DE102012004320A1 - Method for detecting environment of vehicle e.g. motor car, involves determining angle information for recognized object based on vehicle velocity and frequency information determined over oscillations of reflected wave train - Google Patents

Abstract

The method involves executing a pulse response measurement of a pulse that comprises oscillations of a transmitted wave train, is emitted. A time-resolved echo signal (1) is acquired and evaluated. Determination is performed to check whether an echo pulse (7) is incorporated in the echo signal. The frequency information is determined over the oscillations of the reflected wave train, if the echo signal comprises the echo pulse. The angle information is determined for a recognized object (24) based on the determined vehicle velocity and frequency information. An independent claim is included for device for detecting environment of vehicle.

Description

The invention relates to a method for improved environment detection of a vehicle and a corresponding device.

In vehicles, in particular motor vehicles, systems are used which, in order to fulfill their functionality, require information about the presence of objects in the surroundings of the vehicle and about their position and / or extent. By way of example, park support systems may be mentioned here which assist a driver of a vehicle when parking the vehicle in a parking space or perform this parking process semi-automatically with reduced driver intervention.

For example, environment detection devices which operate according to the so-called pulse-measuring method are known from the prior art. By means of a sensor, which works as a transmitter, a temporally short pulse is emitted into the environment. This is reflected on objects in the environment and detected by a receiver operated as a sensor. On the basis of the runtime can with knowledge of the propagation speed. the emitted signal to the distance of the object of transmitter and receiver, taking into account the geometric arrangement of the transmitter and receiver on the vehicle be deduced. Often one and the same sensor is used both as a transmitter and subsequently as a receiver. Particularly common are so-called ultrasonic measuring systems in which ultrasonic transducers are used as measuring sensors which emit sound signals in the ultrasonic range, for example at a sound frequency of about 50 kHz.

With the known from the prior art automotive systems thus a radial distance information, but not an angle information can be determined. This is due to the fact that the sensors used radiate sound in a relatively large angular range and can also detect reflected sound pulses from a relatively large angular range.

In order to be able to localize objects in the environment, it is necessary to perform several measurements with different measurement geometries. A measuring geometry is given here by the relative positioning of transmitter and receiver relative to each other and in particular relative to the environment. If an ultrasound transducer is used both as a transmitter and as a receiver, then a second measurement geometry deviating from the first one can be produced by virtue of the fact that the ultrasound transducer can be moved relative to the surroundings, i. H. in this, being moved.

Localization is often done using a map of the environment in which each area in the environment has one cell associated with an area map. Each cell is in turn assigned at least one occupancy value, which is a measure that the area of the cell corresponding to the cell is occupied. The occupancy values are usually fused from the obtained measurement data using the measurement results of successive measurements using a probabilistic approach, for example according to the Bayesian theorem. After a plurality of measurements, the cells have a high occupancy value at which an object has been detected according to the distance measurement, and those cells for which an object has rarely or never been measured in the distance measurements due to the distance information have a small occupancy value. In the case of a measurement, the occupancy values of all cells whose areas in the surroundings have a radial distance which coincides with the determined distance and which additionally lie in the angular range from which ultrasound signals can be reflected back are increased here.

From the DE 10 2004 047 087 A1 A method for object verification in a radar system for a motor vehicle is known in which distances and relative speeds of located objects are determined on the basis of received radar echoes. The system uses a Frequency Modulated Continuous Wave (FMCW) radar, which modulates the frequency of the transmitted radar signal in a ramp. From a frequency difference between the transmitted and received signal can be closed to the distance and the relative speed, the frequency shift in addition to the transit time effect also has a caused by a Doppler shift frequency component.

