DE102019206806A1 - Determination of the speed and the distance of objects to a sensor system - Google Patents

Abstract

A beat frequency measurement method is described. In the beat frequency measurement method, an electromagnetic reflection signal, which comprises a reflection signal (RM) of a target object (Z), is measured monostatically with at least one of at least two sensors of a cooperative sensor system. Furthermore, an electromagnetic reflection signal (RB), which comprises a reflection signal of a target object (Z), is measured bistatically with at least two sensors of the cooperative sensor system. Furthermore, a beat spectrum (RBS, BSk) is determined on the basis of the recorded measurement data (RM, RB). The beat spectrum (RBS, BSk) comprises a low-frequency monostatic range (MB), which is assigned to the monostatic reflection signal (RM), and a higher-frequency bistatic range (BB) which is assigned to the bistatic reflection signal (RB). On the basis of the determined beat spectrum (RBS), a monostatic beat frequency (MZF) of the target object (Z) in the monostatic range (MB) and a bistatic beat frequency (BZF) of the target object (Z) in the bistatic range (BB) are determined. A position finding method is also described. A speed determination method is also described. A beat spectrum measuring device (60) is also described. A position determining device (130) is also described. A speed determination device (120) is also described. A moving object is also described.

Description

The invention relates to a beat frequency measuring method. With the beat frequency measurement method, reflection signals from a target object are measured to determine position and speed. The invention also relates to a position determination method. The invention also relates to a speed determination method. The invention also relates to a beat spectrum measuring device. The invention also relates to a position determining device. In addition, the invention also relates to a speed determination device. The invention also relates to a moving object.

Autonomous driving requires precise knowledge of the position and speed of objects located in the vicinity of a route of an autonomously controlled vehicle. Radar systems are often used to determine distance and speed. However, radar systems only ever measure the radial speed in the direction from the sensor to the object. A vectorial speed measurement, which determines the speed components of an object in all spatial directions, would be particularly desirable. The determination of individual vectorial speed components could, for example, also be used to calculate the direction of movement of objects.

The detection of the direction of movement of vehicles plays a role in the field of autonomous driving, for example in the lane change detection of vehicles ahead or behind. This could make it possible to differentiate between lane changes and braking processes, which can lead to safety-critical scenarios. Examples of lane change processes and braking processes are in 1 to 4th shown.

So far, no vectorial speeds have been measured with radar devices and radar systems. The direction of movement in combination with the speed can be determined, for example, with the aid of radar or lidar sensors together with complex object tracking algorithms. With such a procedure, the direction of movement is estimated with the aid of several measurements and range-Doppler and range-azimuth evaluations. However, vector velocity components are not measured directly.

In sensor systems with tracking algorithms, several series of measurements often have to be carried out in order to be able to make statements about the direction of movement of objects. In particular in the case of time-critical applications such as autonomous driving, however, the computing effort is too high to be able to provide information in real time.

Conventional lane change assistants measure whether there are vehicles in adjacent lanes at a certain distance without determining the vectorial speed of these vehicles.

The object is therefore to develop a method and a device for determining the direction of movement, position and vectorial speed of a vehicle.

This object is achieved by a beat frequency measuring method according to claim 1, a position determination method according to claim 9, a speed determination method according to claim 10, a beat spectrum measuring device according to claim 11, a position determination device according to claim 13, a speed determination device according to claim 14 and a movable object according to claim 15 solved.

In the case of the beat frequency measuring method according to the invention, an electromagnetic reflection signal, which comprises a reflection signal of a target object, is measured monostatically with at least one of at least two sensors of a cooperative sensor system. In this context, monostatic measurement should be understood to mean that the emitter and receiver for generating or receiving the electromagnetic signal or reflection signal are arranged at the same position or very close to one another and form a common active sensor. A target object can be, for example, a vehicle or a mobile or stationary object located in a movement area of a moving object.

Furthermore, an electromagnetic reflection signal, which comprises a reflection signal of a target object, is measured bistatically with at least one of two sensors of the cooperative sensor system. In a bistatic measurement, two sensors are used, a first sensor being used as an active sensor or as a transmitting unit, while a second sensor is used as a receiving unit for reception of the reflection signal is used. Both sensors are preferably triggered by a common trigger signal. The common trigger signal ensures that the bistatic response is measured within the limits specified by the hardware and software, such as the bandwidth of the beat frequency, the ramp configuration and the sampling frequency of the analog-digital converter. An AD converter is required to convert the analog measurement signals into further processable digital data.

The sampling frequency of the analog-digital converter specifies the highest measurable beat frequency. The trigger signal must ensure that the bistatic response is within this maximum beat frequency. The sampling frequency is usually selected as a function of the maximum bandwidth of the beat frequency, so that the limitation by the sampling frequency does not matter.

A beat spectrum is also determined on the basis of the recorded measurement data. The beat spectrum includes a low-frequency monostatic range, which is assigned to the monostatic reflection signal, and a higher-frequency bistatic range, which is assigned to the bistatic reflection signal. On the basis of the determined beat spectrum, a monostatic beat frequency of the target object in the monostatic range and a bistatic beat frequency of the target object in the bistatic range are determined. This means that the target object can be assigned a specific frequency both in the monostatic range and in the bistatic range of the beat spectrum. This frequency can be identified, for example, by a characteristic shape of the beat spectrum in the range of the frequency of the target object. For example, an increased intensity value can be measured at the frequency of the target object.

A large number of sensors are used, particularly in autonomous vehicles. These can include radar sensors, for example. The existing plurality of sensors can now be used advantageously, for example, to determine monostatic and additionally bistatic beat spectra of objects located in the driving range of vehicles and to assign characteristic frequencies in the beat spectra to the objects. Based on this measurement data, distances, positions and vector speeds of objects can be determined. The security and reliability of object detection can advantageously be improved in the context of autonomous mobility. In addition, with the procedure according to the invention, both the bistatic reflection signal and the monostatic reflection signal can be detected by one and the same sensor, more precisely, the first sensor. In other words, only the measurement signals from a single sensor are required. As a result, the signal processing effort and the memory effort are reduced compared to receiving measurement signals via a plurality of sensors. Fewer transmission lines are also required for transmitting the measurement signals in order to transmit the measurement signals to a computing unit for evaluation. The method according to the invention is not restricted to the use of two sensors. In order to increase the measurement accuracy or to achieve redundancy for safety-critical applications, measurement data from other sensors can also be used for processing.

In the position determination method according to the invention, the beat frequency measurement method according to the invention is first carried out. In addition, a first transit time τ _{11 of} the monostatic reflection signal is determined on the basis of the frequency of the target object in the monostatic range of the determined beat spectrum. In addition, a second transit time τ _{12 of} the bistatic reflection signal is determined on the basis of the frequency of the target object in the bistatic range of the determined beat spectrum. The transit times are proportional to the monostatic or bistatic frequency of the target object. Distances d ₁₁ , d _{12 between} the sensors and the target object are determined on the basis of the determined transit times τ ₁₁ , τ ₁₂ . Finally, a position of the target object is determined by triangulation on the basis of the determined distances d ₁₁ , d ₁₂ . For example, if the distance between the two sensors is known, the position of the target object can be calculated from the three known side lengths of a triangle spanned by the sensors and the target object.

In the speed determination method according to the invention, the beat frequency measuring method according to the invention is carried out. Furthermore, a first Doppler frequency of the monostatic reflection signal of the target object is determined in the monostatic range of the determined beat spectrum. In addition, a second Doppler frequency of the bistatic reflection signal of the target object is determined in the bistatic range of the determined beat spectrum. A first speed component v _{11 of} the target object is determined on the basis of the first Doppler frequency. In addition, a second speed component v _{22 of} the target object is determined on the basis of the second Doppler frequency and the first speed component v ₁₁ . On the basis of the determined first speed component v ₁₁ and the determined second speed component v ₂₂ , a vectorial speed V of the target object is finally determined.

