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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 123 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 496)
Advances in Aerospace Engineering     Open Access   (Followers: 70)
Advances in Aerospace Science and Technology     Open Access   (Followers: 8)
Advances in Astronautics Science and Technology     Hybrid Journal   (Followers: 1)
Advances in Space Research     Full-text available via subscription   (Followers: 458)
Aeronautical Journal, The     Hybrid Journal   (Followers: 13)
Aerospace     Open Access   (Followers: 60)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 19)
Aerospace Science and Technology     Hybrid Journal   (Followers: 430)
Aerospace Scientific Journal     Open Access   (Followers: 18)
Aerospace Systems     Hybrid Journal   (Followers: 6)
Aerospace technic and technology     Open Access   (Followers: 3)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal   (Followers: 4)
AIAA Journal     Hybrid Journal   (Followers: 1196)
Air Force Magazine     Full-text available via subscription   (Followers: 10)
Air Medical Journal     Hybrid Journal   (Followers: 8)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 264)
Annual of Navigation     Open Access   (Followers: 22)
Artificial Satellites     Open Access   (Followers: 23)
ASTRA Proceedings     Open Access   (Followers: 3)
Astrodynamics     Hybrid Journal   (Followers: 4)
Aviation     Open Access   (Followers: 17)
Aviation Advances & Maintenance     Open Access   (Followers: 5)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 10)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 27)
Aviation Week     Full-text available via subscription   (Followers: 438)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 34)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 30)
Chinese Journal of Aeronautics     Open Access   (Followers: 21)
Ciencia y Poder Aéreo     Open Access   (Followers: 2)
Civil Aviation High Technologies     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 315)
Cosmic Research     Hybrid Journal   (Followers: 5)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 24)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 12)
Fatigue of Aircraft Structures     Open Access   (Followers: 15)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Gravitational and Space Research     Open Access  
Gyroscopy and Navigation     Hybrid Journal   (Followers: 260)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 279)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 385)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 39)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 41)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 37)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 2)
International Journal of Aerospace Engineering     Open Access   (Followers: 82)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 23)
International Journal of Aerospace Sciences     Open Access   (Followers: 32)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
International Journal of Aviation Management     Hybrid Journal   (Followers: 9)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 7)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 5)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 11)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 11)
International Journal of Space Structures     Full-text available via subscription   (Followers: 17)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 10)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
International Journal of Turbo and Jet-Engines     Hybrid Journal   (Followers: 6)
Investigación Pecuaria     Open Access   (Followers: 3)
Journal of Aerodynamics     Open Access   (Followers: 18)
Journal of Aeronautical Materials     Open Access   (Followers: 9)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 31)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 69)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 18)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 22)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 34)
Journal of Aerospace Technology and Management     Open Access   (Followers: 7)
Journal of Aircraft     Hybrid Journal   (Followers: 337)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 9)
Journal of Airline and Airport Management     Open Access   (Followers: 12)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 11)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 1)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 205)
Journal of KONBiN     Open Access   (Followers: 3)
Journal of Navigation     Hybrid Journal   (Followers: 280)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 615)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 8)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 773)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 8)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 9)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 17)
Life Sciences in Space Research     Hybrid Journal   (Followers: 4)
MAD - Magazine of Aviation Development     Open Access   (Followers: 2)
Mekanika : Jurnal Teknik Mesin i     Open Access   (Followers: 1)
Microgravity Science and Technology     Hybrid Journal   (Followers: 2)
New Space     Hybrid Journal   (Followers: 6)
Nonlinear Dynamics     Hybrid Journal   (Followers: 20)
npj Microgravity     Open Access   (Followers: 3)
Open Aerospace Engineering Journal     Open Access   (Followers: 1)
Perspectives of Earth and Space Scientists i     Open Access  
Population Space and Place     Hybrid Journal   (Followers: 9)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 46)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 81)
Propulsion and Power Research     Open Access   (Followers: 68)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
RocketSTEM     Free   (Followers: 6)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 24)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Space and Polity     Hybrid Journal   (Followers: 4)
Space Policy     Hybrid Journal   (Followers: 29)
Space Research Today     Full-text available via subscription   (Followers: 48)
Space Safety Magazine     Free   (Followers: 51)
Space Science International     Open Access   (Followers: 202)
Space Science Reviews     Hybrid Journal   (Followers: 97)
SpaceNews     Free   (Followers: 825)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Technical Soaring     Full-text available via subscription   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 1)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 9)
Unmanned Systems     Hybrid Journal   (Followers: 5)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 2)

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Similar Journals
Journal Cover
IEEE Transactions on Aerospace and Electronic Systems
Journal Prestige (SJR): 0.611
Citation Impact (citeScore): 3
Number of Followers: 385  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0018-9251
Published by IEEE Homepage  [229 journals]
  • IEEE Aerospace and Electronic Systems Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Implementation of an Adaptive Wideband Digital Array Radar Processor Using
           Subbanding for Enhanced Jamming Cancellation
    • Authors: Xinzhu Chen;Ting Shu;Kai-Bor Yu;Yu Zhang;Zhiyong Lei;Jin He;Wenxian Yu;
      Pages: 762 - 775
      Abstract: Subbanding technique has been applied in wideband (WB) digital array radar systems to address the challenge of high-speed signal processing and WB jamming cancellation. This article reveals that the well-established subband decomposition by polyphase subband filtering could still leave jamming decorrelation post subbanding, which would deteriorate the jamming cancellation performance. A novel implementation of the subbanding processor is then proposed by isolating digital down conversion incorporated in the subbanding operation and performing it at baseband explicitly. This method provides flexibility to process segments of the digitized spectrum, which accommodates radar receivers to contemporary requirements of frequency agility. This article proceeds to propose a joint jamming cancellation scheme for use in the complicated real-world electronic warfare scenario including both mainlobe and sidelobe jamming. The jamming cancellation performance is evaluated by simulation with a detailed investigation on jamming decorrelation mitigation and subbanding implementation consideration. More results are shown by testing the cancellation scheme on data collected with an experimental airborne WB digital array radar in a multijamming scenario toward sea surface targets.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Employing Unmanned Aerial Vehicles for Improving Handoff Using Cooperative
