Method for checking a static monitoring system installed in a traffic space, and static monitoring system

Abstract

A method of inspecting a static monitoring installation including creating a reference image from signal reflections from static objects in a monitoring space determining a reference value from the reflections of the reference image, creating a comparison image from the signal reflections from the static objects in the space, wherein the comparison image is recorded with a time offset after the reference image, determining at least one comparison value from the reflections of the comparison image, and outputting a fault signal when a deviation of the comparison value and the reference value exceeds a threshold value.

Claims

1. A method of inspecting a static monitoring installation, the method comprising: creating a reference image from signal reflections from static objects in a monitoring space monitored by the monitoring installation; determining at least one reference value from the signal reflections of the reference image creating a comparison image from the signal reflections from static objects in the monitoring space , wherein the comparison image is recorded with a time offset after the reference image; determining at least one comparison value from signal reflections of the comparison mage; and outputting a fault signal based on a deviation of the comparison value and the reference value exceeding threshold value.

2. The method according to claim 1, wherein the reference image and the comparison image are associated with a polar coordinate system grid, wherein the polar coordinate grid system comprising a plurality of grid fields having an angle, a distance, and an intensity , and wherein the intensity of the grid field is based on a number and an intensity of the reflections of the respective grid field.

3. The method according to claim 2, further comprising: determining a first reference value and a first comparison value from the distances and the intensities of the grid fields of the polar coordinate grid; and determining a respective quotient from the distances and the intensities of the grid fields of the polar coordinate grid.

4. The method according to claim 3, wherein determining the first reference value and determining the first comparison value comprises in each case summing the distances and the intensities of the grid fields of the polar coordinate grid.

5. The method according to claim 2, further comprising: determing a second reference value and a second comparison value from the distances and the intensities of the grid fields of the polar coordinate grid; and determining a respective quotient from the angles and the intensities of the grid fields of the polar coordinate grid.

6. The method according to claim 3, wherein determining the second reference value and determining the second comparison value comprises in each case summing the angles and the intensities of the grid fields of the polar coordinate grid.

7. (canceled)

8. The method according to claim 1, wherein the threshold value is adapted on the basis of the deviation of the comparison value and the reference value.

9. (canceled)

10. The method according to claim 1, wherein the reference image is adapted on the basis of the comparison image.

11. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further advantages and features become apparent from the following description in connection with the appended drawings, in which:

[0035] FIG. 1 shows a schematic illustration of a monitoring installation;

[0036] FIG. 2 shows a schematic illustration of a reference image of the monitoring installation from FIG. 1;

[0037] FIG. 3 shows the reference image from FIG. 2 with a polar coordinate grid;

[0038] FIG. 4 shows an illustration of the reflections of the reference image from FIG. 2 in the polar coordinate grid;

[0039] FIG. 5 shows a schematic illustration of a comparison image with a restriction in the horizontal direction; and

[0040] FIG. 6 shows a schematic illustration of a comparison image with a restriction in the vertical direction.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a static monitoring installation 10 for a traffic space 12, in this example an intersection.

[0042] FIG. 1 shows only one monitoring installation 10. The traffic space 12 may however also contain multiple monitoring installations 10, for example in order to be able to monitor the traffic space 12 from different directions and/or perspectives. The monitoring installations 10 may be connected to one another or be connected to a common controller in order for example to compare the data from the monitoring installations 10 and/or to create a three-dimensional image of the traffic space 12.

[0043] The monitoring installation has a signal transmitter 14 and a signal receiver 16. The signal transmitter 14 transmits a signal 18, which is reflected from an object 20. The signal 18 is for example an optical, acoustic and/or electromagnetic signal. By way of example, the signal is a radar (radio detection and ranging) or lidar (light detection and ranging) signal.

[0044] If the signal 18 impacts an object 20, the signal 18 is reflected. The reflected signal 18 is detected by the signal receiver 16. The distance of the object 20 is able to be determined from the time of flight of the signal 18 from the signal transmitter 14 to the signal receiver 16. The direction of the object 20 is additionally able to be determined from the direction in which the signal 18 is transmitted and the direction from which the signal 18 is received by the signal receiver 16.

[0045] An image 26 of the traffic space 12 is able to be created in an evaluation circuit 24 from the received signals 22 or the direction and the distance of the objects 20. Each reflection may in this case be represented in this image 26 in simplified form by a point 28 (see FIG. 2).

