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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date October 2006

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  • IEEE Transactions on Aerospace and Electronic Systems - Table of contents

    Publication Year: 2006 , Page(s): c1
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  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 2006 , Page(s): c2
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  • From the Editor-in-Chief

    Publication Year: 2006 , Page(s): 1185 - 1186
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  • Microsatellite Laser Altimeter

    Publication Year: 2006 , Page(s): 1187 - 1197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1734 KB) |  | HTML iconHTML  

    A feasibility study is presented of a laser altimeter conceived as an auxiliary device of an imaging camera to perform stereo pairs correction by high accuracy range measurements. System configuration is compliant to microsatellite constraints and is integrated to a high-resolution imaging sensor. System performance analysis is carried out by means of analytical models and computer codes and plots are presented to select key parameters allowing definition of a preliminary laser altimeter configuration View full abstract»

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  • Closed-form posterior Cramer-Rao bounds for bearings-only tracking

    Publication Year: 2006 , Page(s): 1198 - 1223
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3815 KB) |  | HTML iconHTML  

    We address the classical bearings-only tracking problem (BOT) for a single object, which belongs to the general class of nonlinear filtering problems. Recently, algorithms based on sequential Monte-Carlo methods (particle filtering) have been proposed. As far as performance analysis is concerned, the posterior Cramer-Rao bound (PCRB) provides a lower bound on the mean square error. Classically, under a technical assumption named "asymptotic unbiasedness assumption", the PCRB is given by the inverse Fisher information matrix (FIM). The latter is computed using Tichavsky's recursive formula via Monte-Carlo methods. Two major problems are studied here. First, we show that the asymptotic unbiasedness assumption can be replaced by an assumption which is more meaningful. Second, an exact algorithm to compute the PCRB is derived via Tichavsky's recursive formula without using Monte-Carlo methods. This result is based on a new coordinate system named logarithmic polar coordinate (LPC) system. Simulation results illustrate that PCRB can now be computed accurately and quickly, making it suitable for sensor management applications View full abstract»

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  • Hard-constrained versus soft-constrained parameter estimation

    Publication Year: 2006 , Page(s): 1224 - 1239
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2056 KB) |  | HTML iconHTML  

    The paper aims at contrasting two different ways of incorporating a priori information in parameter estimation, i.e., hard-constrained and soft-constrained estimation. Hard-constrained estimation can be interpreted, in the Bayesian framework, as maximum a posteriori probability (MAP) estimation with uniform prior distribution over the constraining set, and amounts to a constrained least-squares (LS) optimization. Novel analytical results on the statistics of the hard-constrained estimator are presented for a linear regression model subject to lower and upper bounds on a single parameter. This analysis allows to quantify the mean squared error (MSE) reduction implied by constraints and to see how this depends on the size of the constraining set compared with the confidence regions of the unconstrained estimator. Contrastingly, soft-constrained estimation can be regarded as MAP estimation with Gaussian prior distribution and amounts to a less computationally demanding unconstrained LS optimization with a cost suitably modified by the mean and covariance of the Gaussian distribution. Results on the design of the prior covariance of the soft-constrained estimator for optimal MSE performance are also given. Finally, a practical case-study concerning a line fitting estimation problem is presented in order to validate the theoretical results derived in the paper as well as to compare the performance of the hard-constrained and soft-constrained approaches under different settings View full abstract»

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  • Constrained bearings-only target motion analysis via Markov chain Monte Carlo methods

    Publication Year: 2006 , Page(s): 1240 - 1263
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4010 KB) |  | HTML iconHTML  

    The aim of this paper is to develop methods for estimating the range of a moving target from bearings-only observations and for weakly observable scenarios, by including general constraints about the target trajectories. Throughout this manuscript, it is assumed that the target motion is conditionally deterministic, which leads us to focus on batch algorithms. Another common assumption is poor observability, which results from another constraint: (very) limited amplitude of the observer maneuvers. Classical batch algorithms are based on iterative methods (such as gradient techniques), but they perform very poorly in this context and including constraints is not easy and not reliable in this way. Instead, we consider simulation-based methods, i.e., Monte Carlo Markov chain (MCMC) sampling, developed in a Bayesian context. In this way, it is possible to take into account any type of constraint, and to drastically improve estimation of weakly observable parameters. As a by-product, an estimate of confidence intervals is obtained. This is the aim of the highest probability density (HPD) intervals. This study is illustrated by simulation results, while the benefits of constraint inclusion are analyzed via geometric methods View full abstract»

