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Ingeniería y Sistemas S.A.

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PLANCK AOCS SPECIAL MODULES:SLOSHING, THRUSTING PROFILES, MASS EVOLUTION, FUEL MIGRATION

Alfredo Agenjo, Raúl Sánchez, Demetrio Zorita, Salvador Llorente

demetrio.zorita@sener.es

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INTRODUCTION TO PLANCK & PLANCK AOCS TOOLSPlanck missionPlanck Design SimulatorPlanck Verification Environment

SLOSHING MODULE

THRUSTING PROFILES MODULE

MASS EVOLUTION MODULES

FUEL MIGRATION MODULE

CONCLUSION

CONTENTS

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• SENER responsible Design, Development, Integration and Verification ofPlanck ACMS

• Scientific mission: measure CMB accurately

• Spinning SC at 6º/s in L2

• STR, SAS, CRS, RCS, AAD

PLANCK MISSION

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PLANCK SCANNING LAW

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PLANCK DESIGN SIMULATOR

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• Simulator architecture. Set of libraries including:• Dynamics modules• Sensor modules• Actuator modules• Environment modules• Attitude determination blocks• Control blocks

• Use twofold:• Design the AOCS and validate the design and input to OBS specs• Input to develop the Test Environment

• Matlab/Simulink

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PLANCK TEST ENVIRONMENT

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SLOSHING MODULE. NEEDS

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• Membrane vs. PMD

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SLOSHING MODULE. TANKS

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SLOSHING MODULE: SLOSHING FLOW 3-D (CFD)

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SLOSHING: MODEL DEVELOPMENT STRATEGY

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• 1) SELECT MODEL: pendulum• 2) TUNE PENDULUM PARAMETERS: arm length, mass, inertia, friction• 3) MAKE NEW SC PLANT• 4) VALIDATE NEW SC PLANT: comparison of SC ang. vel & liquid COG

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Ingeniería y Sistemas S.A.

SLOSHING: RESULTS

• Safe domains are reduced• Manoeuvre time increases• DeltaV accuracy decreases• No control inestabilities• STR does not loose track

0 100 200 300 400 500 600 7000

10

20

30

40

50

60

70

80

90

100

time [sec]

Nutation angle [arcmin]

Nutation angle

pendulum model

solid fuel model

0 100 200 300 400 500 600 7005.94

5.96

5.98

6

6.02

6.04

6.06

6.08

6.1

6.12

time [sec]

S/C angular velocity [deg/s] (x-axis)

S/C x-axis angular velocity

pendulum model

solid fuel model

Final decision at System level:Membrane wins PMD

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THRUSTING PROFILES: NEEDS

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60ms60ms60mst_min

25s1NHCM6s20NOCM2s20NSAM

t_maxTRH

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THRUSTING PROFILE: PULSE MODELISATION

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Fo

rce

timetON

tOFF

Evaluation

time

tto ON

tON

FCV delay

FCV delay

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THRUSTING PROFILE: EQUATIONS

Delay = CA + CB* Pinj + CC* Pinj2

F0 = FA + FB* Pinj + FC* Pinj2

F0(P)α(toff)t t ≤ 1/αF(t) F0(P) 1/α < t ≤ ton

F0(P) [1-β (t- ton)] e(-λ (t-ton)) ton+1/β ≥ t > ton0 t > ton+1/β

α = alpha1/(alpha2*toff + alpha3*toff2). no f(Pinj)

β and λ = constants. No f(Pinj)

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MASS EVOLUTION: NEEDS

Mass variation: Large deltaV

Fuel migration: Thermal stability

MASS EVOLUTION: IMPLEMENTATION

Mass variation:t_on & P_inj > mass flow > mass consumption > tank mass > SC mass, SC Inertia, SC CoG

Fuel migration: Maximum mass flow between tanks

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Ingeniería y Sistemas S.A.

Astrium GmhB CFDAnalyticom RCS modelDutch Space Test SW and model supportAlcatel Alenia Space Italy Planck SVM responsibleAlcatel Alenia Space France Planck primeESA Planck owner3rd Astrodynamics Workshop Audience Attention

ACKNOWLEDGMENTS