From the DE 10 2009 028 992 A1 For example, a method and a device for determining the position of an obstacle relative to a vehicle, in particular a motor vehicle, for use in a driver assistance system of the vehicle are known. In this case, at least one ultrasonic pulse is emitted at a predetermined transmission frequency, the emitted ultrasonic pulse is reflected at the obstacle and received again as an echo pulse. The reception frequency of the received echo pulse is determined and, in dependence thereon, an absolute value of an angle of incidence of the echo pulse is determined. From the absolute value of the angle of incidence of the echo pulse, two hypotheses for an angular position of the obstacle are established and one of the hypotheses is identified as true by means of an absolute value of an angle of incidence of at least one further echo pulse reflected at the obstacle. The angle determination is based on the Evaluation of a map of the sensor. The frequency received by the sensor is dependent on the angle of incidence of the sound wave on the sensor. The method compensates for a frequency interference caused by a Doppler shift.

From the EP 1 879 048 A1 are known a method for distance measurement and ultrasonic distance sensor, in which a membrane for emitting and receiving of ultrasound is provided, wherein the membrane has a resonant frequency range and is coupled to a drive means for driving the membrane to a vibration for generating ultrasound, wherein a detection unit for Detecting a differential speed is provided to an obstacle and wherein the membrane is excited by the drive means to a vibration outside the resonant frequency range in response to the differential speed such that the frequency of a received, reflected from the obstacle signal is in the resonant frequency range of the membrane.

The invention has for its object to provide an improved Umweisfassungsverfahren and an improved environment detection device, which in particular easily allows a more reliable angular position determination of objects in the environment.

The object is achieved by a method having the features of patent claim 1 and a device having the features of claim 7. Advantageous embodiments of the invention will become apparent from the dependent claims.

The invention is based on the idea that in an environment detection, which takes place in a moving vehicle, a knowledge of the vehicle movement can be exploited to obtain a significantly improved angle information in an evaluation of ultrasonic measurement signals in a pulse measuring device. For this purpose, it is utilized that the movement of the measuring arrangement, i. H. of the transmitter and the receiver, relative to the objects in the environment leads to a frequency shift between the vibrations of the transmitted transmit pulse and the vibrations in the received echo pulse. This frequency shift is dependent on the relative speed of the measuring system relative to the object in each case along the signal propagation path. The component of the vehicle speed, which operates along the signal propagation direction, thus depends on the angle of the signal travel path with respect to the direction of movement, along which the measuring device moves at the vehicle speed.

In particular, a method is thus proposed for improved environment detection of a vehicle, comprising the steps:
Performing a pulse echo measurement by emitting a pulse comprising a transmit pulse train having oscillations, the vibrations of the transmit train having a transmit frequency, and detecting an echo signal in a time resolved manner; Evaluating the echo signal by determining whether at least one first echo pulse is included in the echo signal, and if so, determining frequency information about the echo wave train oscillations, at least for the first echo pulse comprising echo wave train having oscillations; Detecting a vehicle speed; Determining an angle information based on the vehicle speed and the frequency information for at least one detected object.

Further, there is advantageously provided an apparatus for improved vehicle surroundings detection comprising: a pulse echo measuring means for performing a pulse echo measurement in which a pulse comprising a transmit pulse train having oscillations is emitted, the train of vibrations having a transmit frequency and a time resolved echo signal and an evaluation device for evaluating the echo signal, which comprises an echo pulse detection device for determining whether at least one first echo pulse is contained in the echo signal, and a frequency determination device for at least one detected first echo pulse, which comprises a vibrating Echowellenzug, frequency information about the vibrations of the Echowellenzugs determine vehicle speed device for receiving or detecting a speed of the vehicle, and an angle information detecting means for Ermitt eln of an angle information based on the vehicle speed and the frequency information for at least one of the at least one echo pulse associated detected object.

