Vibration Isolation in a Microgravity Environment

1993 ◽  
Vol 115 (4) ◽  
pp. 477-483
Author(s):  
R. M. Alexander ◽  
C. H. Gerhold ◽  
C. B. Atwood ◽  
J. F. Cordera
Keyword(s):  
Vibration Isolation ◽  
Center Of Mass ◽  
Space Station ◽  
Microgravity Environment ◽  
Isolation System ◽  
Air Jet ◽  
Surrounding Structure ◽  
Jet Control ◽  
Oscillatory Response ◽  
The Mathematical Model

Many in-space research experiments require the microgravity environment attainable near the center of mass of the proposed space station. Since dynamic disturbances to the surrounding structure may undermine an experiment’s validity, isolation of these experiments is imperative. This paper summarizes analytical and experimental work accomplished to develop an isolation system which allows the pay load to float freely within a prescribed boundary while being kept centered with forces generated by small jets of air. An experimental setup was designed and constructed to simulate the microgravity environment In the horizontal plane. Results demonstrate the air jet control system to be effective in managing payload oscillatory response. An analytical model was developed and verified by comparing predicted and measured payload response. The mathematical model is then used to investigate payload response to disturbances likely to be present in the space station.

scholarly journals Vibration Isolation in a Microgravity Environment

1991 ◽  
Author(s):  
Richard M. Alexander ◽  
Carl H. Gerhold ◽  
Clay B. Atwood ◽  
Joseph F. Cordera
Keyword(s):  
Vibration Isolation ◽  
Center Of Mass ◽  
Space Station ◽  
Microgravity Environment ◽  
Isolation System ◽  
Air Jet ◽  
Surrounding Structure ◽  
Jet Control ◽  
Oscillatory Response ◽  
The Mathematical Model

Abstract Many in-space research experiments require the microgravity environment attainable near the center of mass of the proposed Space Station. Since dynamic disturbances to the surrounding structure may undermine an experiments validity, isolation of these experiments is imperative. Analytical and experimental work has been completed in developing an isolation system which allows the payload to float freely within a prescribed boundary while being kept centered with forces generated by small jets of air. An experimental setup was designed and constructed to simulate the microgravity environment in the horizontal plane. Results demonstrate the air jet control system to be effective in managing payload oscillatory response. An analytical model was developed and verified by comparing predicted and measured payload response. The mathematical model is used to predict dynamic payload response to disturbances likely to be present in the Space Station. The figure shown below is a schematic of the test setup to be discussed during the presentation.

Controllable electromagnetic negative stiffness spring for vibration isolator: Design, analyses and experimental verification

2020 ◽  
pp. 1-22
Author(s):  
Kai Meng ◽  
Yong Gu ◽  
Jianhui Ma ◽  
Xidong Liu ◽  
Xiangqian Geng ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Permanent Magnets ◽  
Structural Parameters ◽  
Negative Stiffness ◽  
Axial Stiffness ◽  
Isolation System ◽  
Exciting Current ◽  
Circular Current ◽  
Design Analyses ◽  
The Mathematical Model

In this study, a novel negative stiffness spring is developed. The developed spring possesses the characteristics of the controllable stiffness and can be employed in vibration isolation system with a low resonance frequency. The controllable electromagnetic negative stiffness spring (CENSS) is obtained by the coaxial permanent magnets (PMs) and the circular current-carrying coils. The stiffness control is accomplished by changing the current in the coils. Furthermore, the mathematical model of CENSS is established, based on the filament method. According to the model, the relationship between the exciting current and the axial stiffness is obtained. Moreover, the influence of the structural parameters of CENSS on the magnetic force and the stiffness is analyzed. The results demonstrate that the thickness of PMs and the coils have the ability to adjust the range of the negative stiffness. Finally, performance experimental study of CENSS in the stiffness domain is carried out under different exciting currents and thicknesses. The experimental results have shown a good agreement with the model. It demonstrates that the performance of negative stiffness in CENSS can be controlled efficiently by the exciting current and optimized by the thickness.