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  • Road-map assisted ground moving target tracking

    Publication Year: 2006 , Page(s): 1264 - 1274
    Cited by:  Papers (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1846 KB) |  | HTML iconHTML  

    Tracking ground targets with airborne GMTI (ground moving target indicator) sensor measurements proves to be a challenging task due to high target density, high clutter, and low visibility. The exploitation of nonstandard background information such as road maps and terrain information is therefore highly desirable for the enhancement of track quality and track continuity. The present paper presents a Bayesian approach to incorporate such information consistently. It is particularly suited to deal with winding roads and networks of roads. The target dynamics is modeled in quasi one-dimensional road coordinates and mapped onto ground coordinates using linear road segments taking road map errors into account. The case of several intersecting roads with different characteristics, such as mean curvature, slope, or visibility, is treated within an interacting multiple model (IMM) scheme. Targets can be masked both by the clutter notch of the sensor and by terrain obstacles. Both effects are modeled using a sensor-target state dependent detection probability. The iterative filter equations are formulated within a framework of Gaussian sum approximations on the one hand and a particle filter approach on the other hand. Simulation results for single targets taken from a realistic ground scenario show strongly reduced target location errors compared with the case of neglecting road-map information. By modeling the clutter notch of the GMTI sensor, early detection of stopping targets is demonstrated View full abstract»

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  • Star identification algorithms: novel approach & comparison study

    Publication Year: 2006 , Page(s): 1275 - 1288
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2371 KB) |  | HTML iconHTML  

    A novel approach to the problem of star identification for spacecraft attitude determination based on data provided by a star camera is proposed. The algorithm is based on pattern matching ideas and provides improved reliability with respect to similar methods available in the literature. The achievable performance is demonstrated via a comparison study with two published algorithms View full abstract»

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  • Time-frequency method for detecting an accelerating target in sea clutter

    Publication Year: 2006 , Page(s): 1289 - 1310
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4438 KB) |  | HTML iconHTML  

    The authors design a time-frequency (TF) method for use in high-frequency surface-wave radar (HFSWR) for detecting a small accelerating target in sea clutter. The clutter is modelled by pseudo targets moving with Bragg velocity towards and away from the radar. The design is based on the Wigner distribution (WD) defined by Chan (type-III WD, in our terminology) rather than the WD defined by Claasen and Mecklenbrauker (1980) (2times type-I WD, in our terminology). Like the type-I WD, the type-III WD also concentrates a chirp signal onto a straight line in the TF plane. The type-III WD has the following advantages: 1) Its range of unambiguously measurable frequencies (RUMF) is [-pi,pi] rad/s, whereas for the type-I WD the RUMF is [-pi/2,pi/2] rad/s. 2) It allows a target separated from the clutter by pi rad/s to be detected, whereas the type-I WD coalesces such a target with the clutter and thereby mask it. An ambiguity function (AF) was defined corresponding to the type-III WD and use it to derive a smoothed type-III WD that mitigates the clutter. The smoothed type-III WD method is applied to real radar data and shown to be superior to the conventional Fourier transform method. The advantages of the type-III WD over the type-I WD are also demonstrated. The design principles laid out in the paper can also be used to develop a TF method for use in air traffic control radar (ATCR) for detecting an accelerating target in land clutter View full abstract»

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  • Optimal acknowledgment frequency over asymmetric space-internet links

    Publication Year: 2006 , Page(s): 1311 - 1322
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3043 KB) |  | HTML iconHTML  

