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Project Design Review DIABLO De-rotated Imager of the Aurora Borealis in Low-earth Orbit. Nicole Demandante Laura Fisher Jason Gabbert Lisa Hewitt. Lang Kenney Nick Pulaski Matt Sandoval Tim Sullivan. - PowerPoint PPT Presentation
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Project Design ReviewProject Design ReviewDIABLODIABLO
De-rotated Imager of the Aurora Borealis in Low-earth OrbitDe-rotated Imager of the Aurora Borealis in Low-earth Orbit
Nicole Nicole DemandanteDemandanteLaura FisherLaura Fisher
Jason GabbertJason GabbertLisa HewittLisa Hewitt
Image taken from Space Shuttle over South Pole: http://www.geo.mtu.edu/weather/aurora/images/space/
Lang KenneyLang KenneyNick PulaskiNick Pulaski
Matt SandovalMatt SandovalTim SullivanTim Sullivan
22
AgendaAgenda
Background, objectives, requirementsBackground, objectives, requirements System Design AlternativesSystem Design Alternatives System Design-To-SpecificationsSystem Design-To-Specifications Subsystem Design AlternativesSubsystem Design Alternatives Project Feasibility and Risk AssessmentProject Feasibility and Risk Assessment Project Management PlanProject Management Plan
33
BackgroundBackground
Initial Idea: LASP - Initial Idea: LASP - Monitor ProposalMonitor Proposal
Scientific Purpose: Scientific Purpose: Visible light images Visible light images and in-situ and in-situ observationsobservations
44
ObjectiveObjective
Objective: Provide a Objective: Provide a spinning satellite with a spinning satellite with a de-rotated imaging de-rotated imaging systemsystem
Deliverables:Deliverables: De-rotated imaging De-rotated imaging
assemblyassembly Spinning test bedSpinning test bed Control loopControl loop
Goal: Goal: Achieve the least amount Achieve the least amount
of smear in the imageof smear in the image Model final fight Model final fight
spacecraftspacecraft
55
System Level Design-to-System Level Design-to-SpecsSpecs
The system shall The system shall ……
Optical SystemOptical System Take pictures at Take pictures at
9090°° Pointing within 3Pointing within 3°° Field of view Field of view
minimum of 6minimum of 6°° Earth
12°
Spin Axis
3°
Optical Axis
66
System Level Design-to-System Level Design-to-SpecsSpecs
Control LoopControl Loop Pixel smear - Images can be resolved to better Pixel smear - Images can be resolved to better
than 1 pixel per kilometer than 1 pixel per kilometer ** Sun-shading AssemblySun-shading Assembly
No direct sunlight between 60No direct sunlight between 60°° and 90 and 90°° latitude latitude Test SystemTest System
Test bed range: 2 – 20 rpmTest bed range: 2 – 20 rpm Offset Test – Tilt 1Offset Test – Tilt 1° relative to test bed° relative to test bed Test camera resolution to shutter speed ratio Test camera resolution to shutter speed ratio
similar to flight camerasimilar to flight camera
*Changed from PDD, customer approved
77
System DesignsSystem Designs
Optical and Spin Axis AlignmentOptical and Spin Axis Alignment Design will be used by customerDesign will be used by customer
88
System DesignsSystem Designs
Fixed CamerasFixed Cameras Passive Passive StabilizationStabilization
Spin axis
Cameras
Cameras
Spindirection
Booms
99
System DesignsSystem Designs
Rail CarRail Car Parallel PlateParallel Plate
1010
System Level Design System Level Design ComparisonComparison
