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Journal ArticleDOI

Feedback for physicists: A tutorial essay on control

31 Aug 2005-Reviews of Modern Physics (American Physical Society)-Vol. 77, Iss: 3, pp 783-836
TL;DR: In this paper, a tutorial essay aims to give enough of the formal elements of control theory to satisfy the experimentalist designing or running a typical physics experiment and enough to satisfy a theorist wishing to understand its broader intellectual context.
Abstract: Feedback and control theory are important ideas that should form part of the education of a physicist but rarely do. This tutorial essay aims to give enough of the formal elements of control theory to satisfy the experimentalist designing or running a typical physics experiment and enough to satisfy the theorist wishing to understand its broader intellectual context. The level is generally simple, although more advanced methods are also introduced. Several types of applications are discussed, as the practical uses of feedback extend far beyond the simple regulation problems where it is most often employed. Sketches are then provided of some of the broader implications and applications of control theory, especially in biology, which are topics of active research.

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Citations
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01 Apr 2003
TL;DR: The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it as mentioned in this paper, and also presents new ideas and alternative interpretations which further explain the success of the EnkF.
Abstract: The purpose of this paper is to provide a comprehensive presentation and interpretation of the Ensemble Kalman Filter (EnKF) and its numerical implementation. The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it. This paper reviews the important results from these studies and also presents new ideas and alternative interpretations which further explain the success of the EnKF. In addition to providing the theoretical framework needed for using the EnKF, there is also a focus on the algorithmic formulation and optimal numerical implementation. A program listing is given for some of the key subroutines. The paper also touches upon specific issues such as the use of nonlinear measurements, in situ profiles of temperature and salinity, and data which are available with high frequency in time. An ensemble based optimal interpolation (EnOI) scheme is presented as a cost-effective approach which may serve as an alternative to the EnKF in some applications. A fairly extensive discussion is devoted to the use of time correlated model errors and the estimation of model bias.

2,975 citations

Book
21 Apr 2008
TL;DR: Feedback Systems develops transfer functions through the exponential response of a system, and is accessible across a range of disciplines that utilize feedback in physical, biological, information, and economic systems.
Abstract: This book provides an introduction to the mathematics needed to model, analyze, and design feedback systems. It is an ideal textbook for undergraduate and graduate students, and is indispensable for researchers seeking a self-contained reference on control theory. Unlike most books on the subject, Feedback Systems develops transfer functions through the exponential response of a system, and is accessible across a range of disciplines that utilize feedback in physical, biological, information, and economic systems. Karl strm and Richard Murray use techniques from physics, computer science, and operations research to introduce control-oriented modeling. They begin with state space tools for analysis and design, including stability of solutions, Lyapunov functions, reachability, state feedback observability, and estimators. The matrix exponential plays a central role in the analysis of linear control systems, allowing a concise development of many of the key concepts for this class of models. strm and Murray then develop and explain tools in the frequency domain, including transfer functions, Nyquist analysis, PID control, frequency domain design, and robustness. They provide exercises at the end of every chapter, and an accompanying electronic solutions manual is available. Feedback Systems is a complete one-volume resource for students and researchers in mathematics, engineering, and the sciences.Covers the mathematics needed to model, analyze, and design feedback systems Serves as an introductory textbook for students and a self-contained resource for researchers Includes exercises at the end of every chapter Features an electronic solutions manual Offers techniques applicable across a range of disciplines

1,927 citations


Cites background from "Feedback for physicists: A tutorial..."

  • ...The book by Fradkov [77] and the tutorial article by Bechhoefer [25] cover many specific topics of interest to the physics community....

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Journal ArticleDOI
TL;DR: In this article, the basic principles of modern optical magnetometers, discuss fundamental limitations on their performance, and describe recently explored applications for dynamical measurements of biomagnetic fields, detecting signals in NMR and MRI, inertial rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature.
Abstract: Some of the most sensitive methods of measuring magnetic fields use interactions of resonant light with atomic vapour. Recent developments in this vibrant field have led to improvements in sensitivity and other characteristics of atomic magnetometers, benefiting their traditional applications for measurements of geomagnetic anomalies and magnetic fields in space, and opening many new areas previously accessible only to magnetometers based on superconducting quantum interference devices. We review basic principles of modern optical magnetometers, discuss fundamental limitations on their performance, and describe recently explored applications for dynamical measurements of biomagnetic fields, detecting signals in NMR and MRI, inertial rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature.