The beat spectrum measuring device according to the invention for determining a beat spectrum has a first sensor for monostatic measurement of an electromagnetic reflection signal which comprises a reflection signal of a target object. Part of the beat spectrum measuring device according to the invention is also a second sensor with a known distance d to the first sensor for bistatically measuring an electromagnetic reflection signal which comprises a reflection signal of the target object. The beat spectrum measuring device according to the invention also has a spectrum determination unit for determining a raw data beat spectrum on the basis of the recorded measurement data, the raw data beat spectrum having a low-frequency monostatic range, which is assigned to the monostatic reflection signal, and a higher-frequency bistatic range, which is the bistatic Is associated reflection signal includes. Furthermore, the beat spectrum measuring device according to the invention comprises a beat frequency determination unit for determining a monostatic beat frequency of the target object in the monostatic range on the basis of the determined beat spectrum and for determining a bistatic beat frequency of the target object in the bistatic range on the basis of the determined beat spectrum.

The beat spectrum measuring device according to the invention shares the advantages of the beat spectrum measuring method according to the invention. As already mentioned, the beat spectrum measuring device according to the invention can also comprise more than two sensors in order to increase the measuring accuracy or to achieve redundancy for safety-critical applications. The sensors used can each be equipped with a single transmit and receive channel, which reduces the effort required compared to multi-channel systems.

In order to further reduce the hardware expenditure for possibly additional sensors to improve the accuracy and reliability of the beat spectrum measuring device according to the invention, the beat spectrum measuring device can be designed as a master-slave system. A sensor can be designed as a master and equipped with a transmitter and receiver unit. The slave sensors then each have only one transmission unit for generating a measurement signal, which results in a compact and inexpensive measurement device.

The position determining device according to the invention has the beat spectrum measuring device according to the invention. Furthermore, the position determining device according to the invention comprises a transit time determination unit for determining a first transit time τ _{11 of} the monostatic reflection signal based on the frequency of the target object in the monostatic range of the determined beat spectrum and for determining a second transit time τ _{12 of} the bistatic reflection signal based on the frequency of the target object in the bistatic range of the determined beat spectrum. Part of the position determination device according to the invention is also a distance determination unit for determining distances d ₁₁ , d _{12 of} the sensors to the target object on the basis of the determined transit times τ ₁₁ , τ ₁₂ . Finally, the position determination device according to the invention also includes a position determination unit for determining a position of the target object by triangulation on the basis of the determined distances d ₁₁ , d ₁₂ .

Position determination can advantageously be carried out with the aid of measurement data that come from a single radar sensor. As already mentioned, this reduces the signal processing effort and the storage effort as well as the infrastructural effort for data transmission.

The speed determination device according to the invention comprises the beat spectrum measuring device according to the invention. The speed determination device according to the invention also includes a Doppler frequency determination unit for determining a first Doppler frequency of the monostatic reflection signal of the target object in the monostatic range of the determined beat spectrum and for determining a second Doppler frequency of the bistatic reflection signal of the target object in the bistatic range of the determined beat spectrum. The speed determination device according to the invention also has a speed component determination unit for determining a first speed component v _{11 of} the target object on the basis of the first Doppler frequency and for determining a second speed component v _{22 of} the target object on the basis of the second Doppler frequency and the first speed component v ₁₁ . Furthermore, the speed determination device according to the invention comprises a speed determination unit for determining a vector speed v of the target object on the basis of the determined first and second speed components v ₁₁ , v ₂₂ . With a cooperative sensor system a vectorial speed measurement in all spatial directions and thus a calculation of the direction of movement of objects is possible. In contrast to conventional approaches, such as the use of sensor systems with tracking algorithms, vectorial speed measurement is possible on the basis of a single series of measurements. As a result, the computing effort can be reduced, as a result of which real-time applications, as they occur in autonomous mobility, can be implemented more easily.

The movable object according to the invention comprises a control unit for autonomous or at least partially autonomous control of a movement of the movable object and a beat spectrum measuring device according to the invention and / or a position determining device according to the invention and / or a speed determining device according to the invention. The movable object according to the invention can include, for example, an autonomously or partially autonomously controlled vehicle or flight object.

Some components of the measuring and determining devices according to the invention can for the most part be designed in the form of software components. This applies in particular to parts of the spectrum determination unit and the beat frequency determination unit of the beat spectrum measurement device, the transit time determination unit, the distance determination unit and the position determination unit of the position determination device and the Doppler frequency determination unit, the speed component determination unit and the speed determination unit of the speed determination device. In principle, however, these components can also be implemented in part, especially when particularly fast calculations are concerned, in the form of software-supported hardware, for example FPGAs or the like. Likewise, the required interfaces, for example if it is only a matter of transferring data from other software components, can be designed as software interfaces. However, they can also be designed as hardware-based interfaces that are controlled by suitable software.

A largely software-based implementation has the advantage that computer systems already present in a mobile object or in infrastructure can easily be retrofitted with a software update after a possible addition by additional hardware elements such as sensors, clock generators and trigger components. to work in the manner of the invention. In this respect, the object is also achieved by a corresponding computer program product with a computer program that can be loaded directly into a memory device of such a computer system, with program sections to carry out the steps of the method according to the invention that can be implemented by software when the computer program is executed in the computer system.

In addition to the computer program, such a computer program product can optionally contain additional components, e.g. documentation and / or additional components, including hardware components, such as Hardware keys (dongles, etc.) for using the software include a computer-readable medium, for example a memory stick, a hard drive or another transportable or permanently installed data carrier, for transport to the storage device of the computer system and / or for storage on the computer system in which the program sections of the computer program that can be read and executed by a computer unit are stored. The computer unit can e.g. for this purpose have one or more cooperating microprocessors or the like.

The dependent claims and the following description each contain particularly advantageous embodiments and developments of the invention. In particular, the claims of one claim category can also be developed analogously to the dependent claims of another claim category and their description parts. In addition, the various features of different exemplary embodiments and claims can also be combined to form new exemplary embodiments within the scope of the invention.

In one embodiment of the beat frequency measuring method according to the invention, the sensors include radar sensors. Due to their longer wavelength of around 1 to 10 m, radar waves are suitable for the detection of larger objects, even at greater distances and in poor visibility. The sensors can also include lidar sensors. Lidar sensors enable the detection of objects with increased resolution, but require good visibility in order to function. If both types of sensors are included, optimal object detection takes place in any weather.

The sensors preferably include FMCW sensors. FMCW sensors use a so-called frequency-modulated continuous wave radar, which emits a continuous transmission signal. Such an FMCW radar can change its operating frequency during a measurement, i.e. the transmission signal is frequency modulated. These changes in frequency allow time of flight measurements. Distances can be measured precisely with an FMCW sensor. In addition, the distance and the radial speed can be measured simultaneously.

In a variant of the beat frequency measuring method according to the invention, the at least two sensors are operated fully coherently by a common clock. As a fully coherent operation in this To be understood context that the at least two sensors are synchronized by a clock signal. In fully coherent operation, there are no frequency shifts in the bistatic range of the determined beat spectrum, so that a correction of the measured beat spectrum with the aid of a reference target is not necessary. Such a solution is particularly advantageous in the case of sensors arranged on mobile units, since there the sensors move with them and distances to reference objects may not always be exactly known.