Image Clarity (22%)
Complexity (15%)
Fabrication (15%)
Ease of Verification (15%)
Moment of Inertia
(10%)
Mass (10%)
Comparable to Actual Satellite (13%)
Total Score
Fixed Camera 1 10 9 7 2 2 1 4.64
Passive 3 8 9 1 9 10 1 5.47
Rail Car 7 3 5 7 5 6 6 5.66
Parallel Plate 7 6 6 7 5 6 4 6.00
Axis Alignment 8 7 7 7 7 8 8 7.45
Fixed Camera Passive StabilizationRail Car Parallel Plate Axis Allignment
For more detail see slides 41 - 46
1111
SubsystemsSubsystems
OpticalOptical RotationRotation StructureStructure Electronics & SensorsElectronics & Sensors Controls & Data AcquisitionControls & Data Acquisition PowerPower
1212
Optics
Sizing Camera
Transfer picturesDo not limit FOV
Rotation StructuresElectronics/
SensorsControls Power
Take mutiplepictures
Adjustable shutter speed
1313
SizingSizing Actual spacecraft will use two de-rotated assembliesActual spacecraft will use two de-rotated assemblies
R = 0.75 – 1 m
R = 0.75 – 1 m
h
RTest
6°
“Design-To”Radius
r
R=0.75-1m
Actual test platform does not need to be this large so long as the height Actual test platform does not need to be this large so long as the height is sufficient to meet above requirementis sufficient to meet above requirement
1414
ArrangementArrangement
Requirements on flight Requirements on flight cameracamera Long focal length (~10cm)Long focal length (~10cm) Thermal shieldingThermal shielding Radiation shieldingRadiation shielding
Moment of InertiaMoment of Inertia Camera Choice: COTS Camera Choice: COTS
“point and shoot”“point and shoot”
MirrorMirror
For more detail on camera choice, see slide 47
1515
Resolution Resolution
Operating Range: -90 ° to -60° and 60° to 90°
Depends on Orientation of Orbit
0
2
4
6
8
10
12
14
16
-100 -80 -60 -40 -20 0 20 40 60 80 100
Latitude
Res
olu
tion (pix
els/
km) sg
df
1616
Optics Rotation StructuresElectronics/
SensorsControls Power
Test Bed Motor
De-Rotated Motor
Match test bed rotation with precision of
0.075rpm
Angular velocity range of
2 to 20 rpm
1717
Precision Motor OptionsPrecision Motor Options
Direct Drive Servo MotorDirect Drive Servo Motor Stepper Motor Stepper Motor Brushless Servo Brushless Servo MotorMotor
Static Torque MassMax Power
ConsumptionAccuracy
LV341 Stepper Motor
550 oz-in 3.85 lb 250 W 350 steps/rev
BE232D Servo Motor
476 oz-in 3.1 lb 190 W NA
DM1004B Direct Drive Motor
566 oz-in 6.6 lb 300 W1,024,000 steps/rev
1818
Motor Mounting DesignsMotor Mounting Designs
Stepper/Servo Motor Stepper/Servo Motor MountingMounting
Motor does not support Motor does not support axial loadsaxial loads
Structure must be Structure must be supported by test bedsupported by test bed
Direct Drive Motor MountingDirect Drive Motor Mounting Motor supports axial loadsMotor supports axial loads Structure can be mounted Structure can be mounted
directly to motordirectly to motor
For bearing options, see slide 49
1919
Optics Rotation StructuresElectronics/
SensorsControls Power
Bending Stiffness
Bending < 6 microns (6 pixels)
ωn > Launch VibrationFrequency=50hz
Vibration Frequencies
Bending < 0.3° (6 pixels)
Forcing Frequency ≠ Resonance Frequency (ωn)
Structural DesignStructural DesignOption #1 Option #2 Option #3
Judgment criteria: Lest mass, Moment of inertia, Deflection
Requirement:
•Bending < 6 microns (pixel smear req.)
•Bending < 0.3° (pixel smear req.)
