Showing papers in "IEEE Transactions on Aerospace and Electronic Systems in 1984"
TL;DR: In this article, a derivation of the principal algorithms and an analysis of the performance of the two most important passive location systems for stationary transmitters, hyperbolic location systems and directionfinding location systems, are presented.
Abstract: A derivation of the principal algorithms and an analysis of the performance of the two most important passive location systems for stationary transmitters, hyperbolic location systems and directionfinding location systems, are presented. The concentration ellipse, the circular error probability, and the geometric dilution of precision are defined and related to the location-system and received-signal characteristics. Doppler and other passive location systems are briefly discussed.
1,208 citations
TL;DR: A review of the range-Doppler technique is presented along with a description of radar imaging forms including details of data acquisition and processing techniques.
Abstract: Using range and Doppler information to produce radar images is a technique used in such diverse fields as air-to-ground imaging of objects, terrain, and oceans and ground-to-air imaging of aircraft, space objects, and planets. A review of the range-Doppler technique is presented along with a description of radar imaging forms including details of data acquisition and processing techniques.
732 citations
TL;DR: In this paper, the tracking index, a generalized parameter proportional to the ratio of the position uncertainty due to the target maneuverability to that due to sensor measurement, is presented for the target tracking problem.
Abstract: A generalized, optimal filtering solution is presented for the target tracking problem Applying optimal filtering theory to the target tracking problem, the tracking index, a generalized parameter proportional to the ratio of the position uncertainty due to the target maneuverability to that due to the sensor measurement, is found to have a fundamental role not only in the optimal steady-state solution of the stochastic regulation tracking problem, but also in the track initiation process Depending on the order of the tracking model, the tracking index solution yields a closed form, consistent set of generalized tracking gains, relationships, and performances Using the tracking index parameter, an initializing and tracking procedure in recursive form, realizes the accuracy of the Kalman filter with an algorithm as simple as the well-known α-β filter or α-β-γ filter depending on the tracking order
287 citations
TL;DR: An overview of ARMA spectral estimation techniques based on the modified Yule-Walker equations is presented in this article, where the importance of using order overestimation, as well as of using an overdetermined set of equations, is emphasized.
Abstract: An overview of ARMA spectral estimation techniques based on the modified Yule-Walker equations is presented. The importance of using order overestimation, as well as of using an overdetermined set of equations, is emphasized. The Akaike information criterion is proposed for determining the equation order. A procedure for removing spurious noise modes based on modal decomposition of the sample covariance matrix is derived. The role of the singular value decomposition method in solving the modified Yule-Walker equations is discussed. A number of techniques for estimating MA spectral parameters are presented.
241 citations
TL;DR: From the geometry, one can easily find the arm solution consistently and a computer simulation study conducted on a VAX-11/780 computer demonstrated the validity of the arms solution.
Abstract: A geometric approach for deriving a consistent joint solution of a six-point PUMA1 robot is presented. The approach calls for the definition of various possible arm configurations based on the link coordinate systems and human arm geometry. These arm configurations are then expressed in an exact mathematical way to allow the construction of arm configuration indicators and their corresponding decision equations. The arm configuration indicators are prespecified by a user for finding the joint solution. These indicators enable one to find a solution from the possible four solutions for the first three joints, a solution from the possible two solutions for the last three joints. The solution is calculated in two stages. First a position vector pointing from the shoulder to the wrist is derived. This is used to derive the solution of the first three joints by looking at the projection of the position vector onto the xi-1-yi-1(i = 1,2,3) plane. The last three joints are solved using the calculated joint solution from the first three joints, the orientation matrices, and the projection of the link coordinate frames onto the xi-1-yi-1 (i = 4,5,6) plane. From the geometry, one can easily find the arm solution consistently. A computer simulation study conducted on a VAX-11/780 computer demonstrated the validity of the arm solution.
204 citations
TL;DR: A method of developing in-phase and quadrature samples of a band-limited RF waveform is presented, realized as a pair of 900 phase splitting networks with several symmetries which are exploited to save computation.
Abstract: We present a method of developing in-phase and quadrature samples of a band-limited RF waveform. The problem of matching gain and phase response differences between the two components is avoided by a combination of mixing to an IF frequency, sampling and digitizing, and digital filtering. The novelty of the method is in the design of the digital filter, which is realized as a pair of 900 phase splitting networks with several symmetries which are exploited to save computation.
