PLANCK AOCS SPECIAL MODULES: SLOSHING, THRUSTING PROFILES...
Transcript of PLANCK AOCS SPECIAL MODULES: SLOSHING, THRUSTING PROFILES...
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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
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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 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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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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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