DE102017122578A1 - Method for suppression of false detections, radar system and driver assistance system - Google Patents

Abstract

A method for suppressing false detections (36b) in the determination of object information of an object that is detected by a radar system, in particular of a vehicle, is described. An Ur-detection threshold (42) is realized as a primal window function (44), which has a maximum (46). From the result of a multi-dimensional discrete Fourier transformation of a received signal of the radar system, a signal is determined as a target signal whose amplitude is above a predetermined limit for target signals. The original window function (44) is normalized with respect to the amplitude of the target signal to a normalized window function (54). The window function (54) is shifted in a Doppler-Gate distance-gate dimension of the result of the Fourier transform so that its maximum lies on the target signal. An adjusted detection threshold from the normalized and shifted, matched window function is compared with the original detection threshold (42) of the original window function (44), which has been shifted with its maximum (46) to the maximum of the target signal. If the adjusted detection threshold is above the shifted original detection threshold (42), the adjusted detection threshold for the result of the Fourier transformation is used with respect to the signals having the same Doppler value and / or the same distance value as the target signal. Otherwise, the Ur detection threshold (42) is used.

Description

Technical area

• - bei dem wenigstens ein Teil eines Ergebnisses einer mehrdimensionalen diskreten Fourier-Transformation von wenigstens einem Empfangssignal des Radarsystems mit wenigstens einer anpassbaren Detektionsschwelle verglichen wird und
• - diejenigen Signale aus dem Ergebnis der Fourier-Transformation als Falschdetektionen gekennzeichnet oder verworfen werden, deren Amplituden unterhalb der wenigstens einen Detektionsschwelle liegen.

The invention relates to a method for suppressing false detections in the determination of object information of at least one object which is detected by a radar system, in particular of a vehicle,

• in which at least part of a result of a multi-dimensional discrete Fourier transformation of at least one received signal of the radar system is compared with at least one adaptable detection threshold, and
• - Those signals from the result of the Fourier transform are identified as false detections or discarded, whose amplitudes are below the at least one detection threshold.

• - mit wenigstens einem Sender zum Senden von Sendesignalen in einen Überwachungsbereich,
• - mit wenigstens einem Empfänger zum Empfangen von an dem wenigstens einen Objekt reflektierten Echos der Sendesignale als Empfangssignale und
• - mit wenigstens einer Steuer- und/oder Auswerteeinrichtung, wobei die wenigstens eine Steuer- und/oder Auswerteeinrichtung Mittel aufweist
• - zur Durchführung wenigstens einer mehrdimensionalen diskreten Fourier-Transformation der Empfangssignale,
• - zum Vergleichen wenigstens eines Teils des Ergebnisses der Fourier-Transformation mit einer anpassbar Detektionsschwelle und
• - zum Kennzeichnen oder Verwerfen derjenigen Signale aus dem Ergebnis der Fourier-Transformation als Falschdetektionen, deren Amplituden unterhalb der Detektionsschwelle liegen.

Furthermore, the invention relates to a radar system, in particular of a vehicle, for determining at least one object information of at least one object,

• with at least one transmitter for transmitting transmission signals in a monitoring area,
• - With at least one receiver for receiving reflected at the at least one object echoes of the transmission signals as received signals and
• - With at least one control and / or evaluation, wherein the at least one control and / or evaluation means comprises means
• for carrying out at least one multi-dimensional discrete Fourier transformation of the received signals,
• for comparing at least part of the result of the Fourier transformation with an adaptable detection threshold and
• - To identify or discard those signals from the result of the Fourier transform as false detections whose amplitudes are below the detection threshold.

• - wenigstens eine elektronische Steuereinrichtung zur Steuerung von Funktionseinrichtungen des Fahrzeugs abhängig von Objektinformationen, welche durch wenigstens ein Radarsystem bereitgestellt werden, und
• - wenigstens ein Radarsystem zur Ermittlung von wenigstens einer Objektinformation wenigstens eines Objekts, wobei das wenigstens eine Radarsystem aufweist
• - wenigstens einen Sender zum Senden von Sendesignalen in einen Überwachungsbereich,
• - wenigstens einen Empfänger zum Empfangen von an dem wenigstens einen Objekt reflektierten Echos der Sendesignale als Empfangssignale und
• - wenigstens eine Steuer- und/oder Auswerteeinrichtung, wobei die wenigstens eine Steuer- und/oder Auswerteeinrichtung Mittel aufweist
• - zur Durchführung wenigstens einer mehrdimensionalen diskreten Fourier-Transformation der Empfangssignale,
• - zum Vergleichen wenigstens eines Teils des Ergebnisses der Fourier-Transformation mit einer anpassbaren Detektionsschwelle und
• - zum Kennzeichnen oder Verwerfen derjenigen Signale aus dem Ergebnis der Fourier-Transformation als Falschdetektionen, deren Amplituden unterhalb der Detektionsschwelle liegen.