Alternatively, the at least two sensors can be operated quasi-coherently by additional monostatic and bistatic measurement of a reference target whose position is known. In quasi-coherent operation, there is no common clocking of the at least two sensors. Shifts in the beat spectrum are compensated for by measuring a distance from a reference object. This procedure is advantageous with a stationary arrangement of sensors, for example on units of the traffic or road infrastructure. Because there distances to possible reference objects are known. A common clocking of the sensors can be saved here.

In detail, in the case of a quasi-coherent measurement, a calibration is carried out to determine a corrected beat spectrum. For this purpose, a frequency of the reference target in the bistatic range is determined on the basis of the determined raw data beat spectrum. On the basis of the frequency of the reference target in the bistatic range determined by the measurement and a previously known setpoint frequency of the bistatic reflection signal of the reference target, a value f _{diff of} a frequency shift of the beat spectrum in the bistatic range is determined. The setpoint frequency can be determined or known on the basis of a previously known distance from the reference target. Finally, the raw data beat spectrum is shifted by the determined value f _{diff of} the frequency shift.

The reference target can be a passive reference target which is illuminated with the aid of an active sensor and which reflects the waves emitted by the sensor unchanged. The reference target can advantageously be designed very simply and require no maintenance effort.

Alternatively, the reference target can also be designed as an active reference target. Such an active reference target includes a transmitting / receiving antenna with which waves emitted by an active sensor are received, optionally amplified and / or modulated, and transmitted again. Reliable detection and identification of the reference target can be achieved with such a reference target, since it can be characterized by a specific modulation.

In one embodiment of the beat frequency measuring method according to the invention, a frequency of the reference target in the bistatic range corresponds to a maximum of the beat spectrum. A frequency of a reference target can advantageously be recognized on the basis of the intensity of a spectral value.

In an advantageous variant of the beat spectrum measuring device according to the invention, the spectrum determination unit for determining a corrected beat spectrum has a reference frequency determination unit for determining a frequency of the reference target in the bistatic range on the basis of the determined beat spectrum. In this variant, part of the beat spectrum measuring device according to the invention is also a shift frequency determination unit for determining a value of a frequency shift of the beat spectrum in the bistatic range, based on the frequency of the reference target in the bistatic range determined by the measurement and a previously known setpoint frequency of the bistatic reflection signal of the reference target and a shift unit for shifting the raw data beat spectrum by the determined value of the frequency shift. The beat spectrum measuring device can advantageously be calibrated with the aid of the reference target, so that a more precise frequency measurement based thereon can be used to make precise evaluations of the measurement with regard to the speed and position of an object.

• 1 eine schematische Darstellung von zwei hintereinander fahrenden Fahrzeugen,
• 2 eine schematische Darstellung eines Verkehrsszenarios mit zwei Fahrzeugen, von denen ein Fahrzeug einen Spurwechsel vornimmt,
• 3 eine schematische Darstellung eines Verkehrsszenarios mit drei hintereinanderfahrenden Fahrzeugen,
• 4 eine schematische Darstellung eines Verkehrsszenarios, bei dem eine Einfahrt in eine Straße blockiert ist,
• 5 eine schematische Darstellung eines vollkohärenten kooperativen Radarsystems gemäß einem Ausführungsbeispiel der Erfindung,
• 6 eine schematische Darstellung eines quasikohärenten kooperativen Radarsystems gemäß einem Ausführungsbeispiel der Erfindung,
• 7 ein Schaubild eines Beatspektrums eines quasikohärenten kooperativen Radarsystems gemäß einem Ausführungsbeispiel der Erfindung,
• 8 ein Flussdiagramm, welches ein vollkohärentes Beatfrequenzmessverfahren zum Ermitteln eines Beatspektrums gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht,
• 9 ein Flussdiagramm, welches ein quasikohärentes Beatfrequenzmessverfahren zum Ermitteln eines Beatspektrums gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht,
• 10 ein Flussdiagramm, welches ein Geschwindigkeitsmessverfahren gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht,
• 11 ein Flussdiagramm, welches ein Positionsermittlungsverfahren gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht,
• 12 eine schematische Darstellung einer Geschwindigkeitsermittlungseinrichtung gemäß einem Ausführungsbeispiel der Erfindung,
• 13 eine schematische Darstellung einer Positionsermittlungseinrichtung gemäß einem Ausführungsbeispiel der Erfindung,
• 14 ein Schaubild, welches eine Positions- und Richtungsermittlung auf Basis der Messungen eines ersten Sensors einer Positions- und Geschwindigkeits-Ermittlungseinrichtung gemäß einem Ausführungsbeispiel der Erfindung veranschaulicht,
• 15 ein Schaubild, welches Positions- und Richtungsermittlung auf Basis der Messungen eines zweiten von dem ersten Sensor beabstandeten Sensors veranschaulicht.

The invention is explained in more detail below with reference to the accompanying figures on the basis of exemplary embodiments. Show it:

• 1 a schematic representation of two vehicles driving one behind the other,
• 2 a schematic representation of a traffic scenario with two vehicles, one of which is changing lanes,
• 3 a schematic representation of a traffic scenario with three vehicles driving one behind the other,
• 4th a schematic representation of a traffic scenario in which an entry into a street is blocked,
• 5 a schematic representation of a fully coherent cooperative radar system according to an embodiment of the invention,
• 6th a schematic representation of a quasi-coherent cooperative radar system according to an embodiment of the invention,
• 7th a diagram of a beat spectrum of a quasi-coherent cooperative radar system according to an embodiment of the invention,
• 8th a flowchart which illustrates a fully coherent beat frequency measurement method for determining a beat spectrum according to an embodiment of the invention,
• 9 a flowchart which illustrates a quasi-coherent beat frequency measurement method for determining a beat spectrum according to an embodiment of the invention,
• 10 a flow chart illustrating a speed measurement method according to an embodiment of the invention,
• 11 a flowchart illustrating a position determination method according to an embodiment of the invention,
• 12 a schematic representation of a speed determination device according to an embodiment of the invention,
• 13 a schematic representation of a position determining device according to an embodiment of the invention,
• 14th a diagram which illustrates a position and direction determination based on the measurements of a first sensor of a position and speed determination device according to an embodiment of the invention,
• 15th a diagram which illustrates position and direction determination on the basis of the measurements of a second sensor spaced apart from the first sensor.

In 1 is a scenario 10 shown in which a first vehicle 1 and a second vehicle 2 drive one behind the other. The first vehicle 1 drives at a first speed v _{x, 1} and the second vehicle 2 travels at a second speed v _{x, 2} along a street S. Both vehicles 1 , 2 have only one speed component in the x-direction, ie in the direction of the road. Becomes the second vehicle in front 2 braked, its overall speed is reduced. Because the second vehicle 2 just a speed component v _{x, 2} in the x direction is the change in the speed of the second vehicle 2 equal to the change in speed v _{x, 2} in X direction. The first vehicle 1 measures this change in the speed of the vehicle in front 2 and in this case would also have to reduce the speed in order to maintain the required safety distance or change lanes to avoid the vehicle in front 2 to overtake.

