Method for determining sections of a route subject to a speed limit

Abstract

Method (100) for determining sections (w1) of a covered route (w) that are subject to a speed limit, wherein, when the route (w) is covered by a user, a speed and / or acceleration profile (201, 301) of the user along the route (w) is recorded and, by comparing this speed and / or acceleration profile (201, 301) with predetermined profile properties characterizing a speed limit, a section (w1) of the route (w) that is subject to a speed limit is recognized, wherein • the recorded speed and / or acceleration profile (201, 301) comprises a profile (201; 301) of a longitudinal speed (v) and longitudinal acceleration (b) of the user along the distance travelled (w), • sections (w1) of the distance travelled (w) are determined therefrom in which the longitudinal speed (v) is lower than a predeterminable first threshold value (s1), • in each of these determined sections (w1), a first point (w11) is determined at which the longitudinal acceleration (b) falls below a predeterminable second threshold value (s2), and a second point (w12) is determined along the route (w) following the first point (w11), at which the longitudinal acceleration (b) exceeds a predeterminable third threshold value (s3), and • a region of the route (w) between the first (w11) and the second location (w12) is recognized as a section (w1) of the route (w) subject to a speed limit.

Description

State of the art

[0001] The maximum speed achievable by a road user, e.g., with a vehicle, along a route, in particular a traffic route, e.g., a road, is determined by speed limits regulated by traffic signs, hereinafter referred to as administrative speed limits, and by other characteristics of the route, such as the number of lanes, lane width, road quality, visibility, development, curve radii, and conditional speed limits, hereinafter referred to as implicit speed limits. Data concerning such speed limits are partly included in map data of digital maps, which are used particularly in navigation devices.In order to supplement information on this subject from incomplete or outdated map data, modern motor vehicles equipped accordingly can detect administrative speed limits, partly using a camera based on the corresponding traffic signs, and determine them through electronic analysis using pattern recognition processes. This analysis is difficult when the traffic signs to be detected hardly differ from other structures appearing in analyzed video images, constantly change their shape, or have a rectangular contour; the latter because today's environment contains many more rectangular than round objects. Therefore, the recognition of place-name signs on roads is particularly complex and may not be sufficiently reliable. A method for creating longitudinally distributed speed data is known from US 2011 / 0307165 A1.A method for determining traffic situation information is known from DE 101 33 001 A1. Disclosure of the invention

[0002] The invention aims to create a simplified and reliable method for determining sections of a route on which a speed limit - be it an administrative or an implicit one - applies.

[0003] This object is achieved by a method for determining sections of a travelled route that are subject to a speed limit, wherein, when a user travels the route, a speed and / or acceleration profile of the user along the route is recorded and, by comparing this speed and / or acceleration profile with predetermined profile properties characterising a speed limit, a section of the route that is subject to a speed limit is recognised.

[0004] The core of the method according to the invention thus lies in detecting existing speed limits from a measured speed and / or acceleration profile of the user along the route. The term "route" refers to any type of traffic route that is designed to allow any type of road user, referred to here as the user, to move along or on it, e.g. a road, a path or the like. The route is preferably displayed on a digital map as used by a navigation device. On sections of this route subject to a speed limit, this speed limit, which can be either administrative or implicit, applies to users traveling the route. This traveling of the route occurs through a movement tailored to the type of user.Preferably, this movement of the user along the route takes place by driving a vehicle, which can be of any type. The speed and / or acceleration profile represents a course of the speed and / or acceleration along the route, i.e., over a location coordinate that runs along the route and describes its dimension in the direction of the user's movement, and is measured by measuring the speed and / or acceleration along the route and / or determined from a measurement of the user's location coordinate over time. As explained in more detail below, the acceleration profile can comprise a longitudinal and / or a lateral acceleration.