Moreover, the invention relates to a driver assistance system of a vehicle, comprising

• at least one electronic control device for controlling functional devices of the vehicle depending on object information provided by at least one radar system, and
• - At least one radar system for determining at least one object information of at least one object, wherein the at least one radar system comprises
• at least one transmitter for transmitting transmission signals in a surveillance area,
• at least one receiver for receiving echoes of the transmission signals reflected at the at least one object as received signals and
• at least one control and / or evaluation device, wherein the at least one control and / or evaluation device has means
• for carrying out at least one multi-dimensional discrete Fourier transformation of the received signals,
• for comparing at least part of the result of the Fourier transformation with an adaptable detection threshold and
• - To identify or discard those signals from the result of the Fourier transform as false detections whose amplitudes are below the detection threshold.

State of the art

From the DE 10 2012 024 999 A1 A method is known for setting a detection threshold with which a received signal of a frequency modulation continuous wave radar sensor of a motor vehicle is compared with respect to the detection of a target object in the surroundings of the motor vehicle. In each measurement cycle, the detection threshold is set individually for a subset of at least one frequency bin of a received signal.

The invention has for its object to design a method, a radar system and a driver assistance system of the type mentioned in which false detections, especially due to side lobes of the radar transmission signals or reflections in the vicinity, can be better suppressed.

Disclosure of the invention

• - wenigstens eine Ur-Detektionsschwelle als Ur-Fensterfunktion realisiert wird, welche ein Maximum aufweist,
• - aus dem Ergebnis der Fourier-Transformation direkt oder indirekt wenigstens ein Signal als Zielsignal ermittelt wird, dessen Amplitude über einem vorgegebenen Grenzwert für Zielsignale liegt,
• - die Ur-Fensterfunktion bezüglich der Amplitude des wenigstens einen Zielsignals zu einer normierten Fensterfunktion normiert wird,
• - die Fensterfunktion vor oder nach dem Normieren in einer Dopplertor-Entfernungstor-Dimension des Ergebnisses der Fourier-Transformation so verschoben wird, dass ihr Maximum auf dem wenigstens einen Zielsignal liegt,
• - eine angepasste Detektionsschwelle aus der normierten und verschobenen, angepassten Fensterfunktion mit der Ur-Detektionsschwelle der Ur-Fensterfunktion, welche mit ihrem Maximum zum Maximum des wenigstens einen Zielsignals verschoben wurde, und gegebenenfalls mit einer vorherigen angepassten Detektionsschwelle einer vorherigen angepassten Fensterfunktion, welche bei einem vorherigen Durchlauf des Verfahrens ermittelt wurde, verglichen wird,
• - und falls die angepasste Detektionsschwelle über der verschobenen Ur-Detektionsschwelle und gegebenenfalls über der vorherigen angepassten Detektionsschwelle liegt, die angepasste Detektionsschwelle für das Ergebnis der Fourier-Transformation in Bezug auf die Signale mit dem gleichen Dopplerwert und/oder dem gleichen Entfernungswert wie das wenigstens eine Zielsignal verwendet wird,
• - anderenfalls die Ur-Detektionsschwelle oder gegebenenfalls die vorherige angepasste Detektionsschwelle verwendet wird.

This object is achieved in the method in that

• at least one primary detection threshold is realized as a primary window function, which has a maximum,
• directly or indirectly from the result of the Fourier transformation at least one signal is determined as a target signal whose amplitude is above a predetermined limit value for target signals,
• - the original window function is normalized with respect to the amplitude of the at least one target signal to a normalized window function,
• the window function is shifted before or after normalization in a Doppler-gate distance-gate dimension of the result of the Fourier transformation such that its maximum lies on the at least one target signal,
• an adapted detection threshold from the normalized and shifted, adapted window function with the original detection threshold of the original window function, which has been shifted with its maximum to the maximum of the at least one target signal, and possibly with a previously adapted detection threshold of a previous matched window function, which at a previous run of the procedure was compared,
• and if the adjusted detection threshold is above the shifted original detection threshold and possibly above the previous adjusted detection threshold, the adjusted detection threshold for the result of the Fourier transformation with respect to the signals having the same Doppler value and / or the same distance value as the at least one Target signal is used
• otherwise the original detection threshold or, if appropriate, the previously adapted detection threshold is used.