des zweiten Fahrzeugs 2 konstant. Im Gegensatz zu dem in 1 gezeigten Szenario ändert sich jedoch die Bewegungsrichtung des zweiten Fahrzeugs 2 und somit ändern sich auch die einzelnen Geschwindigkeitskomponenten des zweiten Fahrzeugs 2. Die Geschwindigkeit $\overrightarrow{v_2}$

des zweiten Fahrzeugs 2 setzt sich aus den Komponenten v_x,2 und v_y,2 , d.h. der Komponenten der Geschwindigkeit $\overrightarrow{v_2}$

in x-Richtung und der Komponenten der Geschwindigkeit $\overrightarrow{v_2}$

in y-Richtung zusammen. Da die Gesamtgeschwindigkeit des zweiten Fahrzeugs 2 gleichbleibt und sich das zweite Fahrzeug 2 zusätzlich mit v_y,2 in y-Richtung bewegt, verringert sich auch in diesem Fall die Geschwindigkeit v_x,2 in x-Richtung. Die Änderung der Geschwindigkeit v_x,2 ist dabei abhängig vom Winkel zwischen der Fahrtrichtung und der x-Richtung. Das Radar des ersten Fahrzeugs 1 misst auch in diesem Fall nur die x-Komponente v_x,2 und damit nur die Änderung von v_x,2 . Es ist also nicht möglich für das erste Fahrzeug 1, auf Basis einer Radarmessung zu unterscheiden, ob sich die x-Komponente v_x,2 der Geschwindigkeit $\overrightarrow{v_2}$

des zweiten Fahrzeugs 2 aufgrund eines Bremsvorgangs oder aufgrund eines Spurwechsels verringert. In beiden Fällen müsste das erste Fahrzeug 1 seine Geschwindigkeit verringern bzw. die Spur wechseln. Dies kann zum Beispiel zu einem unnötigen Bremsmanöver führen. Um eine falsche Einschätzung der in 2 gezeigten Verkehrssituation zu vermeiden, müssten alle Geschwindigkeitskomponenten bzw. es müsste die Bewegungsrichtung des zweiten Fahrzeugs 2 gemessen werden.In 2 is a scenario 20th shown where the vehicle in front 2 starts to change from the right to the left lane. The overall speed remains during the lane change $\stackrel{}{v_{}}$$\overrightarrow{{}_2}$

of the second vehicle 2 constant. In contrast to the in 1 however, the direction of movement of the second vehicle changes 2 and thus the individual speed components of the second vehicle also change 2 . The speed $\stackrel{}{v_{}}$$\overrightarrow{{}_2}$

of the second vehicle 2 is made up of the components v _{x, 2} and v _{y, 2} , ie the components of speed $\stackrel{}{v_{}}$$\overrightarrow{{}_2}$

in the x-direction and the components of the speed $\stackrel{}{v_{}}$$\overrightarrow{{}_2}$

in the y-direction together. As the total speed of the second vehicle 2 remains the same and the second vehicle 2 additionally with v _{y, 2} moves in y-direction, the speed is also reduced in this case v _{x, 2} in X direction. The change in speed v _{x, 2} depends on the angle between the direction of travel and the x-direction. The radar of the first vehicle 1 also in this case only measures the x-component v _{x, 2} and thus only the change of v _{x, 2} . So it is not possible for the first vehicle 1 to differentiate on the basis of a radar measurement whether the x-component v _{x, 2} the speed $\stackrel{}{v_{}}$$\overrightarrow{{}_2}$

of the second vehicle 2 decreased due to braking or changing lanes. In both cases the first vehicle would have to 1 reduce your speed or change lanes. This can lead to an unnecessary braking maneuver, for example. To make a wrong assessment the in 2 To avoid the traffic situation shown, all speed components or the direction of movement of the second vehicle would have to be 2 be measured.

A similar problem also arises for a lane change assistant, which checks the traffic behind for possible dangers before overtaking.

In 3 is a scenario 30th with three vehicles driving one behind the other 1 , 2 , 3 shown. Would like the middle vehicle 1 the vehicle in front 2 overtaking, it must be ensured that following vehicles do not pull out and block the left lane required for overtaking or that there is a collision with following vehicles. In this case the middle vehicle would have to 1 the speed components or the direction of movement of the rear vehicle 3 know before the middle vehicle 1 overtaking the vehicle in front is safe 2 can initiate. Used by the middle vehicle 1 only the x component v _{x, 3} of the following vehicle 3 measured, the following vehicle could change lanes 3 from the middle vehicle 1 falsely interpreted as a braking process and thus a safety-critical overtaking process is initiated.

In 4th is another scenario 40 shown, in which an entry into a street is blocked (symbolized by a no entry sign). If lanes are blocked, for example in the area of construction sites or in the event of an accident, autonomous vehicles must be prompted to change lanes or turn off via the infrastructure. If the route of the vehicle is specified by the infrastructure, for example to avoid traffic jams, accidents or construction sites, it is necessary to check that the vehicle is correctly classified in turning lanes and to track the turning process in order to protect the vehicle from dangerous situations. This in 4th The vehicle shown is supposed to turn left at a junction, since the continuation of travel in the x-direction, ie straight ahead, is blocked. During the turning process, there are speed components v _{x, 1} , v _{y, 1} in the x-direction and in the y-direction. Would the vehicle 1 drive straight ahead into the blocked road, only the x-component would be of the traffic infrastructure v _{x, 1} measured. In order to check the execution of the request to turn and to request to turn again if necessary, it is necessary to be able to recognize a lane change or turning process. To do this, however, it is necessary to determine the direction of movement of the vehicle 1 to determine.

In 5 is a schematic representation of a cooperative radar system 50 illustrated according to a first embodiment of the invention. The radar system 50 comprises a first radar sensor R1 and one at a distance d to the first radar sensor R1 positioned second radar sensor R2 . The two sensors R1 , R2 that measure in different spatial directions are combined to form a cooperative radar system. The radar sensors R1 , R2 are designed as conventional stand-alone FMCW radar sensors and each measure a monostatic response from a target Z , ie a monostatic reflection signal RM , which is used to determine the distances d ₁₁ , d ₂₂ between the radar sensors R1 , R2 and the target object Z as well as the speed of the target Z can be used. In addition to the monostatic response can be from the two radar sensors R1 , R2 also a bistatic reflection signal RB be measured. The bistatic reflection signal RB contains information about the distance in the radial direction from the sensor R2 to the goal Z and in the direction of the radar sensor R1 towards the goal Z as well as information on the speed of the target object Z .

In the in 5 The first embodiment shown are the two sensors R1 , R2 by a clock signal generator Tkt synchronized, ie the two radar sensors R1 , R2 are operated fully coherently by a common clock. Such fully coherent operation can be advantageous in an autonomous vehicle, for example.

The transmission of the clock signal from the clock signal generator to the radar sensors R1 , R2 can, for example, via an electrical cable connection between the two radar sensors and the clock signal generator Tkt will be realized.

With the help of the monostatic response, the respective distance can be obtained from the bistatic response d ₁₁ , d ₂₂ from the spatial direction of both sensors R1 , R2 to the goal Z and the speed of the target Z be determined. By having both sensors R1 , R2 are set up at spatially distributed points, is a localization and a vectorial speed measurement of objects in such a cooperative radar system Z possible. To obtain this information, the measurement data from just one of the two sensors is used R1 , R2 needed.

Both sensors R1 , R2 start a measurement by a common trigger signal from a trigger unit TR which with the two sensors R1 , R2 connected either by cable or by radio. The common trigger signal ensures that the bistatic response can be measured within the limits specified by the sensor hardware and software, ie in particular limits for the beat frequency bandwidth, the ramp configuration and the AD converter.

About the monostatic response and the bistatic response on the first sensor R1 to differentiate is a frequency offset between the two radar sensors R1 , R2 realized, ie the FMCW signals from the first and second radar sensors R1 , R2 start at different frequencies f _0.1 , f _0.2 . The bandwidth B and the duration T of the FMCW signal is the same for both sensors R1 , R2 equal. As a result, the bistatic response is shifted by the frequency offset f _off = f _0.1 - f _0.2 to a predefined range in the baseband and can be separated from the monostatic response.