           Game Theory
    • Authors: Shidrokh Goudarzi;Mohammad Hossein Anisi;Domenico Ciuonzo;Seyed Ahmad Soleymani;Antonio Pescapé;
      Pages: 776 - 794
      Abstract: Heterogeneous wireless networks that are used for seamless mobility are expected to face prominent problems in future fifth generation (5G) cellular networks. Due to their proper flexibility and adaptable preparation, remote-controlled unmanned aerial vehicles (UAVs) could assist heterogeneous wireless communication. However, the key challenges of current UAV-assisted communications consist in having appropriate accessibility over wireless networks via mobile devices with an acceptable Quality of Service grounded on the users’ preferences. To this end, we propose a novel method based on cooperative game theory to select the best UAV during handover process and optimize handover among UAVs by decreasing the i) end-to-end delay, ii) handover latency, and iii) signaling overheads. Moreover, the standard design of software-defined network with media-independent handover is used as forwarding switches in order to obtain seamless mobility. Numerical results derived from the real data are provided to illustrate the effectiveness of the proposed approach in terms of number of handovers, cost, and delay.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Affine Quadratic Optimal Control and Aerospace Applications
    • Authors: Luis Rodrigues;
      Pages: 795 - 805
      Abstract: This article proposes a class of mathematical models of aerospace control systems. The article has three main contributions. The first contribution is to present analytical solutions of optimal control problems with affine dynamics and quadratc cost with both cross terms and a tradeoff coefficient that weights time. A second contribution is to solve analytically a class of nonlinear optimal control problems with a single input and a conserved quantity. The analytical solution is obtained through a transformation of variables that leads to an equivalent affine quadratic problem. On a practical level, this article contributes by showing how the proposed class of problems can unify a class of applications in aeronautics and astronautics. The relevance of the proposed methodology is illustrated in examples of trajectory planning with linear drag and wind, as well as orbit intercept.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Finite-Time Cooperative Guidance Strategy for Impact Angle and Time
           Control
    • Authors: Shuai Zhang;Yang Guo;Zhiguo Liu;Shicheng Wang;Xiaoxiang Hu;
      Pages: 806 - 819
      Abstract: In this article, two cooperative guidance schemes with impact angle and time constraints are proposed for multiple missiles cooperatively intercepting a maneuvering target in the presence or absence of a leader missile. First, cooperative interception with impact angle constraint is formulated based on the relative motion equation between the interceptors. Subsequently, the design of the guidance law is divided into two stages. In the first stage, based on finite-time consensus theory and the super-twisting control algorithm, the cooperative guidance law in the direction of the line of sight (LOS) is derived to control the impact time so that all missiles can simultaneously intercept the target in finite time. Then, based on finite-time sliding mode control and the super-twisting control algorithm, a finite-time convergence cooperative guidance law in the normal direction to the LOS is developed to control the intercept angle and the LOS angle rate so that each missile can accurately hit the target at a desired angle. Finally, by controlling the consensus error of flight time in the presence of a leader missile, a finite-time cooperative guidance method in the “leader–follower” scenario is derived for simultaneous arrival at the target. The proposed methods can effectively suppress chattering and ensure fast convergence in finite time. Simulation experiments are conducted to verify the effectiveness of the proposed cooperative guidance schemes.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Destination-Directed Trajectory Modeling, Filtering, and Prediction Using
           Conditionally Markov Sequences
    • Authors: Reza Rezaie;X. Rong Li;
      Pages: 820 - 833
      Abstract: In some problems, there is information about the destination of a moving object. An example is a flight from an origin to a destination. Such problems have three main components: an origin, a destination, and motion in between. We call such trajectories ending up at the destination destination-directed trajectories (DDTs). Described by an evolution law and an initial probability density, a Markov sequence is not flexible enough to model DDT well. The future (including destination) of a Markov sequence is completely determined probabilistically by its initial density and evolution law. One class of conditionally Markov (CM) sequences, called the CM$_text{L}$ sequence (it includes the Markov sequence as a special case), has the following main components: a joint density of two endpoints and a Markov-like evolution law. This article proposes modeling DDT as CM$_text{L}$ sequences. We study the CM$_text{L}$ sequence, its dynamic model, and its realizations, all for DDT modeling. We demonstrate that CM$_text{L}$ sequences naturally model DDT, enjoy several desirable properties for DDT modeling, and can be easily and systematically generalized if necessary. In addition, we study DDT filtering and trajectory prediction based on a CM$_text{L}$ model and compare them with those based on a Markov model. Several simulation examples are presented to illustrate DDT modeling and inference.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Disturbance Observer-Based Finite-Time Control Design for a Quadrotor UAV
           With External Disturbance
    • Authors: Fang Wang;Hongmei Gao;Kun Wang;Chao Zhou;Qun Zong;Changchun Hua;
      Pages: 834 - 847
      Abstract: In this article, a finite-time control scheme is proposed for a quadrotor unmanned aerial vehicle (UAV) with external disturbance. First, a finite-time disturbance observer is designed to cope with external disturbance. Then, a nonsingular terminal sliding-mode control scheme is developed, which avoids singularity problem of conventional terminal sliding-mode control. By Lyapunov stability theory, it is proved that the controller guarantees the tracking errors converge to zero in a finite time. Finally, the effectiveness and superiority of the proposed control strategy is verified by compared simulation.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Bionic Visual Control for Probe-and-Drogue Autonomous Aerial Refueling
    • Authors: Haibin Duan;Yongbin Sun;Yuhui Shi;
      Pages: 848 - 865
      Abstract: The probe-and-drogue autonomous aerial refueling (AAR) docking suffers the multiwind disturbances leading to the low accuracy of receiver position control and drogue relative position estimation. This article proposes a bionic visual navigation control system in a hardware-in-loop simulation environment and further develops an AAR outfield experiment platform for promoting the success of probe-and-drogue AAR docking. The drogue region and markers are detected by the biological method imitating the eagle-eye color vision mechanism. The different visual navigation methods based on the ellipse fitting, marker matching, and marker prediction are, respectively, applied to the three possible situations in AAR docking for precise pose estimation. Moreover, a relative position control scheme of the receiver, which is constructed by back-stepping design technique and gain-adaptive equivalent sliding mode control, is proposed to compensate multi-wind disturbances and model uncertainties. Fuzzy logic position strategy is designed to compensate swing of the drogue caused by the multiwind disturbances. The AAR outfield experiment platform contains two unmanned aerial vehicles to verify a part of the proposed navigation control method. Extensive experimental results are presented to demonstrate the effectiveness of the bionic visual navigation control system for the high accuracy of the visual navigation and antidisturbance position control.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Extension-Deformation Approach to Extended Object Tracking