According to the invention, based on at least one target signal, a primal window function is adapted such that further signals having the same distance value or the same Doppler value as the at least one target signal lie below the adjusted detection threshold and are identified or suppressed as a false signal. A target signal is detected by its amplitude being above a predetermined limit. The limit value is selected to be high enough that only amplitudes of signals which are most likely to originate from a real object lie above it.

The further signals which have the same distance value or the same Doppler value as the at least one target signal may be so-called side lobes of the echo signal. These can be caused in particular by strong reflections. Such sidelobes are referred to as so-called "high peaks". According to the invention, when strong reflections occur, all signals having the same distance value or the same Doppler value as the at least one target signal are eliminated or marked in order to rule out such false detections, so-called ghost signals, being erroneously detected as target signals.

In addition, false detections due to reflections in the near range, so-called near range leakage (NRL), can also be eliminated with the invention. Such reflections in the near range can be caused in particular by a bumper of the vehicle, on which the radar transmission signals can be reflected.

Advantageously, a known method for determining a constant false alarm rate (CFAR) can be used to determine the original window function. The CFAR method can be optimized according to the invention in order to better suppress false detections. By improving the CFAR method, a computing speed can be improved. Furthermore, the suppression of false detections can be performed more efficiently.

Advantageously, in the course of determining at least one object information, at least one multi-dimensional fast Fourier transformation can be carried out as a discrete Fourier transformation. In this way, the at least one Fourier transformation can be calculated faster.

The method can advantageously be realized with at least one means by software and / or hardware. The method can be realized in software and / or hardware in combination with the control and / or evaluation device. The means for carrying out the method can be contained in an already required control and / or evaluation device of the radar system.

Individual steps of the method can also be performed in a different order. Individual process steps can also be conveniently combined.

The radar system can detect stationary or moving objects, in particular vehicles, persons, obstacles, road bumps, in particular potholes or stones, roadway boundaries, free spaces, in particular parking spaces, or the like.

The invention can be used in a vehicle, in particular a motor vehicle. Advantageously, the invention can be used in a land vehicle, in particular a passenger car, truck, a bus, a motorcycle or the like, an aircraft and / or a watercraft. The Invention can also be used in autonomous or at least partially autonomous vehicles.

The radar system may advantageously be connected to or part of a driver assistance system of the vehicle, in particular a parking assistance system, a chassis control and / or a driver information device or the like. In this way, the detected with the radar system object information, in particular distances, directions and / or speeds of an object relative to the vehicle, transmitted to a control of the driver assistance system and for influencing driving functions, in particular the speed, a brake function, a steering function, a chassis control and / or an output of a warning and / or warning signal, in particular for the driver or the like.

In an advantageous embodiment of the method, from the result of the Fourier transformation, at least one signal whose amplitude is above the predetermined limit value for target signals can be recorded in a detection list and the at least one target signal can be indirectly determined therefrom. In this way, the elimination of false detections on the detection level, in particular after a detector module, take place.

In a further advantageous embodiment of the method, the original window function can be realized as a cardinal sine function. A cardinal sine function provides a primal window function with a maximum. Furthermore, such a primal window function may be a priori relatively close to a profile of main lobes and sidelobes of the result of the Fourier transform. In this way, an effort in the standardization and displacement according to the invention can be reduced.

Advantageously, the original window function can be realized as a Hamming window, Blackman window or the like.

In a further advantageous embodiment of the method, the normalized window function can be subjected to an amplitude offset. In this way, the detection threshold can be set correspondingly higher. Thus false detections with higher amplitudes can be marked and / or suppressed.

In a further advantageous embodiment of the method, at least part of the method can be repeated for at least one further target signal. In this way, a plurality of target signals can be analyzed accordingly and optionally suppressed with these associated false signals.

Advantageously, the number of target signals to be examined can be specified. In this way, the number of repetitions of the process can be limited. Thus, a time required can be reduced accordingly.