wobei f_E die Empfangsfrequenz, f_S die Sendefrequenz, v die Fahrzeugsgeschwindigkeit, und c die Schallausbreitungsgeschwindigkeit und α der Winkel gemessen gegen die Richtung der Geschwindigkeit des Fahrzeugs ist, oder der Gleichung c / v( 1 / Y+1) = cos(α) mit

mit Δf = f_E – f_S umfasst. Mit plausiblen Lösungen ist hierbei gemeint, dass nur solche Lösungen betrachtet werden sollen, die zu einem Schallausbreitungsweg gehören, der in dem Winkelmessbereich des Sensors liegt. Die Gleichungen sind nämlich teilweise für Werte von α lösbar, die mit einer Richtung korrespondieren, welche eine Schallausbreitung in oder aus einer Winkelbereich andeutet, der außerhalb des Winkelmessbereichs des Sensors liegt. Welche Lösungen nicht plausibel sind, ergibt sich aus einfachen geometrischen Überlegungen. Z. B. wird geprüft, ob ein ermittelter Winkel in einem Winkelmessbereich des Sensors liegt, der bezüglich der Bewegungsrichtung durch eine Sensorcharakteristik und die Anordnung im Fahrzeug gegeben ist. Die angegebenen Gleichungen sind äquivalent und unterscheiden sich lediglich dadurch, dass diese für bereits unterschiedlich errechnete bzw. ermittelte Anfangswerte ausgelegt sind. Insgesamt ergibt sich die Gleichung anhand folgender Überlegungen.The advantage of the invention is that on the basis of the determined frequency information, which may be a frequency difference to the previously known transmission frequency or an absolute information about the frequency of the wave train in the received echo pulse, an angle information can be derived in a simple manner, the localization of objects in significantly improved because the angular range from which the reflection can be made, is significantly limited under that angular range, originally by the Detection angle range of the measuring arrangement was set. Depending on whether the absolute frequency or only the difference frequency of the oscillations of the received pulse is determined relative to the frequency of the oscillations of the transmission pulse, in one embodiment the angle information is calculated from the frequency information based on a Doppler shift equation, the angle information being all plausible solutions of the equation c / v (β-1 / β + 1) = cos (α) With

where f _{E is} the reception frequency, f _{S is} the transmission frequency, v is the vehicle speed, and c is the sound propagation velocity and α is the angle measured against the direction of the speed of the vehicle, or the equation c / v (1 / Y + 1) = cos (α) With

with Δf = f _E -f _S. In this case, plausible solutions mean that only those solutions are to be considered that belong to a sound propagation path that lies in the angle measuring range of the sensor. In fact, the equations are partially solvable for values of α that correspond to a direction that indicates sound propagation into or out of an angular range that is outside the angular range of the sensor. Which solutions are not plausible results from simple geometrical considerations. For example, it is checked whether a determined angle is in an angle measuring range of the sensor, which is given with respect to the direction of movement by a sensor characteristic and the arrangement in the vehicle. The given equations are equivalent and differ only in that they are designed for already differently calculated or determined initial values. Overall, the equation is based on the following considerations.

While approaching an object, the transmitter transmits vibrations at a constant transmission frequency. In the transmission medium air, a sound wave propagates whose wavelength is linked to the transmission frequency via the sound propagation speed, a property of the transmission medium. With known sound propagation speed, the wavelength can thus be determined. At a distance of this wavelength, the wavefronts of a sound signal are expected at a stationary sensor. However, since the vehicle is moving in the direction of the sound radiation, the vehicle has "traced" a previously transmitted wavefront so that the transmission of the next wavefront takes place at a spatially shorter distance from the previously emitted wavefront than would have been the case for a stationary sensor , Thus, a sound wave with a shorter wavelength arrives at a stationary object, which in turn means that the sound fronts arrive at shorter time intervals and thus an increased frequency is measured. The sound fronts are now reflected on the stationary object in accordance with Huygens' principle, namely with the frequency which the resting observer has determined for the incoming wave on the object. Since the vehicle, according to the assumption, moves towards the object which reflects the sound, it thus approaches the wavefronts which make up the reflected sound signal. Since the vehicle is approaching the wavefronts, the time intervals between the times at which the vehicle detects a wavefront are shortened. The frequency measured by the vehicle is thus higher than the frequency with which the wavefronts were reflected at the stationary object.