•Stiffness of structure
2121
Structural design: SunshadeStructural design: Sunshade
Periscope DimensionsPeriscope Dimensions RequirementsRequirements 12° Field of View12° Field of View Shade lens from Shade lens from
direct sunlightdirect sunlight
Total Height = 17 cmTotal Height = 17 cm
Inner diameter = 7cmInner diameter = 7cm
Outer diameter = 8cmOuter diameter = 8cm
Height from support plates = 5 cmHeight from support plates = 5 cm
Sunshade opening = 6 cmSunshade opening = 6 cm
Sun shade thickness = 0.5 cmSun shade thickness = 0.5 cm
Support plate thickness = 1cmSupport plate thickness = 1cm
2222
Structure design: deflection requirement Structure design: deflection requirement feasibilityfeasibility
Requirement:
•Bending < 6 microns (pixel smear req.)
•Bending < 0.3° (pixel smear req.)
•Stiffness of structure
Meets Requirement Fails Requirement!
Solution: substitution of support rods with truss structure
Approximation: cantilever beam
For more detail, see slide 50
2323
Structural design: Material Structural design: Material selectionselectionDesign to goal: Highest Mass/Stiffness
Other Considerations:
• Availability
• Cost
• Fatigue Strength
• Coefficient of thermal expansion
Mass/Stiffness
AISI 4130 Steel 9.562E-06
Aluminum 1350-H16 9.770E-06
Aluminum 2024-T3 9.434E-06
Aluminum 5182-O 9.475E-06
Aluminum 6061-T6 9.750E-06
Aluminum 7075-T6 9.808E-06
Titanium 6-4 9.697E-06
Good Selections
• Aluminum 2024-T3
• Aluminum 5182-O
• Steel 4130
For more detail on material selection, see slide 51
2424
Optics Rotation StructuresElectronics/
SensorsControls Power
Angular Position VibrationsAngular Velocity
Range: ±360°
Resolution: 0.045°
Microprocessor Compatible
Range: 2 and 20 rpm
Resolution: 0.075 rpm
Microprocessor Compatible
3 Axes
Bandwidth: 1 kHz
Resolution:27.3 mg
2525
SensorsSensors Encoder option preferred Encoder option preferred
over Resolverover Resolver Low speed operationsLow speed operations AccuracyAccuracy Minimal ComplexityMinimal Complexity CostCost Ability to ModifyAbility to Modify Motors/Sensor packageMotors/Sensor package AvailabilityAvailability Absolute PositionAbsolute Position
Encoders can measure Encoders can measure angular position and angular position and velocityvelocity
Tachometer or Rate Gyro Tachometer or Rate Gyro may be used in may be used in conjunction with conjunction with Encoder Encoder
Accelerometers will Accelerometers will be used to measure be used to measure the vibrationsthe vibrations
For more detail on electronics, see slides 52, 53, 54
2626
Optics Rotation StructuresElectronics/
SensorsControls Power
Simulation Microcontroller
DetermineEnvironmental
Torques
DetermineΔposition
DetermineMotor Torque
Within 0.075 Nm
Input velocity & position
ProcessControl algorithm
Output motor current
2727
Simulation and Software Simulation and Software AlgorithmsAlgorithms
Environmental
Torques
Applied Control Torque
Dynamics
(calculate angular rate)
Kinematics
(calculate angular position)
Control Law
(PID)
Angular Velocity Sensor
Position Sensor
Kinematics Dynamics
Control
Law
Motor
Torque
2828
Test Set UpTest Set Up•Verification:
• ωDe-rotated= ωRotated
• ractual=rdesired
• Lflight=Lmodel
•Validation
•Image analysis
For more detail on controls, see slide 57, 58
2929
Optics Rotation StructuresElectronics/
SensorsControls Power
De-RotatedMotor
Sensors Structures Camera Microcontroller
Provide Power:Dependant on Motor Selection
Provide Power:
200mA at 6V
Low Volume:Fit WithinAvailable
Space
Powered byInternalbattery
Provide Power:4mA at 5.5V
Low Mass:Reduce
Required Torque
Transfer power across rotating sections