In a further advantageous embodiment of the method, the primal window function can be taken from a lookup table. In this way, the original window function can be calculated in advance and stored in the lookup table. Thus, a corresponding amount of computation when performing the actual process during operation of the radar system can be reduced. Lookup tables are known to be translation tables available at the computational level. The look-up table can be recorded before commissioning of the radar system, in particular during a constitution.

Furthermore, the object is achieved according to the invention in the radar system in that the control and / or evaluation has means for carrying out the method according to the invention.

In addition, the object according to the invention in the driver assistance system is achieved in that the control and / or evaluation has means for carrying out the method according to the invention.

Incidentally, the features and advantages shown in connection with the method according to the invention, the radar system according to the invention and the driver assistance system according to the invention and their respective advantageous embodiments apply mutatis mutandis and vice versa. The individual features and advantages can, of course, be combined with one another, whereby further advantageous effects can be achieved that go beyond the sum of the individual effects.

list of figures

• 1 ein Kraftfahrzeug mit einem Fahrerassistenzsystem und einem Radarsystem zu Überwachung eines Überwachungsbereichs in Fahrtrichtung vor dem Kraftfahrzeug;
• 2 eine Funktionsdarstellung des Kraftfahrzeugs mit dem Fahrerassistenzsystem und dem Radarsystem aus der 1;
• 3 ein Entfernungstor-Dopplertor-Diagramm einer Ur-Fensterfunktion zur Unterdrückung von Falschdetektionen des Radarsystems;
• 4 ein Entfernungstor-Dopplertor-Diagramm von Signalen aus Echosignalen des Radarsystems nach Anwendung der Ur-Fensterfunktion aus der 3, die auf ein maximales Zielsignal verschoben ist;
• 5 ein Entfernungstor-Dopplertor-Diagramm der Signale entsprechend der 4, wobei hier eine angepasste Fensterfunktion ausgehend von der Ur-Fensterfunktion zur Unterdrückung von Falschdetektionen angewendet wurde;
• 6 ein Ablaufdiagramm eines Verfahrens zur Unterdrückung von Falschdetektionen mithilfe einer angepassten Fensterfunktion;
• 7 ein detailliertes Ablaufdiagramm eines Verfahrensschritts des Verfahrens aus 6;
• 8 ein Dopplertor-Amplituden-Diagramm, in welchem die Ur-Fensterfunktion, die normierte Ur-Fensterfunktion und die angepasste Fensterfunktion beispielhaft für einen Entfernungswert gezeigt sind;
• 9 ein Dopplertor-Amplituden-Diagramm, in dem ein Signalverlauf einer Radarmessung, die Ur-Fensterfunktion, die normierte Fensterfunktion und die angepasste Fensterfunktion beispielhaft für einen Entfernungswert gezeigt sind;
• 10 ein Entfernungstor-Amplituden-Diagramm, in dem ein Signalverlauf der Radarmessung aus 9, die Ur-Fensterfunktion, die normierte Fensterfunktion und die angepasste Fensterfunktion beispielhaft für einen Dopplerwert gezeigt sind;
• 11 ein Entfernungstor-Amplituden-Diagramm, in dem ein Signalverlauf einer Radarmessung in einem Nahbereich, die Ur-Fensterfunktion, die angepasste Fensterfunktion und eine daraus ermittelte konstante angepasste Fensterfunktion gezeigt sind, wobei das Verfahren entsprechend der 6 und 7 angewendet wurde.

Further advantages, features and details of the invention will become apparent from the following description, are explained in more detail in the embodiments of the invention with reference to the drawing. The person skilled in the art will expediently also individually consider the features disclosed in the drawing, the description and the claims in combination and combine these into meaningful further combinations. It show schematically

• 1 a motor vehicle with a driver assistance system and a radar system for monitoring a monitoring area in the direction of travel in front of the motor vehicle;
• 2 a functional representation of the motor vehicle with the driver assistance system and the radar system of the 1 ;
• 3 a range gate Doppler gate diagram of a master window function for suppressing false detections of the radar system;
• 4 a distance-gate Dopplertor diagram of signals from echo signals of the radar system after application of the original window function from the 3 shifted to a maximum target signal;
• 5 a range gate Doppler tensor diagram of the signals corresponding to 4 in which case an adapted window function was used starting from the original window function for the suppression of false detections;
• 6 a flow chart of a method for suppressing false detections using a customized window function;
• 7 a detailed flowchart of a method step of the method 6 ;
• 8th a Dopplertor amplitude diagram in which the original window function, the normalized primal window function and the adjusted window function are shown by way of example for a distance value;
• 9 a Dopplertor amplitude diagram in which a radar measurement waveform, the original window function, the normalized window function, and the adjusted window function are shown by way of example for a distance value;
• 10 a range gate amplitude diagram in which a radar signal waveform is output 9 , the primal windowing function, the normalized windowing function, and the adjusted windowing function are exemplified for a Doppler value;
• 11 a distance-gate amplitude diagram in which a signal waveform of a radar measurement in a near range, the original window function, the adjusted window function and a constant matched window function determined therefrom are shown, the method according to the 6 and 7 was applied.

