MEPMEP(Martian Environmental Pod)(Martian Environmental Pod)
Fall 2003Fall 2003
Aerospace Engineering DepartmentAerospace Engineering Department
University of Colorado-BoulderUniversity of Colorado-Boulder
Critical Design Review
Presentation OverviewPresentation Overview
• Descoping the Project• Request for Action (RFA’s)• System Architecture• Mechanical Design Elements• Electrical Design Elements• Integration Plan• Verification and Test Plan• Project Management Plan
Descoping the ProjectDescoping the Project
• Thermal System– 1 DOF instead of 2 DOF– “Flower configuration” not necessary due to
no requirement of light concentration– No phase change materials (paraffin) due to
complexity
• Actuation System– Paraffin actuator to mechanical system
Request for ActionRequest for Action
RFA Author Solution
Define petal actuation system Peterson N/A due to descope
Compute amount of phase change material
Maute N/A due to descope
Constructing greenhouse:
Avoid molding, consider flat
sphere gores
Peterson Addressed in greenhouse construction
Test and verification plan Argrow Addressed in Test & Verification Section
Project ObjectiveProject Objective
The overall objective of the proposed project
is to conceive, design, fabricate, integrate,
test and verify a deployable greenhouse for
a robotic Mars Lander.
Project RequirementsProject Requirements• Inflatable and deployable structure• Capable of housing one Arabidopsis plant
but dimensionally not exceed 25’’ x 25” x10’’• Mass must not exceed 3.5 kg (7.72 lbs)• Power consumption must not exceed:
– 16 W-hrs. at night– 30 W-hrs during the day
• Maintain delta pressure at 10 – 50 kPa• Monitor temperature inside greenhouse and
reduce heat loss
System ArchitectureSystem Architecture• Greenhouse
– Greenhouse structure– Mounting hardware– Pressure system
• Thermal Shield and Structure– Platform– Petals with gear and axle
• Electrical System– Power supply– Software– Sensors– Thermal Actuation
System DesignSystem Design(Stowed)(Stowed)
Stored SystemStored System
• Dimensions: 21.75’’ x 8.3’’ x 4.3’’– Under initial condtions
• Configuration for flight– Greenhouse structure is deflated
• Configuration for daytime– Greenhouse structure is inflated– Allows for photosynthetic light
System DesignSystem DesignFully DeployedFully Deployed
System DesignSystem Design
• Configuration for night– Retards heat loss– Protects greenhouse from dust storms
Greenhouse Design Greenhouse Design ElementsElements
James Ball
Manufacturing EnclosureManufacturing Enclosure
Material:– Kapton HN (Type 100)
Manufacturing:– Shell made out of rectangular
piece of Kapton and fastened with solvent.
– Circular top will be attached to one end with solvent
Stress on GreenhouseStress on Greenhouse
• Stress
• Tensile Stress of Kapton = 165 MPa
MPat
MPat
t
l
30Pr
152
Pr
Mounting GreenhouseMounting Greenhouse
• Cylinder will be sealed around ring using solvent
• The ring will be secured to the top box using screws and a rubber o-ring
RingRing
O-ringO-ring
Pressure SystemPressure System
• Single gauge regulator
- Output: 0 - 6080 kPa
- 60 psi safety relief valve
- Feed the control valve gas at 50 kPa
• 5 lb CO2 Tank
Control ValveControl Valve
• Latching-type, high density, interface 3-way solenoid valve
- 5 Volts
- 1100 Lohm ( 1.5 minutes to inflate)
- 5.5 mW per switch
- Dimensions: 1.12" long x 0.28" in. diameter
- Mount in electronics package with tubes running into greenhouse
Control Valve MountingControl Valve Mounting
• Mounted on the platform next to the gear slot
• Will be underneath the top box
• A small tube through top of box to enclosure
Check ValveCheck Valve
• CCPI55100695 check valve
- Cracks at 69 kPa
- Flow rate = 250 Lohm
- Passive
- 5.5 mm diameter and 7.5 mm length
- Mounted in the top box with one end inside of the enclosure
Check valve MountingCheck valve Mounting
•Will mount at the topWill mount at the top
of box with one end of box with one end
in the greenhousein the greenhouse
•Solvent to hold it Solvent to hold it
in placein place
Pressure SystemPressure System
Tank RegulatorControlValve
Greenhouse
Check Valve
Test PlansTest Plans
• Verify that the valve inflates enclosure to 50 kPa and then turns off
• Fulfill the requirement that the enclosure is inflatable
• Interpret the data to analyze how well it maintains proper pressure levels
• Basic set up will include a CO2 tank, and a regulator to send CO2 to the control valve
• This test will also be done in a wind tunnel and outside in the cold to verify that it operates in various conditions
Thermal Shield and Thermal Shield and AssemblyAssembly
Sara Stemler
MaterialMaterial
Aluminum– densityal = 2700 kg/m3
– k = 237 W/m*K
Acrylic– densityacrylic = 1400 kg/m3
– k = 0.27 W/m*K
Acrylic reduces the weight and has a lower thermal conductivity by a magnitude of 10
Thermal AnalysisThermal Analysis
Thermal Conductivity– kKapton = 0.12 W/m*K
– kacrylic = 0.2 W/m*K
Thickness of Material– tKapton = 5 mil
– tacrylic = 0.1’’
Heat Transfer Rate
totalR
TTQ 21
Torsion AnalysisTorsion Analysis
Shear stress:
Polar Moment of Inertia:
Torque:
T = F*d
J
Trx
32
4dJ
Torque AnalysisTorque Analysis
• Torque produced by petals = 367 oz-in.