In one embodiment, a signal propagation time of the first echo pulse is additionally determined and from this a radial distance information for the at least one detected object is determined. A corresponding device provides for this purpose a distance detection device. Thus, a clearer localization of the object in the environment is possible. However, ambiguities in the localization due to ambiguities in the angle information are still possible in one level.

Particular preference is given to an embodiment in which, based on the angle information and optionally additionally based on the radial distance information for the at least one detected object, evidence of the presence of the at least one detected object is added to the spatial regions of an environment of the vehicle. Radial distance information is also referred to as radial information. A corresponding device provides that area information of an environment of the vehicle based on the angle information and possibly additionally based on the radial information for the at least one detected object is added to evidence information for a presence of the at least one detected object. As a result, an environment map can be created.

A particularly favorable method for determining the absolute frequency of the oscillations in the echo pulse provides that the frequency the Echopulswellenzugs is determined based on a transformation of the time-resolved echo signal or echo signal section in a frequency space. A corresponding device provides that the frequency determination device comprises a transformation device which is designed to determine the frequency of the echo pulse train by means of a transformation of the time-resolved echo signal or echo signal section into a frequency space.

In one embodiment, a Fast Fourier Transform (FFT) is used as the transformation. The transformation device is then preferably an FFT transformation device.

Due to the fact that there are different angles which lead to the same frequency shift and thus an ambiguity of the absolute angular position, it is provided in one embodiment that at least one further pulse measurement with an altered transmitter-receiver geometry with respect to the transmitter-receiver Geometry of a pulse measurement is carried out and a further echo signal obtained here is evaluated analogous to the one echo signal, and the angle information of a measurement with the angle information of the at least one further measurement is merged taking into account the change of the transmitter-receiver geometry to the angle information to clarify and eliminate previously existing ambiguities.

The invention will be explained in more detail with reference to preferred embodiments with reference to the figures. Hereby show:

1 a schematic representation of an echo signal measured at an ultrasonic transducer;

2a - 2d schematic representations of environment maps, are fused to the measured values of a relative to an object moving sensor, evaluating only the resulting from the measurements radial information;

3a a representation of an environmental scene, as it is for a driver of a vehicle when looking through the windshield;

3b a schematic representation of an environment map, in which a vehicle measuring the environment and the determined based on the measurement results positions of objects in the environment according to the scene of the 3a are drawn;

4 a schematic representation of a sensor relative to two objects in the environment;

5a - 5d schematic representations of environment maps, are fused to the measured values of a relative to an object moving sensor using the radial information and the angle information;

6 a further schematic representation of a vehicle relative to two objects in the environment;

7 a schematic representation of the derived from the radial information and the angle information information for the presence of an object in the vicinity of the moving measuring sensor and

8th a schematic representation of a device for detecting the surroundings in a vehicle.

In 1 schematically is an echo signal measured on an ultrasonic transducer 1 shown graphically. On an abscissa 2 is the time and on the ordinate 3 a signal amplitude is shown. Immediately after the transmission of the transmitted pulse is a decay in the form of a Abschwingkurve 4 recognizable the membrane used for ultrasonic conversion. This is followed by a section of the echo signal 1 in which a signal intensity below defined thresholds 5 . 6 lies. Time then closes a so-called direct echo pulse 7 at. The vibrations in the direct echo pulse 7 have an amplitude which is the thresholds 5 . 6 exceeds. In the further course of time are still Echopulse 8th . 9 . 10 which may result from multiple reflections and / or reflections on other objects.

Only the time span 11 between the transmission of the transmission pulse and the arrival of the first direct echo pulse 7 evaluated, so obtained on the basis of the signal propagation time radial distance information for the object on which the emitted ultrasonic pulse is reflected. The one in the time span 11 The distance traveled by the sound pulse corresponds to twice the (radial) distance between the ultrasonic sensor and the object.

