mep (martian environmental pod)

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?