Yifei Huang 82312 Frank W Wood SURF Fellow 1 Overview Motivation Pneumatic Sampling Concept and feasibility Design amp Testing Nozzle Cyclone Sample Container Pressure Container ID: 558236
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Slide1
Pneumatic Sampling in Extreme Terrain with the Axel Rover
Yifei Huang. 8.23.12Frank W. Wood SURF Fellow
1Slide2
Overview
MotivationPneumatic Sampling Concept, and feasibilityDesign & TestingNozzleCycloneSample Container
Pressure ContainerInstrument DeploymentConclusions
2Slide3
Sampling in Extreme Terrain
Satellite images suggest liquid brine flowSpectroscopy images – negative results for waterDifficulties in samplingNewton Crater: 25-40 degree slopesMER:15 degree slopesCuriosity: 30 degree slopes
SolutionAxel rover: vertical slopes
Figure: http://mars.jpl.nasa.gov
/
. Sources:
http://ssed.gsfc.nasa.gov/sam/curiosity.html
,
http://usrp.usra.edu/technicalPapers/jpl/HooverMay11.pdf
3Slide4
The Axel rover
DuAxel
rover
Instrument deploy
Traversing cliffs
Goal:
Develop a sampling system on Axel
4Slide5
What is pneumatic sampling?
1. Release pressurized airActuator opens and closes a cylinder of pressurized air2. Air flows down the outer tube of the nozzle
3. Air enters inner tube, carrying soil with itNozzle is already embedded in dirt
Up is the path of least resistance4. Soil and air flow up into sample container
Figure: Zacny et al. (2010)
5Slide6
Why Pneumatics?
Fewer moving components, low number of actuators, less risk for failureClosed tubing:
low instrument contaminationEnergy efficient
A small amount of air can lift a large amount of dirt1 g of gas lifted 5000g of soil [Zacny
and Bar-Cohen, 2009]
Easier soil transportation
6Slide7
Design: Nozzle
Round #1
Nozzle #1
Soil Level
Nozzle #2
Nozzle #3
7Slide8
Design: Nozzle
Nozzles built on the 3D printer (ABS plastic)Tests with loose sand (400um size)25psi air was released for 2 sec
8Slide9
Round #2
Design: Nozzle
Nozzle #4
Nozzle #5
Sand:
Dirt:
9Slide10
Design: Cyclone Separator
Used to separate air and soil
Dusty air will enter tangential to cycloneLarger particles have too much inertiaHit the side of cyclone and fall down
Smaller particles remain in the cyclonePushed up into the Vortex Finder by pressure gradient
10
Figure: DB Ingham and L Ma,
“
Predicting the performance of air cyclones
”
Vortex Finder
Cylindrical portion
Conical portion
Small Particle
Large Particle
Design by Honeybee RoboticsSlide11
Design: Sample Container
Objective: Minimize actuation with springs
Cyclone
Sample Container
Spring
Concept:
Design:
11Slide12
Second 4-bar linkage attached to original 4-bar
Motion of 2 4-bars are coupledAdvantages: No actuator on deployed plate
Design: Instrument Deployment
12
Nozzle is attached hereSlide13
Benchtop test stands
Instrument deploy
Sample Caching
13Slide14
Design: Pressure Container
14Slide15
Benchtop Test
15
Tests with loose sand (400um size)
25psi air was released for 2 secSlide16
Contamination
In sandWeighed cyclone, tubing, and nozzle before and after testsNegligible mass: ~0.2% of lifted mass remained in cyclone/tubing/nozzleIn dirtSoil is stuck inside nozzle and cycloneCyclone: 50-300% of lifted massNozzle: 50-150% of lifted mass
16Slide17
Effects of Pressure
17
Tests with loose sand (400um size)
A
ir
from wall was released for 2 secSlide18
Conclusions
Pneumatics is feasible Successfully acquired 2g of soilImprovements needed:Acquiring moist soils (dirt)Taking multiple samples
Placing system inside Axel18Slide19
Acknowledgements
Kristen Holtz, co-workerFunding:Keck Institute for Space Studies
Caltech Summer Undergraduate Research Fellowship (SURF)Mentoring:
Melissa Tanner, Professor Joel Burdick, CaltechJPL Axel Team
Kris
Zacny
, Honeybee Robotics
Prof.
Melany
Hunt, Prof. Bethany
Elhmann
Paul
Backes
, Paulo
Younse
, JPL
19Slide20
Initial Calculations for Earth conditions
Earth conditions:Estimate velocity of air:
Estimate the mass that can be lifted
Assume dirt is inert,
ρ
=2000kg/m
3
Mass = ~12g/s
Mars conditions:
Requires less canister pressure
20