In the 2a to 2d is a schematic data fusion in an environment map 21 shown schematically. The environment maps 21 each represent an illustration of the environment in plan view. X-axis 22 and Y axis 23 the environment maps 21 correspond to just such axes in the vicinity of the measuring sensor or vehicle, wherein the corresponding coordinate system is stationary in the environment. A position of an existing object 24 is indicated by a circle. The position of the moving sensor 25 or the vehicle to which the sensor 25 is attached, is indicated by a rectangle. It can be seen that the vehicle or the sensor 25 moved along the X axis. The environment maps 21 show how the measurement data for four successive measurements, which are successively detected and merged. From a measurement, a radial information can be determined, which indicates in which distance an object is to the measuring sensor or vehicle. An uncertainty in the radial distance is expressed by a stroke width 28 a circular sector element 29 , An angular range 30 of the circular sector element 29 reflects the angle measurement range from which a reflected echo pulse can be received. The area of the circular sector element 29 thus identifies those regions of space in which, according to the pulse measurement, an object can be located which has caused the first detected echo pulse.

In 2 B Now this is the first measurement with a second measurement made at the position where the vehicle or sensor is running 25 in the second environment map 21 of the 2 B is drawn. The circular sector element associated with this second measurement 29-2 is also shown. Points of the area map or areas of the area map, which are in an overlapping area of the two circular sector elements 29-1 . 29-2 lie, ie in an overlapping area 32 , the merger will assign a higher occupancy probability. Generally, every point which is on a detected circle sector element 29 is located, an increased occupancy probability, ie assigned an increased occupancy value. This is preferably done by means of probabilistic methods, for example the Bayesian theorem known from the prior art. Those skilled in the art, these methods are well known, so they will not be explained in more detail here. Likewise, such methods may also take into account the aging of information, resulting in a reduction in the occupancy value for those cells in the environment map for which no evidence of a presence of an object in the environment can be determined according to a newly performed measurement.

In the 2c and 2d Then analogously the situations are shown in which three or four measurements are fused together. It turns out that actually in the area of the object 24 the highest occupancy values indicated by a hatch density can be found in the map, so that in this way a localization of objects in the environment is actually possible, but a large number of measurements must be evaluated.

In 3a is schematically illustrated a situation as it is for a driver when looking through a windshield. To recognize are a roadway 41 , a curb 42 as well as a sidewalk 43 , On this are spaced laterally in front of the vehicle two posts 44 . 45 ,

In 3b is schematically an environment map of this scene of 3a shown how they are after passing the vehicle 52 , which also schematically in the map 51 is located. Hatched are the areas 54 . 55 marked according to the ultrasonic measurement method, in which only the radial information is evaluated, a location of the posts 44 . 45 suggest. Good to see is that the expansions 56 . 57 the areas 54 . 55 parallel to the direction of travel 58 of the vehicle are given much larger than it according to the actual extent of the posts 44 . 45 according to 3a correct would be.

In 4 schematically illustrates a situation in which a vehicle 52 on two objects A 62 and B 63 in the environment 50 moved. The vehicle movement sets a preferred direction 64 firmly. In the example shown, this has the same reference number 62 designated object A. Assuming that the vehicle 52 at a velocity v of the object A 62 approximate, so is the relative velocity along the signal propagation path 65 for one on the object A 62 reflected ultrasound signal this velocity v. If one measures an angle between the signal propagation path and the preferred direction determined by the vehicle speed 64 , this angle is α _A = 0 ° for the sound propagation path 65 between the sensor 66 and the object A 62 ,

For the object B 63 the situation is different. The signal propagation path 67 from the sensor 66 to the object B 63 and back to the sensor 66 closes an angle α _B = 45 ° with respect to the preferred direction 64 one. Parallel to the signal propagation direction is thus the relative velocity, which is of importance for a frequency shift due to the Doppler effect: v _measurement = v _vehicle · cos (α _B )

The relative speed is thus lower, so that a lower frequency increase in the measurement signal is expected. Based on the frequency change can thus be concluded on the angle α, which is included between the signal travel path and the direction of movement. In general: v _measurement (t) = V _vehicle (t) · cos (α).