• Diameter of rod > 0.083 in.
• Shear modulus (G) of acrylic = 167,000 psi
• Polar moment of inertias (r = 0.25 in.)– Solid rod = 3.8*10-4 m4
– Hollow rod = 3.6*10-4 m4
JH > Js meaning lower stresses and less weight
Gearing SystemGearing System
• 4:1 gear ratio will quarter the torque necessary to operate the petals
• 0.5’’ diameter gear mounted on motor shaft
• 2’’ diameter gear mounted on axle
Petal AssemblyPetal Assembly
• Varies in length from 7.5’’ – 14.25’’
• Varies in width from 6.5’’ – 8.3’’
• Tabs are placed along each petal to “catch” the subsequent petal during deployment
Cost and Mass AnalysisCost and Mass Analysis
Cost Mass
Kapton HN $45.00 0.01 lbs
Pressure Valve $50.00 ----
Check Valve $3.50 ----
Thermal Shield $10.87 3.003 lbs
Platform/Axle $3.15 0.870 lbs
Boxes $0.20 0.971 lbs
Total: $112.72 4.854 lbs
Electrical Design ElementsElectrical Design Elements
Tod SullivanTod Sullivan
Electronics OverviewElectronics Overview
• Objectives– Measure pressure and temperature– Control pressure with Lee Co. Micro-Valve– Open/close thermal shield– Plot pressure vs. time & temperature vs. time
Motor
5V Power Supply
+
+
Relay
NC Limit Switch
NC Limit Switch
Valve
Pressure
Read Voltage InputCalculate Pressure
Store to file
Plot Pressure vs. Time
If P >= 50 kPa,then output 0 VIf P < 50 kPa, then output 5 V
Solar Panel+ 5 V daylight
0 V night
TempRead Voltage Input
Calculate TempStore to file
PlotTemp vs. Time
Electronic SubsystemsElectronic Subsystems
• Power Supply
• Software
• Sensors
• Thermal Actuation
Electronic SubsystemsElectronic Subsystems
• Power Supply– 5 V fixed– 3 A max current– Tektronix PS280
Electronic SubsystemsElectronic Subsystems
• Software– LabView Tacklebox Station
• LabView • BNC Terminal Block
– DIO Channel– Analog Input (Pressure Sensor)– Analog Input (Temperature Sensor)
• 12 bit DAQ CardRead Voltage InputCalculate Pressure
Store to file
Plot Pressure vs. Time
If P >= 50 kPa,then output 0 VIf P < 50 kPa, then output 5 V
Read Voltage InputCalculate Temp
Store to file
PlotTemp vs. Time
DIO 1
ACH 0
ACH 1
Electronic SubsystemsElectronic Subsystems
• Thermistor– Omega 44000 series
• 2252 Ω• R1 = 1000 Ω• Resolution: 0.1 °C
5V
V
R1
Electronic SubsystemsElectronic Subsystems
• Pressure Sensor– Omega PX139 Differential Pressure– 4 V span of 30 psi
– Vres = 0.9 mV
– Resolution: 0.5 kPa
5V
V
Electronic SubsystemsElectronic Subsystems• Thermal Actuation
– DC motor open/close the thermal shield• 5 V power supply• Theoretical torque of 367 oz-in
– Faulhaber 2342-006CR• Torque rating = 12.35 oz-in• 5 rpm• 0.1944 lb
– Faulhaber 23/1 planetary gearbox• 989:1 ratio• 0.2425 lb
DC MotorDC Motor
Motor
5V Power Supply
+
+
Relay
NC Limit Switch
NC Limit SwitchSolar Panel
+ 5 V daylight0 V night
DC MotorDC Motor
• Limit Switch– 3 A rated limit switch
• NC
• Relay– Potter & Brumfield– R10E1Y2S200 DPDT– 2 A – 5 V coil
• Solar Panel– 5 V – 100 mA – SC-1 Solar World
Power AnalysisPower Analysis• Power consumption
– Valve• 5.5 mW-s
– Initial fill time = 1.02 min.
