Detection of radar objects using a radar sensor of a motor vehicle

Patent metadata

Field	Value
Publication number	US-9547078-B2
Application number	US-201313937841-A
Country	US
Kind code	B2
Filing date	Jul 9, 2013
Priority date	Jul 23, 2012
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

In a method for detecting radar objects with the aid of a radar sensor of a motor vehicle, a transmitted signal has a sequence of frequency modulations, to each of which a partial signal of a measuring signal is assigned; first information about the relative velocity and the distance of a radar object is ascertained based on a frequency spectrum of at least one of the partial signals; second information about the relative velocity and the distance of the radar object is ascertained based on a frequency spectrum of a time curve of values of frequency spectra of the partial signals at a frequency position of the radar object in these frequency spectra; and the relative velocity and the distance of the radar object are ascertained based on matching of the first information with the second information.

First claim

What is claimed is:

1. A method for detecting a radar object with the aid of a frequency modulated continuous wave (FMCW) radar sensor of a motor vehicle, comprising:
generating, via an analysis unit, a measuring signal by mixing a transmitted signal with a received signal, as received by the analysis unit, the transmitted signal having a sequence of frequency modulations, wherein a partial signal of the measuring signal is assigned to each one of the frequency modulations;
ascertaining, via the analysis unit, first information about a relative velocity and a distance of a radar object, based on a frequency spectrum of at least one of the partial signals, the first information including a relationship between the relative velocity and the distance of the radar object, which relationship assigns different relative velocities to different distances;
ascertaining, via the analysis unit, second information about the relative velocity and the distance of the radar object, based on a frequency spectrum of a time curve of values of frequency spectra of the partial signals at a frequency position of the radar object in the frequency spectra of the partial signals; and
ascertaining, via the analysis unit, the relative velocity and the distance of the radar object, based on matching of the first information with the second information;
wherein in one measuring cycle the transmitted signal has a first sequence of frequency modulations and at least one second sequence of frequency modulations, a partial signal of the measuring signal being assigned to each of the frequency modulations of the two sequences,
wherein a relationship between the relative velocity and the distance, which results for the radar object as the first information, differs for two sequences of frequency ramps, and wherein the second information about the relative velocity of the radar object, which are ascertained from the first sequence and the second sequence of the frequency ramps, have different ambiguity ranges, and wherein the frequency modulations are in a fast ramp and a slow ramp,
wherein the sequence of frequency modulations of the transmitted signal is a sequence of frequency modulations in the form of linear frequency ramps having a ramp center frequency which changes linearly as a function of time,
wherein (i) the change with respect to time of the ramp center frequency within the sequence and (ii) the individual frequency ramps of the sequence have opposite signs, and
wherein if at least two sequences of frequency modulations are used in one measuring cycle, unambiguous ranges for the relative velocity of the second information are selected so that within one analysis range of relative velocity, no correspondences occur between integral multiples of the particular unambiguous ranges.

2. The method as recited in claim 1 , wherein the matching of the first information with the second information is carried out under consideration of an ambiguity of the second information, and wherein the ambiguity of the second information is defined by unambiguous ranges for the relative velocity and the distance.

3. The method as recited in claim 1 , further comprising:
ascertaining further first information about the relative velocity and the distance of the radar object, based on a frequency spectrum of at least one further one of the partial signals, the further first information including a relationship between a relative velocity and a distance of the radar object, which relationship assigns different relative velocities to different distances, and the at least one partial signal and the at least one further partial signal being assigned to different frequency modulations of the transmitted signal;
wherein the ascertainment of the relative velocity and the distance of the radar object is based on matching of the first information with the second information and with the further first information.

4. The method as recited in claim 3 , wherein:
the different frequency modulations are linear frequency ramps; and
the different frequency modulations differ with respect to at least one of a frequency deviation, a ramp duration, and a center frequency of each respective frequency ramp.

5. The method as recited in claim 4 , wherein:
further second information about the relative velocity and the distance of the radar object is ascertained based on a frequency spectrum of a time curve of values of frequency spectra of the partial signals, which are assigned to the at least one second sequence of frequency modulations, at a frequency position of the radar object in the frequency spectra of the partial signals; and
the ascertainment of the relative velocity and the distance of the radar object is based on matching of the first information with the second information and with the further second information.

6. The method as recited in claim 5 , wherein the further second information has associated unambiguous ranges for the relative velocity and the distance, which ranges differ from the unambiguous ranges for the relative velocity and the distance of the second information, and the matching of the first information with the second information and the further second information is carried out under consideration of ambiguity of the second information which is defined by the unambiguous ranges for the relative velocity and the distance of the second information.

7. The method as recited in claim 6 , wherein:
the second information is information about the relative velocity of the radar object; and
the unambiguous range for the relative velocity of the second information is selected in such a way that intrinsic velocity of the motor vehicle does not correspond to an integral multiple of the unambiguous range for the relative velocity of the second information.

8. The method as recited in claim 5 , wherein:
the frequency modulations of the first sequence differ from the frequency modulations of the second sequence;
the at least one partial signal and the at least one further partial signal being assigned to frequency modulations of the transmitted signal from different sequences; and
matching of the first information is carried out with the second information and with the further first information and the further second information.

9. The method as recited in claim 2 , wherein in a selected sequence of frequency modulations of the transmitted signal, the frequency modulations each have the same center frequency, and the second information is information about the relative velocity of the radar object.

10. A frequency modulated continuous wave (FMCW) radar sensor system for a motor vehicle, comprising:
a transmitted-signal generation device generating a transmitted signal which has a sequence of frequency modulations;
an analysis unit analyzing received radar signals, wherein the analysis unit is configured to perform the following:
ascertain first information about a relative velocity and a distance of a radar object, based on a frequency spectrum of at least one of the partial signals, the first information including a relationship between the relative velocity and the distance of the radar object, which relationship assigns different relative velocities to different distances;
ascertain second information about the relative velocity and the distance of the radar object, based on a frequency spectrum of a time curve of values of frequency spectra of the partial signals at a frequency position of the radar object in the frequency spectra of the partial signals; and
ascertain the relative velocity and the distance of the radar object, based on matching of the first information with the second information;

wherein in one measuring cycle the transmit

Assignees

• Bosch Gmbh Robert

Inventors

• Kuehnle Goetz
• Schoor Michael

Classifications

• G01S13/584 Primary

  adapted for simultaneous range and velocity measurements · CPC title

• G01S2007/356

  Physics · mapped topic

• G01S13/931

  of land vehicles · CPC title

• G01S7/356

  involving particularities of FFT processing · CPC title

• G01S13/343

  using sawtooth modulation · CPC title