Showing papers on "Observer (quantum physics) published in 1980"

Quantized scalar field in rotating coordinates

Abstract: Second quantization of the free scalar field is carried out in rotating coordinates and the spectrum of vacuum fluctuations is calculated for an orbiting observer using these coordinates. Normal-mode decomposition is identical to that in Minkowski coordinates except for the definition of positive-frequency modes. Unlike the uniformly accelerating observer, the orbiting observer predicts that the Minkowski vacuum will contain no particles as he would define them. The spectrum of vacuum fluctuations is composed of the usual zero-point energy plus a contribution arising from the observer's acceleration. The latter is not, as with uniformly accelerated motion, thermal. The peak energy appears to be dependent only on the torsion of the observer's world line.

Modal-Space Control of Distributed Gyroscopic Systems

Abstract: This paper presents a control scheme for distributed gyroscopic systems based on modal synthesis. The control parameters for each controlled mode are chosen independently of those for any other mode, thus resulting in a diagonal gain matrix for the controlled modes. The modal control laws are implemented by means of a reduced-order observer that estimates linear combinations of the modal state vector. The proposed scheme considers uncontrolled modes simultaneously and has the advantage that it minimizes truncation effects and that it exhibits no observation spillover instability due to modeled uncontrolled modes. The paper also includes specification of positions of actual control forces and torques and sensors.

Sensitivity Discriminating Observer Design for Instrument Failure Detection

Abstract: A procedure is presented for the design of a pair of sensitivity discriminating Luenberger observers for instrument failure detection (IFD). The proposed IFD scheme permits detection of instrument malfunctions with reduced sensitivity to process parameter variations. The efficiency of detecting instrument malfunctions and the influence of parameter variations are illustrated with an example.

Data collection techniques: observation

Abstract: Use of observation as a measurement procedure, assigning numerals to human behavioral acts, is discussed. Observation has important advantages which makes it best suited for certain kinds of studies, and some limitations which preclude its use in others. The central problems in the use of observation are: (1) the effect of the observer on the observed, which is usually not severe and can be minimized; (2) observer inference, which is a crucial strength and a crucial weakness; and (3) the unit of behavior to be used, which involves the molar-molecular problem. The considerations in planning both unstructured and structured observation studies are discussed, including what to observe, how to record it, how to maximize validity and reliability, and how to handle the relationship between the observer and the observed. Behavior is usually sampled using event sampling or time sampling. The uses and weaknesses of rating scales to assess perceived behavior are summarized.

Observers and duality between observation and state feedback for time delay systems

Abstract: This paper deals with the problem of observer construction for systems with general time-delays in state and output. The spectrum of the infinitesimal generator of the observer semigroup is determined explicitly, and the observer equation is decomposed into a finite- and an infinite-dimensional component. For systems with delays appearing in the state variables only duality results are obtained and the observer is described in the more concrete form of a differential delay equation.

Sensor Fault Detection in a System with Random Disturbances

Abstract: Sensor faults are detected in an operating automatic system by a simplified version of the dedicated observer scheme Control inputs are augmented by a random disturbance of moderate intensity The dedicated observer in this case is a Kalman filter, driven by a single sensor This filter provides estimates of the outputs from the other, nonredundant, sensors A logical combination of these functionally redundant signals with the actual sensor signals provides prompt detection of incipient faults on all instruments without false alarms The scheme is applied to a simulation of the lateral axis control system of a hydrofoil boat in which four sensors are to be covered by the fault detection scheme Tests indicate that the scheme is robust with respect to variations in the intensity of the random disturbance

Can we undo quantum measurements

Abstract: The Schr\"odinger equation cannot convert a pure state into a mixture (just as Newton's equations cannot display irreversibility). However, to observe phase relationships between macroscopically distinguishable states, one has to measure very peculiar operators. An example, constructed explicitly, shows that the classical analog of such an operator cannot be measured, because to do so would violate classical irreversibility. This result justifies von Neumann's measurement theory, without any hypothesis on the role of the observer.

