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Pneumatic Sampling in Extreme Terrain with the Axel Rover Yifei Huang. 8.23.12 Frank W. Wood SURF Fellow 1.

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Presentation on theme: "Pneumatic Sampling in Extreme Terrain with the Axel Rover Yifei Huang. 8.23.12 Frank W. Wood SURF Fellow 1."— Presentation transcript:

1 Pneumatic Sampling in Extreme Terrain with the Axel Rover Yifei Huang Frank W. Wood SURF Fellow 1

2 Overview Motivation Pneumatic Sampling Concept, and feasibility Design & Testing Nozzle Cyclone Sample Container Pressure Container Instrument Deployment Conclusions 2

3 Sampling in Extreme Terrain Satellite images suggest liquid brine flow Spectroscopy images – negative results for water Difficulties in sampling Newton Crater: degree slopes MER:15 degree slopes Curiosity: 30 degree slopes Solution Axel rover: vertical slopes Figure: Sources: 3

4 The Axel rover DuAxel rover Instrument deploy Traversing cliffs Goal: Develop a sampling system on Axel 4

5 What is pneumatic sampling? 1. Release pressurized air Actuator opens and closes a cylinder of pressurized air 2. Air flows down the outer tube of the nozzle 3. Air enters inner tube, carrying soil with it Nozzle is already embedded in dirt Up is the path of least resistance 4. Soil and air flow up into sample container Figure: Zacny et al. (2010) 5

6 Why Pneumatics? Fewer moving components, low number of actuators, less risk for failure Closed tubing: low instrument contamination Energy efficient A small amount of air can lift a large amount of dirt 1 g of gas lifted 5000g of soil [Zacny and Bar-Cohen, 2009] Easier soil transportation 6

7 Design: Nozzle Round #1 Nozzle #1 Soil Level Nozzle #2 Nozzle #3 7

8 Design: Nozzle Nozzles built on the 3D printer (ABS plastic) Tests with loose sand (400um size) 25psi air was released for 2 sec 8

9 Round #2 Design: Nozzle Nozzle #4Nozzle #5 Sand:Dirt: 9

10 Design: Cyclone Separator Used to separate air and soil Dusty air will enter tangential to cyclone Larger particles have too much inertia Hit the side of cyclone and fall down Smaller particles remain in the cyclone Pushed 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 ParticleLarge Particle Design by Honeybee Robotics

11 Design: Sample Container Objective: Minimize actuation with springs Cyclone Sample Container Spring Concept:Design: 11

12 Second 4-bar linkage attached to original 4-bar Motion of 2 4-bars are coupled Advantages: No actuator on deployed plate Design: Instrument Deployment 12 Nozzle is attached here

13 Benchtop test stands Instrument deploy Sample Caching 13

14 Design: Pressure Container 14

15 Benchtop Test 15 Tests with loose sand (400um size) 25psi air was released for 2 sec

16 Contamination In sand Weighed cyclone, tubing, and nozzle before and after tests Negligible mass: ~0.2% of lifted mass remained in cyclone/tubing/nozzle In dirt Soil is stuck inside nozzle and cyclone Cyclone: % of lifted mass Nozzle: % of lifted mass 16

17 Effects of Pressure 17 Tests with loose sand (400um size) Air from wall was released for 2 sec

18 Conclusions Pneumatics is feasible Successfully acquired 2g of soil Improvements needed: Acquiring moist soils (dirt) Taking multiple samples Placing system inside Axel 18

19 Acknowledgements Kristen Holtz, co-worker Funding: Keck Institute for Space Studies Caltech Summer Undergraduate Research Fellowship (SURF) Mentoring: Melissa Tanner, Professor Joel Burdick, Caltech JPL Axel Team Kris Zacny, Honeybee Robotics Prof. Melany Hunt, Prof. Bethany Elhmann Paul Backes, Paulo Younse, JPL 19

20 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


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