In the figures, the same components are provided with the same reference numerals.

Embodiment (s) of the invention

In the 1 is a motor vehicle 10 shown in the form of a passenger car in front view. The car 10 has a radar system 12 , The radar system 12 is exemplary in the front bumper of the motor vehicle 10 arranged. With the radar system 12 can one in the 2 indicated surveillance area 14 in the direction of travel 16 in front of the motor vehicle 10 on objects 18 monitored. The radar system 12 can also be elsewhere on the motor vehicle 10 be arranged and oriented differently. At the objects 18 they may be, for example, other vehicles, people, obstacles, road bumps, such as potholes or stones, roadway boundaries or the like. In the 2 is an object 18 exemplified as a checkered rectangle. The 2 otherwise is merely a functional diagram of some components of the motor vehicle 10 and the radar system 12 that does not serve the spatial orientation.

The radar system 12 is designed for example as a frequency-modulated continuous wave radar. Frequency-modulated continuous wave radars are also referred to in the art as FMCW (Frequency Modulated Continuous Wave) radars. With the radar system 12 For example, a distance, a direction and a speed of the object 18 relative to the motor vehicle 10 be determined.

The radar system 12 is part of a driver assistance system 20 or at least be associated with this. With the driver assistance system 20 For example, a driver of the motor vehicle 10 get supported. For example, the motor vehicle 10 using the driver assistance system 20 at least partially autonomous driving, on or off parking. With the driver assistance system 20 can driving functions of the motor vehicle 10 For example, an engine control, a brake function or a steering function, influences or hints or warning signals are issued. This is the driver assistance system 20 with functional facilities 22 regulating and / or controlling connected. In the 2 are exemplary two functional devices 22 shown. At the functional facilities 22 it may be, for example, an engine control system, a brake system, a steering system, a landing gear control or a signal output system.

The driver assistance system 20 has an electronic control device 24 on, with the appropriate electronic control signals to the functional facilities 22 transmitted and / or received and processed by them.

The radar system 12 includes, for example, a transmitter 26 , an electronic control and evaluation device 28 and a receiver 30 ,

The control and evaluation device 28 is signal technology with the control device 24 connected. With the control device 24 may depend on object information of the radar system 12 Driving functions of the motor vehicle 10 be controlled / regulated.

For the invention, it is not essential whether electrical / electronic control and / or evaluation devices, such as the control device 24 , the control and evaluation device 28 , an engine control unit of the motor vehicle 10 or the like, integrated in one or more components or groups of components or at least partially realized as a decentralized components or groups of components.

With the transmitter 26 can send signals 32 for example, with constantly changing frequency in the surveillance area 14 be sent. The transmission signals 32 be on the object 18 reflected and as corresponding received signals 34 to the recipient 30 sent back and received with this. From the received signals 34 is with the control and evaluation 28 the distance, the direction and the speed of the object 18 relative to the motor vehicle 10 determined.

The procedure for determining object information of objects 18 that with the radar system 12 will be described below by way of example.

With the control and evaluation device 28 becomes the transmitter 26 controlled so that transmission signals 32 in the surveillance area 14 be sent. The transmission signals 32 are generated by way of example from frequency-modulated continuous-wave signals.

With the receiver 30 become the ones on the object 18 reflected echoes of the transmission signals 32 as received signals 34 received and if necessary in one with the control / evaluation 28 brought usable shape.

The received signals 34 be with appropriate resources of the control / evaluation 28 subjected to a two-dimensional fast Fourier transform.