Dynamical feedback control for a class of singularly perturbed linear systems using a full-order observer

Abstract: The dynamic feedback control for a class of singularly perturbed linear time-varying systems with inaccessible state is considered through a separate observer-based controller design for two lower-dimensional subsystems in two different time-scales A composite stabilizing feedback controller using a full-order observer is synthesized from the separate observer-based controllers, the mutually independent gains of which do not require knowledge of the small singular perturbation parameter

Design of multifunctional reduced order observers

Abstract: This paper presents a method for the design of an observer capable of reconstucting several linear functionals of the states of a linear, finite-dimensional system. The goal of this method is the design of an observer having minimum order subject to the restriction that the observer eigenvalues be freely assignable. The method is based on the reduction of a state observer formulated from an observable canonic form for the system when the functionals are treated as if they were additional outputs.

Discrete adaptive observer with fast convergence

Abstract: This paper presents a new scheme for a discrete adaptive observer for single-input single-output linear plants. In this scheme, the observer is constructed in parametrized form, and the adaptive law for parameter adjustment is given by a set of recursive equations which are derived on the basis of an exponentially weighted least-squares method. The proposed adaptive observer converges rapidly and also is able to track time-varying plant parameters quickly. Hence, the technique, can be well used as an identifier for indirect adaptive control systems. Its effectiveness has been demonstrated by computer simulations carried out for a second-order plant.

Feedback Stabilization of Distributed Parameter Systems by a Functional Observer

Abstract: Feedback stabilization of unstable parabolic equations is of great interest. The fact that it is not necessarily possible to stabilize the equations by means of static feedback schemes when both observation and control can be realized only through the boundary is illustratively shown by a simple example. In view of this, a functional observer of Luenberger type is derived and then utilized in order to stabilize unstable parabolic equations for which observation of the state and control can be carried out only through the boundary.

Adaptive state estimation using MRAS techniques--Convergence analysis and evaluation

Abstract: Three adaptive state observers for discrete-time systems derived from MRAS techniques are presented. While in a deterministic environment all of these schemes converge toward the linear asymptotic observer, when used in a stochastic environment for adaptive state estimation their performances present noticeable differences. The schemes considered in the paper are analyzed both in a deterministic and stochastic environment using the "equivalent feedback representation" (EFR) method and "ordinary differential equation" (ODE) method, respectively. Conditions for the convergence of the estimated parameters to the desired ones in a stochastic environment are given. The connections with adaptive Kalman filters are discussed. A comparative evaluation of these schemes in a deterministic and stochastic environment based on simulations concludes the paper.

Rotor measurement system using reflected load transmission

Abstract: An apparatus is provided for obtaining data from sensor measurements made on a body moving rotationally with respect to a stationary observer. Radio frequency energy is reactively coupled between an energy source fixed with respect to the observer and load varying means located on the moving body. The load variance is dependent upon measurement data provided by sensors located on the moving body. The variation in load is reflected back through the reactive coupler to a detector which is fixed with respect to the observer. The detector operates to provide signals indicative of the measurement data provided by the sensors. The apparatus of the present invention may be easily retrofitted to rotational devices such as turbines, motors and generators to provide relevant, continuous, on-line measurements of important parameters associated with such rotating systems. These parameters include such measurements as temperature, pressure, strain and torque. Because of the reflected load nature of the formation transmission, only a single coupling is provided and this coupling serves to carry both power and information signals.

A Note on Nonlinear Observers

Abstract: A general nonlinear expoential observer is presented for nonlinearly perturbed nonlinear systems. This is done by using the nonlinear variation of constants formula.

The deadbeat control of linear multivariable systems with inaccessible state

Abstract: The problem of deadbeat controller design for a class of discrete-time linear multi-variable systems with inaccessible state is considered. A deadbeat controller, based upon a minimal-order observer, and specified by two gain matrices in compact form, is presented which can drive the system state from any arbitrary initial state to the origin in at most νc + ν0 — 1 steps where νc and ν0 respectively are the controllability and observability indices of the system. The simplicity and generality of the design is demonstrated by numerical example.

Design procedure of observer for the linear functions of the state

Abstract: This paper is concerned with the construction of the observer for estimating linear functions of the state of a linear system. The necessary and sufficient condition for constructing the observer is derived in a geometrical way and its design method is presented. The relation between the proposed method and Gopinath's procedure for the state observer is made explicit from the points of minimal realization or the aggregation.

Size constancy fails below half a degree

Abstract: Size constance is a term used to refer to the fact that objects seem to maintain size as their distance from an observer changes, despite change in image size. It is known that size constancy has limits. People seen from the top of tall buildings look small. By observing objects, including the Moon, and after-images, we demonstrate here that size constancy holds when image size is above half a degree, and breaks down when it is less. In other words, image size is scaled for distance only when image size is above half a degree.