    • Authors: Xiaomeng Cao;Jian Lan;X. Rong Li;
      Pages: 866 - 881
      Abstract: This article presents a new approach, named extension-deformation approach (EDA), to extended object tracking (EOT). It models the extension of an object as being deformed from a simple reference extension by moving several control points. Then, a complex object extension can be characterized by these control points given the reference extension. This greatly simplifies the problem of shape description. Thus, modeling and estimation of the extension reduce to those of the control points, which are treated as state components of the extension. A noiseless measurement is a point on the deformed extension that corresponds to a source on the reference extension. Once the source is given, the corresponding measurement model is linear in the state, making state estimation simple and direct. However, the source is unknown and hard to estimate accurately. To handle this problem, a multiple-source approach to kinematic state and extension estimation is proposed. Overall the proposed approach is simple and it can effectively track an object with an extension that can be nonstar-convex. Simulation results are given to illustrate the effectiveness of the proposed approach.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Bearings-Only Filtering Using Uncorrelated Conversion Based Filters
    • Authors: Yingjie Zhang;Jian Lan;Mahendra Mallick;X. Rong Li;
      Pages: 882 - 896
      Abstract: Bearings-only filtering (BOF) is important in many practical applications. It is also a challenging nonlinear filtering problem due to limited information contained in highly nonlinear measurements. Researchers have proposed various nonlinear filters for BOF problems. We propose a new approach to nonlinear filtering using pseudomeasurement construction based uncorrelated conversion for BOF. This approach can more effectively utilize the measurement information than the original linear minimum mean square error estimator. The constructed pseudomeasurement is uncorrelated with the original measurement. Based on the recently proposed uncorrelated conversion based filter (UCF), we propose a UCF using pseudorange construction (UCF-PRC) for the BOF problem. An improved filter, the optimized UCF-PRC, is also proposed to minimize the mean square error. The effectiveness of the new filters is demonstrated by simulation results. Specifically, compared with the particle filter, the UCF-PRC has better estimation accuracy with nearly the same computational cost.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • A New Resonance Phenomenon Observed in UWB 14–50 GHz SAR and Its
           Application to the Retrieval of Thickness and Dielectric Properties of
           Scene Features
    • Authors: Keith Morrison;Daniel Andre;John Bennett;Mark Finnis;David Blacknell;Darren Muff;Matt Nottingham;Claire Stevenson;
      Pages: 897 - 906
      Abstract: We describe the observation of a previously unreported resonance phenomenon in UWB SAR imaging and its application in a novel scheme for the retrieval of thickness and dielectric properties of scene features. The resonance was observed in a 14–50 GHz laboratory study of very high resolution SAR imagery. It presented as a periodic fluctuation in the backscatter of a scene feature in response to changes in the radar measurement frequency. The complimentary static reflectivity measurements of a range of dielectric materials showed the phenomenon could be understood as a material behaving as a resonant microwave cavity. Modeling simulations were able to accurately reproduce the observed nulling characteristics for visually homogeneous materials (acrylic, MDF, and plasterboard) and which displayed a regular frequency spacing between nulls. Those with inhomogeneous structures (chipboard and plywood) showed much more irregular nulling patterns. The spacing of the backscatter nulls is set by the product of the permittivity and thickness of the material. By exploiting diversity in viewing geometry, the two terms can be separated and measured. The scheme offers a new opportunity in the SAR surveillance and monitoring of man-made structures.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Nonlinear Control of a Multilink Aerial System and ASEKF-Based
           Disturbances Compensation
    • Authors: Jose J. Castillo Zamora;Juan Escareno;Islam Boussaada;Joanny Stephant;Ouiddad Labbani-Igbida;
      Pages: 907 - 918
      Abstract: The actual article presents the modeling and control of a multilink unmanned aerial system whose dynamics is computed by means of the Euler–Lagrange approach. The aforementioned system is subjected to lumped disturbances, which comprise external disturbances and parametric uncertainties. An augmented-state extended Kalman filter intended to estimate endogenous and exogenous uncertainties is conceived and a trajectory-tracking controller fulfilling Lyapunov asymptotic stability is synthesized. A simulation stage is conducted to validate the effectiveness of the proposal.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Single-Antenna-Based GPS Antijamming Method Exploiting Polarization
           Diversity
    • Authors: Kwansik Park;Jiwon Seo;
      Pages: 919 - 934
      Abstract: The vulnerability of global positioning system (GPS) receivers to jammers is a major concern owing to the extremely weak received signal power of GPS. Researches have been conducted on a variety of antenna array techniques to be used as countermeasures to GPS jammers, and their antijamming performance is known to be greater than that of single antenna methods. However, the application of antenna arrays remains limited because of their size, cost, and computational complexity. This article proposes and experimentally validates a novel space-time-polarization-domain adaptive processing for a single-element dual-polarized antenna (STPAPS) by focusing on the polarization diversity of a dual-polarized antenna. The mathematical models of arbitrarily polarized signals received by the dual-polarized antenna are derived, and an appropriate constraint matrix for dual-polarized-antenna-based GPS antijam is suggested. To reduce the computational complexity of the constraint matrix approach, the eigenvector constraint design scheme is adopted. The performance of STPAPS is quantitively and qualitatively evaluated through experiments as follows. First, the carrier-to-noise-density ratio (C/N0) of STPAPS under synthetic jamming is demonstrated to be higher than that of the previous minimum mean-squared error (MMSE) or minimum variance distortionless response (MVDR) based dual-polarized-antenna methods. Second, the strengths and weaknesses of STPAPS are qualitatively compared with those of the previous single-element dual-polarized-antenna methods that are not based on the MMSE or MVDR algorithms. Finally, the characteristics of STPAPS (in terms of the directions and polarizations of the GPS and jamming signals) are compared with those of the conventional two-element single-polarized-antenna array method, which has the same degree of freedom as that of STPAPS. This is a GPS L1 C/A-code proof-of-concept study, althoug- STPAPS will extend to higher chipping-rate modernized global navigation satellite system signals.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Gradient-Based Optimization of PCFM Radar Waveforms
    • Authors: Charles A. Mohr;Patrick M. McCormick;Charles A. Topliff;Shannon D. Blunt;J. Michael Baden;
      Pages: 935 - 956
