Freehand, Agile, and High-Resolution Imaging With Compact mm-Wave Radar

Álvarez-Narciandi, Guillermo; López-Portugués, Miguel; Las-Heras, Fernando; Laviada, Jaime

doi:10.1109/access.2019.2929522

Cited by 43 publications

(49 citation statements)

References 29 publications

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“…It is interesting to observe that radar data could be merged to create a synthetic aperture radar from arbitrary positions [ 25 , 26 ]. This kind of processing is very powerful as it enables very high resolution images such as the one used for people screening [ 27 ].…”

Section: Methodsmentioning

confidence: 99%

A Portable Electromagnetic System Based on mm-Wave Radars and GNSS-RTK Solutions for 3D Scanning of Large Material Piles

Álvarez

Álvarez-Narciandi

García-Fernández

et al. 2021

Sensors

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In this paper, a portable three-dimensional (3D) scanning system for the accurate characterization of large raw material (e.g., cereal grain, coal, etc.) stockpiles is presented. The system comprises an array of high resolution millimeter-wave radars and a cm-level accuracy positioning system to accurately characterize large stockpiles by means of a high-resolution 3D map, making it suitable for automation purposes. A control unit manages the data received by the sensors, which are sent to a computer system for processing. As a proof of concept, the entire sensor system is evaluated in a real environment for electromagnetically scan a scaled stockpile of coal, used in the industry for handling raw materials. In addition, a highly efficient processing adaptive algorithm that may reconstruct the scanned structure in real-time has been introduced, enabling continuous dynamic updating of the information. Results are compared with those from a photogrammetry-like technique, revealing an excellent agreement.

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Section: Methodsmentioning

confidence: 99%

A Portable Electromagnetic System Based on mm-Wave Radars and GNSS-RTK Solutions for 3D Scanning of Large Material Piles

Álvarez

Álvarez-Narciandi

García-Fernández

et al. 2021

Sensors

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“…Therefore, the frequency band selection should be performed, considering the tradeoff between imaging resolution and penetration capabilities and the specific requirements of the practical applications of interest. Despite these powerful approaches for uniform data, last advances in electromagnetic imaging have shown that the use of portable scanners, driven by hand, can be useful for a large number of applications, including electromagnetic compatibility [15], people screening [16], or nondestructive evaluation [17]. However, these systems do not provide equally-spaced acquisition points.…”

Section: Green's Function-based Sar Imaging Methods Of Uniform Measurementioning

confidence: 99%

“…The position of the non-uniform measurement points can be recorded by means of affordable systems, such as depth-cameras [16] or motion capture systems [15,17]. Thus, the above problem becomes how to design the multi-layered C-SAR imaging algorithm once the non-uniform measurement points are known.…”

Section: Introductionmentioning

confidence: 99%

Multi-Layered Circular Dielectric Structures’ Synthetic Aperture Radar Imaging Based on Green’s Function Using Non-Uniform Measurements

Álvarez-Narciandi

Laviada

2020

Remote Sensing

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The electromagnetic imaging of multi-layered circular structures can be accomplished by means of different approaches. Among these approaches, the use of synthetic aperture radar (SAR) techniques with the compensation of the Green’s function for multi-layered circular cylinders provides a trade-off between accuracy and computational complexity. Nevertheless, this approach relies on measurement points acquired uniformly. Thus, this prevents the adoption of more flexible sampling schemes, limiting the use of inaccurate positioners or manual scanners. To overcome this limitation, this paper proposes a method to handle non-uniform cylindrically acquired data, enabling multi-layered circular imaging based on non-uniformly acquired measurements. For this purpose, the presented method starts by projecting the non-uniformly measured points onto different circles with equally-spaced points. After that, the Green’s function-based circular-SAR imaging method is applied to each projection circle. Lastly, the final SAR image is obtained by the superposition of the images from the previous step. Numerical simulations and experimental results demonstrated the effectiveness and robustness of the proposed method for practical nondestructive testing (NDT) applications.

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“…This requires integrating a high accuracy real-time positioning system on board the UAV because: (i) the UAV needs accurate positioning to follow the predefined flight path; and (ii) the radar measurements are coherently combined using a Synthetic Aperture Radar (SAR) algorithm, which imposes a geo-referring accuracy several times lower than the smallest working wavelength. Furthermore, the positions of the radar measurements are carefully processed to discard data that could cause unfocusing or resolution degradation in the SAR image (for instance, due to oversampling in some areas [18], since it is very difficult to perform a uniformly sampled acquisition with the UAV). Regarding the processing of the radar data, some improvement steps are also proposed to enhance the resolution and the target discrimination.…”

Section: Introductionmentioning

confidence: 99%

Autonomous Airborne 3D SAR Imaging System for Subsurface Sensing: UWB-GPR on Board a UAV for Landmine and IED Detection

2019

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This work presents an enhanced autonomous airborne Synthetic Aperture Radar (SAR) imaging system able to provide full 3D radar images from the subsurface. The proposed prototype and methodology allow the safe detection of both metallic and non-metallic buried targets even in difficult-to-access scenarios without interacting with the ground. Thus, they are particularly suitable for detecting dangerous targets, such as landmines and Improvised Explosive Devices (IEDs). The prototype is mainly composed by an Ultra-Wide-Band (UWB) radar module working from Ultra-High-Frequency (UHF) band and a high accuracy dual-band Real Time Kinematic (RTK) positioning system mounted on board an Unmanned Aerial Vehicle (UAV). The UAV autonomously flies over the region of interest, gathering radar measurements. These measurements are accurately geo-referred so as to enable their coherent combination to obtain a well-focused SAR image. Improvements in the processing chain are also presented in order to deal with some issues associated to UAV-based measurements (such as non-uniform acquisition grids) as well as to enhance the resolution and the signal to clutter ratio of the image. Both the prototype and the methodology were validated with measurements, showing their capability to provide high-resolution 3D SAR images.

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Freehand, Agile, and High-Resolution Imaging With Compact mm-Wave Radar

Cited by 43 publications

References 29 publications

A Portable Electromagnetic System Based on mm-Wave Radars and GNSS-RTK Solutions for 3D Scanning of Large Material Piles

A Portable Electromagnetic System Based on mm-Wave Radars and GNSS-RTK Solutions for 3D Scanning of Large Material Piles

Multi-Layered Circular Dielectric Structures’ Synthetic Aperture Radar Imaging Based on Green’s Function Using Non-Uniform Measurements

Autonomous Airborne 3D SAR Imaging System for Subsurface Sensing: UWB-GPR on Board a UAV for Landmine and IED Detection

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