LIII. The architecture of observer/method variability and other types of process research

Abstract: Clinical Pharmacology and Therapeutics (1980) 28, 551–563; doi:10.1038/clpt.1980.202

Detection of moving objects

Abstract: A system for detecting and classifying vehicles, moving in the vicinity of a seismic detector, includes a time threshold circuit and, complementary to this circuit, two parallel amplitude detector circuits. One detector circuit utilizes amplitude thresholding to distinguish the seismic vibrations characteristic of moving vehicles, from other seismic vibrations. The other detector circuit utilizes amplitude thresholding to distinguish the seismic vibrations characteristic of a particular kind of moving vehicle (e.g. a tracked vehicle), from other seismic vibrations. The results of these two amplitude detector circuits and of the time threshold circuit are utilized by an indicator circuit and an indication of detected vehicle kind (e.g. tracked or wheeled) provided. Indication may be relayed, to a remote observer, by radio transmission.

An adaptive observer for single-input single-output linear systems with inaccessible input

Abstract: This paper is concerned with the problem of designing full-order adaptive observers for state estimation andl simultaneous identification of parameters of single-input single-output linear systems with single inaccessible disturbance input. An exponential typo polynomial disturbance model is introduced as an approximation of inaccessible input and necessary and sufficient conditions for the existence of an observer are derived. Then a full-order adaptive observer is based on the Lyapunov design. This design method is a modification of that of Kudva and Narendra (1973). A numerical example is also presented to illustrate the effectiveness of the proposed method.

Some Problems Associated with Digital Control of Dynamical Systems

Abstract: Digital control of a continuoiis-time system implies discretization in time of the system. The discretization is likely to bring about changes in the dynamic characteristics of the continuous-time system. Two approaches to the design of a digital control system can be considered: 1) discretization of a previously designed continuoustime control system and 2) direct design in the discrete-time domain. The difference between these two approaches and their effects on a closed-loop control system employing a Luenberger-type observer is demonstrated. The first approach consists of simulating a continuous-tim e control system on a digital computer. Because the possibility exists that a given set of parameters of the continuous-time system, such as gains and observer poles, will produce a change in the dynamic characteristics of the system during digital simulation, the question is how large the sampling time can be without affecting adversely the discrete simulation. An example of an unstable digital simulation of a closed-loop control system employing a deterministic observer that is stable in continuous-ti me is presented. The second approach inherently guards against changes in the dynamic characteristics that may be caused by discretization. The two approaches are compared by using a second-order dynamic system.

Optimal compensators with pole constraints

Abstract: In an observer-based control system, the design freedom which remains after pole assignment is used to minimize-in an average sense-a given quadratic performance index on the plant state and control. The class of controllers and observers satisfying pole constraints is characterized through a certain parameter vector. An algorithm is then developed to compute the optimal controller-observer set. An example is worked out to illustrate that the Optimal controller based on estimated state is not, in general, optimal when the true state is used.

Parameter identification of linear discrete stochastic systems with time delays

Abstract: An identification algorithm that uses the maximum likelihood technique to identify the unknown time delays, plant parameters, and noise covariances of linear discrete stochastic systems is presented. Cases of additive white noise and colored measurement noises are considered. The likelihood function is evaluated using either a minimum-variance (Kalman) filter or a minimal-order observer. The Kalman filter is used in the identification algorithm to provide minimum-variance estimates. The minimal-order observer is a lower-dimensional and computationally simpler filter, and is advantageous especially for systems with long delays. It provides a less optimal solution to the minimum-mean-square state estimation problem. The colored-noise observer algorithm has the disadvantage of having to compute an extra error covariance matrix of lower order.

Optimal control-system design for solar-tracking concentrators

Abstract: An optimal control procedure is presented for minimising the sun tracking error of solar concentrators. The sun tracking system is a point-focusing collector which is subject to wind disturbance. The optimal control law considered herein is a proportional plus integral control, and the following two feedback schemes are used for the controller implementation: 1. state estimation via an observer; and 2. suboptimal control The observer is constructed to estimate the unmeasurable tracking error variables and designed optimally to minimise the deviation of estimated errors from actual error values. The suboptimal control, on the other hand, uses only the output variables available from sensor. Investigation of the comparative performances of the two schemes indicates that sub-optimal control is only marginally inferior and could therefore provide a satisfactory and cost-effective solution under the conditions assumed.