      Abstract: While a number of signal structures have been proposed for radar, frequency modulation (FM) remains the most common in practice because it is well-suited to high-power transmitters, which tend to introduce significant distortion to other waveform classes. That said, various forms of coding provide useful parameterizations for which a variety of optimization methods can be readily applied to accomplish different operational goals. To that end, the polyphase-coded FM (PCFM) implementation was previously devised as a means to bridge this gap between optimizable parameters and physically realizable waveforms. However, the original method employed to optimize PCFM waveforms involved a piecewise greedy search that, while relatively effective, was rather slow and cumbersome. Here, the continuous nature of this framework is leveraged to formulate a gradient-based optimization approach that updates all parameters simultaneously and can be efficiently performed using fast Fourier transforms, thus facilitating a general design methodology for practical waveforms that is directly extensible to myriad waveform-diverse arrangements. Results include a large number of optimization assessments to discern performance trends in aggregate and detailed analysis of specific cases, as well as both loopback and free-space experimental measurements to demonstrate practical efficacy.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Cooperative Active Aircraft Protection Guidance Using Line-of-Sight
           Approach
    • Authors: Shashi Ranjan Kumar;Dwaipayan Mukherjee;
      Pages: 957 - 967
      Abstract: This article proposes sliding-mode-control-based guidance strategies for a team comprised of aircraft and a defending interceptor against an attacker. The proposed guidance strategies are based on the line-of-sight guidance concept. Problems such as performance degradation under large heading angle errors, arising from linearization of engagement dynamics, are circumvented due to the nonlinear framework considered here. We show that knowledge of the bound on attacker acceleration suffices to ensure interception of an attacking interceptor. Cooperative strategies are derived for the aircraft–defender team, corresponding to cost functions based on the $ell _p$ norm, using static optimization at each time instant. Simulations validate the efficacy of the proposed strategies.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Monopulse-Radar Angle Estimation of Multiple Targets Using Multiple
           Observations
    • Authors: Maozhong Fu;Chunxian Gao;Yuhan Li;Zhenmiao Deng;Daqing Chen;
      Pages: 968 - 983
      Abstract: Amplitude comparison monopulse systems encounter the target resolution problem when multiple targets occupy the same range-azimuth cell. To solve this problem, a new angle estimation approach is proposed. The traditional range-cell-based signal processing is improved by modeling the signal in the frequency domain. Thus, the range straddling loss and the range migration problem can be avoided. The closely spaced targets in the same range-azimuth cell can be well resolved by the jointly maximum likelihood estimation of the range and velocity of the targets. Then, the angle estimates are extracted by using the monopulse ratio technique with the estimated parameters of the resolved targets in the two channels. Furthermore, the RELAX algorithm is utilized to reduce the computational burden of the proposed approach. The performance of the proposed estimator is evaluated using Monte Carlo simulation.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Approximating Posterior Cramér–Rao Bounds for Nonlinear Filtering
           Problems Using Gaussian Mixture Models
    • Authors: Shuo Zhang;Defeng Chen;Tuo Fu;Huawei Cao;
      Pages: 984 - 1001
      Abstract: The posterior Cramér–Rao bound (PCRB) is a fundamental tool to assess the accuracy limit of the Bayesian estimation problem. In this article, we propose a novel framework to compute the PCRB for the general nonlinear filtering problem with additive white Gaussian noise. It uses the Gaussian mixture model to represent and propagate the uncertainty contained in the state vector and uses the Gauss–Hermite quadrature rule to compute mathematical expectations of vector-valued nonlinear functions of the state variable. The detailed pseudocodes for both the small and large component covariance cases are also presented. Three numerical experiments are conducted. All of the results show that the proposed method has high accuracy and it is more efficient than the plain Monte Carlo integration approach in the small component covariance case.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • An Adaptive Priority Allocation for Formation UAVs in Complex Context
    • Authors: Lihua Zhu;Yu Wang;Zhiqiang Wu;
      Pages: 1002 - 1015
      Abstract: A novel passing priority allocation method, based on the collision avoidance urgency, used for a formation of UAVs in a serried obstacle laden environment, is presented in this article. The method employs the collision cone and the prediction of the collision time to evaluate the urgency of imminent collision of each UAV, so as to establish a primary criterion for the priority allocation. And, the priority update policy is also innovative designed to alleviate burdens on the instability of frequent shifty context. This article exploits the potential field in a cooperative way to plan the path for each UAV, steering the UAVs to a given 3-D position, which combines the adaptive priorities to guide the UAVs passing through the barriers in turn. Numerical simulations and semi-physical experiments in designed outdoor condition are carried out to compare the performance of the proposed adaptive priorities with the regular-used default priorities. The total passing time and the energy cost of the semi-physical tests provide the promising validation in terms of the efficiency and superiority of the proposed method.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • A Rapid Serial Timing Acquisition Algorithm for Hybrid DS/FFH Packet Radio
           Communication
    • Authors: Jae-Won Kim;Byungju Lim;Young-Chai Ko;
      Pages: 1016 - 1027
      Abstract: In this article, we propose a simple, reliable, and rapid serial timing acquisition algorithm for hybrid direct-sequence and fast frequency-hopping packet radio communication systems. The proposed algorithm is designed in both the frequency domain of frequency hopping and the pseudonoise code domain of direct sequence. We provide the performance analysis for our proposed algorithm and confirm its exactness by simulation. Compared with the conventional serial search algorithm, the proposed algorithm shows much faster acquisition time while obtaining similar performance.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Fast Generation of Chance-Constrained Flight Trajectory for Unmanned
           Vehicles
    • Authors: Runqi Chai;Antonios Tsourdos;Al Savvaris;Shuo Wang;Yuanqing Xia;Senchun Chai;
      Pages: 1028 - 1045
      Abstract: In this article, a fast chance-constrained trajectory generation strategy incorporating convex optimization and convex approximation of chance constraints is designed so as to solve the unmanned vehicle path planning problem. A path-length-optimal unmanned vehicle trajectory optimization model is constructed with the consideration of the pitch angle constraint, the curvature radius constraint, the probabilistic control actuation constraint, and the probabilistic collision avoidance constraint. Subsequently, convexification technique is introduced to convert the nonlinear problem formulation into a convex form. To deal with the probabilistic constraints in the optimization model, convex approximation techniques are introduced such that the probabilistic constraints are replaced by deterministic ones while simultaneously preserving the convexity of the optimization model. Numerical results, obtained from a number of case studies, validate the effectiveness and reliability of the proposed approach. A number of comparative studies were also performed. The results confirm that the proposed design is able to produce more optimal flight paths and achieve enhanced computational performance than other chance-constrained optimization approaches investigated in this article.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Spectral Radon–Fourier Transform for Automotive Radar Applications
    • Authors: Oren Longman;Igal Bilik;
      Pages: 1046 - 1056
