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.

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.

Lower bound of performance index of an on–off damper in a state-space system

2018 ◽  
Vol 233 (12) ◽  
pp. 4288-4298
Author(s):  
La Duc Viet ◽  
Phan Thi Tra My
Keyword(s):  
Lower Bound ◽  
State Space ◽  
Performance Index ◽  
Vibration Isolation ◽  
Space System ◽  
Mass System ◽  
Isolation System ◽  
System A ◽  
Variable Function ◽  
State Space System

This paper presents a theoretical lower bound of the performance index of an on–off damper placed in a state-space system under harmonic disturbance. The bound is obtained by minimizing a single-variable function. The lower bound is a good theoretical benchmark to measure a practical on–off damping controller. The usefulness of the bound is demonstrated through four examples: a vibration isolation system, a quarter-car suspension system, a mass damper system, and a four-mass system. The examples show how the lower bound can be used to improve some conventional controllers.

Global Analyses of Multi-Degree-of-Freedom Nonlinear Vibration Isolation System

2007 ◽  
Author(s):  
Xiang Yu ◽  
Shijian Zhu ◽  
Shuyong Liu
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Mapping Method ◽  
Degree Of Freedom ◽  
High Dimensional ◽  
Isolation System ◽  
Vibration Isolation System ◽  
A Cell

The abundant and complex dynamics of high-dimensional nonlinear systems have drawn increasing attentions in recent years, but further analyses have been confined because of the inefficiency of some analytic methods for high-dimensional systems. This paper focuses on the bifurcation and global analyses of a multi-degree-of-freedom nonlinear vibration isolation system using numerical methods. Firstly, the equations of motion of the multi-degree-of-freedom nonlinear vibration isolation system for onboard machine are formulated. Then, exhaustive bifurcation analyses are carried out and six branches are illustrated in the bifurcation diagrams revealing that several different types of stable motions may coexist in certain parameter regimes. A cell mapping method is modified to analyze the global characteristics including the locations and basins of the coexistent attractors of the multi-degree-of-freedom nonlinear vibration isolation system.

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.

scholarly journals Analysis of vibration isolation performance of parallel air spring system for precision equipment transportation

2019 ◽  
Vol 52 (3-4) ◽  
pp. 291-302 ◽  
Author(s):  
Di Qu ◽  
Xiandong Liu ◽  
Guangtong Liu ◽  
Yifan Bai ◽  
Tian He
Keyword(s):  
Vibration Isolation ◽  
Rigid Body Dynamics ◽  
Dynamics Simulation ◽  
Railway Transportation ◽  
Air Spring ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Precision Equipment ◽  
Spring System ◽  
Isolation Requirements

Precision equipment is usually accompanied with vibrations during road or railway transportation. Sometimes the vibration exceeds the given limit, leading to the damage of the equipment. It is necessary to control the vibration during the transportation. However, it is still difficult to adjust the parameters of a designed vibration isolation system for the transportation of different precision equipment under various road conditions. Aiming at satisfying the vibration isolation requirements of different precision equipment, this paper proposes a parallel air spring vibration isolation system based on the principle of limiting lateral deflection. According to the measured parameters, a rigid-body dynamics simulation model of parallel air spring vibration isolation system is established. Then its feasibility is verified, and the optimal parameters of the vibration isolation system are obtained by a simulation. Finally, the vibration isolation system is built and installed in the equipment to carry out the real vehicle transportation test. The test results show that the transportation vibration isolation system based on the parallel air spring structure has not only excellent vibration isolation efficiency but also acceptable lateral stability. The research results in this paper can provide a reference for the design of the vibration isolation system for the large precision equipment transportation.

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.

Novel Double-Parallelogram Motion Constraining Mechanisms for Vibration Isolation Systems

2007 ◽  
Author(s):  
Jahangir Rastegar ◽  
Farshad Khorrami
Keyword(s):  
Relative Motion ◽  
Vibration Isolation ◽  
Translational Motion ◽  
Linkage Mechanism ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Rocking Motion ◽  
Isolation Systems ◽  
Isolation Device ◽  
Base Structure

Vibration isolation devices are used to attach various systems to their base structure to reduce the transmission of vibration from and/or to the base structure. Vibration isolation devices allow relative motion between the isolated system and the base platform. This relative motion is critical to the effective operation of vibration isolation devices and is used to absorb or divert vibration energy using spring and viscous damping or dry friction elements. In general, larger the allowed relative motion, more effective will be the performance of the isolation system. In certain applications, the introduced relative motion by the vibration isolation device introduces unavoidable and unwanted motion of the isolated system and can significantly degrade its performance, particularly in terms of positioning precision, or limit the range of allowable relative motion, thereby reducing the effectiveness of the isolation system. In this paper, a novel method is presented that uses appropriate linkage mechanisms to constrain relative motions that are introduced by the vibration isolation system that are not necessary for the proper operation of the vibration isolation system but their presence would degrade the performance of the entire system. As an example, a novel double-parallelogram based motion constraining mechanism is presented, which is used to constrain rotational (rocking) motion of an isolation system without hindering its relative translational motion used for vibration isolation. The design of a prototype of such a linkage mechanism used to isolate payloads from launch vehicles during the launch and the results of its successful testing are presented. Other applications of the present method are discussed.

Sign in / Sign up

Export Citation Format

Share Document