The beat signal S _{IF, 1} of the first radar sensor R1 is related to the transit times τ ₁₁ , τ _{12 of} the monostatic reflection signal and the bistatic reflection signal as follows: $$\begin{array}{l}{\mathrm{S.}}_{\mathrm{I.}\mathrm{F.}\mathrm{,1}}={\mathrm{S.}}_{\mathrm{I.}\mathrm{F.}\mathrm{,1,}mOnO}+{\mathrm{S.}}_{\mathrm{I.}\mathrm{F.}\mathrm{,1,}bi}=\text{cos}\left(2\pi \left(\frac{\mathrm{B.}}{T}{\tau }_{11}t+f_{0.1}{\tau }_{11}-\frac{\mathrm{B.}}{2T}{\tau }_{11}^2\right)\right)+\\ \text{cos}\left(2\pi \left(\left(f_{0.1}-f_{0.2}\right)t+\frac{\mathrm{B.}}{T}{\tau }_{12}t+f_{0.2}{\tau }_{12}-\frac{\mathrm{B.}}{2T}{\tau }_{12}^2\right)+{\mathrm{\varphi }}_{0.1}-{\mathrm{\varphi }}_{0.2}\right).\end{array}$$

verhalten sich proportional zum Abstand des Ziels Z. Die Zeiten τ₁₁ und τ_{12_}bezeichnen die Laufzeiten des monostatischen und des bistatischen Signals S_IF,1,mono , S_IF,1,bi . Die beiden Phasenwerte ϕ_0,1, ϕ_{0,2_}sind die Phasen der beiden Sensorsignale, deren Differenz aufgrund der gemeinsamen Taktung bekannt ist.The signal S _{IF, 1} includes a monostatic component S _{IF, 1} , mono and a bistatic component S _{IF, 1, bi} the one on the interaction between the second sensor R2 , the target object Z and the first sensor R1 is due. The terms $\frac{\mathrm{B.}}{T}{\tau }_{11}t,\frac{\mathrm{B.}}{T}{\tau }_{12}t$

behave proportionally to the distance of the target Z . The times τ ₁₁ and τ _{12_} denote the transit times of the monostatic and bistatic signals S _{IF, 1, mono} , S _{IF, 1, bi} . The two phase _values ϕ _0.1 , ϕ _{0.2_} are the phases of the two sensor signals, the difference of which is known due to the common timing.

Part of the in 5 shown beat spectrum measuring device 50 is also an evaluation unit 100a with a spectrum determination unit 101 to determine a raw data beat spectrum RBS based on the recorded measurement data S _{IF, 1} . The raw data beat spectrum RBS has a low frequency monostatic range MB , which corresponds to the monostatic reflection signal RM is assigned, and a higher frequency bistatic range BB on which the bistatic reflection signal RB is assigned to. The two different areas MB , BB of the raw data beat spectrum are in 7th illustrated.

Based on the raw data beat spectrum RBS is finally determined by a beat frequency determination unit 105 a monostatic beat frequency MZF and a bistatic beat frequency BZF of the target object Z determined.

On the basis of these beat frequencies and the known bandwidth B of the signal and the signal duration T, the transit times τ ₁₁ , τ _{12 of} the monostatic reflection signal and the bistatic reflection signal can be determined.

From the transit time τ _{11 of} the monostatic signal S _{IF, 1} , mono, the distance can be derived from the following equation d ₁₁ between the first sensor R1 and the target object Z to calculate: $${\mathrm{<figure-callout\; id="11"\; label="\tau "\; filenames="DE102019206806A1\_0019.png"\; state="\{\{state\}\}">\tau </figure-callout>}}_{11}=2\cdot \frac{d_{11}}{c}.$$

Here, c is the speed of light or the speed of propagation of the radar waves.

From the transit time τ _{12 of} the bistatic signal S _{IF, 1, bi} as well as the determined value d ₁₁ the distance between the first sensor R1 and the target object Z the distance can be calculated using the following equation d ₂₂ between the second sensor R2 and the target object Z to calculate: $${\mathrm{<figure-callout\; id="12"\; label="\tau "\; filenames="DE102019206806A1\_0019.png"\; state="\{\{state\}\}">\tau </figure-callout>}}_{12}=\frac{{\mathrm{<figure-callout\; id="11"\; label="d"\; filenames="DE102019206806A1\_0019.png"\; state="\{\{state\}\}">d</figure-callout>}}_{11}+d_{\mathrm{22nd}}}{c}.$$

From a simple trigonometric calculation based on the now known triangle sides d , d ₁₁ , d ₂₂ can then change the position P of the target object Z relative to the radar system 50 determine.

The speed v = v ₁₁ + v ₂₂ , where v , v ₁₁ , v ₂₂ are vector quantities and v ₁₁ in the direction of d ₁₁ and v ₂₂ in the direction of d ₂₂ shows, results from the Doppler frequencies of the monostatic and bistatic sensor signals S _{IF, 1, mono} , S _{IF, 1, bi}

The Doppler frequency results from the difference between the frequency of an emitted signal and the frequency of the reflected signal. The Doppler frequency can also be calculated with the aid of several signals following one another at a time interval T. The Doppler frequency results from the phase difference between the individual signals at the respective beat frequency of the target object. The Doppler frequency can be calculated in different ways. With static targets, the phase of the beat signal is constant for successive signals. In the case of moving objects, the phase of the beat signal changes proportionally to the change in the distance and thus proportional to the speed in the case of successive signals. This change in phase over time gives the Doppler frequency. This method is also known as the “Range Doppler Algorithm” or “Range Doppler Processing”.

The Doppler frequency f _{d, mono} of the monostatic signal component results as follows: $$f_{d,mOnO}=\frac{2f_{0.1}{v}_{11}}{c}.$$

If the transit time τ _{11 of} the monostatic signal is known, the Doppler frequency f _{d, mono} the speed v ₁₁ , ie the velocity component of the target object Z in the direction of the path between the first sensor R1 and the target object Z determine.

The Doppler frequency f _{d, bi} of the bistatic sensor signal results as follows: $$f_{d,bi}=f_{0.2}\frac{{\mathrm{<figure-callout\; id="11"\; label="v"\; filenames="DE102019206806A1\_0019.png"\; state="\{\{state\}\}">v</figure-callout>}}_{11}+v_{\mathrm{22nd}}}{c}.$$

From the bistatic Doppler frequency f _{d, bi} as well as the determined speed component v ₁₁ the second speed component can then also be used v ₂₂ in the direction of the path between the second sensor R2 and the target object Z determine. From the two vectorial speed components v ₁₁ , v ₂₂ the total vector velocity v of the target object can also be calculated Z calculate to: $$v={\mathrm{<figure-callout\; id="11"\; label="v"\; filenames="DE102019206806A1\_0019.png"\; state="\{\{state\}\}">v</figure-callout>}}_{11}+v_{\mathrm{22nd}}.$$

In 6th is a schematic representation of a cooperative radar system 60 shown according to a second embodiment. The radar system 60 as well as in 5 illustrated radar system 50 a first radar sensor R1 and one at a distance d to the first radar sensor R2 positioned second radar sensor R2 . The in 6th illustrated radar system 60 is different from the one in 5 shown radar system 50 not a fully coherent system, but a quasi-coherent system. The difference to the in 5 The embodiment shown is that the in 6th system shown does not have a clock Tkt for the two sensors. As a result, the sensor signals from different sensors do not have a fixed phase relationship. Instead, the two radar sensors R1 , R2 using a known reference target RO and operated quasi-coherently through appropriate signal processing. In such an operation with a reference target RO the bistatic response becomes with the help of the known and the measured distance dref to the reference target RO corrected.