Since cos (+ α) = cos (-α), it can not be decided whether the object is related to the excellent preferred direction 64 the vehicle right, as in 4 represented, located or left, as by the dashed object B ' 63 ' is indicated. Thus, the measurement result has an ambiguity with respect to the absolute measurement position. Looking at the problem three-dimensionally, in polar coordinates, α indicates the azimuthal angle. With respect to the polar angle, which is a rotation around the by the preferred direction 64 given axis, the problem is rotationally symmetric.

In 5 This situation is again shown, in which the vehicle 52 to two objects B 63 , C 69 approaches. The signal propagation paths 66 . 69 close with regard to the direction of travel or preferred direction determined thereby 64 in terms of magnitude the same angle | α _B | = | α _C | one. Thus, they cause the same frequency shift in the ultrasonic signal.

In 6 is a circular sector 29 whose area indicates the presence of an object according to the evaluation, which takes into account only radial information. About an additional hatching are the two areas 74 . 75 shown, to which the area can be limited, in which an object can be, if additionally the angle information is evaluated. It can be seen that a localization is significantly improved.

In the 7a to 7d is now the situation for driving past a vehicle shown schematically, analogous to the situation in the 2a to 2d , The emission of sound takes place in an angular sector area, whose central axis 81 perpendicular to the vehicle movement direction 82 is oriented. In 3a is only a small angle range 29'-1a of the original circle sector as a possible area in which an object is located. In 7b However, two circular sector areas occur 29'-2a and 29'-2b which provide an indication of the existence of an object based on the second measurement taken. The ambiguity here is due to the fact that an approach to an object which is at an angle α or -α to the direction of travel causes the same frequency shift as a removal of an object which is at the angle α + 180 ° or α -180 °. (For α, an angle in the range of 0 ° to 90 ° is assumed.) In a consideration in which the angle α can take values in an angle range of 0 to 360 °, angles between 0 ° and 90 ° and 270 ° and 360 ° correspond to an approximation. Furthermore, one obtains the same frequency shift for α = β and α = 360 ° - β with 0 ° <β <90 °. Angles between 90 ° and 270 ° correspond to a removal, wherein α = 180 - β and α = 180 + β with 0 ° <β <90 ° again cause the same frequency shift. In general, when considering in the plane that for signal propagation paths with the angles α = β, α = 360 ° - β, α = 180 ° - β and α = 180 ° + β with 0 ≤ β ≤ 90 ° respectively measured the same frequency shift can be. Two of these solutions can be due to the angle measuring range of the sensor used in the rule in the vehicle, taking into account the arrangement on the vehicle relative to the direction of travel as implausible. For β = 0 ° and β = 90 ° there are only two solutions, of which one is usually not plausible.

If one misses, for example, an environment with a sensor whose direction bisecting the measuring range is oriented perpendicular to the direction of travel, then the angle information defines angular ranges which would either match an object or a distance from an object. Immediately when passing by at 90 ° on the obstacle fall then these two angle ranges together. Overall, in the 7a to 7d the measurement data fusion for one, two, three and four measurements are shown, in which both the angle information and the radial information is evaluated. The individual circular sector areas 29'-1b . 29'-2a . 29'-2b . 29'-3a . 29'-3b and 29'-4a are shown. It can be clearly seen that a reliable localization of the object 24 in the environment after two measurements clearly improved compared to the situation in which only the radial information is evaluated, as in 2a to 2d is shown. - For the four measurements, the circular sector areas are superimposed 29'-1b . 29'-2b . 29'-3a , and 29'-4a ,