[0005] The predefined profile properties characterizing a speed limit include speed or acceleration values ​​along the route, i.e., assigned to specific values ​​of the location coordinates, or further parameters determined or determinable therefrom, which are characteristic of the presence of a speed limit, i.e., which the user's speed and / or acceleration profile typically assumes in a section of the route traveled subject to a speed limit. Furthermore, the section subject to a speed limit can also be characterized by a particular characteristic of the speed and acceleration profile directly before and / or directly after the section, in particular by braking before the section or accelerating out of the section.In other words, the profile properties are characteristic curves of the speed and / or acceleration and / or the parameters determined or determinable from them. If a user moves along a route - preferably one shown on a digital map - the location coordinates and the time or the speed or acceleration are measured along at least one selectable section of the route and the speed or acceleration profile along the route is created; this is compared with predetermined profile properties characterizing a speed limit, e.g. characteristic curves or threshold values. From the result of the comparison, it is concluded that a speed limit exists or is in force along the selected section or one or more other sections that are related to it in a predeterminable way, in particular along the location coordinates of neighboring sections.These further sections are determined from the result of the comparison.

[0006] The invention enables a simple and direct detection of sections of a route subject to a speed limit, based solely on simple distance-time, speed, or acceleration measurements, i.e., by analyzing driving dynamics data or measured values. This also makes it possible to determine speed limits that would otherwise be difficult or impossible to determine. This applies in particular to implicit speed limits. A particularly advantageous use of the method according to the invention is the detection of through-town areas.

[0007] Advantageous embodiments of the method according to the invention are characterized in the dependent claims which refer back thereto.

[0008] According to a preferred development of the method according to the invention, the recorded speed and / or acceleration profile comprises a profile of a longitudinal speed and longitudinal acceleration of the user along the route traveled, sections of the route traveled are determined therefrom in which the longitudinal speed is lower than a predefinable first threshold value, in each of these determined sections a first point at which the longitudinal acceleration falls below a predefinable second threshold value and a second point along the route following the first point at which the longitudinal acceleration exceeds a predefinable third threshold value are determined, and a region of the route between the first and the second point is recognized as a section of the route subject to a speed limit.

[0009] The longitudinal speed and longitudinal acceleration refer to a speed and acceleration respectively in the direction of the route, i.e. the spatial coordinate. The first or second location designated by specific values ​​of the longitudinal acceleration is, depending on the course of the longitudinal acceleration profile along the spatial coordinate, a part, area or point on the route with a specific value of the spatial coordinate. The first threshold value determines the maximum speed that the user must adhere to when moving due to the detected speed limit in the relevant sections. The second threshold value for the longitudinal acceleration is preferably obtained from averaging all negative values ​​for the longitudinal acceleration along the entire route, i.e. all sections, i.e. parts or areas in which the user's movement slows down.Particularly preferably, the second threshold value is at least almost half the mean value of all negative longitudinal accelerations. Accordingly, the third threshold value for the longitudinal acceleration is preferably obtained by averaging all positive values ​​for the longitudinal acceleration along the entire route, i.e., all sections in which an increase in the speed of the user's movement occurs, and particularly preferably, the third threshold value is at least almost half the mean value of all positive longitudinal accelerations. The first digit indicates a deceleration process in the user's movement, and the second digit indicates an acceleration process, such as are characteristic at the beginning and end of a section of the route subject to a speed limit and only occur in this sequence.If no two such locations are found in the specified sequence along a section of road where the longitudinal speed is lower than the first threshold, this section is discarded for determining a speed limit. The described sequence is particularly characteristic of sections of the road located within built-up areas. This advantageously allows for the determination of the administrative speed limit within built-up areas.

[0010] In a further preferred embodiment of the method according to the invention, the area of ​​the route between the first and the second point is only recognized as a section of the route subject to a speed limit if the first and the second point along the route are at a predefinable minimum distance apart. This enables a simple distinction to be made between a characteristic acceleration profile in the area of, for example, an intersection, at which the first and the second point along the route follow one another closely or directly, and in sections of the route subject to a speed limit, for example a built-up area, in which the first and the second point are spaced apart along the route by an extent equal to, for example, the built-up area. By comparing this with the minimum distance, it is thus possible in particular to distinguish between intersection areas and the sections subject to a speed limit.

