EP3721259A1 - Method and assembly for determining the speed of a vehicle - Google Patents

Abstract

The invention relates to a method for determining the speed of a vehicle, having the steps of receiving raw image data generated from scans of the route of the vehicle using a radar with a synthetic aperture, generating images of the scanned route from the received raw image data, wherein a reference speed is taken into consideration in order to generate a respective image, analyzing at least one generated image with respect to at least one criterion, selecting an image depending on the analysis, and determining the speed of the vehicle on the basis of at least one piece of information assigned to the selected image. The invention additionally relates to an assembly with devices for carrying out the method.

Description

description

Method and device for determining the speed of a vehicle

The present invention relates to a method for

Determining the speed of a vehicle and an associated arrangement.

The determination or measurement of an actual

Speed of a vehicle is of great importance as it is used as a parameter for various regulatory and

Control systems of the vehicle is used. These can be in particular assistance systems for the vehicle driver or also systems for autonomous driving of the vehicle. In known rail vehicles, the specific

Speed among others for the drive and

Brake control used.

The capture or determination of the actual

Speed of a vehicle with high accuracy, however, represents a major technical challenge.

In principle, the speed of, for example, a rail vehicle can be derived from the rotational speed and the rolling circumference of the wheels of a wheel set, wherein the rotational speed is determined, for example, by means of a speed sensor arranged on the wheel set. However, especially in rail vehicles, the exact circumference of the wheels of a

Wheel set not known, since this depends on the current state of wear of the wheels. Because of the possible

The difference between the amount assumed for the speed determination and the actual volume is the determination of the speed with a certain amount

Uncertainty. Furthermore, it can come especially in a driven wheelset due to slip, a low coefficient of static friction or a lack of adhesion between the wheel and rail to spin wheels, causing the measured speed is not with the actual speed of the vehicle corresponds. In several driven wheelsets of the rail vehicle, it may be due to different ratios of

Frictional connection of the respective wheelset also

different speed measurements come. Even an exemplary averaging of simultaneous measurements

therefore, there is still no certainty that the actual speed of the rail vehicle will increase

to capture .

To increase the safety with regard to the correctness of the speed determined by means of speed sensors, the speed of the rail vehicle is often determined additionally or redundantly by other means. Here is the

For example, the speed of the vehicle is determined based on a distance traveled during a time period, the distance covered using

Receivers for signals of known satellite-based

Positioning systems, such as GPS (Global Positioning System), GLONASS (Global Navigation Satellite System) or GALILEO, based on transit time measurements of satellite signals is determined. For this purpose, one or more such receivers are arranged, for example, on the roof of the vehicle. However, these systems are disadvantageous inaccurate or unsuitable if no line of sight of the receiver or the receiver to a plurality of

Satellites exist, for example, in tunnels, underground routes or when driving on higher mountains or buildings lined roads.

Furthermore, for example, a radar arranged in the underfloor region of a car body of the rail vehicle and directed at an angle to the horizontal in the direction of travel on the route or the track bed for determining the speed of the rail vehicle. In general, radars, the term radar stands for RAdio Detection And Ranging, compared to optical sensors have the advantage that on the one hand to capture a section itself Illuminate and thus no additional light source

on the other hand because of their larger wavelength compared to visible light comparatively

Insensitive to weather conditions such as

For example, rain, fog, snow or heat.

Unmodulated Continuous Wave (CW) radar is commonly used for this purpose, which is based on speed

 Frequency shift or the so-called Doppler effect determined. Unmodulated radar signals or electromagnetic waves are radiated, for example, in a frequency range around 24GHz as a sub-frequency range of the so-called ISM frequency bands (Industrial, Scientific and Medical radio bands) from a transmitting antenna of the radar, reflected from objects or structures with a wavelength for the Radar signal sufficient roughness

(Rayleigh criterion) backscattered and from a

Reception antenna received. Such reflected or

Backscattered signals are also called echoes. If the radar and the reflective object have a relative speed relative to one another, then the frequency of the received signals differs from the frequency of the radiated signals. From the frequency offset between these frequencies, a relative velocity can be determined, since the frequency offset is proportional to the velocity of the

Vehicle and the cosine of the angle, which is defined by the velocity vector and the radiation direction of the antenna. Due to the largely undirected

Radiation emission of radar signals through the transmitting antenna is an assignment of Doppler frequencies to individual reflective or backscattering objects not possible, making this type of velocity determination has the disadvantage that there is no unambiguousness with respect to the objects and as a result, the speed also only with a certain Uncertainty can be determined. The object of the present invention is to provide a more accurate and reliable system and method for determining the speed of a vehicle. This object is achieved by the method and the arrangement according to the features of the independent claims. Further developments of the invention are in each dependent claims

listed.

A first aspect of the invention relates to a method for determining a speed of a vehicle with the

Steps receiving by means of a radar with

synthetic aperture generated from samples of a route of the vehicle generated raw image data, generating images of the scanned route from the received

Raw image data, wherein a reference speed is taken into account for the generation of a respective image, evaluating at least one generated image with respect to

at least one criterion, selecting an image depending on the rating, and determining the speed of the vehicle based on at least one information associated with the selected image.

The use of a synthetic aperture radar (English: Synthetic Aperture Radar, abbreviated SAR), as it

for example, already used in remote sensing, allows to generate images with a high resolution. This high resolution again allows a qualitative rating of the images on the basis of which a particular image is selected. Associated with this selected image

Information finally serves to determine the speed of the vehicle.

Images of the scanned route can thereby from the image raw data provided by the radar by means of known

Algorithms for digital image processing, for example by means of a so-called range Doppler algorithm,

to be generated. Each image includes a respective section of the scanned by the radar route. The algorithm takes into account for the generation of the image a reference speed, which is preferably already in the range of the actual speed of the vehicle. The subsequent evaluation of the generated image on the basis of at least one criterion is used to estimate whether the reference velocity of the actual

Speed equals. Unless the

Reference speed not the actual

For example, in subsequent iterations, the reference speed taken into account for the image generation can be varied or, for example, another generated image can be evaluated until a

Match or close match of the

Speeds based on the criterion is confirmed.

According to a first embodiment of the invention

Method is determined in the step of the evaluation for the generated image, a degree of focus, and evaluated as a criterion of the particular degree of focus.

According to one refinement of the first development, information is determined on the basis of which, in the step of determining, the speed of the vehicle was taken into account, which took into account the generation of the image

Reference speed assigned to the image.

The degree of focus of an image can be determined by means of a

known algorithm can be determined. Since the at the

Generation of the image considered

 Reference speed affects the degree of focus of an image can be determined based on the specific degree of focus, whether the image with a

Reference speed was generated, which is the

actual or near actual speed of the vehicle at the time of sampling by the SAR

equivalent. If the particular degree of focus of a picture is sufficiently good, this picture was taken with a

Reference speed generated, the actual or close to the actual speed. In the final step of determining the

Speed of the vehicle based on the

 Reference speed at which this image was generated determined. In the step of generating the images, the respective reference speed is considered as

Information assigned. Unless the specific

Focusing degree of the image, however, is not sufficiently good, the image was thus generated with a reference speed that does not at least close to the actual speed at the time of sampling, in one or more subsequent iterations

Reference speed varies and generates a respective image based on the same received image raw data, the degree of focus is again determined and evaluated. These iterations are carried out in particular until an image has been generated which is sufficiently good

Focusing degree, or until an abort criterion, such as a timeout, leads to an image from raw image data of a subsequent scan is generated.

According to an alternative or additional development of the method with respect to the step of the evaluation, the generated image is compared with a further image and a criterion of a similarity of the images is evaluated.

A similarity of images can be assessed in particular by means of a correlation known from signal processing or an autocorrelation known from image processing. The correlation of images allows recognition of certain objects or structures. This makes it possible to move a particular example

Object or a specific structure of the sampled

Travel distance over time in successively generated images to capture. From the required time for the movement over a certain distance, in turn, the speed can be determined. The disadvantage, however, is the difficulty determine the distance traveled by the object or structure in the generated images with high accuracy.

Alternatively, the detection of the movement by means of a correlation of images generated from raw image data of different antennas of the radar. These antennas have a certain distance in the direction of travel of the vehicle to each other. In this alternative, for example, starting from a generated image

Raw image data of a first antenna correlates with a generated image from raw image data of a second antenna of the radar in order to determine a similarity of the two generated images, for example with respect to an object or a structure. If there is sufficient similarity of the images or a respective subregion of the images in which the object or the structure is contained, the image of the second antenna for the velocity determination is selected. If, on the other hand, there is no sufficient similarity of the images, in one or more subsequent iterations a respective different image of the second antenna is correlated with the image of the first antenna. These iterations are carried out in particular until an image of the second antenna has been determined which has a sufficient similarity with the image of the first antenna, or until an abort criterion, for example a

Timeout causes a different image of the first antenna to serve as the basis for correlation with images of the second antenna.

According to one embodiment of the above development of the method, in the step of generating a respective image information with respect to a time of

Scanning, in particular the scanning of the image in the picture

pictured section of the route, or one

Time of generation of the image assigned. Furthermore, in the step of determining on the basis of a temporal Difference between the assigned times of images determines the speed of the vehicle.

By means of the assignment of the time of the sampling or the generation of a respective image, a time difference between the images of the first and second antenna can be determined in the alternative detection described above. For this purpose, for example, the duration is determined until an object initially scanned by the first antenna or a scanned structure is subsequently also scanned by the second antenna. From this specific duration or the time difference between the times of the generated images and the distance between the first and the second antenna of the radar, finally, the speed can be calculated.

According to a further development of the method, in the step of generating as a reference speed, a predetermined one in a previous cycle of the method

Speed or a speed determined by means of another device for speed determination.

As already described above, the reference speed is taken into account for the generation of images from received raw image data. It is also important, for example, in the evaluation according to the criterion of the similarity of images, a time difference between the

Estimating images and based thereon an image of the second antenna with a corresponding time difference to the image of the first antenna for a first correlation

select. Since the speed of a vehicle from one cycle of the process to a next cycle usually can change or change only limited, this leads

Estimation that a required number of iterations can be kept small for the selection of an image. In the same way, this reference speed results in the evaluation according to the criterion of the degree of focus Image shows that a first image evaluated in the new cycle has been generated with a reference velocity that can only be limited or differentiated from the speed determined in the previous cycle. This in turn advantageously leads to the fact that a required number of images to be generated can be kept low.

If a reference speed from a previous cycle of the method is not present, for example during a first-time execution of the method or if no speed could be determined in the cycle, a speed can be taken into account for generating in particular a first image or for a first cycle of the method which was determined by another device for determining the speed of the vehicle. Such a further device determines the speed of the vehicle in a known manner, for example based on signals from at least one other radar, one or more speed sensors or a satellite-based

Positioning system, as described in the introduction. In particular, in a first-time execution of the method during or after a standstill of the vehicle, the reference speed can also initially be assumed to be zero.

A second aspect of the present invention relates to an arrangement for determining a speed of a

Vehicle, wherein the arrangement at least one synthetic aperture radar, which scans a travel distance of the vehicle by means of at least one transmitting and at least one receiving antenna, a

 Speed determination device, comprising at least one processor device and a memory device, by means of which images of the scanned travel route are generated from raw image data received by the radar taking into account a reference speed, at least one generated image with respect to at least one criterion

is evaluated, an image selected depending on the rating is based and the speed of the vehicle

at least one associated with the selected image

Information is determined.

The arrangement according to the invention makes it possible to carry out the method according to the invention according to the first aspect of the invention. The specific speed of the vehicle or an information representing this can, for example, by means of an interface of the arrangement further

Devices, in particular a drive and / or

Brake control device of the vehicle to be supplied. Such an interface can be realized in particular wired or wireless, in particular radio-based.

According to a development of the arrangement is the

Speed determination device further thereto

configured to determine a degree of focus of the at least one generated image and the determined

To rate the degree of focus as a criterion.

According to an alternative or additional development of the arrangement, the speed determination device is designed to compare the at least one generated image with another image and to evaluate a similarity of the images as a criterion.

According to a further development of the arrangement, the speed-determining device is configured to use as reference speed a speed determined by another device for speed determination for the generation of the at least one image

account .

Such a further device is, for example, a known device described in the introduction, which

in particular based on signals of at least one further radar, one or more speed sensors or a Satellite-based positioning system determines the speed of a vehicle. The others

For example, the device may be at least partially implemented in or separate from the housing of the device. In the latter case, the speed determined by this device or information representing the speed is supplied via an interface to the speed-determining device. These

In particular, the interface can be a wired or wireless, in particular radio-based, interface using known transmission protocols

be designed.

For example, the synthetic aperture radar is configured as a Frequency Modulated Continuous Wave (FMCW) radar. Depending on the type of evaluation of generated images, the radar may in particular have a transmitting antenna and a

Receiving antenna or a transmitting antenna and at least two receiving antennas have. The transmitting and receiving antennas can each be designed as a known so-called integrated patch antenna, in which a plurality of patches on a substrate a resulting

Antenna diagram defined. In the same way, however, the antennas can also be designed as horn radiators. The antennas of the radar are according to the use of the

Remote sensing orthogonal or at an angle, called a slip angle, to the direction of travel of the vehicle and each aligned at an angle to the plane of the route or to the vertical axis of the vehicle. Such a thing

Aligned radar is also called side view radar

(English: side-looking radar).

According to a further development of the arrangement, the speed determination device is configured to control a change in a radiation direction of the at least one transmission antenna of the radar. If the transmitting antenna of the radar as a known so-called phased array antenna (English: Phased Array Antenna) is designed, in which the

Antenna diagram, for example by feeding individual emitters or patches with a different phase can be pivoted electronically, in particular the angle to the plane of the route or the vertical axis of the antenna pattern of the transmitting antenna can be changed.

 Alternatively or additionally, however, the emission direction can also be changed mechanically, in particular by tilting or pivoting of a housing in or on which the antennas are arranged, by means of a tilting or pivoting device. A change in the emission direction may be particularly useful if the surface of the route scanned by the radar is not suitable for determining the speed of the vehicle on the basis of a rating of generated images of the surface. In particular, this may occur at a surface of the route, which does not have sufficient roughness for a reflection of radar waves, or

Has objects and / or structures. A lack of suitability of the route can be determined in particular in the evaluation of an image by the speed determination device, after which the device is a change of the emission direction, for example an electronic

Panning the antenna diagram or a mechanical one

Panning at least the transmitting antenna drives. By means of a change in the emission direction, transmission signals can be transmitted

For example, another area or section of the route to be directed, which has a sufficient roughness or objects or structures with a suitable geometry or electrical properties that allow evaluation of generated images. The

Antenna diagram of the at least one receiving antenna can in such a case according to the change of the

Be adapted to the antenna pattern.

A third aspect of the present invention finally relates to a vehicle which has at least one inventive arrangement or means for performing the method according to the invention.

Advantageously, the arrangement according to the invention can cover a large speed range by the use of a synthetic aperture radar, in particular a range of almost zero up to 500 km / h when using a

Frequency bands in the frequency range of 24GHz. The arrangement is characterized for use in track-bound vehicles, especially trams, subways, locomotives or trainsets for local and long-distance traffic to the

High speed range, as well as for use in

unmarked vehicles, in particular motor vehicles for passenger and goods transport, including

Lorries, cars or buses, suitable. The arrangement according to the invention can be the introductory

described known systems for

 Speed determination of a vehicle, for example, to increase redundancy or replace one of these known systems, at least temporarily.

In the following the invention is based on

Embodiments explained in more detail. Showing:

1 shows a schematic side view of a

 Railway vehicle,

 2 shows a perspective view of the invention

 Arrangement in the underfloor area of a car body,

3 shows a further view of the arrangement in FIG

 Underfloor area of a car body,

 4a, b are schematic plan views of a housing of the

 Arrangement,

 5 shows a flowchart of a first invention

 Method based on the determination of a

 Focusing degree of a generated image, and

6 shows a flowchart of a second invention

Method based on a correlation of generated images. For clarity, the same reference numerals are used in the figures for the same or equal or almost equal components. Furthermore, a coordinate system is respectively indicated in FIGS. 1, 2 and 3, in which the mutually perpendicular longitudinal axis L, transverse axis Q and vertical axis H are shown. The

Longitudinal axis L also defines the direction of travel F of the vehicle and, with respect to the radar with synthetic

Aperture, the so-called azimuth A. The transverse axis Q

corresponds with respect to the radar, however, the so-called Range R.

1 shows schematically a side view of a

Rail vehicle 1 as an example of a vehicle according to the invention. The rail vehicle 1 is exemplified as an electric multiple unit for passenger transport with a plurality of cars, in the upper part of FIG 1 by way of example a first end car 2 and a verkuppelter with this first center car 3, and in the lower part of FIG 1 with the first Central car 3 verkuppelter second middle car 3 and a coupled with this second end car 2 are shown. More middle cars to increase the number of people to be transported can be provided. The illustrated cars 2, 3 each have a car body 4, which has two

Bogies 5 supported in the form of propulsion or running bogies on rails, not shown. As an alternative to the provision of two bogies per wagon body, as indicated in FIG. 1, in particular in the region of the transitions between the end wagons 2 and the respectively adjacent one

Middle car 3 and between the two middle cars 3 also common bogies, especially so-called Jakobs- bogies, are provided.

The end cars 2 are each subdivided into a plurality of spatial areas with respect to the longitudinal axis L, for example. These

Areas are on the one hand a driver's cab or head module 6 in front or rear area, on the other hand to the

Driver's cab 6 adjacent car body 4. The respective

Car body 4 of the end car 2 and middle car 3 enclosing a passenger compartment 7, in which seats for passengers and their luggage can be provided. The passenger compartments 7 of the carriages 2, 3 can be entered and left by passengers via doors arranged in side walls of the vehicle bodies 4, not shown. Furthermore, passengers can get over car transitions 8 in the passenger compartment 7 of the adjacent carriage 2, 3. Such car transitions 8 are usually by wave or bellows ago

Protected against environmental influences.

On the roof and under the floor or in the underfloor area of the respective car body 4 of the end car 2 and

if appropriate, the middle car 3 are usually

arranged electrical devices or containers for such devices as part of the electrical equipment of the trainset, which are not shown in FIG 1, however. These serve, for example, a drive of the trainset, in particular the supply and control of traction motors, not shown in FIG 1. The traction motors are arranged, for example, in the right bogie 5 of the first end car 2, which is designed as a drive bogie, and in the left bogie of the second end car 2. Further bogies of the trainset can, in particular depending on the required drive power, also be equipped with traction motors. The supply of traction motors, for example, via a respective, arranged in the underfloor area of the car body 4 of the end car 2 transformer whose primary winding, for example via a roof on the first

Center car 3 arranged pantograph with a

For example, high-voltage AC leading

Catenary can be electrically connected. On the

respective roof of the car body 4 of the end car 2, however, for example, a connected to the transformer traction converter for supplying the traction motors with electrical energy is arranged. Furthermore, on the roofs the car bodies 4 usually each at least one

Air conditioning arranged, which serves the air conditioning of the underlying passenger compartment 7. In addition to these components of the electrical equipment of the trainset other components, especially control devices, auxiliary services and facilities for their supply can be arranged in the same way on the roof, in the underfloor area or in the interior of the car bodies.

In the underfloor area of the respective car body 4 of the

End car 2 is an example of a respective arrangement 9 according to the invention or parts of the arrangement 9 according to the invention. The respective arrangement 9 comprises, in addition to a synthetic aperture radar (SAR), further devices, as will be explained in greater detail with reference to FIG. 4 in particular. Preferably, the assembly 9 has a closed housing 10 for placement therein or thereon

Components, components or devices against

To protect environmental influences such as moisture, dust or stone chipping. On one or more outer sides or side walls of the housing 10, for example, transmitting and receiving antennas of the SAR and possibly another radar are arranged while in the housing

Means are arranged for generating transmission signals for one or more transmitting antennas as well as for converting and processing received echoes of these signals. Parts of these facilities can thereby also in a separate housing or container, optionally together with other facilities of the electrical equipment of the trainset on the roof, in the car body 4 or in the underfloor area of the

Endwagen 2 be arranged. When positioning the

Arrangement 9 or the SAR in the underfloor area of the car body 4 is to ensure that the range of the signal radiation of a transmitting antenna of the SAR free of obstacles or

On-board facilities, in particular containers of electrical equipment or parts of the bogies is to unwanted scattering of signals and thus possible

Disorders of the reception of echoes of these signals by the to avoid at least one receiving antenna of the SAR. Unless sufficient space is available in the underfloor area of the end car 2 for this purpose, the arrangement 9 can also be arranged in the underfloor area of the central car 3 as an alternative to the representation in FIG. The provision of two arrangements 9 serves, for example, an advantageous redundancy for increasing the reliability and the accuracy of the system.

Alternatively, an arrangement 9 can also be a respective one

Be assigned to the direction of travel of the rail vehicle. However, the provision of an arrangement 9 is already sufficient for the implementation of the inventive concept.

FIG. 2 shows a perspective view of an exemplary attachment of the arrangement 9 according to the invention

Underfloor area of a car body 4, wherein only a lower visible edge of the car body is shown. The housing 10 of the assembly 9 is over one or more

Brackets 11, in the FIG 2 are two by way of example

Mounts specified 11, mechanically attached to the bottom, in particular to struts or frame parts of the car body. The brackets 11 serve in particular a position-stable and low-vibration attachment of the housing 10 to the car body 4. On a longitudinal side or a

Side wall of the housing 10, three antennas of the SAR are arranged by way of example, as patch antennas with a

respective plurality of patches are configured. On both sides of a transmission antenna 12 arranged, for example, in the middle of the side wall of the housing 10, a first 13.1 and a second receiving antenna 13.2 are arranged. The longitudinal side of the housing 10 is aligned parallel or substantially parallel to the longitudinal axis L of the trainset. Two

Receiving antennas 13.1, 13.2 are in particular for the approach of evaluation of generated images by means of a

Correlation provided, as will be explained in more detail below with particular reference to FIG 6, while for the approach of a valuation of generated images by means of a

Focusing basically only one receiving antenna is sufficient. Also could for the latter approach also a single patch antenna, the majority of patches are divided into respective send and receive patches, are sufficient. For the former approach, two transmit antennas with a respectively assigned receive antenna may alternatively be provided.

In the example of FIG 2, a radiation of

Signals 19 of the transmitting antenna 12 of the SAR according to the orientation in the known use for remote sensing mainly in the direction of the transverse axis Q and in the direction of a vertical axis H below the car body 4 located portion of the route. Of the

Travel route over which the train moves, emitted signals 19 are partially reflected or scattered and received as echoes from the two receiving antennas 13.1, 13.2. Accordingly, with each emission of

Transmitter antenna scanned by the antenna diagram and the distance to the route section of the route scanned by the radar. A track bed of ballast stones as part of the route, as shown in FIG 2 by way of example

is shown, due to the geometry of

Gravelstones, which have good reflection properties

and recognizable structures in a special way for the evaluation of samples generated by scans

Pictures suitable.

The route, of which FIG 2 shows a section, is exemplified as a so-called superstructure 14 and track body running. This usually has a track bed 15 made of ballast stones on which at intervals and across the

Driving direction F thresholds 16 are located, on which in turn parallel rails 17 are mounted in the direction of travel F. The sleepers 16 are made of concrete, wood or steel, for example, and serve to keep the rails 17 at a certain distance from one another, the so-called

Gauge, to fix. The rails 17 are through

suitable fastening means 18, in particular nails,

Threaded bolts, nuts or clamps, held on the sleepers 16. In Germany, for the attachment of Rails on concrete sleepers, for example, the so-called superstructure W used in the so-called Epsilon- clamps are mounted in W-shaped recesses of the thresholds by means of sleeper screws.

FIG. 3 shows the above-described situation of FIG. 2 in a view opposite to the direction of travel F of the multiple unit, to clarify the exemplary attachment of the train

Inventive arrangement 9 in the underfloor area of

Carriage 4. As already described above with respect to FIG 1, the car body 4 is based on bogies on the rails 17 from. By way of example only, the outlines of wheels 20 of such a bogie are shown in FIG 3 by means of dashed lines, which are located outside the section shown in Figure 2 and in FIG

arranged in perspective in the background. The housing 10 of the assembly 9 is mechanically secured via one or more brackets 11 on the underside of the car body 4. On the longitudinal side or side wall of the housing 10 are the

Transmitting and receiving antennas 12 and 13.1, 13.2 of the SAR arranged, wherein the transmitting antenna 12 in turn signals, exemplified by emanating from the transmitting antenna 12 waves 19, in the direction of the track bed 15th

emits below the car body and between the two rails 17.

As already mentioned above for FIG. 2, a

Radiation of signals 19 and radar waves through the

Transmit antenna 12 according to the orientation of a SAR in the remote sensing, i. in the direction of the transverse axis Q or at an angle to this, and at an angle to the vertical axis H in the direction of the track bed 15. Starting from a

Antenna diagram of the transmitting antenna 12, whose main axis is perpendicular to the plane of the patch antenna, is the

Housing 10 in FIG 3, for example, arranged inclined by a corresponding angle to the vertical axis H. The orientation of the housing 10 or the antennas 12, 13.1, 13.2 should preferably by means of a suitable embodiment of the Mounts 11 may be adjustable to select a suitable area of the trackbed to be scanned. In the lower part of FIG. 3, an alternative embodiment of the housing 10 of the arrangement 9 is shown by way of example. According to this

Embodiment is only the side wall of the housing 10, to which the transmitting and receiving antennas 12, 13.1, 13.2

are arranged, aligned at a suitable angle to the vertical axis H, while the bottom and top walls of the housing 10 are parallel to the transverse axis. Furthermore, as a further alternative, in FIG 3 but not specifically

shown embodiment only the antennas 12, 13.1, 13.2 by means of suitable brackets in a suitable

Angle to the vertical axis H to be attached to the housing 10.

As already mentioned above, a track bed with

Gravel stones especially good for a rating of

generated images suitable. For certain applications, especially in high-speed lines, but also superstructure reinforced concrete are used in which

Thresholds and rail mounting brackets are integrated for greater stability and positional security of the rails. Due to a generally much lower roughness of concrete slabs compared to ballast stones is such

Background less for SAR scans

suitable. The angle to the vertical axis H of the radiation through the transmitting antenna 12 should be in such a situation

Preferably, in particular during a movement of the vehicle, for example, can be changed so that alternative objects or structures that allow a meaningful evaluation of generated images are scanned by means of the radar. Such alternative objects may, for example, the above-mentioned tension clamps and sleeper screws for attaching the rails to the

Be Oberbauplatten. These are on the one hand usually made of a metal, which radar waves well

reflected as well as on the other hand recognizable as objects in generated images due to their special form. A change in the angle of radiation towards such objects Structures, as exemplified in FIG. 3 by dashed waves 23 emanating from the transmitting antenna 12, can be indicated by a mechanical pivoting or tilting of the housing 10, indicated by a dashed double arrow next to the left side wall of the housing 10, or

Transmit antenna 12 itself done. When pivoting or tilting the housing 10, the holder 11 may for example have one or more electric servomotors, hydraulic cylinders or pneumatic cylinders, which can change the angle of the housing to the vertical axis H by driving. In this case, the holder 11 and the housing 10th

For example, two defined positions, each having a certain angle of radiation of the transmitting antenna

define, take. Alternatively, at a

Embodiment of the transmitting antenna 12 as a phased array antenna, the antenna pattern can be pivoted electronically by suitable control, so that a mechanical

Pivoting or tilting of the housing 10 is not required.

In the example of FIG. 3, a further transmitting antenna 21 and a receiving antenna 22 are provided on the front or end wall of the housing 10, viewed in the direction of travel F.

arranged. These are, for example, part of a known unmodulated continuous wave radar described above, which is based on a frequency shift or a

Doppler effect determines the speed of the vehicle.

Since such a radar in a known manner also in

Underfloor area of a car body is arranged and

Transmission signals in the direction of travel and in the direction of

Substrate sends, in FIG 3 by way of example

Transmission antenna 21 outgoing waves 24 shown, in particular parts of this radar can also be integrated in or on the housing 10 of the arrangement 9 according to the invention. When arranging and aligning, in particular, the transmitting antenna of this radar, care must be taken that echoes from their radiations can not be received by the receiving antennas of the SAR or with echoes from

Radiation of the SAR can overlap. Alternatively to the illustrated separate transmitting and receiving antennas 21 and

22 in the form of a respective patch antenna, in turn, a single patch antenna can be used, the patches are assigned to either the transmission or the reception branch. The speed determined by this additional radar can be used, for example, as a reference speed and as a redundant speed, in particular for drive and brake controls of the rail vehicle.

4a shows a schematic plan view of the housing 10 of the assembly 9 and an exemplary general overview of the components arranged therein. As already shown in FIGS. 2 and 3, transmitting and receiving antennas 12 or 13.1, 13.2 of the SAR are arranged on a side wall of the housing, while a respective transmitting and receiving antenna 21 or 22 of an unmodulated continuous wave radar is located on the end wall in the direction of travel F. are arranged. The antenna units are each one or more electronic devices 25 and 26 for the generation of high-frequency transmission signals and processing of received signals, including a

Amplification, filtering and conversion of signals upstream or downstream. These devices can be used in particular for the corresponding devices of the radars when used for remote sensing or speed determination

correspond. Furthermore, one is

 Speed determining device 27 is provided in the housing 10 to which the devices 25, 26 are connected. The speed determination device 27 comprises

in particular at least one microprocessor and / or a programmable integrated circuit and a

Memory device by means of which received and converted into a digital format signals can be processed according to the inventive method described below. At least one electrical interface 28 for the supply of electrical energy to the speed-determining device 27 and the devices 25, 26 or to their power supply units is furthermore provided on the housing 10. A further interface 29 on the housing 10 can also an exchange of information with other facilities of the trainset, in particular with respect to the

Speed determining device 27 determined

Speed and possibly one

 Reference speed, serve. Such an interface 29 may be wired, in particular electrically or optically, or else cable-free, in particular as a radio interface.

4b shows a schematic plan view of an alternative embodiment of the arrangement 9. In contrast to the

Arrangement 9 of FIG 4a, the SAR is designed such that on the side wall of the housing 10, in the direction of travel F

seen, in the front and in the rear of the housing, a respective combination of a transmitting and a

Receiving antenna 12.1, 13.1 or 12.2, 13.2 is arranged. Each combination is assigned by way of example a device 25.1 or 25.2, which in turn is connected to the central speed determination device 27. The arrangement of the antennas on the side wall and the expression of the respective antenna diagram of the transmitting antenna is such that echoes of emitted signals of the first transmitting antenna 12.1 can be received exclusively or mainly from the first receiving antenna 13.1, while echoes of signals of the second transmitting antenna 12.2

exclusively or mainly of the second

Reception antenna 13.2 can be received. Around

To largely avoid overlays of echoes, the receiving antennas are arranged by way of example at a distance from each other, which corresponds to the distance of the receiving antennas 13.1, 13.2 of the embodiment of FIG 4a.

According to the examples of FIGS. 4 a and 4 b, all the components or electrical and electronic devices of the SAR and the speed-determining device 27 are arranged in the housing 10. In particular, the

Speed determining device 27 and arranged therein electronic components Environmental influences such as vibrations and

Ambient temperature are relatively sensitive, alternatively, an arrangement of

 Speed determining device 27 together with other electrical or electronic devices of the vehicle in another housing, container or

Switch cabinet, especially within a car body, be useful. Advantageously, this can also reduce the volume of the housing 10, thereby possibly allowing a simpler or more flexible arrangement of the housing in the underfloor area of the carriage.

The following is the operation of a radar with

Synthetic aperture and algorithms for generating images from raw image data of such a radar explained before with reference to FIGS 5 and 6, two exemplary approaches for determining the speed of a vehicle based on generated images are described.

A synthetic aperture radar belongs to the class of imaging radars and is used in particular for remote sensing of the earth. For this purpose, such a radar

For example, on an aircraft with a radiation direction perpendicular to the direction of movement or trajectory and in the direction of the earth's surface arranged to scan by

electromagnetic waves a high-resolution

Two-dimensional recording of a section of the surface to win. The direction of movement is referred to in the literature as azimuth or along track, the transverse direction as a range or cross track. Furthermore, the

Area that the real antenna captures at a time, referred to in the literature as a footprint, as well as the terrain stripe that this footprint passes through the movement of the real antenna, referred to as swath (English: Swath).

Compared to a radar with real aperture (English: Real Aperture Radar, abbreviated RAR), in which a beam width and so that the possible resolution in the direction of movement depends on the physical length of the antenna and is therefore limited, in a SAR by means of the synthetic aperture process the length of the antenna can be increased and advantageously a higher resolution in the dimension of the direction of movement can be achieved. During the movement of the SAR on a track, radar pulses or signals are emitted sequentially and receive the amplitude and phase of echoes of these signals and in an echo memory

saved. Echoes of objects within the sampled swath are received and stored as long as they are within the beam width or the footprint of the antenna, whereby a high angular resolution is achieved. By processing the history of the echoes with respect to their respective Doppler shift a very narrow effective beam width of the antenna and thus advantageously a high resolution in the direction of movement is achieved, which is also independent of the distance of the antenna to the earth's surface.

In the dimension of the transverse direction, image coordinates are acquired by means of a distance measurement. These

Measurement is carried out by evaluation of the different

Signal propagation times of the echoes at different distances

Objects. The basis for such a distance measurement is the use of a frequency-modulated, for example

Continuous wave radar (English: Frequency Modulated Continuous Wave, abbreviated FMCW). By modulating the frequency over the duration of a signal, for example a

By ramping through a particular frequency band, a received wave can be assigned to a precise transmission time within the signal duration, from which the distance of an object whose echo is received can be determined. The maximum distance within which an assignment is possible, as well as the distance resolution are the steepness of the frequency change as well as the

Bandwidth depends. Because of the limited

Frequency bandwidth of the transmitter or receiver is a suitable compromise between the maximum distance and find the range resolution for the specific application.

Various modes of using SAR are known, three of which are briefly described below. A first mode, the so-called scan mode, allows under

Use of a so-called phased array antenna with digital or analog beamforming large-area recordings by pivoting the antenna beam or the

Antenna diagram in the transverse direction. This allows several parallel to the. During a period of time

Movement direction arranged surface sections and thus, in particular in comparison to recordings according to the so-called strip-map mode, a wide terrain strip are detected. However, a disadvantage is a comparatively low resolution in the transverse direction, which can be achieved with this mode.

A second mode, the so-called spotlight mode, is also based on the use of a phased array antenna, but this is the antenna beam to a specific

Area of the site, i. both in the direction of movement and in the transverse direction, pivoted. As a result of the larger number of measured points obtained and different angles, a higher resolution can advantageously be achieved. In a third mode, the so-called strip-map mode, the antenna beam is not swiveled in the transverse direction, so that the scanning takes place along a parallel to the direction of moving terrain strip.

This mode is used in particular for the remote sensing of the earth, in which by means of the SAR linear areas are detected. The stripmap mode is also in the

inventive method used by way of example,

especially because of its property, a

continuous stream to provide raw image data.

The generation of images from the continuous

Signal flow of the SAR by means of a known

Algorithm, for example by means of the so-called range Doppler, chirp scaling or frequency scaling algorithm. These algorithms are each able to digitize raw image data of the SAR by means of suitable digital

Process signal processors in real time. In particular, the range Doppler algorithm advantageously has a comparatively accurate approach to the exact SAR transfer function, making it particularly suitable for use in the method according to the invention. The algorithm thereby performs a compression of the image raw data in the two mutually orthogonal dimensions movement direction (azimuth, A) and transverse direction (range, R) with the target, contained in the image raw data and both in

Movement direction as well as in the transverse direction scattered echoes of a portion of the surface in a corresponding pixel or pixel of the reconstructed image

focus. The sequential four steps of the Range Doppler algorithm are called Range Compression, Azimuth FFT, Range Cell Migration Correction (abbreviated RCMC) and Azimuth Compression.

Further details and explanations of the Range Doppler algorithm and its individual steps can be found

For example, chapter 2.6.1.2.3 "Range Doppler" of the ASAR (Advanced Synthetic Aperture Radar) Product Manual of the European Space Agency (ESA), available at the link:

http://envisat.esa.int/handbooks/asar/toc.html, in the

Version dated 24 July 2014. The chapter 1.1.2 "Scientific Background" and especially the subchapter 1.1.2.3 "Synthetic Aperture Radar (SAR)" of this manual also contain further information on radar

based imaging as well as specifically to SAR.

The range Doppler algorithm can be simplified in the inventive use under certain conditions and the processing of raw image data can be accelerated thereby. For example, in the step of compression in

Transverse direction (range compression) as an alternative to the signal-matched filtering carried out therein by means of a so-called matched filter, a direct evaluation of a Frequency difference between a transmitted signal and the received echo possible. Further, from the performance of the first and the fourth of the above-mentioned four steps of the range Doppler algorithm, the compression in the transverse direction (Range Compression) and in the

Movement direction (Azimuth Compression), provided that by means of the second (Azimuth FFT) and third step (RCMC) already an image with a sufficient

Level of detail for the subsequent determination of

Speed can be gained. Due to the simplified generation of images, an iterative processing, which is described in more detail below, is advantageously made possible for determining the speed of the vehicle. To increase the accuracy of the subsequent evaluation of the images and in particular the accuracy of the derived therefrom

However, the speed of the first and fourth steps of the algorithm can be performed in a known manner, as long as the speed of processing allows it.

For the generation of a recording from the image raw data obtained by means of the SAR by means of the range Doppler algorithm is in the known remote sensing a parallel accurate logging of both the position and the

Speed of the aircraft at each emission

required. Specifically, the second, third and fourth steps (Azimuth FFT, RCMC and Azimuth Compression) of the Range Doppler algorithm take into account each separately detected speed. When using a SAR according to the invention is a precise information about the

Speed of the vehicle at the time of a radiation but not before, which is why generating images of the route from the raw image data obtained initially not possible in principle. However, the primary object of the present invention is not the generation of images but the use of images to determine the speed of the vehicle by means of them. According to the invention, the determination of the current speed of the vehicle based on a rating of images, taking into account a

Reference speed of the vehicle by means of a

aforementioned algorithm, in particular a range Doppler algorithm are generated. In the following, two inventive approaches for the evaluation of generated images and the determination based thereon of the

actual speed of the vehicle.

A first approach concerns evaluation by means of a

Determining the degree of focus of a generated

Image. Various algorithms mentioned by way of example are already called entropy, gradient, Laplace or wavelet-based focus computation, or as

Focus calculations according to Tenengrad, Vollath or Brenner known. An overview of these algorithms is, for example, the article by Pertuz, Said; Puig, Domenec; Garcia, Miguel Angel, "Analysis of focus measure operators for shape-from-focus", published in Pattern Recognition, 2013, Vol 46, Issue 5, pages 1415-1432, and methods for calculating an image focus are already included Remote sensing used for motion compensation.

 In addition to the described detection of position and

Movement data of the aircraft by means of, for example, an inertial navigation system are thereby additionally

Autofocus calculation method used to detect deviations from an ideal trajectory. These computational methods require multiple calculation of SAR image excerpts to determine motion errors to be used in the

Compensate for generation of an image.

The aim of the first approach according to the invention on the basis of a determination of a degree of focus is to obtain from a

A plurality of images generated at different reference speeds to determine an image, which has a good degree of focus. This image was generated at a reference speed that was accurate or sufficient exactly the actual speed of the vehicle

corresponds.

5 shows a flowchart 200 of an exemplary

Method for determining the speed of a vehicle on the basis of a determination of the degree of focus of a vehicle

Image, wherein the method, for example, in one or distributed in multiple processors or integrated

Circuits of the speed determination device 27, as shown in Figures 4a and 4b, can run. The

Method begins in the first method step 201. This first method step 201 is only at a

Initialization of the method carried out, in subsequent cycles of the method, however, only the

Process steps 202 to 208 described below are executed.

In a second method step 202, digitized raw image data is received by the SAR of the vehicle and in a subsequent third method step 203 from the

Raw image data, for example by means of an above

described range Doppler algorithm generates an image. The digitized image raw data are, for example, from the device 25 or 25.1 from the first

Reception antenna 13.1 echoes received by broadcasts of the transmitting antenna 12 and the first transmitting antenna 12.1 of

Speed determining device 27 is provided. The range Doppler algorithm takes into account for the

Processing a reference speed that the

Algorithm is supplied by means of a fourth method step 204. This reference speed may have been determined in a fifth method step 205,

for example, by means of an introductory described

known method or system for determining the

Speed of the vehicle, in particular based on a Doppler shift, speed information of one or more speed sensors or data of a satellite-based positioning system. The feeder of the fifth Process step 205 specific reference speed takes place, for example, only once at a

first-time operation of the above-described steps of the range Doppler algorithm or in a first cycle of the method. Likewise, in particular when the vehicle sets itself from the status of a standstill new or again in motion, in a first course of the algorithm, first a speed of zero or a minimum speed of 0.2 km / h, for example, be assumed. For subsequent operations of the algorithm for generating further images, the reference speed of a particular in a respective previous cycle of the method and in a

 Memory device correspond to cached speed of the vehicle. However, the reference speed determined in the fifth method step 205 may be determined by further units or components of the vehicle control,

In particular, as a further, redundant speed value, continue to be considered in a known manner.

After generation of an image in the third method step 203 taking into account the supplied

 Reference speed is determined in a subsequent sixth step 206, the degree of focus of the generated image using one of the above-exemplified algorithms for focus calculation. The certain one

Focusing degree of the generated image is evaluated in a subsequent seventh step 207. If the

Focusing grade in the seventh method step 207 is evaluated as not sufficiently good (branch "no"), the

Reference speed in the fourth step 204 by a predetermined amount, for example by 0.05km / h or 0.1km / h, increased or decreased to the Range Doppler algorithm for re-processing the same received image raw data to generate another

Picture to be fed. However, if the degree of focus determined for the generated image is evaluated as sufficiently good in the seventh method step 207 (branch "yes"), the image is thus generated at a reference speed that was almost or exactly the actual

Speed of the vehicle at the time of sampling by the SAR corresponds, will pay attention in the following

Step 208 is the underlying

Reference speed as a specific speed

output, i. other units or components of the vehicle control, in particular the drive and / or

Brake control, provided. Furthermore, as already mentioned above, this speed is buffered in a memory device in order to be taken into account by the range Doppler algorithm for the generation of a first image in a subsequent cycle of the method.

The evaluation of the particular degree of focus of a

generated image in the seventh method step 207, for example, by means of a comparison with a

predetermined threshold for the degree of focus. For example, is the particular value of the degree of focus above or equal to this threshold

Threshold value, the degree of focus is rated as sufficiently good (branch "yes") and the method is how

described with the eighth method step 208

continued. On the other hand, in the case where the specific value of the degree of focusing is below the threshold, the degree of focusing is judged not to be sufficiently good (branch "no") and the method as described above with a change of the reference speed in the fourth step 204 and generation of a new image in the third step 203 below

Consideration of the changed reference speed continued.

Alternatively to a comparison of the specific value for the degree of focus of an image with a given one

Threshold, a rating can also be made for example by means of a comparison of several values of the degree of focus. For example, in a previous cycle of the procedure for a generated picture a speed of the vehicle has been determined, then besides the

Speed also the value of the degree of focus, which is the basis of this speed, cached. As described above, the speed determined in a previous cycle becomes

cached and in a current cycle of the

Method considered as the reference speed for the generation of an image. Likewise, the value of the degree of focus determined in the preceding cycle may be temporarily stored and used as a reference for comparison with the currently determined value of the degree of focus in the seventh process step 207 of the current cycle.

If this comparison shows that the current value of the degree of focus is not or only slightly different from the

cached value of the degree of focus

differs, it can be concluded from this that the speed of the vehicle has not changed or only in the range of a detectable tolerance. A small one

Difference of the values can be detected, for example, by comparison with a lower threshold defined from the reference value. So if the currently determined value of the degree of focus is not from the

cached focus level differs as a reference value or within the by the lower

Threshold defined tolerance range, the currently determined value of the degree of focus is evaluated in the seventh step 207 of the current cycle as sufficiently good (branch "yes") and cached for a subsequent cycle of the method, as well as for the

Generation of the image considered

 Reference speed output in the eighth step 208 of the current cycle as a specific speed.

A subsequent cycle of the method in turn begins in the second method step 202 with the receiving digitized raw image data from a subsequent

Sampling of the driving distance of the vehicle by the SAR.

On the other hand, the comparison of the values indicates that the currently determined value of the degree of focus is lower than the cached value of the degree of focus of the

If the previous cycle is below the defined lower threshold value, then the currently determined value of the degree of focus is not rated as sufficiently good (branch "no".) In the following fourth method step 204, the reference speed is then changed by a specific, for example positive, speed value currently determined value of the degree of focus is discarded, so not as a reference value for a

cached subsequent cycle. The subsequently determined in the sixth method step 206 value of

The degree of focusing of the image generated in the third method step 203 on the basis of the changed reference speed is again determined in the seventh method step 207 using the buffered value of the degree of focus of the

compared to the previous cycle. If this comparison shows that the difference between the subsequently determined value and the cached value has decreased and now within the range defined by the lower threshold

Tolerance range is, then the certain value is rated as sufficiently good (branch "yes"). Preferably, as long as the current or subsequent value of the

Focusing level is lower than the cached value, the current or subsequent value discarded, so not cached. This will be a

possible creeping reduction in the quality of the focus of the generated images occurring over several cycles of the method due to a reduction of the cached value of the degree of focus, which is the basis for the comparison in the seventh method step 207 prevented. If, on the other hand, the current or subsequent value of the degree of focus is greater than that

cached value, so should the greater value cached and accordingly serve as a reference value for a subsequent cycle.

In the above example, however, the comparison of the subsequent value with the buffered value in the seventh method step 207 yields that the

Although the difference between the values has decreased, the subsequent value remains below the defined lower value

Threshold value and thus lies outside the tolerance range, then the subsequent value is again rated as not sufficiently good (branch "no") and the

Reference speed in step 204 again changed by a predetermined positive speed value. These method steps are run through until a value of the degree of focus is determined for a generated image that is at least within the defined range

Tolerance range and thus a sufficiently good

Quality.

However, in the example above, due to the positive increase in the reference velocity by a given velocity value, the difference between the subsequent value and the buffered value should be

increase, which in turn in a not sufficiently good evaluation of the subsequent value in the seventh

 Process step 207 results, the original reference speed of the cycle should be changed by a corresponding predetermined negative speed value, since the speed of the vehicle, as can be deduced from the increasing difference, has not increased as compared to the previous cycle, but has decreased.

The described approximation of the reference speed to the actual speed of the vehicle based on a rating of the degree of focus generated

Images lead to the described method steps 203, 206, 207 and 204 in one cycle of the method

if necessary, have to go through several times before a certain speed of the vehicle or a this

Speed representing value in the eighth

Method step 208 can be output. It should be noted that one determined by the method

Speed or a speed value should be output periodically. Control units of the vehicle, in particular for the drive and brake control of a trainset, which this speed value

consider, for example, operate with a

Cycle time of 10ms. Be within that time

Calculations regarding a next control step performed and sent corresponding control commands after the passage of time to other units. Accordingly, the described method should provide a value for the particular speed to the controllers adapted to this cycle time. The processors, circuits and circuits used to determine the speed

Memory devices are thus to be designed such that it is possible to run through a plurality of iterations of the method steps within the cycle time.

Should the actual speed over the

Period of two consecutive cycle times have not changed, so that the determined in the first cycle and taken into account in the second cycle reference speed continues to correspond to the actual speed, already has the first with this reference speed

generated image of the second cycle a sufficiently good value for the degree of focus. In principle, the evaluation would be completed for the second cycle. However, as further scores within the second cycle time would be possible due to the available processing capacity, further scores may be one for example

certain amount higher reference speed and one lower by a corresponding amount

 Reference speed can be performed. If one of the images generated with it has a higher value for the

Focusing degree than that with the reference speed generated corresponding image, the corresponding increased or decreased reference speed as specific

Speed can be output and cached for a subsequent cycle.

A second approach concerns evaluation by means of a correlation of two generated images. Corresponding

In particular, the representations in Figures 2 and 4a, the SAR of the inventive arrangement 9, a transmitting antenna 12 and two receiving antennas 13.1, 13.2, which are arranged on both sides of the transmitting antenna and at a certain distance from each other in or on the housing 10. Alternatively, the SAR, as shown in FIG 4b and two

Transmit antennas 12.1, 12.2 each with an associated

 Reception antenna 13.1 and 13.2 have. Hereinafter, only the case of a single transmitting antenna 12th

considered according to the arrangement of FIG 4a. The

However, explanations apply equally to the

Arrangement of FIG 4b with two transmitting antennas. The

Transmissions of the two transmitting antennas 12.1, 12.2 should preferably be synchronized and the image raw data of the two receiving antennas 13.1, 13.2 a same

Be assigned timestamp. However, if the emissions of the transmitting antennas are offset in time, this must be done accordingly in the subsequent determination of

Speed taken into account.

As the first receiving antenna 13. 1, the receiving antenna arranged in the direction of travel F of the vehicle 1 in front or to the left of the transmitting antenna 12 will be described below

defined as the second receiving antenna 13.2 in the direction of travel behind or right of the transmitting antenna 12th

arranged receiving antenna is defined. The transmitting antenna 12 radiates signals at a pulse repetition frequency

Direction of the route, for example, the track bed 15, over which the vehicle 1 moves from. Of objects in the superstructure, in particular of ballast stones of the bedding, evoked echoes of the transmitted signals are of the Receive antennas 13.1, 13.2 of the arrangement 9 received. The two receiving antennas 13.1, 13.2 generate from the

echoes received by means of a suitable amplification and filtering respectively analog image signals, which for the

subsequent processing to generate images in a known manner into digital image raw data to be converted. Furthermore, the digital raw picture data of the receiving antennas 13.1, 13.2, which correspond to a respective emission of the transmitting antenna 12, are each provided with a time stamp which subsequently fulfills the determination of

Serve speed of the vehicle.

The second approach is based on a comparison of images of the route by means of a correlation. Due to the distance of the two receiving antennas 13.1, 13.2 to each other, these echoes receive a same section of the travel path at different times. The time offset between these times depends on the speed of the vehicle to be determined by the method. For example, if a speed range between a minimum speed of 0.2km / h and a maximum speed of the vehicle of 500km / h can be detected, and the distance between the two is

Receiving antennas, for example, 1000mm, so needed

Vehicle at the minimum detectable speed about 18s, at the maximum detectable speed, however, only 7.2ms, by a distance corresponding to this distance

to cover. Thus, with this approach, it should be noted that the vehicle should have covered only a certain distance, which corresponds at least to the distance between the two receiving antennas, before images of the same

Detail of the route from raw image data of the two

Reception antennas can be meaningfully correlated.

In particular, at a first or renewed start of the vehicle from a standstill is therefore only from the

detectable minimum speed of the vehicle, and after reaching only about 18s later, a correlation of images generated from raw image data of the two Reception antennas useful. Unless then based on the

Correlation a speed of the vehicle could be determined, are subsequent provisions of the

Speed based on the quasi-continuous stream of digital image raw data of the two receiving antennas, however, without further delays possible.

Furthermore, the pulse repetition frequency of the SAR should be dimensioned according to the maximum speed. The

Pulse repetition frequency determined in addition to the number of transmitted ramps per unit time, the number of image rows in the azimuth direction, which can be recorded at a certain speed of the scanned route. At a maximum speed of 500km / h and a distance of the receiving antennas of 1000mm a corresponding number of recordings within the 7.2ms is required for an exemplary resolution of 128 pixels in the azimuth direction. This results in a pulse repetition frequency of 18kHz. to

Achieving such a high pulse repetition frequency, for example, a comparatively short pulse duration can be selected, which in particular due to the comparatively

small distance of the radar to the route and

correspondingly short signal propagation times is possible.

From the above values for the

Speed of the vehicle dependent time offset is also clear that, if the procedure described below to FIG 6 is not at a first or

restarting the vehicle from standstill expires, a good estimate of the speed is required. This serves to estimate the time lag between images of the same section of the route to start from this offset within the typical

Cycle time of 10 ms of control devices of the vehicle to be able to perform correlations of a plurality of images that lead to a suitable for the velocity determination correlation result. Mathematically, the above can be

Representations as follows. When the vehicle is moving at a speed v and a known distance r of the receiving antennas to one another, they pass a same point of the travel path with a time difference r

 At = -

 v

If the two receiving antennas the same point

they receive the same reflections and generate the same image raw data. The images of the two receiving antennas are denoted by Ii (m, n) or I _{2 (} m, n), where n denotes the index of the pixels in the range direction, while m refers to the direction of travel. Adjacent pixels or pixels are thereby in the direction of travel with a time difference

1

 TpRF - 7

TPRF sampled or stored, where f _PRF the

Pulse repetition frequency. This relationship can be formulated as follows: assuming:

At = LT _prf , L e N

The spacing of the pixels is hereafter referred to as

At

 Am = -

TPRF, where Am is the number of radiations of the

Transmit antenna or transmit antennas during the period that the two receiving antennas need to pass the same point called. The speed of the vehicle can be calculated accordingly by r

 n (Dhί) =

AmT _pRF

Since Am e TL applies, the resolution of the speed is not infinitely fine. The normalized resolution of

Speed is therefore defined as follows:

To determine Am, the maximum of the cross-correlation of the images Ij and I2 must be found. The

 Cross-correlation function is calculated as follows:

with Dm = argmax C (rrr)

The Dίh for which the correlation value is maximum denotes an estimated value of the image shift Am, from which the velocity v (Am) of the vehicle is calculated according to the above equation. The variables M and N

define the size of the image under consideration or those considered for the calculation of the correlation

Pixels, where the variable M defines the number of radiations in the direction of travel and the variable N the number of pixels in the range direction.

6 shows a flowchart 300 of another

exemplary method for determining the speed of a vehicle based on a correlation of Raw image data from two receiving antennas generated images. The method illustrated by way of example can be implemented in one or distributed in several processors or integrated in accordance with the method of FIG. 5 described above

Run off circuits of the speed determination device. The method begins in the first method step 301, this method step corresponding to

5 is carried out only during an initialization of the method, while in subsequent cycles of the method, the first

Process step 301 are performed subsequent method steps.

In parallel running second method steps 302.1, 302.2 digital raw image data of the two

Receive receiving antennas, which in third

Method steps 303.1, 303.2 turn means

For example, a range Doppler algorithm for

Generation of images are processed. The generation of images by means of parallel algorithms is not absolutely necessary. Alternatively, the digital raw image data of a scan received by the two receive antennas can also be processed sequentially, wherein, for example, an image is first displayed

Raw image data of the first receiving antenna 13.1 is generated and buffered in a memory device, and then one or more images of image raw data of the second receiving antenna 13.2 by means of the algorithm

to be generated. Preferably, however, due to the continuous flow of raw image data to be processed, parallel processing of raw image data occurs.

For the generation of an image, the respective range Doppler algorithm in the third method steps 303.1, 303.2 takes into account a reference speed, which is fed to the algorithms in a fourth method step 304. The algorithms take into account the same

Reference speed. According to the above described method of FIG 5, this

Reference speed previously in a fifth

Method step 305 has been determined. The supply of the determined in the fifth method step 305

 For example, the reference speed only occurs once when the algorithm is run for the first time.

Alternatively, however, in the case of a first sequence of the algorithm, initially also a speed of zero or a minimum speed of, for example, 0.2 km / h can be assumed. For subsequent processes of the respective range Doppler algorithm, a reference speed determined in a respectively preceding cycle of the method and temporarily stored in a memory device

Speed of the vehicle considered.

As mentioned above, the algorithm used to generate images may be simplified as needed. Particularly in the case of the range Doppler algorithm mentioned by way of example, a direct evaluation of a frequency difference between the transmitted signal and the received echo can take place in the step of compression in the transverse direction (range compression) as an alternative to the signal-adapted filtering performed therein. Furthermore, from the implementation of the first and / or fourth, the

respective compression in the transverse direction (Range

Compression) and in the direction of movement (Azimuth

Compression), the above-mentioned four steps of the range Doppler algorithm are omitted, if by means of the second (Azimuth FFT) and third step (RCMC) images can already be obtained with sufficient degree of detail, allowing a suitable correlation for the velocity determination. Advantageously, this can be the

Processing the image raw data, in particular the second

Receiving antenna can be accelerated so that within the available period of a cycle time, a larger number of generated images of raw image data of the second

Receiving antenna can be correlated with a generated image from raw image data of the first receiving antenna. In the third method steps 303.1, 303.2 off

Picture raw data of the first and second receiving antenna and taking into account a supplied reference speed generated images will pay attention in a subsequent

Process step 308 correlates. However, as explained above, it should be noted that the time offset between images of a same section of the route at a detectable speed range between 0.2km / h and 500km / h and a distance of the receiving antennas of 1000mm in a range between about 7ms and ca 18s can lie.

Due to this large possible temporal spectrum of the time offset, it is necessary to have a respective one

Image raw data of the first receiving antenna generated image in a eighth method step 308 upstream sixth method step 306.1 together with the associated

Timestamp for a period in a storage device between store. Preferably, an image is thereby stored until the cycle of the method with respect to this image with the eleventh method step 311, the

Output of the specific speed of the vehicle, has been completed. In the same way, a generated from image raw data of the second receiving antenna

each image together with the associated time stamp in a memory device until it is outside the time range in which it could potentially be subjected to a correlation in the eighth method step 308.

In the seventh method step 307, a selection of generated images of the first and second receive antenna is carried out for a correlation to be carried out in the following eighth method step 308. Due to the described

Time lag and the limited number of possible ones

Correlations of images within the period of a typical cycle time, the reference speed is considered for the selection of images of the first and second receiving antenna for a first correlation. This is in the Flowchart of FIG 6 by the dashed line

between the fourth method step 304 and the seventh method step 307 illustrated. Starting from a first image of the first receiving antenna is in the seventh method step 307 taking into account the

Reference speed a first image of the second

Receiving antenna selected, the neck of the

Travel should at least approximately correspond to the section of the first image of the first receiving antenna. The reference speed, on the basis of which the time offset for the selection of the first image of the second receiving antenna is determined for a first correlation, is preferably taken into account at the time of selection of the current reference speed. The choice of this reference speed makes sense, since the speed of the vehicle,

especially at low speeds or with strong positive or negative acceleration of the vehicle, during the time offset, i. in the period between the sampling of a section of the route through the first receiving antenna and the sampling of the same section by the second receiving antenna, may have changed significantly. Therefore, one should be as current as possible

Speed can be considered as the reference speed for the selection of the image of the second receiving antenna.

After selecting the first image of the second receiving antenna in the seventh method step 307, this will pay attention to the first image of the first receiving antenna in the following

Process step 308 correlates. The correlation compares two images for common image parts. In the following ninth method step 309, the result of the correlation is evaluated. If the correlation is rated as sufficiently good (branch "yes"), ie the images have a high degree of similarity or map with a high probability a same segment of the route, the method continues in the following tenth method step 310. The evaluation of the correlation can for example, again by means of a Comparison of the result with a predetermined threshold, which has been defined, for example, 0.9 done. In this tenth method step 310, the time offset is determined by means of the respective time stamp of the correlated images, and determined therefrom

Time offset and the known distance between the two

Receiving antennas to each other calculated the speed of the vehicle. This specific speed is subsequently output in the following eleventh method step 311, that is to say in accordance with the eighth described above

Method step 208 of the flow chart of FIG. 5 further units or components of the vehicle control,

in particular a drive and / or brake control of the vehicle provided. Furthermore, the

certain speed as the new reference speed by means of feeding via the fourth method step 304 in the generation in the third method steps 303.1, 303.2 and the selection of pictures in the seventh

Considered method step 307.

Subsequently, in the seventh method step 307, a subsequent second picture of the first receiving antenna

selected. This second image may, for example, be a time offset corresponding to the typical cycle time to the already correlated first image of the first receiving antenna

respectively. Thus, in this case, it may be useful to generate only one image per cycle time for the first receive antenna and store it in a memory device in order to subsequently correlate this with one or more generated images of the second receive antenna within a cycle time. Advantageously, the computational or storage capacity required for the generation and storage of the images of the first receiving antenna can thereby be reduced.

On the other hand, if the correlation in the ninth method step 309 is not rated as sufficiently good (branch "no"), the following seventh method step 307 is entered another, second generated and cached image of the second receiving antenna is selected, which is assigned to the previously selected first image earlier or later time stamp and correspondingly represents a higher or lower speed of the vehicle. The selection of the second image of the second receiving antenna for the

Correlation with the first image of the first receiving antenna can in turn depend on the reference speed and optionally on the type of vehicle or its positive and negative acceleration capacity.

The above with respect to the 5 and 6 described

Approaches each allow a comparatively accurate and reliable determination of the speed of a vehicle, in particular a rail vehicle described by way of example with reference to FIG. Since both approaches the same or similar devices, in particular a synthetic aperture radar and processors, integrated circuits and memory devices, to carry out the respective

Use method, they can also be realized together in an inventive arrangement. It can be determined by means of the two approaches each

For example, speeds combined with each other to increase the accuracy of the

 To determine the speed. Furthermore, they can also be output as redundant values independently of each other.

Claims

claims

A method for determining a speed of a

Vehicle (1), with the steps:

 Receiving (202, 302, 1, 302.2) image raw data generated by means of a synthetic aperture radar from samples of a travel distance of the vehicle,

 Generating (203, 303.1, 303.2) images of the scanned travel route from the received raw image data, wherein for the generation of a respective image a

Reference speed is taken into account,

 Evaluating (206, 308) at least one generated image with respect to at least one criterion,

 Selections (207, 309) of an image depending on the

Rating, and

 Determining (208, 310) the speed of the vehicle based on at least one information associated with the selected image.

2. The method of claim 1, wherein

in the step of evaluating (206) for the generated image, a degree of focus is determined, and as a criterion, the determined degree of focus is evaluated.

3. The method of claim 2, wherein

as information on the basis of which, in the step of determining, the speed of the vehicle is taken into account, which took into account for the generation of the image

Reference speed is assigned to the image.

4. A method according to any preceding claim, wherein in the step of evaluating (308) the generated image is compared with another image and as criterion a

Similarity of the pictures is evaluated.

5. The method of claim 4, wherein

in the step of generating (303.1, 303.2) a respective image with respect to a time of Sampling or timing of the generation of the image is assigned, and

determining, in the determining step (310), the speed of the vehicle based on a time difference between the assigned times of the images.

6. The method according to any preceding claim, wherein in the step of generating (203, 303.1, 303.2) as

Reference speed, a speed determined in a previous cycle of the method or a speed determined by means of another device for speed determination is taken into account.

7. Arrangement for determining a speed of a vehicle (1), comprising at least

 - A synthetic aperture radar, which by means of at least one transmitting antenna (12) and at least one

Receiving antenna (13.1, 13.2) scans a route of the vehicle,

 a speed determination device (27),

comprising at least one processor device and a

Memory device, by means of which images of the scanned travel route from raw image data received by the radar are generated taking into account a reference speed, at least one generated image is evaluated with respect to at least one criterion, an image is selected depending on the rating and the speed of the

Vehicle (1) is determined on the basis of at least one of the selected image associated information.

8. Arrangement according to claim 7, wherein

the speed determination device (27) thereto

is configured to determine a degree of focus of the at least one generated image and the determined

To rate the degree of focus as a criterion.

9. Arrangement according to claim 7 or 8, wherein

the speed determination device (27) thereto

is configured to compare the at least one generated image with another image and to evaluate a similarity of the images as a criterion.

10. Arrangement according to one of claims 7 to 9, wherein the speed determining means (27) thereto

is designed as a reference speed determined by another device for speed determination speed for the generation of the at least one

Picture to consider.

11. Arrangement according to one of claims 7 to 10, wherein the speed determining means (27) thereto

is configured to control a change in a radiation direction of the at least one transmitting antenna (12) of the radar.

12. vehicle, comprising at least

an arrangement according to one of claims 7 to 11 or

Devices for carrying out the method according to one of claims 1 to 6.