In the previous description in connection with 7a to 7d it was assumed that only the amount of the frequency shift was evaluated. If one observes the sign, ie whether a frequency increase or a decrease in frequency with respect to the original transmission frequency is measured, an ambiguity can arise with regard to solutions in the angular range -90 ° (-π / 2) to + 90 ° (+ π / 2) and solutions in the angular range 90 ° (π / 2) to 260 ° (3π / 2) are eliminated. In a frequency increase, plausible solutions that approximate an object can only have angles between 0 ° (0) and 90 ° (π / 2) or 270 ° (3π / 2) and 360 ° (2π). With a frequency reduction, the angle can only be in the range 90 ° (π / 2) to 270 ° (3π / 2), which corresponds to a distance from the object. The angle 0 ° (0) always coincides with the travel direction vector. In 7a to 7d could the solutions presented 29'-2a and 29'-3b be excluded. Solutions with the lowercase letter "a" belong to a distance and are only plausible for a f _E <f _S. Solutions with the lowercase letter "b" belong to an approximation f _E > f _S.

In 8th schematically a device for measuring the environment using the angle information is shown. The vehicle 52 includes a measuring device 100 for environment detection. This includes a pulse echo device 101 , The pulse echo device 101 comprises one or more sensors, in the example illustrated a measuring sensor 102 , This is for example designed as an ultrasonic transducer. The Pulse echo measuring device 101 is designed to perform pulse echo measurements and to detect an echo signal. This is sent to a control device 103 forwarded, which evaluates the echo signal. The control device 103 includes an evaluation device 104 , By means of an echo pulse recognition device 105 the echo signal is examined to determine the presence of a first echo pulse. The echo pulse detection device 105 preferably also determines a signal transit time until the arrival of the first echo pulse. It also determines the time domain of the echo signal in which the first echo pulse is located in the echo signal. With a frequency determination device 106 Subsequently, the frequency of the oscillations is determined in the time portion of the echo signal corresponding to the first echo pulse. The frequency information determined in this case can be, for example, the absolute frequency of the oscillations of the wave train in the echo pulse or a difference frequency to the transmission frequency with which the oscillations are generated in the transmitted pulse. The absolute reception frequency can advantageously be determined by means of a Fourier transformation. For this purpose, the frequency determining device 106 a transformation device 112 include. The difference frequency can alternatively be determined by a frequency mixing method.

The vehicle 52 For example, it includes a wheel pulse sensor 110 which determines a vehicle speed. About a yaw rate sensor 111 In addition, a yaw rate can be determined. The measuring signals of the wheel pulse sensor 110 and the yaw rate sensor 111 are also sent to the evaluation device 104 the device 100 transmitted to the environment detection. A vehicle speed device 107 determines the speed or receives a speed information. In the latter case, the vehicle speed device 107 just be an interface. In other embodiments, the vehicle speed may vary in magnitude and direction from the measurement signals of the wheel pulse sensor 110 and the yaw rate sensor 111 be determined. The speed information may also be provided by other information, such as a GPS system, other inertial navigation sensors, etc. These may also be part of the environment detection device 100 be.

The evaluation device further comprises an angle information determination device 108 which determines angular information using the velocity information and the frequency information, as explained above, using equations for Doppler shift. A distance determining device 109 Optionally, the signal transit time provided by the echo pulse detection device 105 is supplied, determine a radial information. The angle information and optionally the radial information are then from a fusion device 120 used this in an environment map 121 to merge, for example, in a memory 123 is stored. The individual described devices of the evaluation device can be completely or partially implemented in their own special circuits or implemented by means of one or more microprocessors or one or more field programmable gate arrays. Implementations are preferred by means of a program-controlled microprocessor. The corresponding program can be in the memory 123 be filed. The device may include the angle information, the radial information and / or information from the environment map of other vehicle systems of the vehicle 52 so that they can fulfill their functionality.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004047087 A1 [0007]
• DE 102009028992 A1 [0008]
• EP 1879048 A1 [0009]

Claims (10)

