METHOD FOR DETERMINING DIRECTION INFORMATION

Abstract

A method for determining direction information for at least one target object in a radar system for a vehicle. The first detection information is provided by at least two receive antennas of the radar system, wherein the first detection information is specific for a first radar signal transmitted by a first transmit antenna of the radar system. The second detection information is provided by the at least two receive antennas of the radar system, wherein the second detection information is specific for a second radar signal transmitted by a second transmit antenna of the radar system. A first angle determination and a second angle determination are performed. At least one comparison of the first angle information with the second angle information is performed in order to detect an ambiguity in the first angle determination for the determination of the direction information.

Claims

1. A method for determining direction information for at least one target object in a radar system for a vehicle, the method comprising: providing the first detection information by at least two receive antennas of the radar system, the first detection information being specific for a first radar signal transmitted by a first transmit antenna of the radar system; providing second detection information by the at least two receive antennas of the radar system, the second detection information being specific for a second radar signal transmitted by a second transmit antenna of the radar system; performing a first angle determination from the first and second detection information to determine a first angle information therefrom, so that the first angle information is specific for the first and second radar signal; performing a second angle determination from the first or second detection information to determine a second angle information therefrom, so that the second angle information is specific for one of the radar signals; and performing at least one comparison of the first angle information with the second angle information to detect an ambiguity in the first angle determination for the determination of the direction information.

2. The method according to claim 1, wherein the following step is performed before carrying out the first and second angle determinations: performing a processing of the detection information to determine a range and a relative velocity to the target object.

3. The method according to claim 2, wherein a compensation value is determined for the first angle determination from the determined relative velocity.

4. The method according to claim 3, wherein the ambiguity is in the form of an ambiguity in the determined relative velocity and leads to a phase error in the compensation value.

5. The method according to claim 4, wherein a correction value for the phase error is provided, and further comprising: performing a third angle determination from the first and second detection information to determine a third angle information therefrom, wherein in contrast to the first angle determination (111), the correction value is used.

6. The method according to claim 5, wherein, when performing the at least one comparison, the third angle information is additionally compared with the second angle information in order to determine a first deviation of the first and second angle information and a second deviation of the second and third angle information by the comparisons in order to determine the direction information as a function of the deviations.

7. The method according to claim 6, wherein the direction information is determined from the first angle information, if the first deviation is smaller than the second deviation and is otherwise determined from the third angle information.

8. The method according to claim 1, wherein the transmission of the first radar signal over the first transmit antenna and the transmission of the second radar signal over the second transmit antenna are carried out alternately in time.

9. The method according to claim 1, wherein the transmission of the first radar signal over the first transmit antenna and the transmission of the second radar signal over the second transmit antenna are carried out offset in time.

10. The method according to claim 1, wherein the first detection information is determined from the receive signals of the receive antennas such that the first detection information is specific for the first radar signal transmitted by the first transmit antenna of the radar system, reflected on the target object, and delayed by a first transit time, wherein the first detection information has a first phase difference as a function of a direction of the target object and as a function of a distance of the receive antennas to one another, and wherein the second detection information is determined from the receive signals of the receive antennas such that the second detection information is specific for the second radar signal transmitted by the second transmit antenna of the radar system reflected on the target object and delayed by a second transit time, wherein the second detection information has a second phase difference as a function of the direction of the target object and the distance between the receive antennas, and wherein the first detection information has a third phase difference to the second detection information as a function of the direction of the target object and a distance of the transmit antennas to one another, and wherein the first and second phase difference has a phase deviation with respect to one another due to a relative velocity of the target object, which deviation for determining the third phase difference is compensated by measuring the relative velocity in order to carry out the first angle determination using the third phase difference.

11. The method according to claim 10, wherein the compensation of the phase deviation takes place by a compensation value which is ambiguously defined by the measured relative velocity.

12. The method according to claim 1, wherein the at least two receive antennas are designed as at least four receive antennas.

13. The method according to claim 1, wherein the first, and in particular third, angle determination is carried out using a MIMO method and the second angle determination is carried out using a SIMO method.

14. A radar system for a vehicle comprising an electronic processing device to perform the steps of the method according to claim 1.

15. A computer program comprising commands which, when executed by a processing device of a radar system executes the steps of the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0034] FIG. 1 is a schematic diagram of parts of a radar system of the invention;

[0035] FIG. 2 is a schematic diagram of parts of a radar system of the invention;

[0036] FIG. 3 is a schematic visualization of a method of the invention,

[0037] FIG. 4 is a schematic diagram of the method steps; and

[0038] FIG. 5 is a diagram of a transmission scheme of the method of the invention.