99 citations
TL;DR: In this paper, the probability of detection for radars employing non-coherent integration and a fixed threshold or cell-averaging constant false alarm rate (CA-CFAR) processor is computed by numerical contour integration in the complex plane.
Abstract: The probability of detection for radars employing noncoherent integration and a fixed threshold or cell-averaging constant false alarm rate (CA-CFAR) processor is computed by numerical contour integration in the complex plane. The technique is applied to both nonfluctuating and chi-squared fluctuating targets. A bound on the truncation error allows for a simple stopping rule for the numerical integration. The method has applicability to many problems in radar detection theory.
60 citations
TL;DR: The major growth of systems engineering is expected to be in the improvement of its tools and in the enlargement of the range of problems to which it is applied.
Abstract: Systems engineering is described as the design of the whole as distinguished from the design of the parts. Systems engineers create the architecture of the system, define the criteria for its evaluation, and perform tradeoff studies for optimization of the subsystem characteristics. In addition to their own brains, the principal tool of systems engineers is the computer. Systems engineering has evolved during a long series of major developments, in particular the intercontinental ballistic missile (ICBM) program. The major growth of systems engineering is expected to be in the improvement of its tools and in the enlargement of the range of problems to which it is applied.
49 citations
TL;DR: The evolution of the application of the Kalman filter in the aerospace arena is traced in this paper, where the major programs that were the driving forces for the filter's acceptance are noted, as well as specific threads of activity for refining and enhancing the initial contribution.
Abstract: The evolution of the application of the Kalman filter in the aerospace arena is traced. The major programs that were the driving forces for the filter's acceptance are noted, as are the specific threads of activity for refining and enhancing the initial contribution. These efforts brought the fundamental ideas presented by Kalman to the point where actual application was possible. Clearly the concepts of the Kalman filter are now "mature." This is also noted and substantiated.
45 citations
TL;DR: In this article, the roll angle is used to assist present trackers during maneuvers to achieve accuracies comparable to those achieved during straight-line ine flight, but their performance during maneuvers is sometimes degraded.
Abstract: Present day radar trackers used for air traffic control purposes perform satisfactorily during straight-line flight, but their performance during maneuvers is sometimes degraded The introduction of the secondary surveillance radar mode S system makes transmission of several airborne measurements to the ground station possible This paper investigates the use of one such parameter, roll angle, to assist present trackers during maneuvers to achieve accuracies comparable to those achieved during straightline ine flight
42 citations
Journal Article•
TL;DR: In this paper, quinze articles d'auteurs differents portant sur la technologie des gyroscopes are presented. André et al. present a survey of the latest advances in gyroscope technology.
Abstract: Revue comprenant quinze articles d'auteurs differents portant sur la technologie des gyroscopes
TL;DR: In this paper, an exact stability analysis of the buck regulator system is presented, where the input filter parameter values are varied and system instability is predicted for the case without feedforward, and the eigenvalues of the system can be brought back into the unit circle and the system thus stabilized with the addition of the feedforward loop.
Abstract: The interaction between the input filter and the regulator often causes serious degradation of performance. The reduction in loop gain due to input filter interaction can result in system instability. An exact stability analysis of the buck regulator system is presented. The input filter parameter values are varied and system instability is predicted for the case without feedforward. The eigenvalues of the system can be brought back into the unit circle and the system thus stabilized with the addition of the feedforward loop. Measurements made for the cases with and without feedforward confirm the analytical prediction.
TL;DR: In this paper, an improved power converter model is developed by combining the average and discrete modeling techniques, and the parameter determination of the proposed discrete-average model is shown to be dependent on the type of duty cycle control law and the nature of the error processor used in the feedback loop.
Abstract: An improved power converter model is developed by combining the average and discrete modeling techniques. The parameter determination of the proposed discrete-average model is shown to be dependent on the type of duty cycle control law and the nature of the error processor used in the feedback loop. Furthermore, the paper pinpoints deficiencies of the conventional loop gain measurement technique which is widely used in industries.
TL;DR: Bistatic cross sections applicable to scattering from a cloud of randomly positioned and randomly oriented resonant dipoles, or chaff, are found in this paper, and several examples are developed to illustrate the ease with which the general results can be applied in practice.