From the result of the two-dimensional discrete Fourier transformation go out of the transmission signals 32 corresponding target signals 36a of physically existing targets and their respective amplitudes. A target object is an area of the object 18 , Multiple targets can be from the same object 18 or from different objects. By reflection in the near range, which are referred to in English as "near range leakage" (NRL), or due to side lobes of a window function explained below by strong reflections, so-called "high peaks", there is a risk that falsely so-called "ghost targets" as False detections in the form of false signals 36b be detected. The core of the invention is to suppress such false detections.

In the 4 and 5 are exemplary two target signals 36a indicated in a distance gate-Dopplertor matrix each with a cross. Accordingly, there are some false signals 36b indicated as black dots. Exemplary signal curves 39 the result of the Fourier transform with corresponding target signals 36a and false signals 36b are in the 9 in a Dopplertor amplitude diagram and in the 10 shown in a range gate amplitude diagram.

The in the 3 to 5 shown range gate Dopplertor matrix consists of cells, which are each characterized by a distance value and a Doppler value and having an amplitude. The amplitudes characterize the intensity of any signal 36a or 36b in the cell or, if no signal is received, the local noise. In the range gate doppler matrix, the range gates correspond to so-called "range bins" or pitch intervals. The Doppler doors correspond to so-called relative speed gates or "Doppler bins". The range gate Doppler gate matrix includes, by way of example, 256 range gates and 128 Doppler gates.

In order to suppress false detections, the method described below is used, which is described with reference to an exemplary flowchart according to the 6 is explained.

In one step 40 becomes a primary detection threshold 42 as a primal window function 44 realized. The original window function 44 can either be calculated or taken from a lookup table. For example, the lookup table may be prior to the initial startup of the radar system 12 to be created. The original window function 44 For example, it may be a so-called Hamming window, a Blackman window, or the like.

In the 3 is an example of the original window function 44 shown. The original detection threshold 42 has an extension in Doppler direction, for example in the range gate with the distance value 128 , and an extension in Distance direction, by way of example with the distance value 64 , Overall, the Ur-detection threshold extends 42 roughly cross-shaped, being a maximum 46 in the center of the cross. The course of the Ur-detection threshold 42 in the Doppler dimension is in the 8th shown in a Dopplertor amplitude diagram. The 8th shows by way of example the individual phases in the adaptation of the window function in the course of the process.

In one step 48 become from the result of the Fourier transform those signals as a target signal 36a determines their amplitude above a predetermined limit 50 lies. The limit 50 is for example in the 9 indicated in a Dopplertor amplitude diagram. The limit 50 is chosen so that strong signals with larger amplitudes are most likely to stem from real object targets. If the amplitudes of the signals are given in decibels, the limit 50 for example 60 dB.

In one step 52 becomes the original window function 44 to one of the determined target signals 36a normalized. The thus normalized window function 54 is for example in the 8th and 9 shown.

In an optional step 56 becomes the normalized window function 54 with an amplitude offset 58 applied. The standardized window function acted upon with the offset is referred to below as the "normalized offset window function 60 "And is in the 8th shown.

In one step 62 becomes the normalized offset window function 60 in the distance direction and in Doppler direction shifted so that their maximum 46 on the target signal 36a lies, as in the 9 and 10 is shown. 9 shows the Doppler dimension and 10 the distance dimension. The 9 and 10 show the phases of the window function in the course of the procedure, wherein the shift of the window function in the representation of the 9 and 10 before normalization was performed. Therefore, the corresponding phases of the window function and the waveform 39 of the result of the Fourier transformation.

The shifted normalized offset window function 60 is hereafter referred to as "custom window function 64 " designated. The curve of the adjusted window function 64 forms an adapted detection threshold 66 whose maximum is at the maximum of the target signal used 36a lies.

In one step 68 becomes the adjusted detection threshold 66 with a shifted primary detection threshold 42 the original window function 44 compared, where the primal window function 44 also with their maximum 46 to the corresponding target signal 36a was postponed.

Will be in one step 70 found that the adjusted detection threshold 66 with respect to the amplitude above the original detection threshold 42 lies, is in one step 72 the customized window function 64 used as a new window function.

Subsequently, in one step 74 all signals from the result of the Fourier transformation with the same distance value or the same Doppler value as the target signal used 36a below the adjusted detection threshold 66 the new window function, as false signals 36b detected and discarded.

If the check in step 70 shows that the adjusted detection threshold 66 below the original detection threshold 42 the moved original window function 44 lies, is in one step 76 the moved original window function 44 used as a new window function and accordingly the suppression of the false signals 36b in step 74 carried out.

