SAR imaging in an automotive scenario

Abstract

In this paper a 77 GHz patch array radar is used in combination with the line processing and range Doppler algorithms to produce synthetic aperture radar (SAR) images of automotive scenarios. Measurements are made using a linear rail unit and the images are briefly discussed. In the latter part of the paper, a position error investigation is carried out, where the measurements are customised to fit a real automotive scenario where the automobile experiences acceleration errors which are not detected by the acceleration sensors fixed in the car. The images with errors are then presented and a quantitative analysis is carried out.

Automotive Radar — From First Efforts to Future Systems

“…The advantage of SAR images over grid maps is the resulting resolution, which can be improved from a couple of 10 cm to centimeters or even millimeters [111], [112]. Due to the small wavelength, this high-resolution image requires high-precision localization methods, which generally cannot be achieved by the use of GNSS solely [113]. Radar networkbased ego motion estimation is one approach for localization allowing for coherent SAR images, being processed on the basis of various position estimates for short measurement sequences over a few seconds, see Fig.…”

Implementation of a SAR Demonstrator for Automotive Imaging

“…IMPLEMENTATION The 77 GHz radar sensor used to carry out these measurements [6] was fixed on a trolley such that the radar boresight direction is perpendicular to the trajectory of the trolley. The height of the sensor above ground was 40 cm, which represents the height of a typical automotive radar located in the bumper of a car.…”

“…Rather, for every radar measurement, only the relative position with respect to the previous measurement is very accurately known. Coupled with the fact that all measurements with the SAR demonstrator are unique and cannot be reproduced exactly, since the demonstrator is moved by a human (as opposed to a precise motor [6]) and it is not possible to reproduce the exact same movements (velocities, accelerations and their durations), leads to the fact that the accuracy of the processed SAR image has to be gauged by the relative distances between points in the target scenery.…”

“…It was previously demonstrated that the SAR algorithms, although sensitive to motion errors, can be made robust against inaccuracies of inertial measurement units (IMUs) or acceleration sensors which are typically used in cars, for example by reducing the length of the 'synthetic aperture' [6]. Building upon that, the goal of the research for this work was to present a low cost realistic SAR implementation using minimal hardware as a proof of concept.…”

Imaging radar for automated driving functions

“…The most promising radar technique for achieving fine resolution images of parked cars and other immobile objects is synthetic aperture radar (SAR). There have been numerous implementations of automotive SAR which have been published in recent times [5][6][7][8][9][10][11][12]. Initially, it was necessary to adapt the SAR algorithms for automotive scenarios and also to examine the effects of motion on SAR [5,7].…”