Method for improved detection of surroundings of a vehicle ( 52 comprising the steps of: performing a pulse echo measurement by emitting a pulse comprising a transmitted transmit train, wherein the oscillations of the transmit train have a transmit frequency (f _S ), and an echo signal is detected time resolved, evaluating the echo signal by determining whether at least one first echo pulse is contained in the echo signal, and if so, at least for the first echo pulse comprising a vibrating echo wave train, determining frequency information (f _E , Δf) about the vibrations of the echo wave train, detecting or Determining a vehicle speed (v), determining an angle information (α) based on the vehicle speed (v) and the frequency information (f _E , Δf) for at least one detected object ( 24 ). Method according to Claim 1, characterized in that the angle information (α) is calculated from the frequency information (f _E , Δf) on the basis of a Doppler shift equation, the angle information being all plausible solutions of the equation c / v (β-1 / β + 1) = cos (α) With

where f _{E is} the reception frequency, f _{S is} the transmission frequency, v is the vehicle speed, and c is the sound propagation velocity and α is the angle measured against the vehicle speed direction, or the equation c / v (1 / Y + 1) = cos (α) With

with Δf = f _E -f _S. A method according to claim 1 or 2, characterized in that in addition a signal delay for the first echo pulse is determined and from this a radial distance information for the at least one detected object is determined. Method according to one of the preceding claims, characterized in that space regions of an environment of the vehicle ( 52 ) based on the angle information (α) and optionally additionally based on the radial information for the at least one detected object ( 24 ) Evidence information for the presence of the at least one detected object ( 24 ) is added. Method according to one of the preceding claims, characterized in that the frequency of the Echowellenzugs is determined by means of a transformation of the time-resolved echo signal or echo signal section in a frequency space. Method according to one of the preceding claims, characterized in that at least one further pulse echo measurement is carried out with an altered transmitter-receiver geometry with respect to the transmitter-receiver geometry of the one pulse echo measurement and a further echo signal obtained in this case is evaluated analogously to the one echo signal, and the angle information of the one measurement is fused with the angle information of the at least one further measurement taking into account the change of the transmitter-receiver geometry in order to specify the angle information and to eliminate any ambiguities that may exist. Contraption ( 100 ) for improved environment detection of a vehicle ( 52 ) comprising: a pulse echo device ( 101 ) for carrying out a pulse echo measurement, in which a pulse which comprises a transmitted transmission wave train is emitted, wherein the oscillations of the transmission wave train have a transmission frequency (f _S ), and an echo signal is detected time-resolved, and an evaluation device ( 104 ) for evaluating the echo signal, which comprises an echo pulse recognition device ( 105 ) for determining whether at least one first echo pulse is contained in the echo signal, and a frequency determination device ( 106 ) to determine frequency information about the oscillations of the echo train, at least to a detected first echo pulse comprising echo wave train having oscillations, vehicle speed device ( 107 ) for receiving, determining and / or detecting a speed (v) of the vehicle, and an angle information determination device ( 108 ) for determining an angle information (α) on the basis of the vehicle speed (v) and the frequency information (f _E , Δf) for at least one detected object associated with the at least one echo pulse ( 24 ). Contraption ( 100 ) according to claim 7, characterized in that the frequency determining device ( 106 ) a transformation device ( 112 ), which is designed to determine the frequency of the Echowellenzugs based on a transformation of the time-resolved echo signal or echo signal section in a frequency space. Contraption ( 100 ) according to claim 7 or 8, characterized in that the evaluation device ( 104 ) a distance determination device ( 109 ) for determining a radial distance information for the object associated with the at least one detected echo pulse on the basis of the signal propagation time of the at least one detected echo pulse. Contraption ( 100 ) according to one of claims 7 to 9, characterized in that the evaluation device ( 104 ) a fusion device ( 121 ), the areas in the vicinity of the vehicle based at least on the angle information (α) and optionally additionally on the basis of the radial distance information for the at least one detected object ( 24 ) Evidence information for the presence of the at least one detected object ( 24 ).

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