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

Back to controls

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

Back to controls

5858

ScheduleSchedule

Back to fall schedule

5959

ScheduleSchedule

Back to fall schedule

6060

Schedule for Spring Schedule for Spring SemesterSemester

Back to spring schedule

6161

Schedule for Spring Schedule for Spring SemesterSemester

Back to spring schedule