    The acknowledgement (ACK) strategy of transmission control protocol (TCP) has been modified to delay the ACKs for a configurable period of time that is related to the round-trip time (RTT) to improve its performance in asymmetric links such as space communications. A general relationship between the asymmetric channel ratio and the optimal ACK frequency to achieve maximum throughput is not available. This paper studies the optimal ACK frequency with respect to the channel RTT to achieve the maximum throughput over various asymmetric, geo-stationary earth orbit (GEO)-satellite links using a test-bed. It is found that when the asymmetric channel ratio is as high as about 100/1, the optimal ACK frequency must be increased with an increase in asymmetric ratio to complement the impact of the reduction of ACK channel rate. As a rule of thumb, every two-fold increase in asymmetric ratio requires the optimal ACK frequency to be increased by one ACK per RTT. A regression model was built to reflect the relationship between the optimal ACK frequency and the asymmetric channel ratio and has been validated View full abstract»

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  • Fuzzy gain-scheduled missile autopilot design using evolutionary algorithms

    Publication Year: 2006 , Page(s): 1323 - 1339
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6078 KB) |  | HTML iconHTML  

    The paper presents the lateral acceleration control design of a missile model using the evolution strategy (ES). The nonlinear fixed-structure-like controller is represented by the singleton fuzzy model. This allows a variation of shapes of the gain functions to be explored, and subsequent modification is fairly easy. Instead of finding an optimal decomposition of the fuzzy controller, a set of fuzzy rules is unconventionally optimized for the overall gain surfaces that guarantee acceptable performances for the closed-loop system over the whole operating envelope. The simulation results show that the designed fuzzy gain-scheduled controller is a robust tracking controller for all perturbation vertices View full abstract»

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  • Evaluation of estimation algorithms part I: incomprehensive measures of performance

    Publication Year: 2006 , Page(s): 1340 - 1358
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3541 KB) |  | HTML iconHTML  

    Practical metrics for performance evaluation of estimation algorithms are discussed. A variety of metrics useful for evaluating various aspects of the performance of an estimation algorithm is introduced and justified. They can be classified in two different ways: 1) absolute error measures (without a reference), relative error measures (with a reference), or frequency counts (of some events), and 2) optimistic (i.e., how good the performance is), pessimistic (i.e., how bad the performance is), or balanced (neither optimistic nor pessimistic). Pros and cons of these metrics and the widely-used RMS error are explained. The paper advocates replacing the RMS error in many cases by a measure called average Euclidean error View full abstract»

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  • New track correlation algorithms in a multisensor data fusion system

    Publication Year: 2006 , Page(s): 1359 - 1371
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3058 KB) |  | HTML iconHTML  

    In order to resolve the problem of track-to-track association in a distributed multisensor situation, this paper presents independent and dependent sequential track correlation algorithms based on Singer's and Bar-Shalom's algorithms. Based on sequential track correlation algorithm, the restricted and attenuation memory track correlation algorithms and sequential classic assignment rules are proposed. In this paper, these algorithms are described in detail. Then, the track correlation mass and multivalency processing methods are discussed as well. Finally, simulations are designed to compare the correlation performance of these algorithms with that of Singer's and Bar-Shalom's algorithms. The simulation results show that the performance of these algorithms proposed here is much better than that of the classical methods under the environments of dense targets, interfering, noise, track cross, and so on. Under the above situations, their correct correlation ratio is improved about 69 percent over the classical methods View full abstract»

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  • Automatic target recognition for hyperspectral imagery using high-order statistics

    Publication Year: 2006 , Page(s): 1372 - 1385
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2943 KB) |  | HTML iconHTML  

    Due to recent advances in hyperspectral imaging sensors many subtle unknown signal sources that cannot be resolved by multispectral sensors can be now uncovered for target detection, discrimination, and identification. Because the information about such sources is generally not available, automatic target recognition (ATR) presents a great challenge to hyperspectral image analysts. Many approaches developed for ATR are based on second-order statistics in the past years. This paper investigates ATR techniques using high order statistics. For ATR in hyperspectral imagery, most interesting targets usually occur with low probabilities and small population and they generally cannot be described by second-order statistics. Under such circumstances, using high-order statistics to perform target detection have been shown by experiments in this paper to be more effective than using second order statistics. In order to further address a challenging issue in determining the number of signal sources needed to be detected, a recently developed concept of virtual dimensionality (VD) is used to estimate this number. The experiments demonstrate that using high-order statistics-based techniques in conjunction with the VD to perform ATR are indeed very effective View full abstract»

