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Miniature Parachute-Probe Miniature Parachute-Probe Dynamics Test-BedDynamics Test-Bed

Jessica Dooley*Jessica Dooley*

Ralph Lorenz**Ralph Lorenz**

*Aerospace and Mechanical Engineering Department, University of Arizona*Aerospace and Mechanical Engineering Department, University of Arizona

**Lunar and Planetary Laboratory, University of Arizona**Lunar and Planetary Laboratory, University of Arizona

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IntroductionIntroduction Importance of detailed kinematics of descentImportance of detailed kinematics of descent Motions affect scientific measurementsMotions affect scientific measurements Wind shear response allows shears to be measuredWind shear response allows shears to be measured

Critical reviewCritical review Complex degree-of freedom modelsComplex degree-of freedom models Large cost for full-scale,Large cost for full-scale,

instrumented vehiclesinstrumented vehicles

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Objective:Objective:

Create a miniature test-bed…Create a miniature test-bed… Low costLow cost

-Off-the-shelf components-Off-the-shelf components

Easy to use Easy to use -Small-scale parachute-sensor packages-Small-scale parachute-sensor packages

-Hand-dropped from within a building-Hand-dropped from within a building

Gain familiarity with sensor data andGain familiarity with sensor data and

corresponding motions of systemcorresponding motions of system

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InstrumentationInstrumentation Instrumentation on the probesInstrumentation on the probes BASIC Stamp 2 and Basic-X24 micro controllersBASIC Stamp 2 and Basic-X24 micro controllers Orthogonal triad of FGM-1 fluxgate magnetometersOrthogonal triad of FGM-1 fluxgate magnetometers ADXL202 2-axis accelerometersADXL202 2-axis accelerometers MPi resonant piezo-electric rotation sensorsMPi resonant piezo-electric rotation sensors Nutex wireless video cameraNutex wireless video camera Daventech SRF-04 sonar moduleDaventech SRF-04 sonar module

ParachutesParachutes Apogee RocketsApogee Rockets

BasicX24 board, accel., gyro, SRF-04

Inside of multi-sensor probe

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Testing and Set-upTesting and Set-up Testing PhasesTesting Phases Preliminary pendulumPreliminary pendulum Preliminary dropsPreliminary drops Compact probe dropsCompact probe drops Probe drops with on-board cameraProbe drops with on-board camera Multi-sensor dropsMulti-sensor drops

Camcorder footage of descentwith yellow chute

Three versions of the parachute-probeDynamics test-bed

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Data Analysis (1 of 4)Data Analysis (1 of 4) General visualization with camcorder dataGeneral visualization with camcorder data Vector between parachute apex and probe centerVector between parachute apex and probe center Cannot capture swings and motion towards and away from the cameraCannot capture swings and motion towards and away from the camera

Possible solution- use length of vector to indicate motion in other Possible solution- use length of vector to indicate motion in other plane plane

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Data Analysis (2 of 4)Data Analysis (2 of 4) Horizontal and vertical velocity with camcorderHorizontal and vertical velocity with camcorder Reveal general patterns associated with simple pendulum Reveal general patterns associated with simple pendulum

motionmotion

--sinusoidal patternsinusoidal pattern

-horizontal velocity has double the period of vertical velocity-horizontal velocity has double the period of vertical velocity

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Data Analysis (3 of 4)Data Analysis (3 of 4) On-Board sensor dataOn-Board sensor data Z-axis acceleration record is asymmetric, not sinusoidalZ-axis acceleration record is asymmetric, not sinusoidal

-Broad troughs and narrow peaks-Broad troughs and narrow peaks Spikes often superimposedSpikes often superimposed

“hand-guided”pendulum testwith 180 degreerotation at end-points

“hand-guided”pendulum testwith 180 degreerotation at mid-points

Compact probe drop utilizingpurple parachute.

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Data Analysis (4 of 4)Data Analysis (4 of 4) On-board camera dataOn-board camera data Plot constructed from frame by framePlot constructed from frame by frame

camcorder analysis shown belowcamcorder analysis shown below Results inspired the use of gyrosResults inspired the use of gyros

3.06 3.13 3.26 3.33 3.46

3.53 3.63 3.73 3.86 3.93

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Simple Pendulum ModelSimple Pendulum Model Assumes probe-parachute system is a rigid pendulumAssumes probe-parachute system is a rigid pendulum Parameters include length Parameters include length ll, initial angular displacement , initial angular displacement theta0, phasetheta0, phase, ,

bias,bias, and and dragdrag

Model rarely matched data for more than one oscillation using measured

values for model parameters

Accelerometer data for 6th drop on June 10th(on-board camera data on previous slide).

No drag, relatively same effective l.Drag=0.40, l model=2.8m

(where l measured = 2.11m)

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SummarySummary Salient results:Salient results: Correlation of spin with bottom of swingCorrelation of spin with bottom of swing Need for an effective pendulum Need for an effective pendulum ll longer than measured longer than measured ll

Miniature test-bed helped explore…Miniature test-bed helped explore… Descent kinematics of planetary probe through an atmosphereDescent kinematics of planetary probe through an atmosphere Interactions of parachute system with in-situ measurementsInteractions of parachute system with in-situ measurements

Experiments… Experiments… Relatively inexpensive and easy to assembleRelatively inexpensive and easy to assemble May be useful in an educational settingMay be useful in an educational setting

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