The two sensors R1 , R2 that measure in different spatial directions are combined to form a cooperative radar system. The radar sensors R1 , R2 are designed as conventional stand-alone FMCW radar sensors and each measure a monostatic response from the target Z and the reference target RO , ie a monostatic reflection signal RM which is used to determine the distance d ₁₁ , d _ref as well as the speed of the target Z or reference target RO in the radial spatial direction from the sensor R1 , R2 to the goal Z or reference target RO can be used. In addition to the monostatic response, as in the 5 shown embodiment of the two radar sensors R1 , R2 also a bistatic reflection signal RB measured.

The bistatic reflection signal contains information on the distance and speed in the radial direction from the sensor R2 to the goal Z and in the direction of the radar sensor R1 towards the goal Z . The same applies to the reference target RO .

As with the in 5 The embodiment shown start both sensors R1 , R2 a measurement by a common trigger signal from the trigger unit TR which with the two sensors R1 , R2 connected either by cable or by radio. The common trigger signal ensures that the bistatic response can be measured within the limits specified by the sensor hardware and software, ie in particular limits for the beat frequency bandwidth, the ramp configuration and AD converter.

About the monostatic response and the bistatic response on one sensor R1 to differentiate is a frequency offset between the two radar sensors R1 , R2 realized, ie the FMCW signals of the radar sensors start at different frequencies. The bandwidth and duration of the FMCW signal is the same for both sensors R1 , R2 equal. As a result, the bistatic response is shifted by the frequency offset f _off to a predefined range in the baseband and can be separated from the monostatic response.

After determining a beat spectrum, it now takes place differently than in 5 shown embodiment a correction of the bistatic portion of the beat spectrum. This process is related to 7th explained in detail.

The corrected beat spectrum is then analogous to that in 5 described procedure used to set a position P and a speed v of the target object Z to determine.

As related to 5 explained, with the help of the monostatic response from the bistatic response, the distance and the speed in the direction of the sensor R2 to the target object Z be determined. Will both sensors R1 , R2 set up at spatially distributed points, then in such a cooperative radar system a localization and a vectorial speed measurement of objects is necessary Z possible. To obtain this information, the measurement data from only one of the two sensors is used R1 , R2 needed.

The quasi-coherent operation can also be implemented with the help of a GPS-controlled system or a radio link between the individual sensors. GPS or radio links between the sensors can be the trigger unit TR replace. Both variants can be used for coherent and quasi-coherent operation.

With GPS signals, a very stable "Pulse Per Second" signal (GPS 1 PPS) is sent (frequency 1 Hz). This signal can be received by the sensors of the system during operation outdoors and a trigger signal can then be generated locally from it. This can be implemented with the help of a separate phase-locked loop, which uses the 1 PPS signal as the reference signal.

A radio connection between the sensors requires a master-slave operation between the sensors. The master sensor can send a trigger signal to the slave sensor. This can be done both within the radar frequency band used for distance measurement and with additional hardware in other frequency bands. In addition, frequency and phase offsets can be compensated for, similar to a pilot tone method, with the aid of a previously defined signal form which is sent from the master to the slave sensor.

An example of synchronization using a direct radio link between two radar sensors is given in the paper “Precise Distance Measurement with Cooperative FMCW Radar Units” by A. Stelzer, M. Jahn and S. Scheiblhofer, 1-4244-1463-6 / 08 / $ 25.00 2008 IEEE, pp. 771 to 774. However, only the distance between the sensors is measured here.

Part of the in 6th shown beat spectrum measuring device 60 is also an evaluation unit 100 with a spectrum determination unit 101 to determine a raw data beat spectrum RBS based on the recorded measurement data S _{IF, 1} . The raw data beat spectrum RBS has a low frequency monostatic range MB , which corresponds to the monostatic reflection signal RM is assigned, and a higher frequency bistatic range BB on which the bistatic reflection signal RB assigned. The raw data beat spectrum RBS is sent to a reference frequency determination unit 102 which is set up to a frequency RF of the reference target RO in the bistatic area BB based on the determined raw data beat spectrum RBS to determine. The frequency RF of the reference target RO is sent to a shift frequency determining unit 103 that is set up to transmit a value f _diff a frequency shift of the beat spectrum RBS in the bistatic area BB , based on the frequency determined by the measurement RF of the reference target RO in the bistatic area BB and a previously known setpoint frequency SFB of the bistatic reflection signal of the reference target RO to determine.

The value f _diff the frequency shift and the raw data beat spectrum RBS are attached to a displacement unit 104 transmitted. The displacement unit is used to move the bistatic part of the raw data beat spectrum RBS by the determined value of the frequency shift f _diff to move. In this process, a corrected beat spectrum BS _{k is} determined, which can serve as the basis for a position calculation and a speed calculation.

Based on the corrected beat spectrum BS _k is finally determined by a beat frequency determination unit 105 a monostatic beat frequency MZF and a bistatic beat frequency BZF of the target object Z determined.

In 7th is a graph 70 illustrates what a so-called beat spectrum of a measurement with the in 6th shown arrangement 60 illustrated. This in 7th The beat spectrum shown was recorded in quasi-coherent operation. It shows the magnitude M in decibels plotted against the frequency f in kilohertz.

During the measurement, the two radar sensors were not fully synchronized R1 , R2 by a clock signal Tkt instead of. Instead, a monostatic reflection signal was used RM and a bistatic reflection signal RB both from the target object Z as well as a reference target RO measured. In the beat spectrum are the monostatic range MB and the bistatic area BB from each other by a vertical black line L. separated, which is approximately at a frequency of 250 kHz. In the monostatic range MB are maxima RF , ZF that the reference target RO and are assigned to the target object ZO. The frequency IF that the target object Z corresponds to is approximately 50 kHz and the frequency RF that the reference target RO corresponds to is approximately 100 kHz.

Also in the bistatic area BB of the beat spectrum are maxima RFB , ZFB corresponding to the reference target RO and correspond to the target object ZO, recognizable. The frequency ZFB, which corresponds to the target object ZO, is approximately 530 kHz and the frequency RFB that the reference target RO is approximately 570 kHz. The solid line indicates the raw data RD of the radar sensor R1 , ie the data which has not yet been used with the help of the reference target RO corrected. By correcting the beat spectrum BS in the bistatic range BB become the frequencies of the two target objects RO , Z shifted to the right in the beat spectrum. The shifted spectrum CD is indicated by a dashed line. With the help of the corrected spectral data CD, the distance d ₂₂ between the second radar sensor R2 and the goal Z determine. Knowing the distances d ₁₁ , d ₂₂ between the radar sensors R1 , R2 and the goal Z can now be the unknown destination Z localize by triangulation, ie its position P determine. Furthermore, the vector velocity can also be determined by determining the Doppler frequency v of the target object Z be determined. To determine both variables, monostatic and bistatic responses are evaluated. These supply distance values or speed values in two spatial directions.

In 8th is a flow chart 800 shown, which illustrates a fully coherent beat frequency measurement method for determining a beat spectrum.

At the step 8.I is first a monostatic radar signal RM of a target object Z from a radar sensor R1 detected. Furthermore, in step 8.II a bistatic, non-coherent electromagnetic reflection signal RB , which is a reflection signal of a target object Z includes, with the same radar sensor R1 measured. At the step 8.III the recorded measurement data are used to create a raw data beat spectrum RBS to determine. The raw data beat spectrum RBS includes a low frequency monostatic range MB , which corresponds to the monostatic reflection signal RM is assigned, and a higher frequency bistatic range BB which corresponds to the bistatic reflection signal RB assigned. At the step 8.IV is based on the raw data beat spectrum RBS a monostatic beat frequency MZF and a bistatic beat frequency BZF of the target object Z determined.