      Abstract: Fast Fourier transform (FFT) is one of the fundamental signal processing algorithms widely used in radar applications. The Radon–Fourier transform (RFT) can be seen as an FFT generalization that can overcome some of its limitations. This work derives three spectral RFT (SRFT) based approaches to address major challenges of the multiple-input multiple-output automotive radars. First, two SRFT-based approaches are derived to increase maximal target detection range by mitigation of target migration in range and direction of arrival, jointly, and by multidwell integration processing, which increases the radar coherent integration time without compromising its detection update rate. Next, SRFT-based approach is proposed to address the cluster-to-track association problem that arises in multiple distributed target tracking scenarios that characterize automotive radar operation in dense urban environments.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Software-Defined Radio Based Station for Projectile Tracking and Telemetry
           Reception Enhancement
    • Authors: Clément Campo;Hervé Boeglen;Jean-Marie Paillot;Étienne Bieber;Sébastien Hengy;Loïc Bernard;
      Pages: 1057 - 1068
      Abstract: Past decades technological breakthroughs have made software-defined radio (SDR) a viable alternative to analog architectures for many applications. However, projectile tracking is traditionally performed using dedicated architectures, not taking advantage of SDR reconfigurability. This article aims at developing a projectile tracking ground station using low cost commercial SDR. The principles, technical constraints, and experimental setup are detailed, and measurement results are presented for projectiles fired at Mach 0.8.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Impact Angle Control Guidance of Glide-Capable Munition Using a Vector
           Field Approach
    • Authors: Suwon Lee;Youdan Kim;Chanho Song;
      Pages: 1069 - 1083
      Abstract: A vector field-based guidance law is proposed for the speed and impact angle control of an unpowered, glide-capable air-to-ground munition. An artificial 3-D space is designed for the glider vehicle to satisfy the terminal constraints. The glider vehicle is guided to the target position by the proposed vector field-based guidance law while satisfying the desired impact angle and final speed constraints. In the numerical simulations, various wind conditions are considered to demonstrate the performance of the proposed guidance law.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • DVB-T-Based Passive Forward Scatter Radar: Inherent Limitations and
           Enabling Solutions
    • Authors: Fabiola Colone;
      Pages: 1084 - 1104
      Abstract: This article investigates the target detection capability of a passive forward scatter radar (PFSR) exploiting a digital video broadcasting – terrestrial (DVB-T) transmitter as illuminator of opportunity. By means of theoretical and simulated analyses, it is shown that conventional processing schemes might suffer from significant performance degradation when exploiting orthogonal frequency division multiplexing (OFDM) waveforms of opportunity compared to other broadcast transmissions (e.g., frequency modulation radio broadcast). Specifically, the direct application of conventional processing approaches to the case of a DVB-T PFSR is demonstrated to yield: 1) a nonnegligible increase of the competing background level and 2) a steeper fading of the target response due to the intrinsic characteristics of the exploited waveforms of opportunity, above all the modulation scheme and the signal spectral characteristics. Therefore, appropriate signal processing techniques are proposed to avoid these effects which jeopardize the target detection capability. The conceived processing scheme exploits the digital nature of the employed waveforms and a subband approach for improving both the interference cancellation stage and the target signature extraction. The benefits of the proposed approach are illustrated by means of theoretical and simulated analyses. The application of the resulting processing scheme against experimental data proves its effectiveness in practical scenarios.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Reachable Domain of Ground Track With a Single Impulse
    • Authors: Haiyang Zhang;Gang Zhang;
      Pages: 1105 - 1122
      Abstract: The reachable domain of ground track under a single upper-bounded impulse for a given initial orbit is solved based on the Gauss's variational equations. Considering the linear $J_2$ perturbation, the reachable domain problem is transformed into solving the ranges of longitude difference between the maneuvering and reference orbits at all feasible latitudes. For the coplanar impulse, the longitude difference is a monotonically decreasing function only of the transfer-time difference, and then the extreme values of the transfer-time difference are obtained by the Newton–Raphson iterations. For the noncoplanar impulse, the reachable domain is related to both the orbital plane change and the transfer-time difference, and then the extreme values of the longitude difference are solved by the sequence quadratic programming algorithm. Finally, the envelopes of the reachable domain are obtained by comparing the extreme values and the boundary values of the longitude difference. Several numerical examples with coplanar and noncoplanar impulses are provided to verify the effectiveness of the proposed method for solving the envelopes of the reachable domain.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Fast Approximation of Optimal Perturbed Long-Duration Impulsive Transfers
           via Artificial Neural Networks
    • Authors: Yue-he Zhu;Ya-zhong Luo;
      Pages: 1123 - 1138
      Abstract: The design of multitarget rendezvous missions requires a method to quickly and accurately approximate the optimal transfer between any two rendezvous targets. In this article, an artificial neural-network-based method is proposed for the rapid approximation of optimal perturbed long-duration impulsive transfers. The relationship between the optimal transfer velocity increments and the initial right ascension of the ascending node difference between the departure body and the rendezvous target is analyzed, and the result suggests that the perturbed long-duration impulsive transfers should be divided into three types. An efficient database generation method is developed. Three regression multilayer perceptrons (MLPs) are trained individually and applied to approximate the corresponding types of transfers. The simulation results show that the well-trained MLPs are capable of quickly estimating the optimal velocity increments with a relative error of less than 3% for all three types of transfers. Additional tests of the debris chains with total velocity increments of several thousand m/s show that the estimation results are very close to the optimized results, with a final estimation error of less than 10 m/s.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Singular Value Decomposition of a Matrix Representation of the Costas
           Condition for Costas Array Selection
    • Authors: James K. Beard;
      Pages: 1139 - 1161
      Abstract: Costas arrays are permutation matrices that meet the additional Costas condition. The Costas condition requires that when a Costas array defines the frequencies in a frequency jump burst and a signal is processed with a matched filter, then for any time or Doppler offset other than both zero, only one pulse will be at peak response at a time. Specific formulations of the Costas conditions provide a vector-matrix arithmetic representation where the matrix has eigenvalues that are square roots of integers and eigenvectors that can be scaled to have elements that are all integers. Polynomials are given for squared eigenvalues and for elements of scaled right eigenvector elements. A database of these singular value decompositions is provided on IEEE DataPort for orders from 3 to 1030, with left eigenvectors to order 100. We include proofs of validity and configuration. The right eigenvectors and the eigenvalues map a Costas array vector into its eigenspace. Functions of these vectors can be associated with system performance metrics so that these mapped vectors may be used to select and rank Costas arrays and is suitable for real-time system implementation.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Privacy and Utility Aware Data Sharing for Space Situational Awareness
           From Ensemble and Unscented Kalman Filtering Perspective
    • Authors: Niladri Das;Raktim Bhattacharya;
      Pages: 1162 - 1176