– Pressure Sensor• 5V * 2 mA = 0.01 W
– Thermistor• 5V * 1.5 mA = 0.0077 W
– DC motor• 5V * 1 A = 5
Power AnalysisPower AnalysisPower Consumption 24 hrs
0
5
10
15
20
25
30
0 200 400 600 800 1000 1200 1400
Time (min)
Po
we
r (W
) Power Valve
Power Motor
Power Press
Power Temp
Power Total
Power Limit
Power Limit
Motor OnInitial Gas Fill
Power AnalysisPower AnalysisPower Consumption 24 hrs
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Time (min)
Po
we
r (W
) Power Valve
Power Motor
Power Press
Power Temp
Power Total
Power Limit
Total Power
Valve Power
Sensor Power
Power AnalysisPower AnalysisPower Consumption 24 hrs
0
5
10
15
20
25
30
715 716 717 718 719 720 721 722 723 724 725
Time (min)
Po
we
r (W
) Power Valve
Power Motor
Power Press
Power Temp
Power Total
Power Limit
Power Limit Night
Power Limit Day
Motor Operation
Electronic Noise AnalysisElectronic Noise Analysis
• Noise– Usual noise from lab stations
• 0.02 mV
– Signal Resolution• 0.01 v
– Signal to Noise Ratio• Noise at 0.02 mV
– S/N = 50
• Noise at 1 mV– S/N = 10
Electronic SystemElectronic System
• Mass & Cost Distribution
Cost Mass
Motor $219.30 0.4369 lb
Pressure Sensor $85.00 0.07 lb
Thermistor $15.00 0.0013 lb
Resistor $1.00 0.00066 lb
Solar Panel $20.00 0.2 lb
Relay $4.10 0.024 lb
Limit Switches $6.00 0.10 lb
Total $350.40 0.633 lb
IntegrationIntegration
Sub-AssembliesSub-Assemblies
• Thermal Shield – Petals– Platform– Axle/Axle Mount
• Mounting Box– Greenhouse– Ring
• Electronics Box– Circuit– Motor
x 10
Electronics Package
Platform
Mounting Box
Greenhouse
Thermal Petals
Thermal Shield Sub-AssemblyThermal Shield Sub-Assembly
Verification NeedsVerification Needs
• Deployable and inflatable
• Maintain delta pressure of 10 – 50 kPa
• Thermal shield actuation
• Reduction of heat loss
• Power consumption ≤ 16 W-hrs
• Motor Circuit
• Temperature and pressure sensor outputs
Testing and VerificationTesting and VerificationThermal ShieldThermal Shield
• Ability of thermal shield to open and close– Examination
• Torque produced by petals– Analysis of current draw of motor
• Rate of heat transfer at varying temperature– Testing in different temperature conditions
Structural OperationStructural Operation
• Hypothesis: The thermal shield will open and close in approximately 10 secs
• Test– Through examination, verify that the thermal shield
operates– Time the 180° rotation of the petals
• Purpose: To ensure the thermal shield can open and close based on structural design
Torque Analysis Torque Analysis
• Objective: Measure the torque required by the motor to operate the petals
• Current draw (A) → km → Torque
• km = 0.817 oz-in/A
– Property of motor
• Measure current draw using ammeter to derive the torque produced by the motor
• Need? – Drives torque of motor necessary
Rate of Heat TransferRate of Heat Transfer
• Objective: Calculate the rate of heat loss when the temperature drops at night
• Using the temperature sensor readings for internal temperature, set up a thermistor outside of the structure to record temperature.