Abstract: Bistatic cross sections applicable to scattering from a cloud of randomly positioned and randomly oriented resonant dipoles, or chaff, are found. The chaff cloud can have an arbitrary location relative to an illuminating radar and the radar antenna can have an arbitrarily specified polarization. The receiver can be located arbitrarily in relation to the radar and chaff cloud and can also have arbitrary polarization (different from the transmitter antenna). Average cross sections are found for a preferred receiver polarization and the corresponding orthogonal polarization. Results are reduced to simple, easily applied expressions, and several examples are developed to illustrate the ease with which the general results can be applied in practice.
TL;DR: In this paper, the authors presented an analysis and design procedure aimed at developing a feed-forward loop to cancel the undesirable interaction between an input filter and a switching regulator, which is a function of the input filter parameters and also of the supply voltage.
Abstract: An input filter is frequently employed between a switching regulator and its power source. However, its presence often results in degradation of dynamic performances and stability. The detrimental interaction is between an input filter and a switching regulator and is a function of the input filter parameters and also of the supply voltage. An earlier paper presented an analysis and design procedure aimed at developing a feed-forward loop to cancel this undesirable interaction. The feed-forward design is extended here to encompass a scheme that automatically accounts for changes in the supply voltage; the result is an adaptive compensation that tracks the input voltage variations. Experimental results are presented that confirm the adaptive nature of the design.
TL;DR: In this article, a new technique for tracking a maneuvering target in a cluttered environment is developed, which does not rely on a statistical description of the maneuver as a random process, instead, the state model for the target is changed when a maneuver is detected.
Abstract: A new technique for tracking a maneuvering target in a cluttered environment is developed. This approach does not rely on a statistical description of the maneuver as a random process. Instead, the state model for the target is changed when a maneuver is detected. Undesired measurements due to clutter or false alarms are assumed to occur uniformly and independently distributed. The Probabilistic Data Association Filter is used for both state models of the target. Measurement sequences over a window are tested for occurrence of possible maneuver. In the process, tracks are formed, deleted and merged. Simulation has shown the effectiveness of the scheme.
TL;DR: In this article, the authors compare the baseline (conventional) hydraulic flight control system with an all-electric airplane concept including quantitative comparisons of weight, reliability and maintainability, and life cycle costs.
Abstract: Electromechanical actuation is a critical element that must be developed and verified to make the all-electric aircraft a viable concept For several years the Flight Control Division of the Air Force Wright Aeronautical Laboratories has sponsored activities to demonstrate the credibility of electromechanical actuation systems (EMAS) for primary flight control actuation functions The foundation for these EMAS activities and several electromechanical actuation development programs are described here One involves the design, fabrication, and laboratory test of a rotary, hingeline electromechanical actuator Another involves the development and flight test demonstration of a linear electromechanical actuator for controlling an aileron of a C-141 aircraft A third involves the design and development of a linear electromechanical actuator for missiles having severe performance, temperature, and volumetric requirements In addition, a brief summary of the results from two aircraft actuation trade studies compare the baseline (conventional) hydraulic flight control system with an all-electric airplane concept including quantitative comparisons of weight, reliability and maintainability, and life cycle costs
TL;DR: In this paper, the authors consider the problem of tracking a maneuvering target in clutter and present a new approach to overcome the limitations of the present approaches, such as optimization of detection characteristics and features that can be used in the plot-to-track correlation process.
Abstract: We consider the problem of tracking a maneuvering target in clutter. In such an environment, missed detections and false alarms make it impossible to decide, with certainty, the origin of received echoes. Processing radar returns in cluttered environments consists of three functions: 1) target detection and plot formation, 2) plot-to-track association, and 3) track updating. Two inadequacies of the present approaches are 1) Optimization of detection characteristics have not been considered and 2) features that can be used in the plot-to-track correlation process are restricted to a specific class. This paper presents a new approach to overcome these limitations. This approach facilitates tracking of a maneuvering target in clutter and improves tracking performance for weak targets.
TL;DR: In this paper, a nonlinear feedback control law for the attitude control of a satellite containing symmetric rotors, in a circular orbit, is derived, given trajectories of pitch, yaw and roll angles are asymptotically followed, and set point control of attitude is accomplished.
