SAR/毫米波雷达 论文阅读 | Freehand, Agile, and High-Resolution Imaging, IEEE Access 2019

原文链接：https://mp.weixin.qq.com/s/0MDkGUGWSAjnphkD9Rmj0w

论文阅读: G. Álvarez-Narciandi, M. López-Portugués, F. Las-Heras, and J. Laviada, “Freehand, Agile, and High-Resolution Imaging With Compact mm-Wave Radar,” IEEE Access, vol. 7, pp. 95516–95526, 2019, doi: 10.1109/ACCESS.2019.2929522.

Abstract

• Aim of this paper:

  • present a freehand scanning system with a compact mm-wave radar

• This freehand, scanning, compact mm-Wave system :

  • exploits the free movements of the radar to create a synthetic aperture $\Rightarrow$ High-resolution imaging
  • 但 允许不规则的轨迹 (Conventional SAR 需要 canonical acquisition surfaces (e.g., planes or cylinders) )
  • 包括 a commercial motion capture system and an mm-wave module $\Rightarrow$ 易于 deploy and calibrate

• Methods

  • study different techniques to compensate for the impact of irregular sampling $\Rightarrow$ reduce the artifacts in the image

    ✅ inexperienced users 也可以进行扫描

1 Introduction

动机

• mmWave imaging system can be very compact enabling on-chip systems
  • 因为 high frequency
  • robust and affordable
  • 但是 high resolution 需要 relatively bulky structures formed by large antennas based on reflectors or arrays $\Rightarrow$ 降低了compactness

本文工作

• 主要组成:
  • Motion capture system: Track the position of the radar
  • Radar imaging system (SAR): synthesis the aperture based on the tracking results
• 即：using inertial navigation systems for imaging applications
• 意义
  • the first time that a completely 3D freehand scanning with such a compact device

文章结构

• 1 the structure of the scanner and its workflow
• 2 the radar processing implemented in the demonstrator
• 3 error simulations, calibrations and results

2 Freehand mmWave Imaging

2.1 System Architecture

• Main goals of the system :

  • 1 High resolution imaging :

    ✅ Wavelength: ~mm

    ✅ accuracy of the position of the radar ：must be much smaller than the wavelength $\Rightarrow$ ~sub-mm

  • Freehand system:

    ✅ the scanner must build the images while it is freely moved

    ✅ 从而使得operator can dynamically choose the areas where to spend more time scanning to refine the image

  • 3 Real-time operation :

    ✅ the image must be updated as more data is acquired by the scanner

    

• 3个Subsystems

  • Control and processing subsystem : setting up the scanning system

    ✅ establishing the communication with the other two subsistems

    ✅ defining the volume under test

    ✅ querying both the radar frames and the position of the radar,

    ✅ processing the obtained information

    🚩 PC, Usb with radar, Ethernet with positioning system

  • Radar subsystem :

    ✅ radar-onchip BGT60TR24B by Infineon

    ✅ $f_c=60GHz$, $BW=6GHz$, chirp duration $T_s=512us$

    ✅ 2 transmitting and 4 receiving, 但配置成了1发1收

  • Positioning subsystem :

    ✅ estimates the position and the attitude of the radar module by means of an optical tracking system

    ✅ motion capture system of Optitrack

    ✅ 原理 ：The infrared cameras of the system track the reflective markers attached to the radar module $\Rightarrow$ 再进行修正以match the position of the radar imaging

    ✅ 至少4 cameras, 能在几分钟内easily deployed and calibrated

    

2.2 Imaging Technique

• the signal transmitted by the radar : s t x ( t ) = e j 2 π ( f c t + 1 2 α t 2 ) s_{t x}(t)=e^{j 2 \pi\left(f_c t+\frac{1}{2} \alpha t^2\right)} stx​(t)=ej2π(fc​t+