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  • Paired overbounding for nonideal LAAS and WAAS error distributions

    Publication Year: 2006 , Page(s): 1386 - 1395
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1566 KB) |  | HTML iconHTML  

    A significant challenge in fielding space-based and ground-based augmentation systems (SBAS and GBAS) for GPS involves the validation of navigation integrity, which requires the establishment of error bounds for aircraft position. This paper introduces a new approach to validating position-domain integrity by using two-sided envelopes for each ranging source. This paired-bounding approach allows for error distributions of arbitrary form and thus improves on earlier integrity validation approaches restricted to zero-mean, symmetric, and unimodal distributions View full abstract»

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  • Closed-form solution of hyperbolic geolocation equations

    Publication Year: 2006 , Page(s): 1396 - 1404
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    A 3-dimensional (3D), closed-form solution for the time difference of arrival (TDOA) problem that does not depend on range data is given. Such a solution did not exist previously in the literature. For aerospace and military applications, the solution is precise. For civilian cellular phone applications, however, the solution is susceptible to unrelated errors from the phenomenon of multipath delays in the channels. This phenomenon is factored in mathematically in the solution and a simulation that characterizes its error bounds is presented View full abstract»

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  • Noncoherent approach to through-the-wall radar localization

    Publication Year: 2006 , Page(s): 1405 - 1419
    Cited by:  Papers (42)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2651 KB) |  | HTML iconHTML  

    A noncoherent through-the-wall radar system approach, based on stepped-frequency signal synthesis and trilateration technique, is presented. This approach involves multiple independent monostatic radar units and as such, provides flexibility in positioning the units with various standoff distances and inter-element spacing. The performance of the proposed noncoherent localization system was demonstrated using simulated and real data. The results show that the radar is able to detect and locate multiple targets behind walls View full abstract»

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  • Landing system verification based on petri nets and a hybrid approach

    Publication Year: 2006 , Page(s): 1420 - 1436
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4147 KB) |  | HTML iconHTML  

    One of the most important activities of control system design is its verification. Verification ensures that the controlled system will behave as expected under any circumstances it may operate. In this context, the purpose of this paper is to introduce a new method for the verification of aircraft control systems. The focus of this method is on aircraft systems that are characterized as hybrid, i.e., that merge continuous and discrete dynamics. The method proposed is divided into two main parts: the system modeling and the verification of behavioral properties. In the first part, Petri net, differential equation systems, and object oriented concepts are used concurrently in order to model complex hybrid systems. In the second part, the distributed nature of the model is explored in order to decompose a complex verification problem into series of simple local problems. Linear logic is used as a basis of a theorem-proving approach for the verification from the discrete-event point of view. The verification method has been applied to a number of case studies. Among them is the landing system of a military aircraft, which is described in this paper View full abstract»

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  • Third world radiation threats to satellites

    Publication Year: 2006 , Page(s): 1437 - 1445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1728 KB) |  | HTML iconHTML  

    The era of hardening military satellites against nuclear events, lasers, and high-power microwaves, appears to have come to an end. A case is made here for maintaining rudimentary nuclear, laser, and high-power microwave (HPM) hardening requirements in order to protect against developing third world threats. The third world nuclear threat is well known. Less appreciated is the fact that third world laser and microwave threats have changed radically in the past few years View full abstract»

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  • Optimal Cooperative Sensing using a Team of UAVs

    Publication Year: 2006 , Page(s): 1446 - 1458
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB) |  | HTML iconHTML  

    The authors investigates the joint optimal estimation of both the position and velocity of a ground moving target (GMT) using pulse Doppler radars on-board unmanned aerial vehicles (UAVs). The problem of cooperative estimation using a UAV team and the optimization of the team's configuration to achieve optimal GMT position and velocity estimates are addressed. Based on the Cramer-Rao bound, the minimum achievable error variance of the GMT position and velocity estimates is derived. The expression of the minimum achievable estimation error variance for unbiased estimation provided by the Cramer-Rao bound is minimized yielding the optimal configuration of the UAV team. Our solution is complete in that it addresses various GMT tracking scenarios and an arbitrary number of UAVs. Optimal sensor geometries for typical applications are illustrated View full abstract»

