A New Approach to Active Vibration Isolation for Microgravity Space Experiments PDF Download
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Author: Alok Sinha
Publisher:
ISBN:
Category : Reduced gravity experiments
Languages : en
Pages : 14
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Book Description
Author: Alok Sinha
Publisher:
ISBN:
Category : Reduced gravity experiments
Languages : en
Pages : 14
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781725004016
Category :
Languages : en
Pages : 30
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Book Description
A new method was developed to design an active vibration isolation system for microgravity space experiments. This method yields the required controller transfer functions for a specified transmissibility ratio. Hence, it is a straightforward task to guarantee that the desired vibration isolation performance is achieved at each frequency. The theory for such a controller design was presented by considering a single degree of freedom system. In addition, the magnitude of the input required by the new method has been found to be less than that used by a standard phase lead/lag compensator. Sinha, Alok and Kao, Chikuan K. and Grodsinsky, Carlos M. Glenn Research Center NASA-TM-102470, E-5257, NAS 1.15:102470 NAG3-949; RTOP 694-03-03...
Author: Bibhuti Bhusan Banerjee
Publisher:
ISBN:
Category : Reduced gravity environments
Languages : en
Pages : 412
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722370763
Category :
Languages : en
Pages : 36
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Book Description
Manned orbiters will require active vibration isolation for acceleration-sensitive microgravity science experiments. Since umbilicals are highly desirable or even indispensable for many experiments, and since their presence greatly affects the complexity of the isolation problem, they should be considered in control synthesis. A general framework is presented for applying extended H2 synthesis methods to the three-dimensional microgravity isolation problem. The methodology integrates control and state frequency weighting and input and output disturbance accommodation techniques into the basic H2 synthesis approach. The various system models needed for design and analysis are also presented. The paper concludes with a discussion of a general design philosophy for the microgravity vibration isolation problem. Hampton, R. D. and Knospe, C. R. and Allaire, P. E. and Grodsinsky, C. M. Glenn Research Center NCC3-365; RTOP 963-70-OH...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 424
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Book Description
Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781729015452
Category :
Languages : en
Pages : 38
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Book Description
Many acceleration-sensitive, microgravity science experiments will require active vibration isolation from the manned orbiters on which they will be mounted. The isolation problem, especially in the case of a tethered payload, is a complex three-dimensional one that is best suited to modern-control design methods. These methods, although more powerful than their classical counterparts, can nonetheless go only so far in meeting the design requirements for practical systems. Once a tentative controller design is available, it must still be evaluated to determine whether or not it is fully acceptable, and to compare it with other possible design candidates. Realistically, such evaluation will be an inherent part of a necessary iterative design process. In this paper, an approach is presented for applying complex mu-analysis methods to a closed-loop vibration isolation system (experiment plus controller). An analysis framework is presented for evaluating nominal stability, nominal performance, robust stability, and robust performance of active microgravity isolation systems, with emphasis on the effective use of mu-analysis methods. Hampton, R. D. and Knospe, C. R. and Allaire, P. E. and Grodsinsky, C. M. Glenn Research Center NCC3-365; RTOP 963-70-OH...
Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781729015629
Category :
Languages : en
Pages : 38
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Book Description
Manned orbiters will require active vibration isolation for acceleration-sensitive microgravity science experiments. Since umbilicals are highly desirable or even indispensable for many experiments, and since their presence greatly affects the complexity of the isolation problem, they should be considered in control synthesis. A general framework is presented for applying extended H2 synthesis methods to the three-dimensional microgravity isolation problem. The methodology integrates control and state frequency weighting and input and output disturbance accommodation techniques into the basic H2 synthesis approach. The various system models needed for design and analysis are also presented. The paper concludes with a discussion of a general design philosophy for the microgravity vibration isolation problem. Hampton, R. D. and Knospe, C. R. and Allaire, P. E. and Grodsinsky, C. M. Glenn Research Center NCC3-365; RTOP 963-70-OH...
Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781729083284
Category :
Languages : en
Pages : 26
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Book Description
Certain experiments contemplated for space platforms must be isolated from the accelerations of the platforms. An optimal active control is developed for microgravity vibration isolation, using constant state feedback gains (identical to those obtained from the Linear Quadratic Regulator (LQR) approach) along with constant feedforward (preview) gains. The quadratic cost function for this control algorithm effectively weights external accelerations of the platform disturbances by a factor proportional to (1/omega)(exp 4). Low frequency accelerations (less than 50 Hz) are attenuated by greater than two orders of magnitude. The control relies on the absolute position and velocity feedback of the experiment and the absolute position and velocity feedforward of the platform, and generally derives the stability robustness characteristics guaranteed by the LQR approach to optimality. The method as derived is extendable to the case in which only the relative positions and velocities and the absolute accelerations of the experiment and space platform are available. Hampton, R. D. and Grodsinsky, C. M. and Allaire, P. E. and Lewis, D. W. and Knospe, C. R. Glenn Research Center RTOP 694-03-0C...
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723767845
Category : Science
Languages : en
Pages : 38
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Book Description
Vibration acceleration levels on large space platforms exceed the requirements of many space experiments. The Microgravity Vibration Isolation Mount (MIM) was built by the Canadian Space Agency to attenuate these disturbances to acceptable levels, and has been operational on the Russian Space Station Mir since May 1996. It has demonstrated good isolation performance and has supported several materials science experiments. The MIM uses Lorentz (voice-coil) magnetic actuators to levitate and isolate payloads at the individual experiment/sub-experiment (versus rack) level. Payload acceleration, relative position, and relative orientation (Euler-parameter) measurements are fed to a state-space controller. The controller, in turn, determines the actuator currents needed for effective experiment isolation. This paper presents the development of an algebraic, state-space model of the MIM, in a form suitable for optimal controller design. The equations are first derived using Newton's Second Law directly; then a second derivation (i.e., validation) of the same equations is provided, using Kane's approach.Hampton, R. David and Tryggvason, Bjarni V. and DeCarufel, Jean and Townsend, Miles A. and Wagar, William O.Glenn Research CenterVIBRATION ISOLATORS; MATHEMATICAL MODELS; VIBRATION DAMPING; STRUCTURAL DESIGN; CONTROLLERS; STRUCTURAL VIBRATION; SPACECRAFT COMPONENTS; SPACEBORNE EXPERIMENTS; MICROGRAVITY; SPACE STATIONS; ACTUATORS; SUSPENSION SYSTEMS (VEHICLES); FEEDBACK CONTROL; SPACECRAFT EQUIPMENT
Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781729083437
Category :
Languages : en
Pages : 26
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Book Description
In order to achieve adequate low-frequency vibration isolation for certain space experiments an active control is needed, due to inherent passive-isolator limitations. Proposed here are five possible state-space models for a one-dimensional vibration isolation system with a quadratic performance index. The five models are subsets of a general set of nonhomogeneous state space equations which includes disturbance terms. An optimal control is determined, using a differential equations approach, for this class of problems. This control is expressed in terms of constant, Linear Quadratic Regulator (LQR) feedback gains and constant feedforward (preview) gains. The gains can be easily determined numerically. They result in a robust controller and offers substantial improvements over a control that uses standard LQR feedback alone. Hampton, R. D. and Knospe, C. R. and Grodsinsky, C. M. and Allaire, P. E. and Lewis, D. W. Glenn Research Center ...