Abstract: A control law is presented for asymptotic function reproducibility in a class of nonlinear-systems such that the output of the system asympotically tends to a given function. The controller consists of a prefilter and a servocompensator. Based on this result, a nonlinear feedback control law for the attitude control of a satellite containing symmetric rotors, in a circular orbit, is derived. In the closed-loop system, given trajectories of pitch, yaw, and roll angles are asymptotically followed, and set point control of attitude is accomplished. Digital simulation results are presented to show the capability of the nonlinear controller.
TL;DR: In this article, the performance of an optimum radar signal processor and more conventional techniques (such as MTI, adaptive MTI and cqherent integration) are compared and a mathematical method is suggested and applied to several cases of practical interest.
Abstract: The performance of an optimum radar signal processor and more conventional techniques (such as MTI, adaptive MTI, and cqherent integration) are compared. A mathematical method is suggested and applied to several cases of practical interest. A number of operative conditions are discovered in which the conventional processing techniques give very poor performance and the optimum radar processor becomes necessary.
TL;DR: The National Aeronautics and Space Administration (NASA) has sponsored or conducted a number of activities to foster the development of an all-electric airplane as mentioned in this paper, and the results of these activities are presented.
Abstract: The previous papers have offered the distant vision of an all-electric aircraft?one which fully exploits the intrinsic features of electric power and electronic controls. This paper examines the path to that vision and the barriers along the way?some of which appear relatively easy to overcome while others are more formidable. It is interesting to conjecture what an all-electric aircraft will look like. The all-electric technologies may offer many design options and this paper suggests some tantalizing possibilities. The National Aeronautics and Space Administration (NASA) has sponsored or conducted a number of activities to foster the development of an all-electric airplane. The results of these activities are presented. Finally, in a look to the future, two NASA new initiatives are briefly discussed.
TL;DR: The conceptual design of the DME/P that evolved from the ICAO process is discussed in this paper, where comptability issues are highlighted, and it is shown how they are accommodated in the system synthesis which also treats the obvious need for a guidance function of high integrity and robust performance in the severe multipath environment encountered in approach and landing operations.
Abstract: The International Civil Aviation Organization (ICAO) has completed technical standards for the precision distance measuring equipment (DME/P). The DME/P is an integral element of the microwave landing system (MLS) and will provide the precision ranging function to complement the already standardized azimuth and elevation guidance functions of the system. In 1978 an ICAO meeting concluded that the DME/P should be integrated into the existing standards for the conventional DME (DME/N) as a compatible service. The motivation for this was economic. It was reasoned that a single L-band airborne unit could satisfy the need for both existing enroute and the new precision approach and landing services, thereby avoiding unnecessary duplication of on-board ranging equipment. Furthermore, this approach would permit existing conventional airborne equipment to obtain service from the new DME/P ground facilities at least during the initial stages of MLS implementation. These compatibility requirements were later incorporated into the DME/P statement of operational requirements which was accepted at an ICAO meeting in April 1981. Further, they have been a primary focus in the DME/P standardization effort which has been actively pursued since late 1980. The conceptual design of the DME/P that evolved from the ICAO process is discussed here. The comptability issues are highlighted, and it is shown how they are accommodated in the system synthesis which also treats the obvious need for a guidance function of high integrity and robust performance in the severe multipath environment encountered in approach and landing operations.
TL;DR: A class of registration algorithms that are reasonably efficient and robust for translational displacement has been considered and a new measure, namely, coefficient of variation, is defined to take into account effects of contrast and sharpness of the images.
Abstract: The automatic determination of local similarity between two images (image registration) is one of the most fundamental problems of image processing and pattern recognition. A class of registration algorithms that are reasonably efficient and robust for translational displacement has been considered to determine relative shift between reference and search images. Stochastic image models defined on a rectangular region of support are used to determine feature vectors associated with reference and search images. A new measure, namely, coefficient of variation, is defined to take into account effects of contrast and sharpness of the images. Based upon this measure, a computationally efficient two-stage algorithm is obtained by combining the image-model based algorithm with a template matching technique. Simulation results with several synthetic and real images are presented to evaluate the performance of the algorithms.
TL;DR: The sample matrix inversion technique is used for Doppler and/or array processing and a probability of detection analysis has been performed, showing that the detection loss is larger than that computed by the SINR measure.