1,489 citations


Cites background from "Feedback for physicists: A tutorial..."

  • ...However, if the bandwidth is increased by a factor K over the natural bandwidth, the magnetometer output noise also increases by the same factor K [47]....

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Journal ArticleDOI
TL;DR: In this article, B. Sonnenschein, E.R. dos Santos, P.J. Schultz, C.A. Ha, M.K. Choi and C.P.

683 citations

Journal ArticleDOI
TL;DR: This work addresses the physically important issue of the energy required for achieving control by deriving and validating scaling laws for the lower and upper energy bounds.
Abstract: The outstanding problem of controlling complex networks is relevant to many areas of science and engineering, and has the potential to generate technological breakthroughs as well. We address the physically important issue of the energy required for achieving control by deriving and validating scaling laws for the lower and upper energy bounds. These bounds represent a reasonable estimate of the energy cost associated with control, and provide a step forward from the current research on controllability toward ultimate control of complex networked dynamical systems.

392 citations

References
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Journal Article
TL;DR: This work uses a mixed signal composed of a standard driving signal and a feedback signal consisting of the amplified and phase shifted oscillation signal to identify the resonance frequency of the cantilever by mechanical excitation of the fluid.

133 citations


"Feedback for physicists: A tutorial..." refers background in this paper

  • ...An example is “active Q control,” where reduced oscillator damping increases the sensitivity for detecting small forces (Tamayo et al., 2000)....

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Book
22 Jan 2019
TL;DR: This book fills the gap between introductory feedback control books and advanced robust control books, and covers basics of robust control and incorporates new techniques for time delay systems, as well as classical and modern control.
Abstract: From the Publisher: There are many feedback control books out there, but none of themcapture the essence of robust control as well as Introduction to Feedback Control Theory. Written by Hitay Ozbay, one of the top researchers in robust control in the world, this book fills the gap between introductory feedback control books and advanced robust control books The book covers basic concepts such as dynamical systems modeling, performance objectives, the Routh-Hurwitz test, root locus, Nyquist criterion, and lead-lag controllers. It introduces more advanced topics including Kharitanov's stability test, basic loopshaping, stability robustness, sensitivity minimization, time delay systems, H-infinity control, and parameterization of all stabilizing controllers for single input single output stable plants. This range of topics gives insight into the key issues involved in designing a controller Introduction to Feedback Control Theory covers the basics of robust control and incorporates new techniques for time delay systems, as well as classical and modern control. Researchers, professionals, and students can use this reference to find basic and advanced information, and up-to-date techniques. It occupies an important place in the field of control theory

127 citations

Journal ArticleDOI
TL;DR: The paper ends with an analysis of a two-gene regulation system, the results of which point to the existence of a "soft-switching" mechanism that may account for the "on-off" hypothesized behavior of some gene networks.

123 citations


"Feedback for physicists: A tutorial..." refers background in this paper

  • ...” The theoretical analysis of simple networks has a long history (Wolf and Eeckman, 1998)....

    [...]

  • ...) See (Becksei and Serrano, 2000) for the full equations and (Wolf and Eeckman, 1998) for the thermodynamic background....

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Journal ArticleDOI
TL;DR: In this paper, a system that combines the passive isolation of mechanical springs and an optical table floating on compressed air with an active system that measures the acceleration of the mass to be isolated and feeds back to a solenoid actuator to cancel this motion is presented.
Abstract: We have constructed a system that isolates a key element of our experimental setup from vertical motions of the ground and the surrounding apparatus. This system combines the passive isolation of mechanical springs and an optical table floating on compressed air with an active system that measures the acceleration of the mass to be isolated and feeds back to a solenoid actuator to cancel this motion. Passive isolation alone reduces the acceleration error signal by a factor of 30–1000 from 10 to 100 Hz and by as much as a factor of 1000 above 100 Hz. With the feedback path closed, the system acts like a spring-mass system with a natural resonance frequency of 0.033 Hz. The acceleration error signal is reduced by an additional factor of up to 300 from 0.1 to 20 Hz. This system has enabled us to make precision atom interferometric measurements that would have been impossible without vibration isolation.

114 citations