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  • Monopulse tracking with phased array search radar in the presence of specular reflection from sea surface [Correspondence]

    Publication Year: 2006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (939 KB) |  | HTML iconHTML  

    Extraction of elevation information with phased array search radar in the presence of specular reflection from sea surface is presented. Specular reflection from sea causes large peak errors in the measurement of low elevation angle. An algorithm based on complex indicated angle is derived to reduce specular reflection component. From the complex indicated angle and the exactly known or approximately known data, the authors can generate a specular reflection error finding function (SREFF). SREFF clearly indicates where the measurements are much affected by the specular reflection in the complex indicated angle data. View full abstract»

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  • New approach for suppression of FM jamming in GPS receivers

    Publication Year: 2006 , Page(s): 1464 - 1474
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1650 KB) |  | HTML iconHTML  

    A new approach is proposed for the suppression of FM jammers in C/A code GPS receivers. This approach is based on the cascading of the augmented-state approximate conditional mean (ASACM) filter and the discrete wavelet transform (DWT) filter. An ASACM filter for single interference suppression in spread-spectrum systems has been reported in the recent literature. However, the formulation of the ASACM filter and its performance analysis is lacking in the case of suppression of multiple FM interferences. The ASACM filter is formulated here for the suppression of multiple FM jammers. Further, a DWT filter using biorthogonal wavelet is suggested for the suppression of FM jammers. Finally, these two filters are cascaded to get an optimum performance for higher jammer to signal ratio, which is of importance in the GPS, for the case of suppression of multiple FM jammers. The performance of the proposed filters is analyzed through simulation examples for the suppression of single and multiple FM jammers in GPS receivers View full abstract»

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  • Multisensor deployment using PCRLBS, incorporating sensor deployment and motion uncertainties

    Publication Year: 2006 , Page(s): 1474 - 1485
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (993 KB) |  | HTML iconHTML  

    Recently, a general framework for sensor resource deployment (Hernandez, et. al. 2004) has been shown to allow efficient and effective utilization of a multisensor system. The basis of this technique is to use the posterior Cramer-Rao lower bound (PCRLB) to quantify and control the optimal achievable accuracy of target state estimation. In the original formulation (Hernandez, et. al. 2004) it was assumed that the sensor locations were known without error. In the current paper, the authors extend this framework by addressing the issues of imperfect sensor placement and uncertain sensor movement (e.g., sensor drift). The crucial consideration is then how these two forms of uncertainty are factored into the sensor management strategy. If unaccounted for, these uncertainties will render the output of the resource manager inaccurate and overoptimistic. The authors adjust the PCRLB to account for sensor location uncertainty, and we also allow for measurement origin uncertainty due to missed detections and false alarms. The work is motivated by the problem of tracking a submarine by adaptively deploying sonobuoys from a helicopter. Simulation results are presented to show the advantages of accounting for sensor location uncertainty within this focal domain of antisubmarine warfare. The authors note that the generic nature of the technique allows it to be utilized within other problem domains, including tracking ground-based targets using unattended ground sensors (UGSs) or unmanned aerial vehicles (UAVs) View full abstract»

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  • Attitude stabilization with actuators subject to switching restrictions: an approach via exact relay control methods

    Publication Year: 2006 , Page(s): 1485 - 1492
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1818 KB) |  | HTML iconHTML  

    On-off thrusters are frequently used as actuators for attitude control. Typically these thrusters are subject to switching constraints. A limit cycle is the normal steady state operation mode of such attitude control systems. This contribution deals with controller design for precision attitude stabilization using actuators whose switching restrictions are explicitly considered. An exact approach is presented using ideas from established relay control methods. The design procedure is illustrated with an attitude controller design to attain a limit cycle with prescribed characteristics View full abstract»

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Aims & Scope

IEEE Transactions on Aerospace and Electronic Systems focuses on the equipment, procedures, and techniques applicable to the organization, installation, and operation of functional systems designed to meet the high performance requirements of earth and space systems.

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Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory