The Experts below are selected from a list of 129567 Experts worldwide ranked by ideXlab platform
Moeness G. Amin - One of the best experts on this subject based on the ideXlab platform.
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Target localization in moving radar platform exploiting range and Doppler information through semidefinite relaxation
Proceedings of SPIE, 2010Co-Authors: Yimin Zhang, Moeness G. AminAbstract:Moving radar platforms form Synthetic Apertures for effective target localization. One of the important target localization techniques is to multilaterate the position of a target based on the own positions of the radar and the range estimates obtained at each radar position. In practical applications, the radar positions as well as the range estimates are subject to error due to maneuvering, timing error, as well as measurement noise. Previous works have shown that, by incorporating the semidefinite relaxation techniques which permit the use of convex optimization approaches to solve a large class of nonconvex estimation problems, improved target location estimates can be achieved over those obtained from conventional techniques, such as least square methods. In some radar applications, on the other hand, it may be advantageous to incorporate the Doppler measurements. Doppler frequency information is often complementary to range measurements in target localization and is particularly helpful when range information alone does not provide satisfactory target localization performance. In this paper, we consider the problem of target localization based on both range and Doppler estimates obtained at multiple radar locations, where such information as well as the radar locations are subject to certain random errors. Semidefinite relaxation is applied to formulate convex solutions for this problem. Simulation results are provided to demonstrate performance improvement by utilizing both range and Doppler estimates.
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ICASSP - Robust target localization in moving radar platform through semidefinite relaxation
2009 IEEE International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Yimin Zhang, Kehu Yang, Moeness G. AminAbstract:Accurate target localization is an important task in various commercial and military applications. One way to achieve this goal is to use the time-of-arrival (TOA) or time-delay-of-arrival (TDOA) information observed at multiple distributed sensors. On the other hand, there is a great need to use moving sensors to form a radar platform with Synthetic Apertures. In this paper, we consider the problem of target localization based on the range information estimated from two-way time-of-flight (TW-TOF) at multiple Synthetic array locations, where the position of these Synthetic array locations is subject to certain random errors. The nonconvex estimation problem is approximated by a convex optimization problem using the semidefinite relaxation (SDR) approach. Simulation results show that the proposed estimator provides mean square position error performance close to the Cramer-Rao lower bound.
Yimin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Target localization in moving radar platform exploiting range and Doppler information through semidefinite relaxation
Proceedings of SPIE, 2010Co-Authors: Yimin Zhang, Moeness G. AminAbstract:Moving radar platforms form Synthetic Apertures for effective target localization. One of the important target localization techniques is to multilaterate the position of a target based on the own positions of the radar and the range estimates obtained at each radar position. In practical applications, the radar positions as well as the range estimates are subject to error due to maneuvering, timing error, as well as measurement noise. Previous works have shown that, by incorporating the semidefinite relaxation techniques which permit the use of convex optimization approaches to solve a large class of nonconvex estimation problems, improved target location estimates can be achieved over those obtained from conventional techniques, such as least square methods. In some radar applications, on the other hand, it may be advantageous to incorporate the Doppler measurements. Doppler frequency information is often complementary to range measurements in target localization and is particularly helpful when range information alone does not provide satisfactory target localization performance. In this paper, we consider the problem of target localization based on both range and Doppler estimates obtained at multiple radar locations, where such information as well as the radar locations are subject to certain random errors. Semidefinite relaxation is applied to formulate convex solutions for this problem. Simulation results are provided to demonstrate performance improvement by utilizing both range and Doppler estimates.
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ICASSP - Robust target localization in moving radar platform through semidefinite relaxation
2009 IEEE International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Yimin Zhang, Kehu Yang, Moeness G. AminAbstract:Accurate target localization is an important task in various commercial and military applications. One way to achieve this goal is to use the time-of-arrival (TOA) or time-delay-of-arrival (TDOA) information observed at multiple distributed sensors. On the other hand, there is a great need to use moving sensors to form a radar platform with Synthetic Apertures. In this paper, we consider the problem of target localization based on the range information estimated from two-way time-of-flight (TW-TOF) at multiple Synthetic array locations, where the position of these Synthetic array locations is subject to certain random errors. The nonconvex estimation problem is approximated by a convex optimization problem using the semidefinite relaxation (SDR) approach. Simulation results show that the proposed estimator provides mean square position error performance close to the Cramer-Rao lower bound.
Stig Asle Vaksvik Synnes - One of the best experts on this subject based on the ideXlab platform.