[0046] The image 26 is constantly updated in order to recognize changes in the traffic space 12, for example moving objects 30 such as vehicles. By way of example, the signal transmitter 14 is pivoted or moved such that it captures the entire area to be monitored regularly or at a predefined frequency.

[0047] If a moving object 30 is located in the traffic space 12, this may be recognized through the fact that the reflections, that is to say the points 28 of this object in the image 26 change, for example change their position, or the time of flight and/or the frequency of the signal 22 increases or decreases.

[0048] Static objects, for example houses or traffic signs, on the other hand, provide a reflection of the signal 22 that is always the same, meaning that the points 28 that represent these static objects in the image 26 always remain unchanged.

[0049] As may be seen in FIGS. 3 and 4, the monitoring area is divided into a polar coordinate grid. In other words, starting from an origin, the monitoring area 31 is divided into concentric rings that are divided equally into grid fields 32 in the circular direction.

[0050] These grid fields 32 may each be identified unambiguously by the distance from the origin and the angle with respect to a reference plane. In addition, an intensity is specified for each of these grid fields 32, this being dependent on the number of reflections within this grid field 32 and on the strength of these reflections. At least one reference value is ascertained from the data of the individual grid fields 32.

[0051] By way of example, a first reference value may be a graph or a quotient that is formed from the summed distances and the summed intensities of the individual grid fields 32.

[0052] A second reference value may be for example a graph or a quotient that is formed from the summed angles and the summed intensities of the individual grid fields 32.

[0053] These reference values are stored in the evaluation circuit.

[0054] During operation of the monitoring installation, a comparison image of the current state of the monitoring area is created from the current reflections and is updated constantly.

[0055] A first comparison value or a second comparison value is ascertained from the comparison images or the reflections of the comparison images, in the same way as the first reference value or the second reference value, respectively.

[0056] These comparison values are each compared with the corresponding reference value in order to recognize pivoting of the monitoring area about a vertical axis (movement about the azimuth angle) and/or about a horizontal axis (height angle).

[0057] By way of example, external influences may cause the monitoring installation to pivot or rotate about a vertical axis. Incorrect or defective attachment of the monitoring installation may for example lead to tilting of the monitoring installation, and thus to pivoting about a horizontal axis.

[0058] In order to detect pivoting about a vertical axis, the first comparison value is compared with the first reference value.

[0059] Pivoting of the monitoring installation about the vertical axis results in movement of the pattern from which the first comparison value or first reference value are ascertained (FIG. 5). For illustrative purposes, the original positions of the reflections 28b in the polar coordinate grid 32 are illustrated in dashes. The distances to the individual reference points or reference patterns thus also change in the polar coordinate system. The intensities in the individual grid fields of the polar coordinate grid are thereby also moved. This leads to the first comparison value being changed such that there is a large deviation from the first reference value.

[0060] If the deviation of the first reference value by the first reference value exceeds a first threshold value for the first reference value, a fault signal is output, in particular containing information about the fact that the first threshold value has been exceeded or that pivoting about a vertical axis has taken place.

[0061] Selecting the method for ascertaining the first reference value or the first comparison value appropriately may additionally make it possible to conclude as to the angle of the pivoting.

[0062] By way of example, the cumulative intensities of the reference image and of the comparison image may be plotted graphically against the azimuth angle. The residual sum of squares (RSS) of both curves may be used as indicator for the pivoting.

[0063] In order to detect pivoting of the monitoring installation about a horizontal axis, the second comparison value is compared with the second reference value.

[0064] In the event of tilting of the monitoring installation, that is to say pivoting about a horizontal axis, this does not result in movement of the static reflections from the static objects, since the distance and the azimuth angle of the monitoring installation relative to the static objects remain the same. The tilting however results in individual static reflections leaving the monitoring field of the sensor in the vertical direction or new reflections being added (FIG. 6).

[0065] This may be detected by comparing the second comparison value with the second reference value, since such a movement leads to a change in the position of the intensities in the polar coordinate system.

[0066] The residual sum of squares (RSS) of both curves may be likewise be used to acquire the angle of the pivoting.

[0067] The method described above offers a simple and reliable method for recognizing pivoting of the monitoring installation 10. Dividing the monitoring area into a polar coordinate grid in particular makes it possible to significantly reduce the amount of data and thus computing effort. By way of example, a polar coordinate grid comprises 200 azimuth sectors, 200 distance increments, and 8 bits for the intensity increments. This corresponds to a total of only 40 kB of memory.