The Range Gate Doppler Gate Diagram 4 shows the application of the moved original window function 44 on the waveform 39 , In comparison, the shows 5 the application of the custom window function 64 on the waveform 39 , In a comparison can be seen that in the 4 still detected false signals 36b with the same Doppler value or the same distance value as the target signal used 36a with the customized window function 64 be suppressed and therefore in 5 are no longer visible. The target signal used 36a is located in the center of the cross of the displaced primal window function 44 or the adapted window function 64 , As an example, another target signal 36a which is above the adjusted detection threshold 66 even if the custom window function is used 64 recognized.

In one step 78 is checked if there is another strong target signal 36a is present, for a corresponding adjustment of the original window function 44 should be done. If so, the steps become 52 . 56 . 62 . 68 . 70 . 72 . 74 . 76 and 78 for this further target signal 36a repeated.

If in the step 78 shows that no further strong target signal 36a is used, the procedure, starting with the step 48 , to determine another strong target signal 36a repeated.

In the 7 are exemplary sub-steps of the process step 74 from the 6 shown. These Sub-steps can be performed, for example, when the signals 36 be taken from a detection list. The detection list can be generated in a manner not of further interest following a radar measurement and corresponding distance values, Doppler values and amplitudes of the signals 36 contain.

In one step 74a become signals 36 with the same distance value as the selected target signal 36a searched. These further signals 36 may, for example, in the distance dimension as false signals 36b out. These false signals 36b For example, sidelobe effects of the target signal used 36a originate. These further signals 36 will be labeled "Det Range Det" below.

In one step 74b becomes from a shift of the original window function 44 so their maximum 46 in the same Doppler distance gate lies as the maximum of the target signal used 36a is a relative distance to the signal marked "Det Range Det" 36 calculated.

In one step 74c becomes the amplitude of the signal marked Det-Range-Det 36 with the adjusted detection threshold 66 compared.

If the amplitude of the signal marked Det-Range-Det 36 below the adjusted detection threshold 66 lies, is in one step 74d the signal marked Det-Range-Det 36 discarded and as a false signal 36b recognized.

Then the process steps 74a to 74d instead of the distance values for the selected target signal 36a corresponding Doppler values performed.

Subsequently, according to the procedure from the 6 with the step 68 continued.

In the 11 Shown is a range gate amplitude diagram illustrating the use of the method of rejecting false signals 36b in the near field represents. For example, distance values become smaller than 20 designated. In the near field dominated by a noise effect. The original detection threshold 42 is there usually too low to false signals 36b to suppress. This leads in particular to stationary targets which exemplify the Doppler value 65 may have to false detections. These false detections are caused by the so-called Near Range Leakage (NRL).

With the method according to the invention, this NRL can be compensated. For this purpose, the adjusted detection threshold 66 for a stationary target, exemplified by the Doppler value 65 , fixed. The fixed, adjusted detection threshold is in the 11 With 66a designated.

The NRL may be after the receiver 30 be compensated by the procedure for strong target signals 36a is used as it is in the 6 and 7 is described. In this case, the target signal 36a be used from a main reflection for the compensation, for example, from a bumper of the vehicle 10 for example with the Doppler value 0 can come. For this purpose, the maximum amplitude of the signals in the range gates 0 to 5 certainly. These signals result from reflections on the bumper. As a rule, the amplitude value of these signals is constant. If the amplitude of the bumper reflection is given in decibels, the amplitude may vary between about 1 dB and 2 dB. The variation of the amplitude can vary in particular with long-term measurements with the measurement duration and, for example, temperature changes.

For example, when parking, it may be helpful to be able to recognize other actual target objects in the near field. For this purpose, the maximum amplitudes in the near-field range gates can be monitored over a corresponding period of time. By correspondingly large amplitude differences or fluctuations signals with these amplitudes can be distinguished from the determined bumper reflections.

To carry out the method of the 6 and 7 to suppress false detections in the near field become signals 36 with maximum amplitude, for example, in the first five range gates at a Doppler value of, for example, 0 and as corresponding target signals 36a used. These destination signals 36a themselves are discarded as invalid since they may result from reflections on the bumper.

Subsequently, analogously to the method according to 6 and 7 the original window function 44 based on one of these target signals 36a standardized according to an amplitude offset and with its maximum 46 to the rejected target signal 36a postponed.