In 9 is a flow chart 900 shown, which illustrates a quasi-coherent beat frequency measurement method for determining a beat spectrum. At the step 9.I is initially a monostatic Radar signal RM of a target object Z and a reference target RO from a radar sensor R1 detected. Furthermore, in step 9.II a bistatic, non-coherent electromagnetic reflection signal RB , which is a reflection signal of a target object Z and a reference target RO includes, with the same radar sensor R1 measured. Both step 9.III the recorded measurement data RM , RB used to create a raw data beat spectrum RBS too determined. The raw data beat spectrum RBS includes a low frequency monostatic range MB , which corresponds to the monostatic reflection signal RM is assigned, and a higher frequency bistatic range BB which corresponds to the bistatic reflection signal RB assigned.

At the step 9.IV becomes a frequency RFB of the reference target RF in the bistatic area BB based on the determined raw data beat spectrum RBS determined. The reference target RO corresponds to a maximum of the spectrum in the bistatic range. From the known location of the reference target RO is also a setpoint frequency SFB of the bistatic reflection signal RB of the reference target RO known with the one from the raw data beat spectrum RBS known frequency RFB can be compared.

At the step 9.V now becomes a value f _diff a frequency shift of the beat spectrum in the bistatic range BB based on the frequency determined by the measurement RFB of the reference target RO in the bistatic area BB and the previously known setpoint frequency SFB of the bistatic reflection signal RB of the reference target RO determined by forming the difference.

At the step 9.VI the raw data beat spectrum RBS is increased by the determined value f _diff shifted the frequency shift, creating a corrected beat spectrum BS _k is obtained.

Finally, at the step 9.VII based on the corrected beat spectrum BS _k a monostatic beat frequency MZF and a bistatic beat frequency BZF of the target object Z determined.

In 10 is a flow chart 1000 which illustrates a speed measurement method according to an embodiment of the invention.

At the step 10.I the in 8th or 9 illustrated beat spectrum measurement method performed. This is followed by the step 10.IIa determining a first Doppler frequency f _{d, mono} of the monostatic reflection signal RM of the target object Z in the monostatic range MB of the determined beat spectrum RBS , BS _k . Additionally takes place at the step 10.IIb determining a second Doppler frequency f _{d, bi} of the bistatic reflection signal RB of the target object Z in the bistatic area BB of the determined beat spectrum RBS , BS _k . Furthermore, in step 10.III a first speed component v ₁₁ of the target object Z based on the first Doppler frequency f _{d, mono} determined and at the step 10.IV a second speed component v ₂₂ of the target object Z based on the second Doppler frequency f _{d, bi} and the first speed component v ₁₁ determined. Eventually it becomes a vector velocity V of the target object Z based on the determined first speed component v ₁₁ and the determined second speed component v ₂₂ determined. The determination of the Doppler frequencies f _{d, mono} , f _{d, bi} as well as the speed V can be related to the 5 illustrated manner.

In 11 is a flow chart 1100 which illustrates a position determination method according to an embodiment of the invention. At the step 11.I the in 8th or 9 illustrated beat spectrum measurement method performed. This is followed by the step 11.II determining distances d ₁₁ , d ₂₂ of the sensors R1 , R2 to the target object Z based on the corrected beat spectrum BS _k . Finally, at the step 11.III a position P of the target object Z by triangulation based on the determined distances d ₂₁ , d ₁₂ determined. The determination of the distances d ₁₁ , d ₂₂ was used in connection with the detailed description of 5 and 6th explained in detail.

In 12 is a speed determining device 120 shown schematically according to an embodiment of the invention. The speed determination device 120 includes the in 5 or alternatively in 6th shown beat spectrum measuring device 50 , 60 . Furthermore, the speed determination device comprises 120 a Doppler frequency determination unit 12 for determining a monostatic Doppler frequency f _{d, mono} and a bistatic Doppler frequency f _{d, bi} on the basis of the beat spectrum measuring device 50 , 60 determined beat spectrum RBS or the monostatic and bistatic beat frequencies derived therefrom MZF , BZF . The one from the Doppler frequency determination unit 12 determined Doppler frequencies f _{d, mono} , f _{d, bi} is sent to a speed determination unit 13 transmitted, which is also part of the speed determination device 120 is. The speed determination unit 13 is set up to have a first speed component v ₁₁ of the target object Z based on the monostatic Doppler frequency f _{d, mono} and a second speed component v ₂₂ of the target Z based on the bistatic Doppler frequency f _{d, bi} and the first speed component v ₁₁ to determine. Part of the speed determination device 120 is also a speed determination unit 13a for determining a vector velocity V of the target object Z based on the determined first and second speed components v ₁₁ , v ₂₂ .

In 13 is a schematic representation of a position determining device 130 illustrated according to an embodiment of the invention. The position determining device 130 includes the in 5 or alternatively in 6th shown beat spectrum measuring device 50 , 60 . Part of the position determination device 130 is also a runtime determination unit 14th for determining a first transit time τ _{11 of} the monostatic reflection signal RM based on frequency MZF of the target object Z in the monostatic range MB of the determined beat spectrum and to determine a second transit time τ _{12 of} the bistatic reflection signal RB based on frequency BZF of the target object Z in the bistatic area BB of the determined beat spectrum RBS , BS _k .

The position-determining device also includes 130 a distance determining unit 15th for determining distances d ₁₁ , d ₂₂ the radar sensors to the target object Z based on the beat spectrum RBS or the monostatic and bistatic beat frequencies derived therefrom MZF , BZF . Part of the position determination device 130 is also a position determination unit 16 which a position P of the target object Z by triangulation based on the determined distances d ₁₁ , d ₂₂ determined.

In 14th and 15th are the results of a localization and speed measurement with an in 6th illustrated measuring device illustrates. The sensors connected to the cooperative system R1 , R2 are at the positions (x, y) = (0; 0) and at (x, y) = (2.03; 0) meters. The unknown destination Z moves in a straight line over a distance S of 2.5 meters and at a speed of 1 m / s from both sensors R1 , R2 path. The actual path R of the goal Z is indicated by a dashed line. In 14th were the measurement data from the left sensor R1 in position (x; y) = (0; 0) used for evaluation. In 15th was the data from the right sensor R2 used when (x; y) = (2.03; 0). The circles mark the local position P of target Z while moving. The arrows indicate the measured direction of movement D of the target Z and its length the measured speed. The result is an average deviation of the measured positions P and the actual positions of the target Z of about 26 millimeters. The direction of movement D of the target Z was determined with a deviation of less than 3 °. These results illustrate the applicability of the in 6th shown radar system 60 for the in 1 to 4th illustrated scenarios.

Finally, it is pointed out once again that the methods and devices described above are merely preferred exemplary embodiments of the invention and that the invention can be varied by a person skilled in the art without departing from the scope of the invention, insofar as it is specified by the claims. For the sake of completeness, it is also pointed out that the use of the indefinite article “a” or “an” does not exclude the possibility of the relevant features being present several times. Likewise, the term “unit” does not exclude that it consists of several components, which may also be spatially distributed.