[0011] According to another embodiment of the method according to the invention, the recorded speed and / or acceleration profile comprises a profile of a lateral acceleration of the user along the route traveled, in each of the determined sections of the route traveled in which the longitudinal speed is lower than the predeterminable first threshold value, all peak values ​​of the lateral acceleration that exceed a predeterminable fourth threshold value are determined, and a first mean value is formed from the peak values ​​of the lateral acceleration thus determined for the relevant determined section, a second mean value of the lateral acceleration is formed for each of the determined sections of the route traveled, a third mean value and a standard deviation are formed from a distribution function of the second mean values ​​of all determined sections of the route traveled,a fifth threshold is calculated from the third mean value and the standard deviation, and a determined section is then recognised as a section of the route subject to a speed limit if the first mean value for the determined section in question is less than the fifth threshold value.

[0012] This embodiment of the method is particularly advantageous for distinguishing sought-after sections of the route subject to a speed limit from tight, winding hairpin bends and motorway on- and off-ramps, which form sections of the route with a longitudinal speed and longitudinal acceleration of the user similar to a speed limit. In order to be able to distinguish the sought-after sections from the hairpin bends and motorway on- and off-ramps, a further auxiliary condition is introduced: the lateral acceleration, i.e. an acceleration occurring transversely to the spatial coordinate running along the route. Firstly, for each section of the route in which the longitudinal speed is lower than the first threshold value, the first mean value of the peak values ​​of the lateral acceleration is calculated.Only those peak values ​​with a lateral acceleration greater than the fourth threshold are used for averaging. The fourth threshold is preferably equal to the average lateral acceleration along the entire route.

[0013] The mean values ​​of all road sections form a distribution function, the mean value, referred to here as the third mean, and the standard deviation of which are used to distinguish sections of the road subject to a speed limit from tight, winding sections. All road sections are recognized as sections subject to a speed limit, e.g., as a built-up area, whose mean maximum lateral acceleration is less than the fifth threshold, which is preferably equal to the sum of the third mean value of the aforementioned distribution function and half the standard deviation of this distribution function.

[0014] In a further preferred embodiment of the method according to the invention, a median value and / or a variance of the lateral acceleration is determined for each of the determined sections of the route travelled in which the longitudinal speed is lower than the predefinable first threshold value, and the section in question is then recognized as a section of the route subject to a speed limit if the median value of the lateral acceleration for the section in question is lower than a sixth threshold value and / or if the variance of the lateral acceleration for the section in question is greater than a seventh threshold value.

[0015] This embodiment of the method is particularly advantageous for distinguishing desired sections of the route subject to a speed limit from motorway on- and off-ramps, which have larger curve radii and thus lower lateral acceleration than serpentines. Motorway on- and off-ramps cannot therefore always be reliably distinguished from sections of the route subject to a speed limit, which may also contain curves, by averaging the lateral acceleration alone. For this reason, the median value and the variance of the lateral acceleration of a route section are also taken into account. In the case of a section of the route subject to a speed limit, e.g. a built-up area, the lateral acceleration along the route only shows isolated deviations from an average value. Along most sections of the route, the lateral acceleration is low.Thus, the median value is comparatively low. At a motorway entrance or exit, the lateral acceleration is greater over other sections of the route, but exhibits smaller deviations or scatter there. Thus, the median value at a motorway entrance or exit is characteristically greater than in a section of the route subject to a speed limit, e.g., a built-up area, and the variance at a motorway entrance or exit is characteristically lower than in a section of the route subject to a speed limit. To identify these characteristic ratios, the median value is compared with the sixth threshold and the variance with the seventh threshold.In other words, using the median value of each section, a distribution function with a fourth mean is also established, which allows a distinction to be made between a section of the route subject to a speed limit, e.g., a built-up area, and a motorway entrance or exit. Any section of the route is identified as a section of the route subject to a speed limit, e.g., a built-up area, that has a lower median value than the sixth threshold. Preferably, the sixth threshold is 0.85 times the fourth mean.

[0016] According to a preferred development of the method according to the invention, data relating to at least one of the sections of the route identified as being subject to a speed limit are stored in a digital map in which the route traveled is stored at least in sections. The sections of the route identified as being subject to a speed limit are preferably stored in the digital map in the form of an attribution. In this way, the digital map is enriched or updated by the speed limits identified while the route is being covered. Advantageously, the digital map is thus enriched, for example, during a journey, with a wide variety of information that cannot otherwise be recorded or can only be recorded with great effort.In a preferred development, the method according to the invention completely replaces the detection of speed limits by means of a camera based on the detection of associated traffic signs.