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challenges in seafloor imaging and mapping with Synthetic aperture sonar
IEEE Transactions on Geoscience and Remote Sensing, 2011Co-Authors: Roy Edgar Hansen, H J Callow, Torstein Olsmo Sabo, Stig Asle Vaksvik SynnesAbstract:Synthetic aperture sonar (SAS) is emerging as an imaging technology that can provide centimeter resolution over hundreds-of-meter range on the seafloor. Although the principle of SAS has been known for more than 30 years, SAS systems have only recently become commercially available. The success of SAS is critically dependent on overcoming several challenges related to the ocean environment. The sonar has to be positioned with accuracy better than a fraction of a wavelength along the Synthetic aperture. We use the sensor itself for navigation, in combination with aided inertial navigation. The sound velocity has to be accurately estimated for successful focusing of SAS images. We calculate a simple rule of thumb for tolerance and show the effect of incorrect sound velocity. For nonstraight Synthetic Apertures, the bathymetry must be estimated. We use real aperture interferometry to map the scene before SAS processing. We calculate the required bathymetry accuracy and show the effects of insufficient mapping. Vehicle instability and nonstraight tracks, in combination with insufficient navigation accuracy, can cause grating lobes in the SAS images, which is not common in single-channel Synthetic aperture radars. We show example imagery with severe grating lobes. In shallow waters, the acoustic signals will interact with the sea surface, possibly causing multipath. This will reduce the SAS quality. We use coherence to map the signal to multipath and, thereby, the valid sensor range. This paper illustrates the different challenges using examples from the HISAS 1030 interferometric SAS.
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challenges in seafloor imaging and mapping with Synthetic aperture sonar
Synthetic Aperture Radar (EUSAR) 2010 8th European Conference on, 2010Co-Authors: Roy Edgar Hansen, H J Callow, Torstein O Saeboe, Stig Asle Vaksvik SynnesAbstract:The success of Synthetic aperture sonar (SAS) is critically dependent on overcoming several challenges. The sonar has to be positioned with accuracy better than a fraction of a wavelength along the Synthetic aperture. The ocean environment, and particularly the sound velocity, has to be accurately estimated for successful focusing of SAS images. For nonstraight Synthetic Apertures, the bathymetry of the scene to be imaged must be known. Kongsberg Maritime and FFI have developed the HISAS 1030 wideband widebeam interferometric SAS. This paper describes the system and show example results from data collected by a HUGIN 1000-MR autonomous underwater vehicle.
Martin Vossiek - One of the best experts on this subject based on the ideXlab platform.
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uhf rfid localization based on Synthetic Apertures
IEEE Transactions on Automation Science and Engineering, 2013Co-Authors: Robert Miesen, Fabian Kirsch, Martin VossiekAbstract:Reading ranges are being extended in the wake of recent advances in UHF radio frequency identification (RFID) systems, and with the advent of larger reading ranges, tag localization has moved into the spotlight. Recently, we introduced a new UHF RFID tag localization technique. The proposed method is based on phase measurements taken along a Synthetic aperture. A holographic image is calculated based on the scanned phase values. The image represents the spatial probability density function for the actual tag location. This paper presents this innovative method in detail. Simulations that illustrate the effect of the given trajectory are included. Extensive measurements obtained in a reflective lab environment are presented. We discuss the method's effectiveness with respect to measurement errors, antenna phase center distortions, and the available phase information. The results show the potential practical applications for the method in moving reader antennas, such as handheld readers or readers mounted on vehicles like forklifts or mobile robotic systems.
Andreas Stelzer - One of the best experts on this subject based on the ideXlab platform.
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localization of passive uhf rfid tags based on inverse Synthetic Apertures
International Conference on RFID, 2014Co-Authors: Martin Scherhaufl, Markus Pichler, Andreas StelzerAbstract:This paper introduces a 2D localization system for passive UHF RFID tags based on phase evaluation of the backscattered transponder signals. To increase the accuracy and robustness of the position estimates an inverse Synthetic aperture radar approach is performed. A MIMO system where paths take turns to act as transmitter with the remaining paths serving as receivers, is used to enable the position estimation. For proof of concept, a local position measurement system demonstrator comprising an RFID reader, passive EPC Gen 2 RFID tags, several transceivers, baseband hardware, and signal processing was built. Measurements were carried out in an indoor office environment, which was surrounded by drywalls and concrete floor and ceiling, and the experimental results show a robust and accurate localization with a root-mean-square deviation below 0.1 and a median error of 0.01m.