Claims (17)

Beat frequency measuring method, comprising the steps: - Monostatic measurement of an electromagnetic reflection signal, which comprises a reflection signal (RM) of a target object (Z), with at least one of at least two sensors (R1, R2) of a cooperative sensor system (50, 60), bistatic measurement of an electromagnetic reflection signal (RB), which comprises a reflection signal of a target object (Z), with at least two sensors (R1, R2) of the cooperative sensor system, - determination of a beat spectrum (RBS, BS _k ) on the basis of the recorded measurement data (RM, RB), the beat spectrum comprising a low-frequency monostatic range (MB), which is assigned to the monostatic reflection signal (RM), and a higher-frequency bistatic range (BB), which is assigned to the bistatic reflection signal (RB), - determining a monostatic beat frequency (MZF) of the target object (Z) in the monostatic range (MB) based on the determined beat spectrum (RBS, BS _k ) - Determining a bistatic beat frequency (BZF) of the target object (Z) in the bistatic region (BB) on the basis of the determined beat spectrum (RBS, BS _k ). Procedure according to Claim 1 , wherein the sensors (R1, R2) comprise radar sensors and / or lidar sensors. Procedure according to Claim 1 , wherein the sensors (R1, R2) comprise FMCW sensors. Method according to one of the Claims 1 to 3 , wherein the at least two sensors (R1, R2) are operated fully coherently by a common clock. Method according to one of the Claims 1 to 3 , the at least two sensors (R1, R2) being operated quasi-coherently by an additional monostatic and bistatic measurement of a reference target (RO) whose position is known. Procedure according to Claim 5 , wherein a calibration for determining a corrected beat spectrum (BS _k ) is carried out, with the following steps: determining a frequency (RFB) of the reference target (RO) in the bistatic range (BB) based on the determined beat spectrum (RBS), - determining a value (f _diff ) of a frequency shift of the beat spectrum in the bistatic range (BB), based on the frequency (RFB) of the reference target (RO) in the bistatic range (BB) determined by the measurement and a previously known target frequency (SFB) of the bistatic reflection signal ( RB) of the reference target (RO), - Shifting the beat spectrum (RBS) by the determined value (f _diff ) of the frequency shift. Procedure according to Claim 5 or 6th , the reference target (RO) being designed as a passive reference target. Procedure according to Claim 5 or 6th , the reference target (RO) being designed as an active reference target. Position determination method, comprising the steps: - Carrying out the method according to one of the Claims 1 to 8th - Determination of a first transit time (τ ₁₁ ) of the monostatic reflection signal (RM) on the basis of the frequency (MZF) of the target object (Z) in the monostatic range (MB) of the determined beat spectrum (RBS, BS _k ), - Determination of a second transit time ( τ ₁₂ ) of the bistatic reflection signal (RB) based on the frequency (BZF) of the target object (Z) in the bistatic area (BB) of the determined beat spectrum (RBS, BS _k ), - Determination of distances (d ₁₁ , d ₂₂ ) of the sensors (R1, R2) to the target object (Z) on the basis of the determined transit times (τ ₁₁ , τ ₁₂ ), - determination of a position (P) of the target object (Z) by triangulation on the basis of the determined distances (d ₁₁ , d ₂₂ ) . Speed determination method, comprising the steps: - Carrying out the method according to one of the Claims 1 to 8th - Determination of a first Doppler frequency (f _{d, mono} ) of the monostatic reflection signal (RM) of the target object (Z) in the monostatic range (MB) of the determined beat spectrum (RBS, BS _k ), - Determination of a second Doppler frequency (f _{d, bi} ) of the bistatic reflection signal (RB) of the target object (Z) in the bistatic area (BB) of the determined beat spectrum (RBS, BS _k ), - Determination of a first speed component (v ₁₁ ) of the target object (Z) on the basis of the first Doppler frequency (f _{d, mono} ), - determination of a second speed component (v ₂₂ ) of the target object (Z) on the basis of the second Doppler frequency (f _{d, bi} ) and the first speed component (v ₁₁ ), - determination of a vectorial speed (V) of the target object (Z) on the basis of the determined first speed component (v ₁₁ ) and the determined second speed component (v ₂₂ ). Beat spectrum measuring device (50, 60) for determining a beat spectrum (RBS, BS _k ), comprising: - a first sensor (R1) for monostatic measurement of an electromagnetic reflection signal which comprises a reflection signal (RM) of a target object (Z), second sensor (R2) with known distance (d) to the first sensor (R1) for bistatic measurement of an electromagnetic reflection signal (RB), which comprises a reflection signal of the target object (Z), - a spectrum determination unit (101) for determining a beat spectrum (RBS, BS _k ) on the basis of the recorded measurement data (RB, RM), the beat spectrum (RBS, BS _k ) being a low-frequency monostatic area (MB), which is assigned to the monostatic reflection signal (RM), and a higher-frequency bistatic area ( BB), which is assigned to the bistatic reflection signal (RB), comprises - a beat frequency determination unit (105) for determining a monostatic beat frequency (MZF) of the target object (Z) in the monostatic range (MB) based on the determined beat spectrum (RBS, BS _k ) and for Determining a bistatic beat frequency (BZF) of the target object (Z) in the bistatic area (BB) on the basis of the determined beat spectrum (RBS, BS _k ). Beat spectrum measuring device (60) according to Claim 11 , wherein the spectrum determination unit for determining a corrected beat spectrum (BS _k ) comprises: - a reference frequency determination unit (102) for determining a frequency (RF) of the reference target (RO) in the bistatic range (BB) on the basis of the determined beat spectrum (RBS) ), - a shift frequency determination unit (103) for determining a value (f _diff ) of a frequency shift of the beat spectrum in the bistatic range (BB) based on the frequency (RF) of the reference target (RO) in the bistatic range (BB) determined by the measurement ) and a previously known setpoint frequency (SFB) of the bistatic reflection signal (RB) of the reference target (RO), - a shift unit (104) for shifting the beat spectrum (RBS) by the determined value (f _diff ) of the frequency shift. Position determining device (130), comprising: - the beat spectrum measuring device (50, 60) after Claim 11 or 12 - A transit time determination unit (14) for determining a first transit time (τ ₁₁ ) of the monostatic reflection signal (RM) on the basis of the frequency (MZF) of the target object (Z) in the monostatic range (MB) of the determined beat spectrum (RBS, BS _k ) and to determine a second transit time (τ ₁₂ ) of the bistatic reflection signal (RB) based on the frequency (BZF) of the target object (Z) in the bistatic area (BB) of the determined beat spectrum (RBS, BS _k ), - a distance determination unit (15) for Determination of distances (d ₁₁ , d ₂₂ ) of the sensors (R1, R2) to the target object (Z) on the basis of the determined transit times (τ ₁₁ , τ ₁₂ ), - a position determination unit (16) for determining a position (P) of the Target object (Z) by triangulation based on the determined distances (d ₁₁ , d ₂₂ ). Speed determining device (120), comprising: - the beat spectrum measuring device (50, 60) according to Claim 11 or 12 - A Doppler frequency determination unit (12) for determining a first Doppler frequency (f _{d, mono} ) of the monostatic reflection signal (RM) of the target object (Z) in the monostatic range (MB) of the determined beat spectrum (RBS, BS _k ) and for determining a second Doppler frequency (f _{d, bi} ) of the bistatic reflection signal (RB) of the target object (Z) in the bistatic area (BB) of the determined beat spectrum (RBS, BS _k ), - a speed component determination unit (13) for determining a first speed component (v ₁₁ ) of the target object (Z) based on the first Doppler frequency (f _{d, mono} ) and for determining a second speed component (v ₂₂ ) of the target object (Z) based on the second Doppler frequency (f _{d, bi} ) and the first speed component (v ₁₁ ), - a speed determination unit (13a) for determining a vectorial speed of the target object (Z) on the basis of the determined first and second speed components (v ₁₁ , v ₂₂ ). Movable object, comprising - a control unit for autonomous or semi-autonomous control of a movement of the movable object and - a beat spectrum measuring device (50, 60) Claim 11 and / or a position determining device (130) according to Claim 13 and / or a speed determination device (120) according to Claim 14 . Computer program product with a computer program which can be loaded directly into a storage unit of a control device of a movable object, with program sections to carry out all steps of a method according to one of the Claims 1 to 10 execute when the computer program is executed in the computer unit. Computer-readable medium on which program sections executable by a computer unit are stored in order to carry out all steps of the method according to one of the Claims 1 to 10 execute when the program sections are executed by the computer unit.

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