Modelling of tuning of an ultra low frequency Roberts Linkage vibration isolator

Dumas, J. C.; Li, Ju; Blair, David

doi:10.1016/j.physleta.2010.07.025

Cited by 6 publications

(8 citation statements)

References 11 publications

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“…This leaves one degree of freedom for the (two-dimensional) Roberts linkage, namely the rotation θ(t) of the frame. In the following, we will largely adopt the notation of Dumas and Blair [13]. The positions of the center of mass of the frame and the load (effectively located at the vertex P l ) can be written…”

Section: Suspension-thermal Noise Of a Roberts Linkagementioning

confidence: 99%

Suspension-thermal noise in spring–antispring systems for future gravitational-wave detectors

Harms

Mow–Lowry

2017

Class. Quantum Grav.

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Spring-antispring systems have been investigated as possible low-frequency seismic isolation in high-precision optical experiments. These systems provide the possibility to tune the fundamental resonance frequency to, in principle, arbitrarily low values, and at the same time maintain a compact design of the isolation system. It was argued though that thermal noise in spring-antispring systems would not be as small as one may naively expect from lowering the fundamental resonance frequency. In this paper, we present a detailed calculation of the suspension thermal noise for a specific spring-antispring system, namely the Roberts linkage. We find a concise expression of the suspension thermal noise spectrum, which assumes a form very similar to the well-known expression for a simple pendulum. It is found that while the Roberts linkage can provide strong seismic isolation due to a very low fundamental resonance frequency, its thermal noise is rather determined by the dimension of the system. We argue that this is true for all horizontal mechanical isolation systems with spring-antispring dynamics. This imposes strict requirements on mechanical spring-antispring systems for the seismic isolation in potential future low-frequency gravitational-wave detectors as we discuss for the four main concepts: atom-interferometric, superconducting, torsion-bars, and conventional laser interferometer.

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Section: Suspension-thermal Noise Of a Roberts Linkagementioning

confidence: 99%

Suspension-thermal noise in spring–antispring systems for future gravitational-wave detectors

Harms

Mow–Lowry

2017

Class. Quantum Grav.

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“…Antispring geometries are implemented into various stages to reduce fundamental mode frequencies. 11,16,17 The preisolator consists of several ultralow frequency ͑ULF͒ stages: the inverse pendulum, the LaCoste linkage, 18 and the Roberts linkage, 19 each with their resonant frequencies in the order of 100 mHz. The inverse pendulum stage can be tuned close to 0.05 Hz to provide low frequency horizontal preisolation.…”

Section: A Isolator Componentsmentioning

confidence: 99%

“…The Roberts linkage provides the second horizontal preisolation stage. 11 The combination of coil and magnet provides the actuation for the positioning and damping for both the inverse pendulum and the LaCoste stages. Additional heating of the coil springs at the LaCoste stage provides a means of compensating for slow temperature drifts in the vertical direction as well as correcting for creep in the isolation chain.…”

Section: A Isolator Componentsmentioning

confidence: 99%

“…The compactness is made possible through the use of novel isolation techniques with multiple preisolation stages. 11 Pendulum normal modes are passively damped through self-damping. 12 Feedback is applied to the preisolation stages and the penultimate suspension stage to steer the mirrors and maintain alignment and positioning, while correcting for various sources of drift such as temperature fluctuations.…”

Section: Introductionmentioning

confidence: 99%

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Compact vibration isolation and suspension for Australian International Gravitational Observatory: Local control system

Dumas

Barriga

Zhao

et al. 2009

Review of Scientific Instruments

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High performance vibration isolators are required for ground based gravitational wave detectors. To attain very high performance at low frequencies we have developed multistage isolators for the proposed Australian International Gravitational Observatory detector in Australia. New concepts in vibration isolation including self-damping, Euler springs, LaCoste springs, Roberts linkages, and double preisolation require novel sensors and actuators. Double preisolation enables internal feedback to be used to suppress low frequency seismic noise. Multidegree of freedom control systems are required to attain high performance. Here we describe the control components and control systems used to control all degrees of freedom. Feedback forces are injected at the preisolation stages and at the penultimate suspension stage. There is no direct actuation on test masses. A digital local control system hosted on a digital signal processor maintains alignment and position, corrects drifts, and damps the low frequency linear and torsional modes without exciting the very high Q-factor test mass suspension. The control system maintains an optical cavity locked to a laser with a high duty cycle even in the absence of an autoalignment system. An accompanying paper presents the mechanics of the system, and the optical cavity used to determine isolation performance. A feedback method is presented, which is expected to improve the residual motion at 1 Hz by more than one order of magnitude.

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“…Another limit of the Scott-Russel linkage comes from the need to realize a slot joint for the bottom fixing points, which may introduce undesired friction phenomena. Some potential advantages have been recognized in the implementation of a horizontal seismic isolation stage through the 3-D Roberts linkage [10][11][12], shown in Fig. 1, middle.…”

Section: Introductionmentioning

confidence: 99%

Design, manufacturing, and performance verification of a Roberts linkage for inertial isolation

Bosetti

Biral

Bortoluzzi

2014

Precision Engineering

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Modelling of tuning of an ultra low frequency Roberts Linkage vibration isolator

Cited by 6 publications

References 11 publications

Suspension-thermal noise in spring–antispring systems for future gravitational-wave detectors

Suspension-thermal noise in spring–antispring systems for future gravitational-wave detectors

Compact vibration isolation and suspension for Australian International Gravitational Observatory: Local control system

Design, manufacturing, and performance verification of a Roberts linkage for inertial isolation

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