      Abstract: This article presents an optimization-based formulation for privacy-utility tradeoff in the ensemble and unscented Kalman filtering framework, focusing on the space situational awareness. Privacy and utility are defined in terms of lower and upper bound on the state estimation error covariance. The synthetic sensor noise is used to satisfy these bounds and is determined by solving an optimization problem. Given privacy and utility bounds, this article present optimization problem formulations to determine the maximum noise for which the utility is satisfied or the estimation errors are upper bounded, the minimum noise for which the privacy is satisfied or the estimation errors are lower bounded, the optimal noise that satisfies utility constraints and maximizes privacy, and the optimal noise that satisfies privacy constraints and minimizes the uncertainty. We demonstrate the application of these formulations to the tracking of the International Space Station and highlight the optimal privacy versus utility tradeoff for this dynamical system.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Influence of Attitude Parameters on Image Quality of Very High-Resolution
           Satellite Telescopes
    • Authors: Walid A Wahballah;Fawzy Eltohamy;Taher M. Bazan;
      Pages: 1177 - 1183
      Abstract: The image quality of very high-resolution satellite telescopes (VHRSTs) is affected by several factors, including optics, detector, pointing accuracy errors, attitude stability errors, and altitude variations. The charge-coupled devices with a time delay and integration (TDI) feature play a significant role along with the satellite attitude parameters in characterizing the VHRST image quality. The imperfection of the satellite control system to maintain the required pointing accuracy and attitude stability can lead to severe degradation in the quality of the acquired imagery. Hence, it is required to investigate their impacts carefully during the satellite preliminary design phase. In this article, the combined effect of the TDI steps, satellite attitude parameters, and orbital altitude variations on the image quality are investigated in detail. The results show that the image quality in the along- and cross-track directions are affected seriously in certain situations by the roll and pitch angular velocity bias. Furthermore, the proposed mathematical model in this article reveals that total modulation transfer function (MTF), as an image quality metric, is affected severely by the satellite altitude variation, particularly when employing a high number of TDI steps. For example, for a given scenario, when employing TDI steps of 64, the mathematical results show that the effect of a satellite altitude variation of 10 km will result in a 65% reduction in total system MTF.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Designing Unimodular Waveform(s) for MIMO Radar by Deep Learning Method
    • Authors: Jinfeng Hu;Zhiyong Wei;Yuzhi Li;Huiyong Li;Jie Wu;
      Pages: 1184 - 1196
      Abstract: A fast and excellent unimodular waveform with good autocorrelation and cross-correlation design method for the multiple-input multiple-output radar is devised. Unlike the existing methods that only optimize partial metrics or only optimize the short sequence in acceptable time, we propose a comprehensive waveform design method to minimize the weighted sum of almost entirely metrics under the constant modulus constraint. Then, a deep learning framework, named as the comprehensive optimization network, is derived to handle the problem. Numerical results show that the proposed method has superior performance and acceptable optimization time compared with the existing methods.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Iterative Semidefinite Relaxation for Geolocation of Uncooperative Radars
           Using Doppler Frequency Measurements
    • Authors: Mustafa Atahan Nuhoglu;Yasar Kemal Alp;Aydin Bayri;Hakan Ali Cirpan;
      Pages: 1197 - 1210
      Abstract: In this article, we propose a novel method utilizing iterative semidefinite relaxation for geolocation of stationary uncooperative radars. In our scenario, the geolocation is to be performed in a receiver located on a moving platform. The proposed method uses frequency measurements that are Doppler-shifted due to the platform motion. First, constructed nonconvex maximum likelihood cost function for position estimation is relaxed to a convex optimization problem by applying linearization to range variables. Then, at each iteration of the method, carrier frequency and position of the radar are estimated jointly. Conducted experiments show that a few iterations are enough for convergence to accurate estimates. The proposed method is computationally less expensive compared to traditional techniques, which require extensive grid search procedures in either position or carrier frequency parameter space. In the experiments, the performance of the proposed method is compared to the state-of-the-art techniques and the Cramer–Rao lower bound (CRLB). It is observed that the proposed method attains the CRLB at low noise levels while still providing accurate solutions at high noise cases. Furthermore, it is also seen that platform-radar geometry has an impact on the proposed method's performance. If the radar lies in the convex hull of the receiver path, the proposed method performs significantly better due to improvement in the linearization of range values.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Sparse Array Beamforming Design for Wideband Signal Models
    • Authors: Syed A. Hamza;Moeness G. Amin;
      Pages: 1211 - 1226
      Abstract: We develop sparse array receive beamformer design methods achieving maximum signal-to-interference plus noise ratio for wideband sources and jammers. Both tapped delay line filtering and the DFT realizations to wideband array processing are considered. The array sparsity stems from the limited number of available radio frequency (RF) transmission chains that switch between the sensors, thereby configuring different arrays at different times. The sparse array configuration design problem is formulated as a quadratically constraint quadratic program and solved by using semidefinite relaxation. A computationally viable approach through successive convex relaxation is also pursued. In order to realize an implementable design, in presence of missing autocorrelation lags, we propose parameter-free block Toeplitz matrix completion to estimate the received data correlation matrix across the entire array aperture. It is shown that the optimum wideband sparse array effectively utilizes the array aperture and provides considerable performance improvement over suboptimal array topologies.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Practical Implementation of Adaptive Threshold Energy Detection using
           Software Defined Radio
    • Authors: Michael V. Lipski;Sastry Kompella;Ram M. Narayanan;
      Pages: 1227 - 1241
      Abstract: Spectrum awareness is a fundamental characteristic of cognitive radio, and spectrum sensing is the local procedure by which the cognitive radio gains knowledge of spectrum users. Energy detection is the most widely used and widely studied form of spectrum sensing. Much of the information about energy detector performance comes from theory and simulation rather than experimental data. We acknowledge a need for empirical data that can be used to evaluate a hardware energy detector and establish expectations on the differences in performance when comparing a hardware energy detector with simulations. In this article, we build and test a real-time, adaptive threshold energy detector using a USRP software-defined radio (SDR). While several groups have built energy detectors using SDRs, we found that there is still a lack of data on the parameters and performance characteristics of SDR-based energy detectors. Our work covers in detail the construction of the SDR energy detector and includes specific hardware and software parameters as well as several practical considerations. We discuss the procedure used to benchmark the energy detector and include experimental results that show how several implementation parameters affect the detector performance. Our work also explores the use of moving average windows to formulate the detection statistic and focuses on the importance of the length of the window as well as the shape of the window.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Minimum Variance Pole Placement in Uncertain Linear Control Systems
