# US 12,111,414 B2 · Method for object classification using polarimetric radar data and device suitable therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,111,414 B2 - Document ID: US12111414B2 - Status: Granted - Kind: B2 - Application number: 16/487,570 - Filed: 2018-02-23 - Published: 2020-01-23 - Granted: 2024-10-08 - Earliest claimed: 2017-02-24 - Assignees: Cruise Munich GmbH - Applicants: ASTYX GmbH - Inventors: Stefan Trummer - Web page: https://patentgrep.com/patent/US12111414B2 ## CPC - G01S 7/026: {involving the transmission of elliptically or circularly polarised waves} - G01S 7/411: {Identification of targets based on measurements of radar reflectivity (G01S7/415 takes precedence)} - G01S 13/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S13/46) - G01S 13/931: of land vehicles - G01S 2013/462: {using multipath signals} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract The invention relates to a method for object classification which comprises the following steps for providing an ellipti-cally or circularly polarized transmission signal which is transmitted to the object to be classified: generating a first radar image from the copolarly polarized reflection signal and generating a second radar image from the cross-polarized reflection signal and comparing the first radar image with the second radar image. ## Claims ### Claim 1 A method for object classification of an object to be classified, the method comprising: providing an elliptically or circularly polarized transmission signal, which is transmitted onto the object to be classified from a transmitter; evaluating a first minima of a cross-polar component of a first reception signal when the object is at a first distance from the transmitter, wherein the cross-polar component is cross-polar in relation to the transmission signal; evaluating a second minima of a cross-polar component of a second reception signal when the object is at a second distance from the transmitter, wherein the cross-polar component is cross-polar in relation to the transmission signal; and determining the height of the object based on the first minima and the second minima. ### Claim 2 (depends on 1) The method as claimed in claim 1, further comprising: generating a first radar image from a co-polarly polarized reflection signal; generating a second radar image from a cross-polarly polarized reflection signal; and determining an object classification of the object to be classified based on at least one of the first radar image and the second radar image. ### Claim 3 (depends on 2) The method as claimed in claim 2, wherein the generation of the first and second radar images is carried out from at least one of left-circular signal components or right-circular signal components. ### Claim 4 (depends on 2) The method as claimed in claim 2, wherein the generation of the first and second radar images is carried out from linearly horizontal and linearly vertical signal components. ### Claim 5 (depends on 2) The method as claimed in claim 2, wherein steps of determining the object classification, evaluating the first minima, and evaluating the second minima are carried out using at least one signal property selected from a plurality of signal properties of a target region of the object. ### Claim 6 (depends on 5) The method as claimed in claim 5, wherein the plurality of signal properties comprise: a number of co-polar local maxima, a number of cross-polar local maxima, an average magnitude ratio between co-polarization and cross-polarization, a maximum magnitude ratio between co-polarization and cross-polarization, a minimum magnitude ratio between co-polarization and cross-polarization, a phase ratio between co-polarization and cross-polarization, a position of local maxima with a high or low magnitude ratio between co-polarization and cross-polarization, or a speed evaluation. ### Claim 7 (depends on 2) The method as claimed in claim 2, wherein further object subclasses are provided, which are divided, at least in a case of a radar sensor transmitting the transmission signal, into a distance of the object from the radar sensor, an angle of a direction of the object with respect to the radar sensor, an orientation of the object with respect to the radar sensor, and a relative speed of the object with respect to the radar sensor. ### Claim 8 (depends on 2) The method as claimed in claim 2, wherein the object classification relates to detecting a position and an orientation of an automobile. ### Claim 9 (depends on 2) The method as claimed in claim 2, further comprising: determining a front objection; and in response to the determination of the front objection, evaluating at least one of a front region of an automobile, a front wheel well region of an automobile, a steering-wheel region of an automobile, or a side mirror region of an automobile. ### Claim 10 (depends on 1) The method as claimed in claim 1, further comprising: transmitting with a time offset, by at least one transmission antenna, one of a left-circularly polarized wave and then a right-circularly polarized wave, or a left-rotating elliptical wave and then a right-rotating elliptical wave; and evaluating only the left-rotating or the right-rotating component of a reflection signal. ### Claim 11 (depends on 1) The method as claimed in claim 1, further comprising: simultaneously transmitting, using a plurality of transmitters, identically polarized waves that are phase-encoded, wherein a transmission sequence is obtained that consists of simultaneous use of right-rotatingly polarized transmission signals and, with a time offset before or after, of simultaneous use of left-rotatingly polarized transmission signals. ### Claim 12 A device for establishing an object classification of an object to be classified, the device comprising: means for providing an elliptically or circularly polarized transmission signal, which is transmitted onto the object to be classified; means for evaluating a first minima of a cross-polar component of a first reception signal when the object is at a first distance from the means for providing the elliptically or circularly polarized transmission signal, wherein the cross-polar component is cross-polar in relation to the transmission signal; means for evaluating a second minima of a cross-polar component of a second reception signal when the object is at a second distance from the means for providing the elliptically or circularly polarized transmission signal, wherein the cross-polar component is cross-polar in relation to the transmission signal; and means for determining the height of the object based on the first minima and the second minima. ### Claim 13 (depends on 12) The device as claimed in claim 12, further comprising: means for generating a first radar image from a copolarly polarized reflection signal and for generating a second radar image from a cross-polarized reflection signal; and means for determining an object classification of the object to be classified based on at least one of the first radar image and the second radar image. ### Claim 14 (depends on 13) The device as claimed in claim 13, wherein means are provided for generating the first and second radar images from at least one of left-circular signal components or right-circular signal components. ### Claim 15 (depends on 13) The device as claimed in claim 13, wherein means are provided for generating the first and second radar images from linearly horizontal and linearly vertical signal components. ### Claim 16 (depends on 13) The device as claimed in claim 13, wherein the generation of the first and second radar images is carried out simultaneously, by means of the transmission signal. ### Claim 17 (depends on 13) The device as claimed in claim 13, wherein the means for determining an object classification, the means for evaluating the first minima, and the means for evaluating the second minima use at least one signal property selected from a plurality of signal properties of a target region of the object. ### Claim 18 (depends on 13) The device as claimed in claim 13, wherein, with a time offset, a left-circularly polarized wave and then a right-circularly polarized wave, or, with a time offset, a left-rotating elliptical wave and then a right-rotating elliptical wave, are transmitted by at least one transmission antenna, and only the left-rotating or the right-rotating signal component of a reflection signal is evaluated. ### Claim 19 (depends on 13) The device as claimed in claim 13, wherein identically polarized waves are transmitted simultaneously and phase-encoded using a plurality of transmitters, so that a transmission sequence is obtained which consists of simultaneous use of right-rotatingly polarized transmission signals and, with a time offset before or after, of simultaneous use of left-rotatingly polarized transmission signals. ### Claim 20 (depends on 13) The device as claimed in claim 13, wherein, in addition to the object classification, a friction coefficient of a road surface is determined by using a determined area of the road surface for analysis, and local maxima thereof are evaluated at least in respect of one of a cluster formation, scattering, an extent of a cluster formation, a mean value of phase difference positions of a cluster formation, a mean value of amplitude magnitude ratios of a cluster formation, a standard deviation of phase difference positions of a cluster formation, a standard deviation of amplitude magnitude ratios of a cluster formation, a number of local maxima, or a signal amplitude of local maxima.