Development of Six Degrees of Freedom Vibration Isolation System for Microgravity Environment

1995 ◽  
Author(s):  
Toshiyuki Suzuki ◽  
Koji Tanida ◽  
Akira Tanji ◽  
Koichi Okubo
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Parabolic Flight ◽  
Microgravity Environment ◽  
External Disturbances ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Six Degrees Of Freedom ◽  
Active Vibration ◽  
Good Agreement

Abstract An active vibration isolation system, under development for use in microgravity environment, provides electromagnetic suspension by means of voice coils arranged in pairs to control the translational and rotational movements of the payload, three pairs of which cover the three axes to ensure control of payload movement in all six degrees of freedom. A series of tests performed on this system in microgravity environment created by parabolic flight proved that external disturbances in frequencies above 0.1 Hz were effectively reduced by applying the system. Also, good agreement was obtained between the measured performance and results of numerical simulation.

Evaluation of a Treadmill with Vibration Isolation and Stabilization (TVIS) for Use on the International Space Station

1999 ◽  
Vol 15 (3) ◽  
pp. 292-302 ◽  
Author(s):  
Jean L. McCrory ◽  
David R. Lemmon ◽  
H. Joseph Sommer ◽  
Brian Prout ◽  
Damon Smith ◽  
...  
Keyword(s):  
International Space Station ◽  
Vibration Isolation ◽  
Space Station ◽  
Lower Extremities ◽  
Structural Safety ◽  
Microgravity Environment ◽  
Zero Gravity ◽  
Experimental Conditions ◽  
International Space ◽  
Angular Displacements

A treadmill with vibration isolation and stabilization designed for the International Space Station (ISS) was evaluated during Shuttle mission STS-81. Three crew members ran and walked on the device, which floats freely in zero gravity. For the majority of the more than 2 hours of locomotion studied, the treadmill showed peak to peak Linear and angular displacements of less than 2.5 cm and 2.5°, respectively. Vibration transmitted to the vehicle was within the microgravity allocation limits that are defined for the ISS. Refinements to the treadmill and harness system are discussed. This approach to treadmill design offers the possibility of generating 1G-like loads on the lower extremities while preserving the microgravity environment of the ISS for structural safety and vibration free experimental conditions.

scholarly journals Parametric Design and Multiobjective Optimization of Maglev Actuators for Active Vibration Isolation System

2014 ◽  
Vol 6 ◽  
pp. 215358 ◽  
Author(s):  
Qianqian Wu ◽  
Honghao Yue ◽  
Rongqiang Liu ◽  
Liang Ding ◽  
Zongquan Deng
Keyword(s):  
Multiobjective Optimization ◽  
Vibration Isolation ◽  
Heat Dissipation ◽  
Parametric Design ◽  
Space Station ◽  
Small Scale ◽  
Isolation System ◽  
Active Vibration ◽  
Set Up ◽  
Active Vibration Isolation

The microvibration has a serious impact on science experiments on the space station and on image quality of high resolution satellites. As an important component of the active vibration isolation platform, the maglev actuator has a large stroke and exhibits excellent isolating performance benefiting from its noncontact characteristic. A maglev actuator with good linearity was designed in this paper. Fundamental features of the maglev actuator were obtained by finite element simulation. In order to minimize the coil weight and the heat dissipation of the maglev actuator, parametric design was carried out and multiobjective optimization based on the genetic algorithm was adopted. The optimized actuator has better mechanical properties than the initial one. Active vibration isolation platforms for different-scale payload were designed by changing the arrangement of the maglev actuators. The prototype to isolate vibration for small-scale payload was manufactured and the experiments for verifying the characteristics of the actuators were set up. The linearity of the actuator and the mechanical dynamic response of the vibration isolation platform were obtained. The experimental results highlight the effectiveness of the proposed design.

