$0.00
$0.00
$59.95
$372.10
$0.00
$25.00
Sipex chip
SP232EEP
Mouser
1
N/A
N/A
Y
N/A
$1.05
PCB Board
Stepper Motor Driver
Servo Motor Driver
Misc. Electronics parts
DRV8834
ATA6832-DK
N/A
Advanced Circuits
Polulu
Atmel
JB Saunders
1
2
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Y
Y
Need 1
N
N
N/A
N/A
N
$33.00
$9.95
~$50.00
Flathead Torx
Friction-Resistant Shoulder
Flathead Phillips
Flathead Phillips
Hex Nut
Set Screw
Flathead Phillips
Flathead Phillips
Hex Nut
Washer
92703A207
95446A652
91771A053
91771A170
90545A111
92313A109
91771A168
91771A175
90480A002
90107A003
McMaster
McMaster
McMaster
McMaster
McMaster
McMaster
McMaster
McMaster
McMaster
McMaster
72
2
20
20
2
8
8
4
12
4
4-40 x 5/16"
10-32 x 1/4 x 7/16"
0-80 x 5/32"
1-72 x 1/2"
10-32 x 3/8 W x 1/8" H
4-40 x 1/2"
1-72 x 3/8"
1-72 x 1"
1-72 x 5/32 x 3/64"
1/8 ID x 1/4" OD
2
2
1
1
2
1
1
1
1
1
Y
Y
Y
N
N
N
N
N
N
N
Y
Y
Y
N
N
N
N
N
N
N
$15.20
$5.76
$8.62
$13.93
$5.26
$10.00
$12.78
$9.64
$2.92
$2.64
Theoretical Mass
Measured Mass
Notes
0.062
0.168
0.132
0.0245
0.0245
0.0964
0.15
0.215
0.023
0.018
0.009
0.0136
0.0059
0.046
0.041
0.0056
0.0033
0.060
0.160
0.130
0.020
0.020
0.100
0.160
0.230
0.023
0.017
0.010
0.013
0.010
May want to cut out triangles
0.07
0.05
0.085
0.393
0.073
May want to cut out triangles
May want to cut out triangles
Needs to be press fit onto stepper motor
Needs to be press fit onto servo motor
0.043
0.080
Encoder and motor ordered together, company interfaced them for us
Theoretical mass based off entire blade length
0.006667
0.080
0.034
None
None
0.00045
0.00770
0.00013
0.00026
0.00363
0.00064
0.00026
0.00026
0.00013
0.00013
0.070
Currently only have 1 because of supply shortage with distributor
Wires, resistors, capacitors, etc…
0.00040
Connecting all walls to cubes
Launch Locks
Connecting stabillizers to walls
Connecting tip mass to walls
Launch Lock Nuts
Securing pitching axle into hub
Connecting servo motor clamps to walls
Connecting servo motor clamps together
Nuts for connecting servo motor clamps to walls and together
Appendix
55
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
Res
Microcontroller
Logic Supply
+5V
+3.5V
Motor
Supply
DAC
Logic Supply
Stepper
Driver
(Deploy
ment)
Logic Supply
Motor
Supply
Encoder Supply
Servo
Driver
(Pitching)
Servo Motor
Encoder
Stepper Motor
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
58
DAC Output Signal