[0017] According to another embodiment of the method according to the invention, data relating to at least one of the sections of the route identified as being subject to a speed limit is forwarded to other users via a data transmission connection. This also provides the other users with information about speed limits along routes they have not yet traveled. Advantageously, comparing speed limits identified by one user with other users via a central communications and / or computing unit, e.g., a server, also increases the accuracy of identifying sections of the route subject to a speed limit.

[0018] The object mentioned at the outset is further advantageously achieved by a computer program product comprising program parts for carrying out a method of the type described, by a machine-readable, in particular computer-readable, data structure generated by such a method and / or by at least one computer program product of the type described above, and by a machine-readable, in particular computer-readable, data carrier on which at least one computer program product of the type described above is recorded and / or stored and / or on which at least one data structure of the type described above is kept ready for retrieval.

[0019] An embodiment of the invention is illustrated in the drawing and will be described in more detail below, wherein corresponding elements are provided with the same reference numerals in all figures and a repeated description of these elements is omitted. They show: Fig. 1 an example of a profile of a longitudinal speed of a user along a route travelled by him, Fig. 2 an example of a profile of a longitudinal acceleration of the user along the route travelled by him, Fig. 3 a rough schematic representation of an example of the route travelled by the user, contained in a representation of a digital map, and Fig. 4 a roughly schematic representation of a flow diagram of an example of the method according to the invention, which diagram also represents an example of a structure of a device or circuit arrangement for carrying out the example of the method according to the invention.

[0020] In Fig. 1, a diagram 200 shows a profile 201 of a longitudinal speed v of a user along a distance w traveled by the user. From the profile 201, sections of the distance w subject to a speed limit are to be identified according to the method according to the invention. The profile 201 has, between a starting point 202 and an end point 203 along the distance w traveled by the user, a section w1 of the traveled distance w in which the longitudinal speed v is lower than a first threshold value s1. As an example, the detection of a speed limit of 50 km / h in a built-up area is described, for which the first threshold value s1 is selected to be 60 km / h. The section w1 of the distance then represents a preselection from all sections or areas of the distance w, which is examined in more detail in the further course of the method.Beyond the end point 203, the longitudinal velocity v rises above the first threshold value s1 in a short section of the route w, only to become lower than the first threshold value s1 again from a further starting point 204. The next section of the route w, beginning with this point and in which the longitudinal velocity v is lower than the first threshold value s1, is not considered further.

[0021] In Fig. 2, a diagram 300 shows a profile 301 of a longitudinal acceleration b of the user, assumed to be along the Fig. 1 are plotted. The section w1 of the route w in which the longitudinal speed v is lower than the first threshold value s1 is plotted between a starting point 302 and an end point 303. A predeterminable second threshold value s2 for negative longitudinal accelerations b, i.e. deceleration, of the user and a predeterminable third threshold value s3 for positive longitudinal accelerations b, i.e. speed increases, of the user are plotted in the diagram 300 on both sides of a zero line 304 of the longitudinal acceleration b. In the section w1 there is a first point w11 at which the longitudinal acceleration b falls below the second threshold value s2 in a negative peak, and a second point w12 along the route w following the first point w11 at which the longitudinal acceleration b exceeds the third threshold value s3 in a positive peak.These peaks are characteristic of a town entrance with a deceleration process, or a town exit with an acceleration out of the town. A section of the route w between the first point w11 and the second point w12 forms a section of the route w that is recognized as subject to a speed limit, i.e., in the present example, as the town with the town entrance at the first point w11 and the town exit at the second point w12. Here, the town extends at least largely over the section w1 of the route w.