3030
PowerPower Design CriteriaDesign Criteria
ComplexityComplexity CostCost MassMass VolumeVolume
Possible SolutionsPossible Solutions Slip Rings:Slip Rings:
Mercotac Rotary Electrical ConnectorsMercotac Rotary Electrical Connectors Conductix R Series Slip RingsConductix R Series Slip Rings Moog 6300 Series Slip RingsMoog 6300 Series Slip Rings
BatteriesBatteries Nickel CadmiumNickel Cadmium Nickel Metal HydrideNickel Metal Hydride Lithium IonLithium Ion
Slip Ring/Battery CombinationSlip Ring/Battery Combination
For more detail on power, see slide 55, 56
3131
Work Breakdown StructureWork Breakdown StructureDIABLO
Scheduling
Task Management
Group Management
Risk Management
Camera Selection
Testbed Sizing
Define Pixel Smear
Geometry Design
Imaging Platform Design
Sunshade Design
Testbed Design
CAD Model
Rotation Design
Motor Selection
Bearing Selection
Identify Power Needs
Hardware Selection
Identify VerificationNeeds
Hardware Selection
Data Acquisition and
signal conditioning
Software Diagrams
Test Set Up
Testbed Simulation
Integration withSensors
FEM analysis
Fabrication
Software Algorithm
Final Testing
ControlsLisa HewittTim SullivanNick Pulaski
Verification
Nicole Demandante
Power
Nick Pulaski
RotationMatt SandovalJason Gabbert
StructuresTim SullivanLaura FisherLang Kenney
Optics
Jason Gabbert
Systems Engineer
Management
Laura Fisher
3232
Schedule through CDRSchedule through CDR
For rest of detailed schedule, see slide 59
3333
Schedule for Spring Schedule for Spring SemesterSemester
More detailed schedule, see slide 61
3434
Cost EstimatesCost EstimatesTeam Component Unit Cost Quantity Approx Cost Margin Total Cost
Optics Camera $500 1 $500 20 $600
Mirror $50 1 $50 25 $62.50
Mirror Mount $100 1 $100 25 $125
Electronics and Sensors Encoders $50 2 $100 25 $125
Rate Gyro/Tachometer $50 2 $100 25 $125
Accelerometer $12 2 $24 20 $28.80
Miscellaneous $100 1 $100 25 $125
Rotation Motor $600 1 $600 20 $720
Drive $1,500 1 $1,500 20 $1,800
Controller $1,000 1 $1,000 20 $1,200
Testbed Motor $200 1 $200 20 $240
Bearings $150 2 $300 20 $360
Power Slip Rings $85 2 $170 25 $212.50
Batteries $20 1 $20 15 $23
Miscellaneous $30 1 $30 15 $34.50
Structures Bulk Material $150 1 $150 20 $180
$4,944 $5,961
3535
Mass EstimatesMass EstimatesMass kg
sun shade 0.437
Periscope 15
Test Bed 6.09
4 Support Rods 7.09
1 Support Plate 0.574
Camera 0.5
Motors 7.5
Electronics/Sensors 0.3
Power system 0.5
Total Rotating 23.401
Total + Test bed 37.99
Total with 25% margin 47.49
3636
Risk MatrixRisk MatrixInaccurate Inaccurate SensorsSensors
Motor does Motor does not work as not work as specifiedspecified
UnderestimatUnderestimate Vibratione Vibration
Behind in Behind in schedulingscheduling
Over budgetOver budget
Parts are Parts are delayeddelayed
Fabrication Fabrication errorerror
Control Control software is software is inaccurateinaccurate
Compression Compression in camera in camera imageimage
Mounting Mounting inaccuracyinaccuracy
Probability
Con
sequ
ence
3737
ConclusionConclusion System design and subsystem design options will System design and subsystem design options will
fulfill customer requirements and expectationsfulfill customer requirements and expectations System design is feasible within the budget, time, System design is feasible within the budget, time,
and expertise leveland expertise level
Image – FAST satellite artist sketch: http://sprg.ssl.berkeley.edu/fast/
3838
ReferencesReferences
Fundamentals of mechanical vibrations, S. Fundamentals of mechanical vibrations, S. Graham Kelly, McGraw-Hill, Inc. Graham Kelly, McGraw-Hill, Inc.