• Calculate and plot Q, rate of heat transfer
totalR
TTQ 21
Testing and VerificationTesting and VerificationPressure SystemPressure System
• Verify that the valve inflates enclosure to 50 kPa and then turns off
• Fulfill the requirement that the enclosure is inflatable
• Interpret the data to analyze how well it maintains proper pressure levels
• Basic set up will include a CO2 tank, and a regulator to send CO2 to the control valve
• This test will also be done in a wind tunnel and outside in the cold to verify that it operates in various conditions
Testing and VerificationTesting and VerificationPressure SystemPressure System
• Increase pressure above 69 kPa to verify that check valve functions properly
• Meet the requirement that it maintains an internal pressure below 69 kPa
• Analyze data to be sure that proper pressure levels are maintained
• Basic set up:– Tank and pressure valve sending gas to the
control valve
Testing and VerificationTesting and VerificationPressure SystemPressure System
• For a leak rate of 5 g/m2/day we predict to lose 0.14 L/day which will reduce pressure by 5.5 kPa
• This should require that the valve should open each day for 3 seconds
• Monitor pressure data• Determine the leakage rate and compare to
prediction• Determine how often to open valve (and for how
long) in order to maintain pressure• Basic setup includes previous setup and the
LabView Tackle Box
Testing & VerificationTesting & VerificationElectronicsElectronics
• Electronics Subsystems Testing– Analytical Testing
• Power Consumption Test
– Verification Testing• Motor Circuit
– Relay Operation– Motor Reversal– Motor Direction
• Pressure Sensor• Thermistor
Power ConsumptionPower Consumption
• Measure the power consumption of system– Use ammeter to measure current draw
• P = IV
– Compare to Theoretical Calculations
• Power Consumption Success– Does not exceed limits
• 30 W-hr Day• 16 W-hr Night
Motor CircuitMotor Circuit• Verify Relay Operation
– Use Lab Station to Toggle 5 V coil– Measure Voltage at motor connection– Results: Input 5V = Output 5V
Input 0V = Output -5V• Motor Direction
– Use Lab Station to Toggle = +/- 5V motor connection– Results: +5V = CW -5V = CCW
• Motor Reversal– Use Lab Station to Toggle 5 V coil– Verify integration of relay & motor– Results: Relay Input 5 V = Motor Output of CW
Relay Input 5 V = Motor Output of CCW
Pressure SensorPressure Sensor
• Verify Pressure Sensor Operation– Apply 5 V to sensor at Lab Station– Measure voltage output– Apply pressure to sensor
– Results: Vout = 2.25 V no pressure
Vout = 2.25 + V pressure
ThermistorThermistor
• Verify Temperature Sensor– Apply 5 V to thermistor at lab station– Measure voltage output
– Record Vout & ambient temperature
– Place thermistor is ice bath– Measure voltage output
– Record Vout & ambient temperature
– Verify results with conversion values
Martian Environmental PodProject Manager
Sara Stemler
ProjectAdvisory Board
AdvisorsProf. Jean KosterProf. Jim Maslanik
CFOTod Sullivan
WebmasterTod Sullivan
Safety EngineerJames Ball
ManufacturingJames Ball
StructureSara Stemler
Data AcquistionTod Sullivan
MaterialsSara Stemler
Org. Chart
Work Breakdown StructureWork Breakdown Structure
MEP
1.0 Proj. Mgmt. 2.0 Sys. Eng. 3.0 Design 4.0 Fabricate 5.0 Test & Verify 6.0 Tech. Report
1.1 Planning
1.2 Task Mgmt.
1.3 Financial
1.4 Website
2.1 Objectives
2.2 Specs
3.1 Greenhouse
3.2 Thermal Controls
3.3 Electronics
3.4 Interface
5.1 Inflation
5.2 Deployment
5.3 Thermal Shield
5.4 Actuation System
6.1 Reviews
6.2 Reports
4.1 Greenhouse
4.2 Thermal Controls
4.3 Electronics2.3 Trade Studies
5.5 Pressure System
ReferencesReferences
1.) Drost, MK et al. MicroHeater. Pacific Northwest National Laboratory, 1999.
2.) Kedl, RJ. Wallboard with latent heat storage for passive solar applications. Oak Ridge National Laboratory, May 1991.
3.) Mattingly, Jack. Elements of Gas Turbine Propulsion: McGraw- Hill,1996.
4.) Vable, Madhukar. Mechanics of Materials: Oxford University Press, 2002.
5.) Consolmagno/Schaefer. Worlds Apart: Prentice Hall, 1994.
Questions?Questions?