[0022] The profiles 201 and 301 of the longitudinal speed v and the longitudinal acceleration b shown as examples contain, within the section w1, a further first point w13 at which the longitudinal acceleration b falls below the second threshold value s2 in a negative peak, and a further second point w14 along the route w following the further first point w13, at which the longitudinal acceleration b exceeds the third threshold value s3 in a positive peak. In the area of ​​these further first and second points w13, w14 along the route w, the profile 201 of the longitudinal speed v shows a further negative peak 205. This formation of the profiles 201, 301 of the longitudinal speed v and the longitudinal acceleration b are characteristic of a bend or an intersection before which, such as at the entrance to a town, there is a deceleration and behind which there is an acceleration, while the bend or intersection isThe intersection itself is traveled at least partially at a reduced speed. Unlike the town entrance and exit, the further first point w13 and the further second point w14 along the route w do not have a predeterminable, required minimum distance, which makes them distinguishable from the town entrance and exit.

[0023] Fig. 3 illustrates a roughly schematic representation of an example of a digital map 400, here a city map, in which the distance w traveled by the user is shown alongside other map elements, of which only additional streets 401 and railway lines 402 are sketched as examples. The actual town entrance 403 and the actual town exit 404 are marked with symbols for town signs. A first arrow 405 indicates the first point w11 at which a town entrance is recognized by the method, and a second arrow 406 indicates the second point w12 at which a town exit is recognized. Due to the user's excessive speed in the area of ​​the actual town entrance 403, only a point shifted along the distance w is recognized as the town entrance.

[0024] Fig.4 shows a flow diagram 100 of an example of the method according to the invention in a roughly schematic representation. The diagram 100 also represents an example of the structure of a device or circuit arrangement for carrying out the example of the method 100 according to the invention. Accordingly, blocks of the diagram 100 symbolize both method steps and device blocks, in particular circuit blocks for signal processing of a device or circuit arrangement for carrying out the method 100. Beginning optionally with a time measurement in block t and a measurement of the location coordinate along the distance w in block w and therefrom a calculation of the profiles 201, 301 of the longitudinal velocity v and the longitudinal acceleration b in blocks v andb or with a direct measurement of the distance w, the longitudinal speed v and the longitudinal acceleration b, the profile 201 of the longitudinal speed v is compared in a first comparison block 101 with the first threshold value s1, which is predetermined by a block s1. In the first comparison block 101, the sections w1 are determined in which the longitudinal speed v is lower than the first threshold value s1. Via a first blanking block 102, only those parts of the profile 301 of the longitudinal acceleration b in the sections w1 are selected, each fed to a detection block 103 for positive or 104 for negative peaks of the longitudinal acceleration b and compared therein with a third threshold value s3 for the positive or a second threshold value s2 for the negative peaks. Only the peaks which fall below or exceed these threshold values ​​s2 or s3 are checked for recognition in a subsequent evaluation block 105 as the first position w11 orsecond location w12 is evaluated taking into account a minimum distance predeterminable by a block 106. If a section subject to a speed limit is identified from this, this information is passed to a combination block 107. The second s2 and third s3 threshold values ​​are obtained from an averaging 108 for the negative peaks and 109 for the positive peaks of the longitudinal acceleration b of the entire route w. A lateral acceleration detected along the route w in a block q is selected in the section w1 by a second blanking block 110. From this, in block 111, all peak values ​​of the lateral acceleration q are determined which exceed a fourth threshold value s4, which is obtained from an averaging 112 over the lateral acceleration q of the entire route w.From the peak values ​​of the lateral acceleration q thus determined for the section w1, a first mean value m1 is formed, and for each section w1 of the route w, a second mean value m2 of the lateral acceleration q is formed. From a distribution function of the second mean values ​​m2 of all sections w1, a third mean value m3 and a standard deviation sv are formed, and from both, a fifth threshold value s5 is formed. A section w1 is then recognized as a section of the route w subject to a speed limit if a comparison 113 shows that the first mean value m1 for the section w1 in question is smaller than the fifth threshold value s5. Furthermore, a median value me and a variance va of the lateral acceleration q are determined from the lateral acceleration q selected in the section w1 by the second blanking block 110.If the median value me is less than a sixth threshold value s6 and / or the variance va is greater than a seventh predeterminable threshold value s7, which conditions are checked in comparisons 114 and 115, respectively, the section w1 is identified as being subject to a speed limit. The sixth threshold value s6 is preferably 0.85 times a fourth mean value m4 of a distribution function established using the median value me. The evaluation block 105 and the comparisons 113, 114, 115 combine detection results in the combination block, and preferably the section w1 is only identified as being subject to a speed limit if all of these results agree. In accordance with the above, parallel detection of a plurality of predefined maximum speeds is also feasible.