Analogous to the process steps 74a to 74b from the 7 For example, for the Doppler values of, for example, 0 to 32, all signals will be the same distance value as the rejected target signal used 36a searched, marked with "Det-Range-Det", with the adapted detection threshold 66 compared and accordingly as false signals 36b marked or discarded.

The in conjunction with the 6 and 7 explained method steps can also be performed in a different order. It is also possible to combine several process steps expediently. The flowcharts of 6 and 7 serve essentially the exemplary explanation of the method according to the invention.

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Cited patent literature

• DE 102012024999 A1 [0004]

Claims (8)

Method for suppressing false detections (36b) in the determination of object information of at least one object (18) detected by a radar system (12), in particular of a vehicle (10), in which at least part of a result of a multi-dimensional discrete Fourier transformation at least one received signal (34) of the radar system is compared with at least one adaptable detection threshold (66) and - those signals from the result of the Fourier transformation are identified or rejected as false detections (36b) whose amplitudes are below the at least one detection threshold (66). lying, characterized in that - at least one Ur-detection threshold (42) as a primal window function (44) is realized, which has a maximum (46), - directly or indirectly from the result of the Fourier transform at least one signal as a target signal ( 36a) whose amplitude exceeds a predetermined limit value (50) f r is a normalized window function (54), the window function (54) is normalized before or after normalization in a Doppler gate Distance gate dimension of the result of the Fourier transformation is shifted such that its maximum lies on the at least one target signal (36a), an adjusted detection threshold (66) from the normalized and shifted, matched window function (64) with the original detection threshold ( 42) of the original window function (44), which has been shifted with its maximum (46) to the maximum of the at least one target signal (36a), and possibly with a previous adjusted detection threshold of a previous matched window function, which was determined in a previous run of the method is compared, and if the adjusted detection threshold (66) is above the shifted primary detection threshold (42) and if above the previous adjusted detection threshold, the adjusted detection threshold (66) for the result of the Fourier transform with respect to the signals (36) having the same Doppler value and / or the same distance value as the at least one target signal (36a) is used, otherwise the original detection threshold (42) or, if appropriate, the previous adjusted detection threshold is used. Method according to Claim 1 , characterized in that from the result of the Fourier transform at least one signal whose amplitude is above the predetermined limit value for target signals (36a) is recorded in a detection list and from this indirectly the at least one target signal (36a) is determined. Method according to Claim 1 or 2 , characterized in that the primal window function (44) is implemented as a cardinal sine function. Method according to one of the preceding claims, characterized in that the normalized window function (54) is subjected to an amplitude offset (58). Method according to one of the preceding claims, characterized in that at least part of the method is repeated for at least one further target signal (36a). Method according to one of the preceding claims, characterized in that the primal window function (44) is taken from a look-up table. Radar system (12) in particular of a vehicle (10) for determining at least one object information of at least one object (18), - with at least one transmitter (26) for Transmitting transmission signals (32) into a monitoring area (14), having at least one receiver (30) for receiving echoes of the transmission signals (32) reflected at the at least one object (18) as received signals (34) and having at least one control - and / or evaluation device (28), wherein the at least one control and / or evaluation device (28) comprises means - for performing at least one multi-dimensional discrete Fourier transform of the received signals (34), - for comparing at least part of the result of the Fourier Transformation with an adaptable detection threshold (66) and - for identifying or discarding those signals from the result of the Fourier transformation as false detections (36b) whose amplitudes are below the detection threshold (66), characterized in that the control and / or Evaluation device (28) comprises means for carrying out the method according to the invention. A driver assistance system (20) of a vehicle (10), comprising - at least one electronic control device (24) for controlling functional devices (22) of the vehicle (10) depending on object information provided by at least one radar system (12), and - at least one Radar system (12) for determining at least one object information of at least one object (18), wherein the at least one radar system (12) - at least one transmitter (26) for transmitting transmission signals (32) in a monitoring area (14), - at least one Receiver (30) for receiving at the at least one object (18) reflected echoes of the transmission signals (32) as received signals (34) and - at least one control and / or evaluation (28), wherein the at least one control and / or Evaluation device (28) comprises means - for performing at least one multi-dimensional discrete Fourier transform of the received signals (34), - for comparing little at least part of the result of the Fourier transformation with an adjustable detection threshold (66) and - for marking or discarding those signals from the result of the Fourier transformation as false detections (36b) whose amplitudes are below the detection threshold (66), characterized the control and / or evaluation device (28) has means for carrying out the method according to the invention.

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