Dynamic Simulation of Muscle Loading During ARED Squat Exercise on the International Space Station

2013 ◽  
Author(s):  
Christopher D. Fregly ◽  
Brandon T. Kim ◽  
John K. De Witt ◽  
Benjamin J. Fregly
Keyword(s):  
International Space Station ◽  
Vibration Isolation ◽  
Space Station ◽  
Critical Issue ◽  
Force Transmission ◽  
Isolation System ◽  
International Space ◽  
Long Duration ◽  
Squat Exercise ◽  
Muscle Moments

Loss of muscle mass due to reduced mechanical loading is a critical issue for long duration spaceflight on the International Space Station (ISS) [1]. To address this issue, NASA has developed the Advanced Resistive Exercise Device (ARED) that allows astronauts to perform resistance exercise on the ISS. To minimize force transmission to the ISS, the ARED is mounted to a vibration isolation system (VIS). During squat exercise, ARED rotates relative to the ISS, functioning like a nutcracker to compress the astronaut with a load provided by two vacuum cylinders. Though the ARED is an effective exercise countermeasure device, the extent to which squat exercise on the ISS achieves Earth-equivalent muscle moments remains unknown.

scholarly journals A “Kane’s Dynamics” Model for the Active Rack Isolation System

1999 ◽  
Author(s):  
R. David Hampton ◽  
Geoffrey Beech
Keyword(s):  
State Space ◽  
Vibration Isolation ◽  
Equations Of Motion ◽  
Space Station ◽  
Optimal Controls ◽  
Magnetic Actuation ◽  
Isolation System ◽  
Algebraic Set ◽  
Isolation Requirements ◽  
Isolation Device

Abstract Many microgravity space-science experiments require vibratory acceleration levels unachievable without active isolation. The Boeing Corporation’s Active Rack Isolation System (ARIS) employs a novel combination of magnetic actuation and mechanical linkages, to address these isolation requirements on the International Space Station (ISS). ARIS provides isolation at the rack (International Standard Payload Rack, or ISPR) level. Effective model-based vibration isolation requires (1) an appropriate isolation device, (2) an adequate dynamic (i.e., mathematical) model of that isolator, and (3) a suitable, corresponding controller. ARIS provides the ISS response to the first requirement. This paper presents one response to the second, in a state-space framework intended to facilitate an optimal-controls approach to the third. The authors use “Kane’s Dynamics” to develop an state-space, analytical (algebraic) set of linearized equations of motion for ARIS.

scholarly journals Active Vibration Control in Microgravity Environment

1988 ◽  
Vol 110 (1) ◽  
pp. 30-35 ◽  
Author(s):  
C. H. Gerhold ◽  
R. Rocha
Keyword(s):  
Control System ◽  
Flow Rate ◽  
Aerodynamic Drag ◽  
Space Station ◽  
Control Process ◽  
Microgravity Environment ◽  
Damping Factor ◽  
Air Jets ◽  
Air Jet ◽  
Enclosed Space

The low gravity environment of the Space Station is suitable for experiments or manufacturing processes which require near zero-g. Such experiments are packaged to fit into rack-mounted modules approximately 106.7 cm (42 in.) wide × 190.5 cm (75 in.) high × 76.2 cm (30 in.) deep. The mean acceleration level of the Space Station is expected to be on the order of 10−6 g (9.81 × 10−6 m/s2). This steady state acceleration is a superposition of aerodynamic drag, centripetal forces, and the gravitational attraction of the earth and of the moon. Excitations such as crew activity or rotating unbalance of nearby equipment can cause momentary disturbances to the vibration-sensitive payload which degrade the microgravity environment and compromise the validity of the experiment or process. Isolation of the vibration-sensitive payload from structure-borne excitation is achieved by allowing the payload to float freely within an enclosed space. Displacement-sensitive transducers indicate relative drift between the payload and the surrounding structure. Small air jets fixed to the structure direct air flow to impinge on the payload. This thrust force keeps the payload centered within the enclosed space. The mass flow rate of the air jets is controlled such that the resultant acceleration of the payload is less than a criterion of 10−5 g. It is expected that any power or fluid lines that connect the experiment to the Space Station structure can be designed such that their transmitted vibration levels are within the criterion. An experiment has been fabricated to test the validity of the active control process and to verify the flow and control parameters identified in a theoretical model. Zero-g is approximated in the horizontal plane using a low-friction air-bearing table. An analog control system has been designed to activate calibrated air jets when displacement of the test mass is sensed. The experiment demonstrates that the air jet control system introduces an effective damping factor to control oscillatory response. The amount of damping as well as the flow parameters, such as pressure drop across the valve and flow rate of air, are verified by the analytical model.

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