    • Authors: Habib Ghanbarpourasl;
      Pages: 1242 - 1251
      Abstract: The pole-placement issue for linear multi-input multi-output (MIMO) dynamic systems with uncertain parameters has been addressed in this article. A static feedback matrix has been designed for minimizing variances of closed-loop poles (CLPs) and for assigning poles to the nominal system at the desired places. It is assumed that the joint probability density function (PDF) of uncertain parameters is known and the system has more than one input. A new unknown vector is used like an eigenvector for a stochastic closed-loop system matrix to state the problem. The variances of poles are considered as cost functions, and the means of poles are termed constraints. This form of the problem statement has helped us to simply find a solution. In the first step, the optimization problem with constraints was handled by solving the equality constraint, and then, the problem was converted to a classic extended eigenvalue optimization problem. Later, the eigenvalue optimization problem was solved by the Rayleigh quotient and the feedback matrix was accomplished. Finally, this approach was simulated and validated using the MATLAB simulations, and the results were compared with a robust pole-placement method, which MATLAB control toolbox uses. The Monte Carlo simulations showed lower covariance for CLPs around the mean poles as compared to the robust pole-placement method.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Mismatched Filters for Incoherent Pulse Compression in Laser Radar
    • Authors: Michael J. Lindenfeld;
      Pages: 1252 - 1260
      Abstract: A pulsed laser system is considered for long-range target detection. Single-pulse power received from a target may be low compared to the noise and background clutter power. Due to long-range and short laser wavelength, multi-pulse coherent processing is not possible, so incoherent detection is employed. Incoherent pulse compression sums received power from numerous pulses to increase SNR while maintaining single pulse range resolution. Following Levanon, aperiodic burst waveforms of on–off Keying (OOK) modulated transmitted pulses are derived from binary codes with optimal auto-correlation minimum integrated sidelobe level and minimum peak sidelobe level codes. Pulse compression uses real, continuous mismatched filters of lengths equal to or greater than the OOK code length. Filter values minimize a weighted sum of ISL and filter output power, the latter to increase SNR gain relative to that of a single pulse. Weighting can be adjusted to lower ISL for multiple target discrimination or to increase SNR gain for dim targets. A simple evolutionary modulation of the initial OOK code exchanges pairs of dissimilar samples to keep the number of on samples from decreasing and improves ISL performance. A very fast filter calculation is employed that permits an exploration of a wide variation in parameters.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Fault-Tolerant Quantized Control for Flexible Air-Breathing Hypersonic
           Vehicles With Appointed-Time Tracking Performances
    • Authors: Xingling Shao;Yi Shi;Wendong Zhang;
      Pages: 1261 - 1273
      Abstract: This article contrives a fault-tolerant quantized control for flexible air-breathing hypersonic vehicles (FAHVs) with appointed-time tracking performances. At first, to online identify the lumped effect of actuator faults, flexible modes, parameter uncertainties as well as external disturbances, a hysteresis quantizer based neural estimator (HQNE) using finite precision state information is proposed, enabling a reduced communication load and computational time with a competitive estimation capability. Utilizing the estimation of HQNE, fault-tolerant quantized control laws equipped with auxiliary systems are established for FAHVs to realize a stable reference tracking result using discrete-time control signals, where auxiliary systems are employed to automatically monitor the impact of input saturation for command regulation. Furthermore, an appointed-time prescribed performance control based on a hyperbolic cosecant function is developed to make the tracking errors of velocity and altitude reach to the pregiven residual sets with a prescribed time in the absence of exact initial system states. The presented controller achieves a preassigned-time tracking performance for FAHVs under actuator faults and input saturation maintaining a decreased communication burden. The ultimately uniformly bounded stability of closed-loop system is proved through Lyapunov stability analysis, while numerical simulations are designed to verify the effectiveness of presented controller.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Adaptive Transmit Waveform Design Using Multitone Sinusoidal Frequency
           Modulation
    • Authors: David A. Hague;
      Pages: 1274 - 1287
      Abstract: This article presents an adaptive waveform design method using multitone sinusoidal frequency modulation (MTSFM). The MTSFM waveform's modulation function is represented as a finite Fourier series expansion. The Fourier coefficients are utilized as a discrete set of design parameters. These design parameters can be modified to shape the spectrum, auto-correlation function (ACF), and ambiguity function (AF) shapes of the waveform. The MTSFM waveform model naturally possesses the constant envelope and spectral compactness properties that make it well suited for transmission on practical radar/sonar transmitters which utilize high power amplifiers. The MTSFM has an exact mathematical definition for its time-series using generalized Bessel functions which allow for deriving closed-form analytical expressions for its spectrum, AF, and ACF. These expressions allow for establishing well-defined optimization problems that finely tune the MTSFM's properties. This adaptive waveform design model is demonstrated by optimizing MTSFM waveforms that initially possess a “thumbtack-like” AF shape. The resulting optimized designs possess substantially improved sidelobe levels over specified regions in the range-Doppler plane without increasing their time-bandwidth product. Simulations additionally demonstrate that the optimized thumbtacklike MTSFM waveforms are competitive with thumbtacklike phase-coded waveforms derived from design algorithms available in the published literature.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Adaptive Compensation for Actuation Sign Faults of Flexible Spacecraft
    • Authors: Yajie Ma;Hao Ren;Gang Tao;Bin Jiang;
      Pages: 1288 - 1300
      Abstract: This article develops a multiple-model-based adaptive control scheme to compensate for actuation sign faults of the flexible spacecraft using an error transformation. Multiple control signals are designed based on multiple estimators and an error transformation among estimation errors, tracking errors of estimators, and a virtual control error. A switching mechanism is established using a group of cost functions to choose the most proper control signal that can guarantee the desired system stability and asymptotic tracking performance.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Two-Stage Guidance Law With Constrained Impact via Circle Involute
    • Authors: Ziqi Wang;Qinglei Hu;Tuo Han;Ming Xin;
      Pages: 1301 - 1316
      Abstract: The mission of simultaneous attack and warhead lethality enhancement requires the constraints on impact time and angle in the guidance design. To this end, a two-stage guidance law considering constrained impact as well as the robustness against external disturbances and heading errors is proposed. The first stage is based on a circle involute geometrical rule that guarantees the desired velocity direction at the involute's end. With this goal achieved, the involute guidance is switched to the guidance of nullifying line-of-sight rate such that near-zero maneuver in the second stage is ensured. To achieve both impact time and angle constraints, a simple parameter determination approach is provided to find explicit solutions for the desired two-stage trajectory. Meanwhile, a robust two-stage guidance law is constructed to implement the geometrical rule, guarantee terminal constraints, and ensure robustness. The proposed technique is easy to implement, in that it does not involve model linearization, time-to-go estimation, and numerical optimization routine. Additionally, the achievable range of different constraints is analyzed considering practical issues such as initial launch angles, initial line-of-sight angles, and acceleration limits. Extensive simulations are carried out in various engagement scenarios under uncertainties and disturbances to validate the effectiveness and robustness of the proposed guidance law.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Adaptive Clutter Suppression in Randomized Stepped-Frequency Radar
