quiet hydraulic actuators for ligo

173 Pages·2008·9.86 MB·English

QUIET HYDRAULIC ACTUATORS
FOR LIGO
a dissertation
submitted to the department of mechanical engineering
and the committee on graduate studies
of stanford university
in partial fulfillment of the requirements
for the degree of
doctor of philosophy
Corwin Hardham
February 2005
c Copyright by Corwin Hardham 2005
!
All Rights Reserved
ii
I certify that I have read this dissertation and that, in
my opinion, it is fully adequate in scope and quality as a
dissertation for the degree of Doctor of Philosophy.
Dan DeBra
(Principal Adviser)
I certify that I have read this dissertation and that, in
my opinion, it is fully adequate in scope and quality as a
dissertation for the degree of Doctor of Philosophy.
Chris Gerdes
I certify that I have read this dissertation and that, in
my opinion, it is fully adequate in scope and quality as a
dissertation for the degree of Doctor of Philosophy.
Dave Beach
Approved for the University Committee on Graduate
Studies:
iii
Preface
To be prefaced
iv
Acknowledgements
to my dearest Emily
v
Contents
Preface iv
Acknowledgements v
1 Introduction 1
1.1 Gravitational Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Gravitational Wave Sources . . . . . . . . . . . . . . . . . . . 2
1.2 Gravitational Wave Detection . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1 Laser Interferometric Detection . . . . . . . . . . . . . . . . . 3
1.2.2 LIGO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.3 Suspension Systems in LIGO . . . . . . . . . . . . . . . . . . 7
1.3 The Quiet Hydraulic Actuator . . . . . . . . . . . . . . . . . . . . . . 11
1.3.1 Candidate Actuators . . . . . . . . . . . . . . . . . . . . . . . 12
1.3.2 Quiet Hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4 Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.5 Research Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 The Hydraulic Flapper Valve 17
2.1 Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2 Nozzle Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2.1 Nozzle Exit Shape . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2.2 The Variable Nozzle/Flapper Resistance . . . . . . . . . . . . 22
vi
3 Actuator Design Synthesis 27
3.1 A Static Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2 Fluid Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.3 A Dynamic Model of the Actuator . . . . . . . . . . . . . . . . . . . 31
3.3.1 Pole Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.3.2 Hydraulic Resonance . . . . . . . . . . . . . . . . . . . . . . . 35
3.3.3 Foundation and Connection Stiffness . . . . . . . . . . . . . . 36
3.4 Design Trades Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4 Actuator and Platform Design 39
4.1 The Design Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.1.1 Natural Frequency Selection . . . . . . . . . . . . . . . . . . . 40
4.1.2 Actuator Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.2 Quiet Hydraulic Actuator Design . . . . . . . . . . . . . . . . . . . . 43
4.2.1 The Quiet Hydraulic Piston . . . . . . . . . . . . . . . . . . . 43
4.2.2 Parallel Motion Flexures . . . . . . . . . . . . . . . . . . . . . 44
4.2.3 The Tripod Flexure . . . . . . . . . . . . . . . . . . . . . . . . 45
4.2.4 First Actuator Prototype Results . . . . . . . . . . . . . . . . 45
4.2.5 The Quiet Hydraulic Actuator Bolted Prototype . . . . . . . . 46
4.2.6 The Final Quiet Hydraulic Actuator Design . . . . . . . . . . 48
4.3 The Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.3.1 Design for Control in Active Platforms . . . . . . . . . . . . . 52
4.3.2 The Quiet Hydraulic Test Platform . . . . . . . . . . . . . . . 57
4.3.3 HEPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5 The Bellows Breathing Resonance 69
5.1 Breathing Stiffness Improvements . . . . . . . . . . . . . . . . . . . . 69
5.1.1 Breathing Stiffness . . . . . . . . . . . . . . . . . . . . . . . . 70
5.1.2 Bellow Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.1.3 Final Bellow Design . . . . . . . . . . . . . . . . . . . . . . . 74
5.2 The Bypass Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
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5.2.1 Bypass Network Pole Frequency . . . . . . . . . . . . . . . . . 76
5.2.2 Bypass Resistance . . . . . . . . . . . . . . . . . . . . . . . . 79
5.2.3 Final Bypass Design . . . . . . . . . . . . . . . . . . . . . . . 82
5.2.4 Bypass Performance . . . . . . . . . . . . . . . . . . . . . . . 83
6 Control Synthesis 84
6.1 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.1.1 Displacement Sensors . . . . . . . . . . . . . . . . . . . . . . . 85
6.1.2 Seismometers . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.2 Control Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.2.1 Sensor Blending . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.2.2 Sensor Correction . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.3 Control of the Quiet Hydraulic Test Platform . . . . . . . . . . . . . 94
6.3.1 Controller Design and Implementation . . . . . . . . . . . . . 95
6.3.2 Results from the Test Platform . . . . . . . . . . . . . . . . . 99
6.3.3 Test Platform Results in the Horizontal Direction . . . . . . . 103
6.4 The LASTI Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.4.1 Controller Design and Implementation for the LASTI BSC . . 105
6.4.2 Results from the HEPI Installation at LASTI . . . . . . . . . 112
6.5 HEPI at the LIGO Livingston Observatory . . . . . . . . . . . . . . . 114
6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
7 Future Work 117
7.1 Actuator Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
7.1.1 The As-Built HEPI Actuator Housing . . . . . . . . . . . . . 118
7.1.2 A Proposed Actuator Housing . . . . . . . . . . . . . . . . . . 120
7.2 The Floating Seal Actuator . . . . . . . . . . . . . . . . . . . . . . . 123
7.2.1 Hydraulic Bearings . . . . . . . . . . . . . . . . . . . . . . . . 124
7.2.2 Design of the Floating Seal Actuator . . . . . . . . . . . . . . 132
A The DYP2S Valve 138
A.1 Valve Asymmetries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
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A.2 Flapper Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
A.2.1 Flapper Snap Down . . . . . . . . . . . . . . . . . . . . . . . . 140
A.2.2 Flapper Oscillation . . . . . . . . . . . . . . . . . . . . . . . . 140
B Design Synthesis Appendix 142
B.1 Impedance Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
B.2 The Electromagnetically Actuated EPI . . . . . . . . . . . . . . . . . 142
B.3 Natural Frequency Temperature Dependence . . . . . . . . . . . . . . 143
B.4 Collocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
C Controls Appendix 147
C.1 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
C.1.1 The Optical Displacement Sensor . . . . . . . . . . . . . . . . 147
C.1.2 Seismometers . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
C.1.3 Sensor Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
C.2 Tilt-Horizontal Coupling . . . . . . . . . . . . . . . . . . . . . . . . . 150
Bibliography 154
Bibliography 155
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List of Tables
1.1 Candidate actuator technologies for the EPI system. . . . . . . . . . . 11
3.1 Adesigntradeschartforthehydraulicactuator. A indicatesastrong
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