Engineering Mechanics Dynamics, Engineering Mechanics Dynamics, Bedford/Fowler, Prentice Hall, 2005Bedford/Fowler, Prentice Hall, 2005
http://www.mercotac.com/html/products.htmlhttp://www.mercotac.com/html/products.html http://www.conductix.comhttp://www.conductix.com http://www.polysci.comhttp://www.polysci.com http://www.onlybatteries.comhttp://www.onlybatteries.com http://www.panasonic.com/industrial/battery/oem/http://www.panasonic.com/industrial/battery/oem/ http://www.bbma.co.uk/batterytypes.htm http://www.bbma.co.uk/batterytypes.htm
BACKUP SLIDESBACKUP SLIDES
4040
Pros and ConsPros and ConsFixed CameraFixed Camera
Pros:Pros: Mechanically less complicated, no moving partsMechanically less complicated, no moving parts Control system not requiredControl system not required Proven technologyProven technology
Cons:Cons: Complete coverage would require 30 cameras with a 12° Complete coverage would require 30 cameras with a 12°
field of view.field of view. For the given camera shutter speed (100ms), resolution For the given camera shutter speed (100ms), resolution
(1Meg), and field of view (12°) and assuming only a 1 (1Meg), and field of view (12°) and assuming only a 1 pixel smear, the maximum rotation rate would be pixel smear, the maximum rotation rate would be 0.11718°/s. Actual rotation rate is ~72°/s.0.11718°/s. Actual rotation rate is ~72°/s.
Back to system level choice
4141
Pros and ConsPros and ConsPassive StabilizationPassive Stabilization
Pros:Pros: Simple design, easy to constructSimple design, easy to construct No de-spun motor requiredNo de-spun motor required Aligns camera with magnetic field lines without help Aligns camera with magnetic field lines without help
from main satellitefrom main satellite No control loop neededNo control loop needed
Cons:Cons: Difficulty with verificationDifficulty with verification Potential interference with the science hardwarePotential interference with the science hardware Possible pointing and stability issuesPossible pointing and stability issues Can’t point camera off of magnetic field lines if desiredCan’t point camera off of magnetic field lines if desired
Back to system level choice
4242
Passive Stabilization Passive Stabilization CalculationsCalculations Assuming that the de-rotated section is a solid cylinder of radius Assuming that the de-rotated section is a solid cylinder of radius
R=15cm with mass m=0.5kg the moment of inertia I is:R=15cm with mass m=0.5kg the moment of inertia I is:
If we want to be able to accelerate the despun portion to an angular If we want to be able to accelerate the despun portion to an angular velocity ω of 72 degrees/s (the speed of the satellite) within 1 second velocity ω of 72 degrees/s (the speed of the satellite) within 1 second in a frictionless environment, the required torque τ will be:in a frictionless environment, the required torque τ will be:
To get the desired torque with a magnetic field strength of B=20,000 To get the desired torque with a magnetic field strength of B=20,000 nT (the field strength from orbit) the magnet must have a linear dipole nT (the field strength from orbit) the magnet must have a linear dipole moment μ of:moment μ of:
Using the magnetic torquers found at Using the magnetic torquers found at http://http://www.smad.com/analysis/torquers.pdfwww.smad.com/analysis/torquers.pdf a torque rod which can generate a torque rod which can generate a linear dipole moment of 80 Am2 has a length of 0.5m, 2 coils, and a linear dipole moment of 80 Am2 has a length of 0.5m, 2 coils, and draws 4.7W of power at 28V. This gives a turn density n and current i draws 4.7W of power at 28V. This gives a turn density n and current i of:of:
At the center of a long solenoid the magnetic field strength B=μni At the center of a long solenoid the magnetic field strength B=μni where μ=μ0*k. The relative permeability of a nickel alloy for the core where μ=μ0*k. The relative permeability of a nickel alloy for the core is about k=8000, so the field strength generated by this magnet is:is about k=8000, so the field strength generated by this magnet is:
Back to system level choice
4343
Rail Car CalcuationsRail Car Calcuations
Pros:Pros: A small movement in the motor will not result in a large deviation in A small movement in the motor will not result in a large deviation in
pointing accuracypointing accuracy Not as stringent requirements on motor sensitivity as other suggested Not as stringent requirements on motor sensitivity as other suggested
designs.designs. Cons:Cons:
Thermal expansion would cause large errorsThermal expansion would cause large errors Radius could expand by up to 5% (depends on material)Radius could expand by up to 5% (depends on material)
Momentum balancing requirements would require additional masses Momentum balancing requirements would require additional masses and precise balancingand precise balancing
Scaling with actual satellite would not be a feasible size, requiring an Scaling with actual satellite would not be a feasible size, requiring an unreasonably large trackunreasonably large track
Changing moment of inertia would result in scaling issue for the control Changing moment of inertia would result in scaling issue for the control looploop
Electrical system very complicated and expensive – would require large Electrical system very complicated and expensive – would require large slip ringslip ring
Back to system level choice
4444
Parallel Plate CalculationsParallel Plate Calculations
Pros:Pros: Simple constructionSimple construction
Cons:Cons: Masses not evenly balanced would create Masses not evenly balanced would create
precession in the top plate.precession in the top plate. Requires the addition of excess massRequires the addition of excess mass May not be able to meet the sun shading May not be able to meet the sun shading
requirementrequirement
ScalingScaling
Back to system level choice
4545
Optical and Spin Axis Optical and Spin Axis Allignment CalculationsAllignment Calculations
Pros:Pros: Easiest to balance massEasiest to balance mass Lots of space and flexibility in mounting cameraLots of space and flexibility in mounting camera Smallest amount of mass (lack of ballast)Smallest amount of mass (lack of ballast) Less susceptible to thermal expansion issuesLess susceptible to thermal expansion issues Scalable to actual flight instrumentScalable to actual flight instrument
Cons:Cons: Complicated attachment to testbedComplicated attachment to testbed Stability issuesStability issues
Jitter, vibrationJitter, vibration
Back to system level choice
4646
CameraCameraLevel 1 Trade StudyLevel 1 Trade Study
Features: Zoom, Wireless, Timers