    • Authors: Shuai Liu;Yunhe Cao;Tat-Soon Yeo;Wenhua Wu;Yutao Liu;
      Pages: 1317 - 1333
      Abstract: Randomized stepped-frequency (RSF) radar, which transmits random-frequency pulses in a coherent processing interval (CPI), has an excellent electronic counter-countermeasures (ECCM) performance and the ability to synthesize wide-frequency band with a narrow bandwidth receiver. However, due to the use of different frequency pulses, RSF waveform is incompatible with the conventional moving-target-detection (MTD) technique, which makes clutter suppression a difficult problem for RSF radar and limits its application. In this article, the effect of clutter on the coherent processing for RSF radar is first analyzed. The result shows that coherent processing can improve the signal-to-clutter ratio on target Doppler channel by $N$ (number of pulses in one CPI) times, which suppresses weak clutter scatterers to a large extent whilst strong clutter scatterers would still be left influential. Focusing on dominant clutter scatterers, the adaptive range-Doppler clutter suppression algorithm, which is based on designing clutter suppression filters with two-dimensional property to obtain the clear high-range-resolution profile of moving target in clutter environment, is then proposed for RSF radar. The proposed algorithm, which takes into account clutter Doppler extension, can be used for RSF radar coherent processing in clutter environment.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Fault Tolerant Model Reduction and Actuator/Sensor Placement for Flexible
           Spacecraft
    • Authors: Chencheng Zhang;Hao Yang;Bin Jiang;
      Pages: 1334 - 1344
      Abstract: This article addresses the issues of model reduction and actuator/sensor placement for flexible spacecraft with plant, actuator, and sensor faults. First, the sensitivity of controllability and observability with respect to faults is analyzed; Second, instead of a complete redesign of balanced truncation, a fault tolerant truncation method is proposed by estimating the bounds of Hankel singular value of faulty spacecraft and is fully based on the original balanced truncation structure; Third, a reconfiguration scheme of actuator/sensor placement is developed based on the reduced-order faulty flexible spacecraft.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Development and Experimentation of a CubeSat Magnetic Attitude Control
           System Testbed
    • Authors: Guglielmo Cervettini;Stefano Pastorelli;Hyeongjun Park;Dae Young Lee;Marcello Romano;
      Pages: 1345 - 1350
      Abstract: For CubeSats requiring high pointing accuracy and slewing agility, ground-based hardware-in-the-loop simulations are strongly demanded to test and validate spacecraft subsystems and guidance, navigation, and control algorithms. In this article, a magnetic attitude control system (MACS) testbed for a CubeSat is developed utilizing a spherical air bearing and a Helmholtz cage. The design, development, and verification procedure of MACS is presented together with different test scenarios. To generate enough torque with the magnetorquer system in the dynamic testbed, the Helmholtz coil system of the testbed has driven to provide an augmented magnetic field. As an example of experimentation, the B-dot control algorithm was implemented to dissipate the angular momentum of the dynamic MACS testbed. The experimental results were compared with those of the numerical simulations.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Extraction of Global and Local Micro-Doppler Signature Features From FMCW
           Radar Returns for UAV Detection
    • Authors: Beom-Seok Oh;Zhiping Lin;
      Pages: 1351 - 1360
      Abstract: In this article, an unmanned aerial vehicles detection system is proposed for an X-band ground-based surveillance frequency modulated continuous wave Doppler radar. Two novel features are directly extracted from the Doppler processing results without a time-frequency analysis. Experimental results on measured radar echo signals show that our system consistently outperforms the state of the art in terms of detection accuracy and computational efficiency.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Quadratic Optimization of Initial State for Dynamic Controller in Linear
           Systems
    • Authors: Namhoon Cho;Youdan Kim;
      Pages: 1361 - 1370
      Abstract: This study presents an optimization-based controller state initialization method for improving the initial transient response. Uncertainties in the uncontrolled periods around transition events or a large change in the reference may result in unexpected growth of initial tracking error. The proposed method mainly aims to regulate out the initial error at the instance of feedback control initiation with a small amount of control effort and a short settling time. The proposed method minimizes a cost function given by a weighted sum of infinite-horizon square integrals, provided that the other controller parameters are fixed a priori to yield closed-loop stability. The performance-oriented initial controller state optimization is desirable for efficient and rapid initial error convergence in systems such as missiles where agility is of major concern. This study suggests performance-related optimization as an alternative for controller state setting besides zero filling or solving for bump-less transfer in switching systems. The concept and the effectiveness of the proposed method is demonstrated by numerical simulation considering the three-loop missile acceleration autopilot as an example application.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • Area Resolution for Bistatic Ultrawideband Ultrawidebeam SAR
    • Authors: Viet T. Vu;
      Pages: 1371 - 1377
      Abstract: Conventional SAR resolution equations cannot be applied to ultrawideband ultrawidebeam systems, particularly, bistatic ultrawideband ultrawidebeam systems. This is because the dependence of system frequency response in the range and across range is not considered. In this case, area resolution, i.e., area of the resolution cell, will be an alternative. This article introduces a new area resolution formula for bistatic ultrawideband ultrawidebeam SAR systems based on the relationship between radar signal frequency, range, and cross-range wavenumbers for bistatic synthetic aperture radar.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
  • A New Method to Bound the Integrity Risk for Residual-Based ARAIM
    • Authors: Peng Zhao;Mathieu Joerger;Xiao Liang;Boris Pervan;Yongming Liu;
      Pages: 1378 - 1385
      Abstract: This article develops a tight integrity risk bound for residual-based (RB) advanced receiver autonomous integrity monitoring (ARAIM). ARAIM measurement models include nominal biases accounting for unknown but bounded errors, and faults of unbounded magnitude. In RB methods, upper bounding the integrity risk requires that one finds the worst-case directions of both the multisatellite fault vector and of the all-in-view nominal bias vector. Previous methods only account for the worst-case fault direction assuming zero nominal bias. To address this issue, in this article, we derive a new bounding method in parity space. The method establishes a direct relationship between mean estimation error and RB test statistic noncentrality parameter, which accounts for both faults and nominal errors. ARAIM performance is evaluated to quantify the improvement provided by the proposed method over previous approaches.
      PubDate: April 2021
      Issue No: Vol. 57, No. 2 (2021)
       
 
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