Claims

[1] Method (100) for determining sections (w1) of a route (w) covered which are subject to a speed limit, wherein, when the route (w) is covered by a user, a speed and / or acceleration profile (201, 301) of the user along the route (w) is recorded and, by comparing this speed and / or acceleration profile (201, 301) with predetermined profile properties characterising a speed limit, a section (w1) of the route (w) which is subject to a speed limit is recognised, wherein • the recorded speed and / or acceleration profile (201, 301) comprises a profile (201; 301) of a longitudinal speed (v) and longitudinal acceleration (b) of the user along the distance travelled (w), • sections (w1) of the distance travelled (w) are determined therefrom in which the longitudinal speed (v) is lower than a predeterminable first threshold value (s1), • in each of these determined sections (w1), a first point (w11) is determined at which the longitudinal acceleration (b) falls below a predeterminable second threshold value (s2), and a second point (w12) is determined along the route (w) following the first point (w11), at which the longitudinal acceleration (b) exceeds a predeterminable third threshold value (s3), and • a region of the route (w) between the first (w11) and the second location (w12) is recognized as a section (w1) of the route (w) subject to a speed limit. [2] Method (100) according to claim 1, characterized by that the area of ​​the route (w) between the first (w11) and the second point (w12) is only recognized as a section (w1) of the route (w) subject to a speed limit if the first (w11) and the second point (w12) along the route (w) have a predeterminable minimum distance (106). [3] Method (100) according to claim 1 or 2, characterized by , that • the recorded speed and / or acceleration profile (201, 301) comprises a profile of a lateral acceleration (q) of the user along the distance travelled (w), • in each of the determined sections (w1) of the distance travelled (w) in which the longitudinal speed (v) is lower than the predeterminable first threshold value (s1), all peak values ​​of the lateral acceleration (q) are determined which exceed a predeterminable fourth threshold value (s4), and a first mean value (m1) is formed from the peak values ​​of the lateral acceleration (q) thus determined for the relevant determined section (w1), • a second mean value (m2) of the lateral acceleration (q) is calculated for each of the determined sections (w1) of the distance travelled (w), • a third mean value (m3) and a standard deviation (sv) are formed from a distribution function of the second mean values ​​(m2) of all determined sections (w1) of the distance travelled (w), • a fifth threshold value (s5) is formed from the third mean value (m3) and the standard deviation (sv) and • a determined section (w1) is recognized as a section (w1) of the route (w) subject to a speed limit if the first mean value (m1) for the determined section (w1) in question is smaller than the fifth threshold value (s5). [4] Method (100) according to claim 3, characterized bythat for each of the determined sections (w1) of the route (w) travelled in which the longitudinal speed (v) is lower than the predefinable first threshold value (s1), a median value (me) and / or a variance (va) of the lateral acceleration (q) is determined, and that the determined section (w1) in question is then recognized as a section (w1) of the route (w) subject to a speed limit if the median value (me) of the lateral acceleration (q) for the determined section (w1) in question is lower than a sixth threshold value (s6) and / or if the variance (va) of the lateral acceleration (q) for the determined section (w1) in question is greater than a seventh threshold value (s7). [5] Method (100) according to one or more of the preceding claims, characterized bythat in a digital map (400), in which the distance (w) travelled is stored at least in sections, data relating to this speed limit are stored for at least one of the sections (w1) of the route (w) recognised as being subject to a speed limit. [6] Method (100) according to one or more of the preceding claims, characterized by that, for at least one of the sections (w1) of the route (w) identified as being subject to a speed limit, data relating to this speed limit are forwarded to other users via a data transmission connection. [7] Computer program product comprising program parts for executing a method (100) according to at least one of the preceding claims 1 to 6. [8] Machine-readable, in particular computer-readable, data structure, generated by a method (100) according to at least one of claims 1 to 6 and / or by at least one computer program product according to claim 7. [9] Machine-readable, in particular computer-readable, data carrier on which at least one computer program product according to claim 7 is recorded and / or stored and / or on which at least one data structure according to claim 8 is kept ready for retrieval.

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