DETAILED DESCRIPTION

[0039] In FIG. 1 a radar system 2 for a vehicle 1 is shown which has a processing device 4 in order to perform the steps of a method of the invention. Radar system 2 can comprise at least one radar sensor 3, which in turn has at least two transmit antennas 21, 22 and at least two receive antennas 31, 32 (see FIG. 2). Further, radar system 2 can serve to perform a determination of direction information for at least one target object 5 by means of the method of the invention. Target object 5 is located outside vehicle 1 and has a direction d, a range r, and a velocity v relative to it. The determination of these parameters r, v, and d is shown in FIG. 2 with further details. According to a first method step, in this regard, first detection information 201 can be provided by the at least two receive antennas 31, 32 of radar system 2, wherein first detection information 201 is specific for a first radar signal 221 transmitted by a first transmit antenna 21 of radar system 2, reflected on target object 5, and delayed by a transit time. According to a second method step, in addition, second detection information 202 can be provided by the at least two receive antennas 31, 32 of radar system 2, wherein second detection information 202 is specific for a second radar signal 222 transmitted by a second transmit antenna 22 of radar system 2, reflected on target object 5, and delayed by a transit time. Detection information 201, 202 can be determined in this case as digital information from the signals received by receive antennas 31, 32 by processing device 4.

[0040] According to FIG. 3, the aforementioned parameters r, v, and d can be determined by the subsequent processing 105 of detection information 201, 202. A first angle determination 111 can then be performed from the first and second detection information 201, 202 in order to determine first angle information 231 therefrom, so that first angle information 231 is specific for first and second radar signal 221, 222 (and thereby for both transmit antennas 21, 22). Subsequently, a second angle determination 112 can be performed from the first or second detection information 201, 202 in order to determine a second angle information 232 therefrom, so that second angle information 232 is specific (only) for one of the radar signals 221, 222 or (only) for one of the transmit antennas 21, 22. A third angle determination 113 can then also be carried out from the first and second detection information 201, 202 in order to determine third angle information 233, so that third angle information 233 is specific for first and second radar signal 221, 222 (and thereby for both transmit antennas 21, 22). First and third angle determination 111, 113 can thus be performed in the same way. At least one comparison 110 of first angle information 231 with second angle information 232 can then be performed in order to detect an ambiguity in first angle determination 111 for the determination of the direction information.

[0041] This procedure is visualized in FIG. 4 with further details. A compensation value p for the first and third angle determination 111, 113 can thus be determined from the determined parameter v, therefore, the determined relative velocity v. Because the ambiguity can be in the form of an ambiguity of the determined relative velocity v, this can further lead to a phase error in the compensation value p. A correction value for the phase error can therefore be provided and taken into account in step 114. Third angle determination 113 can then take place from the first and second detection information 201, 202 in order to determine third angle information 233 therefrom, wherein the correction value is used in contrast to first angle determination 111. The background here is that there are two possible correction values (0 and π), wherein only one of the correction values can be the correct one. Different correction values of these correction values are thus used in the first and third angle determination 111, 113. Then, when performing the at least one comparison 110, third angle information 233 can be compared additionally with second angle information 232 in order to determine a first deviation 241 of the first and second angle information 231, 232 and a second deviation 242 of the second and third angle information 232, 233 based on the comparisons 110. In this way, the direction information can be determined as a function of deviations 241, 242. According to decision step 115, the direction information can be determined from first angle information 231, if first deviation 241 is smaller than second deviation 242, and it is otherwise determined from third angle information 233.

[0042] In FIG. 5, the transmission of radar signals 221, 222 over the time t and with the schematic representation of the frequency f is shown by way of example. It can be seen that the particular transmitted radar signal 221, 222 can have rapid ramps (chirps) of the duration T.sub.C and bandwidth B. In this regard, during a measurement period T.sub.M N ramps can be output per transmit antenna 21, 22.

[0043] Reference characters 221 and 222 above the ramps each indicate the assignment of the ramps to the radar signals 221, 222. The ramps with a solid line are thus assigned to first radar signal 221 and the ramps with a dashed line are assigned to second radar signal 222. Radar signals 221, 222 are thus transmitted over the various transmit antennas 21, 22 within the measurement time T.sub.M offset in time and alternating.

[0044] The respective detection information 201, 202 can be assembled after measurement time T.sub.M from the received signals of receive antennas 31, 32. Further, processing 105 of detection information 201, 202 can take place after measurement time T.sub.M. According to the MIMO transmission scheme, M Tx transmit antennas can be operated in time-division multiplex, and K Rx receive antennas are sampled on the receive side. Detection information 201, 202 can be formed from the sampled signal received at receive antennas 31, 32.

[0045] The above explanation of the embodiments describes the present invention solely in the context of examples. Of course, individual features of the embodiments can be freely combined with one another, if technically feasible, without departing from the scope of the present invention.

[0046] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.