Adjustability: Shutter, Aperture, Flash
Ease of
Alignment (7%)Cost
(31%)Features
(17%)Required
Skill (24%)Adjustability
(21%) Total
Component Level 1 1 1 1 1 29
Single Lens Reflect (SLR) 3 1.5 2 2 3 61.5
Point and Shoot (PS) 2.5 3 3 3 2 80
SamplesSamples
Back to optics
4747
RotationRotation Test Bed MotorTest Bed Motor
Simulates the rotation of spinning satelliteSimulates the rotation of spinning satellite Does not require precise controlDoes not require precise control No size, weight or power constraintsNo size, weight or power constraints
OptionsOptions AC or DC motorAC or DC motor
InexpensiveInexpensive Single voltage inputSingle voltage input Simple manual controlSimple manual control
4848
Bearing OptionsBearing Options
Thrust Ball BearingsThrust Ball Bearings Ball Bearings Cylindrical Roller Ball Bearings Cylindrical Roller Tapered Roller Tapered Roller
Bearings BearingsBearings Bearings
Radial Load Radial Load SupportSupport
Axial Load SupportAxial Load Support
Thrust BearingsThrust Bearings NoNo YesYes
Ball BearingsBall Bearings YesYes NoNo
Roller BearingsRoller Bearings YesYes NoNo
Tapered BearingsTapered Bearings YesYes YesYes
Back to rotation
4949
Structural designStructural design
F =mrω²
r
Satellite
Periscope
ω
S/C Configuration:
Modeled As Cant. Beam:
m = ¼ Total System Mass
v θ
L
Back to structure
5050
Material SelectionMaterial SelectionFeasibility Feasibility
Matrix Matrix MaterialMaterial
density density (lb/in³)(lb/in³) 0.70.7
Modulus of Modulus of Elasticity Elasticity
(ksi)(ksi) 0.70.7 CTE, linear 250°CTE, linear 250°
(µin/in-°F)(µin/in-°F) 0.30.3
AISI 4130 SteelAISI 4130 Steel 0.2840.284 0.70.7 0.3370.337 2970029700 0.70.7 11 77 0.30.3 0.3310.331
Aluminium 1350-Aluminium 1350-H16H16 0.09770.0977 0.70.7 0.9790.979 1000010000 0.70.7 0.3360.336 14.214.2 0.30.3 0.1630.163
Aluminum 2024-Aluminum 2024-T3T3 0.10.1 0.70.7 0.9570.957 1060010600 0.70.7 0.3560.356 13.713.7 0.30.3 0.1690.169
Aluminium 5182-OAluminium 5182-O 0.09570.0957 0.70.7 11 1010010100 0.70.7 0.3400.340 14.414.4 0.30.3 0.160.16
Aluminium 6061-Aluminium 6061-T4T4 0.09750.0975 0.70.7 0.9820.982 1000010000 0.70.7 0.3360.336 1414 0.30.3 0.1660.166
Aluminium 7075-Aluminium 7075-T6T6 0.1020.102 0.70.7 0.9380.938 1040010400 0.70.7 0.3500.350 1414 0.30.3 0.16580.1658
Titanium 6-4Titanium 6-4 0.160.16 0.70.7 0.5980.598 1650016500 0.70.7 0.550.55 5.115.11 0.30.3 0.450.45
Invar 36Invar 36 0.2910.291 0.70.70.3290.329
88 2050020500 0.70.7 0.690.69 2.322.32 0.30.3 11
Shear Shear StrengtStrengthh 0.80.8 CostCost 0.90.9
Fatigue Strength Fatigue Strength (psi)(psi) 0.90.9 TotalTotal
130,000130,000 0.80.8 11 13.4813.48 0.90.9 0.3530.353 0.90.9 002.153112.15311
33
1100011000 0.80.8 0.0840.084 11.2511.25 0.90.9 0.4230.423 0.90.9 001.418861.41886
77
4100041000 0.80.8 0.3150.315 12.5312.53 0.90.9 0.3790.379 2000020000 0.90.9 0.8620.8622.340602.34060
44
2180021800 0.80.8 0.1670.167 4.764.76 0.90.9 11 2000020000 0.90.9 0.8620.8622.796392.79639
66
2400024000 0.80.8 0.1840.184 5.915.91 0.90.9 0.80540.8054 1400014000 0.90.9 0.6030.603 2.388152.38815
4800048000 0.80.8 0.3690.369 11.3711.37 0.90.9 0.41860.4186 2300023000 0.90.9 0.9910.9912.516002.51600
44
7980079800 0.80.8 0.6130.613 41.2541.25 0.90.9 0.1150.115 2320023200 0.90.9 112.438712.43871
11
0.80.8 00 59.9359.93 0.90.9 0.0790.079 0.90.9 001.084851.08485