Abstract: The sample matrix inversion (SMI) technique is used for Doppler and/or array processing. Previous analysis of the technique has been in terms of signal-to-interference plus noise ratio (SINR). For Gaussian statistics, this performance measure gives the same loss values as does a probability of detection analysis for linear-time invariant systems. It is often somewhat less valid for nonlinear or time variant systems. As SMI is a nonlinear technique, a probability of detection analysis has been performed. It is shown that the detection loss is larger than that computed by the SINR measure. It is also shown that though the loss predicted by the SINR measure only depends upon the number of measurements used to estimate the covariance matrix, the detection loss depends upon the false alarm probability and the number of adaptable elements in addition to the number of measurements.
TL;DR: In this article, a fourth-order extended Kalman filter was developed to estimate target maneuvers, and a guidance law using these estimates was implemented, which is based on the guidance law.
Abstract: A fourth-order extended Kalman filter is developed to estimate target maneuvers, and a guidance law using these estimates is implemented.
TL;DR: The result of applying the design methodology for designing suboptimal rules based on the Bayesian approach to an example shows that this approach is potentially a useful one.
Abstract: The formulation of the decision making process of a failure detection algorithm as a Bayes sequential decision problem provides a simple conceptualization of the decision rule design problem As the optimal Bayes rule is not computable, a methodology that is based on the Bayesian approach and aimed at a reduced computational requirement is developed for designing suboptimal rules A numerical algorithm is constructed to facilitate the design and performance evaluation of these suboptimal rules The result of applying this design methodology to an example shows that this approach is potentially a useful one
TL;DR: In this paper, the performance of the maximum likelihood estimator (MLE) for the time of arrival of a rectangular pulse in additive white Gaussian noise is investigated. And upper and lower bounds for the mean square error are derived for both medium and large energy-to-noise ratios.
Abstract: We consider the performance of the maximum likelihood estimator (MLE) for the time of arrival of a rectangular pulse in additive white Gaussian noise. Upper and lower bounds are derived for the mean square error. These bounds are tight for both medium and large energy-to-noise ratios.
TL;DR: A detection system that meets the requirement of finding one and only one target in the automatic detection phase of a "fire-and-forget" weapon is presented and there is good correspondence between the empirical results and the theoretical performance.
Abstract: The automatic detection of targets in cluttered infrared imagery is considered. The environment for the problem is that of a "fire-and-forget" weapon, and the mission philosophy for such a weapon dictates that the weapon has to find one and only one target in the automatic detection phase. A detection system that meets this requirement is presented. The system uses techniques of image processing and pattern recognition, with the extension that ranking methods are used instead of thresholds to accommodate the requirement of finding one and only one target. A probability model of the system is developed to determine the system performance as a function of throughput and expressions derived for the probability that the object chosen by the system as the target is actually a target. In order to validate the theoretical results, the actual performance of the detection system on a database of 68 infrared images is determined and compared with the predicted performance of the system. It is shown that there is good correspondence between the empirical results and the theoretical performance.
TL;DR: In this article, the effects of aircraft acceleration on the depth of field for three types of SAR processing are analyzed: (1) conventional processing (range-Dopper processing), (2) variable pulse-repetition frequency (PRF) changes to compensate for aircraft acceleration, and (3) polar format.
Abstract: Processing synthetic array radar (SAR) data is difficult if the depth of field is small. Aircraft acceleration can severely reduce the depth of field and thereby increase the processing. The effects of aircraft acceleration on the depth of field for three types of SAR processing are analyzed: (1) conventional processing (range-Dopper processing), (2) variable pulse-repetition frequency (PRF) (PRF changes to compensate for aircraft acceleration), and (3) polar format. Polar format is a technique for processing high resolution SAR which has a much larger depth of field in the ground plane than conventional processing. On the other hand, aircraft acceleration will limit the vertical depth of field for polar format to about the same value as for conventional processing. In addition, for polar format, the only component of aircraft acceleration that limits the vertical depth of field is the component normal to the slant plane containing the velocity and range vectors. Vector notation is used to graphically show the effects of aircraft acceleration. In addition to better insight, the vector notation gives equations for SAR compensation that do not depend on a specific coordinate system.
TL;DR: In this paper, six modes of operation for push-pull 4c-to-dc converter are presented by taking into account the magnetizing current of the transformer and the region where the output voltage is abnormally high is expanded in the load characteristics.
Abstract: Six modes of operation for the push-pull 4c-to-dc converter are presented by taking into account the magnetizing current of the transformer If the inductance of the transformer is decreased, the region where the output voltage is abnormally high is expanded in the load characteristics