55
AISI 4130 SteelAISI 4130 Steel
Aluminium 1350-Aluminium 1350-H16H16
Aluminum 2024-Aluminum 2024-T3T3
Aluminium 5182-OAluminium 5182-O
Aluminium 6061-Aluminium 6061-T4T4
Aluminium 7075-Aluminium 7075-T6T6
Titanium 6-4Titanium 6-4
Invar 36Invar 36
Back to materials
5151
Electronic Requirements on Electronic Requirements on Angular Position and Angular Angular Position and Angular
VelocityVelocity Requirement from OpticsRequirement from Optics
Maximum of 6 pixels smeared per lineMaximum of 6 pixels smeared per line 1595 pixels in 121595 pixels in 12° field of view – 0.0075 °/pixel° field of view – 0.0075 °/pixel 6 pixels = 0.045 °6 pixels = 0.045 ° Shutter Speed ~ 0.1 secShutter Speed ~ 0.1 sec Only can smear 0.045 ° per 0.1 sec Only can smear 0.045 ° per 0.1 sec
exposureexposure Thus smear => 0.451 °/sec = 0.075 rpmThus smear => 0.451 °/sec = 0.075 rpm
Back to electronics
5252
Encoder and Resolver MatrixEncoder and Resolver MatrixEncoderEncoder ResolverResolver TotalTotal
Low speed operationsLow speed operations
AccuracyAccuracy
Minimal ComplexityMinimal Complexity
CostCost
ModificationModification
Motors/Sensor Motors/Sensor packagepackage
AvailabilityAvailability
Absolute PositionAbsolute Position
Back to electronics
5353
Electronic Requirements on Electronic Requirements on VibrationsVibrations
ResolutionResolution aa = ω x (ω x r)= ω x (ω x r) ωω = 1/3 rev/sec =2.09 rad/sec = 1/3 rev/sec =2.09 rad/sec r = 6.13 cm r = 6.13 cm a = 26.79 cm/sa = 26.79 cm/s22
Acceleration = 27.3 mg => resolution is 27.3 mgAcceleration = 27.3 mg => resolution is 27.3 mg BandwidthBandwidth Shutter speed = 0.1 secShutter speed = 0.1 sec Frequency due to camera = 10 HzFrequency due to camera = 10 Hz f = 1 kHz f = 1 kHz
Back to electronics
5454
PowerPowerSlip Rings Size (in^3) Weight Cost
Mercotac 2.6 ~4 oz $170
Conductix 71 ~10 lbs $700
Polysci 4.3 ~8 oz $440
Batteries
NiCd 0.65 1 oz $5
total w/ motor 84.5 8.6 lbs $690
total w/o motor 5.2 8 oz $40
NiMH 0.65 1 oz $6
total w/ motor 84.5 8.6 lbs $828
total w/o motor 5.2 8 oz $48
Li-Ion 1.5 1.5 oz $15
total w/ motor 69 4.3 lbs $690
total w/o motor 4.5 4.5 oz $45
Back to power
5555
Batteries and Slip RingsBatteries and Slip Rings
CostCost ComplexityComplexity MassMass SizeSize
Mercotac Mercotac SRSR
88 77 99 1010
Conductix Conductix SRSR
44 77 33 55
Moog SRMoog SR 66 77 99 1010
NiCdNiCd 44 88 55 44
NiMHNiMH 33 88 55 44
Li-IonLi-Ion 44 88 77 55
CombinatioCombinationn
1010 66 88 88
Back to power
5656
Functional Block DiagramFunctional Block Diagram•Torques
•Environmental (E1 & E2)- drag
•Friction (F1 & F2)
•Spinning Platform Motor (M2)
•Applied Torques
•De-rotated Platform Motor (M1)
•Equations of Motion
112222
1111
2
1
MFEFMnet
MFEnet
I
I
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5757
MicrocontrollerMicrocontroller Input: position and Input: position and
velocity sensor datavelocity sensor data Output: signal to de-Output: signal to de-
rotating motorrotating motor Process PID or PI Process PID or PI
control lawcontrol law
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5858
ScheduleSchedule
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ScheduleSchedule
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6060
Schedule for Spring Schedule for Spring SemesterSemester
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