Method for detecting degradation of a lidar sensor and method for operating a vehicle and / or a robot - Patents.com

Abstract

The invention relates to a method for detecting degradation of a lidar sensor, comprising emitting lidar pulses by a lidar sensor, detecting reflections of the emitted lidar pulses by the lidar sensor, detecting an object (O) reflecting the lidar pulses in an environment surrounding the lidar sensor, tracking the detected object (O) over a number of time cycles, determining the lidar pulses that would be reflected by the object when tracking the object (O) taking into account a distance (d) of the tracked object (O) to the lidar sensor and a geometry of the tracked object (O), determining a failure rate (a) indicative of how often an expected reflection is not detected within a predefined period of time, and inferring degradation of the lidar sensor based on the failure rate (a) and the distance (d) to the tracked object (O). The invention further relates to a method for operating a vehicle and / or a robot.

Description

[Technical field]

[0001] The present invention relates to a method for detecting degradation of a LIDAR sensor.

[0002] The invention further relates to a method for operating a vehicle and / or a robot. [Background technology]

[0003] From DE 10 2018 008 903 A1 a method is known for determining the field of view of a beam-based sensor of a vehicle for detecting the surrounding environment. A sensor beam of known intensity is emitted by the beam-based sensor, a reflection of the sensor beam is detected by the sensor and the reflection intensity is evaluated. The measured distance and the reflection intensity are correlated to determine whether the field of view of the sensor is reduced compared to the maximum field of view of the sensor. Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present invention to provide a novel method for detecting degradation of a lidar sensor and a novel method for operating a vehicle and / or a robot. [Means for solving the problem]

[0005] The above object is achieved according to the invention by a method for detecting deterioration of a lidar sensor having the features of claim 1 and by a method for operating a vehicle and / or a robot having the features of claim 6.

[0006] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0007] According to the present invention, in a method for detecting degradation of a lidar sensor, a lidar pulse is emitted by the lidar sensor and a reflection of the emitted lidar pulse is detected by the lidar sensor. Furthermore, an object reflecting the lidar pulse is detected in the environment of the lidar sensor, and the detected object is tracked over a number of time cycles. Taking into account the distance of the tracked object to the lidar sensor and the geometry of the tracked object, a lidar pulse that will be reflected by the object when tracking the object is determined. Furthermore, a failure rate is determined, which indicates how often an expected reflection is not detected within a predetermined period of time. Degradation of the lidar sensor is inferred based on the failure rate and the distance to the tracked object.

[0008] Besides determining the current degradation of the lidar sensor, which is influenced for example by environmental influences or contamination, the method also enables reliable determination of aging and loss of individual transmitter-receiver pairs of the lidar sensor, which allows a particularly reliable and safe operation of automatic, in particular highly automatic or autonomous vehicles and / or robots, since this information can be used on the one hand to adapt the current driving style of the vehicle and / or robot to the degradation of the lidar sensor and on the other hand to identify the aging state of the lidar sensor.

[0009] In a possible embodiment of the method, a decrease in the coverage of the lidar sensor is determined as degradation. Thus, the current driving style of the vehicle and / or robot can be adapted to the current coverage of the lidar sensor. For example, the driving speed of the vehicle and / or robot can be reduced as the at least one lidar sensor becomes increasingly degraded.

[0010] In another possible embodiment of the method, a failure rate is determined for each receiver pixel of the lidar sensor, which ensures that in the event of degradation of a portion of the lidar sensor, information detected by receiver pixels outside the degraded region can still be used for the automatic operation of the vehicle, thereby minimizing limitations of the automatic operation.

[0011] In another possible embodiment of the method, a comparison is performed between the determined failure rate of each receiver pixel and the determined failure rates of adjacent receiver pixels depending on the distance to the tracked object in order to determine defects and / or aging of each receiver pixel, which can further increase the reliability of the method.

[0012] In another possible embodiment of the method, the range of the lidar sensor is determined from the reflection intensity of the lidar pulse reflected by the object and the distance of the lidar sensor to the object. Such a range determination can be performed in a particularly simple, reliable and accurate manner.

[0013] In the method of the present invention for operating a vehicle and / or robot, the surrounding environment of the vehicle and / or robot is detected by at least one lidar sensor and, depending on the data detected by the lidar sensor, an automatic, in particular highly automatic or autonomous operation of the vehicle and / or robot is performed, taking into account the degradation of the at least one lidar sensor detected by the aforementioned method.

[0014] The method allows for reliable detection of lidar sensor degradation, thereby enabling autonomous vehicles to operate with similar reliability, thereby improving road safety.

[0015] In a possible embodiment of the method, during autonomous driving operation, the driving speed of the vehicle and / or robot can be reduced as the degradation of at least one lidar sensor progresses, thereby always allowing safe operation of the vehicle and thus high road safety depending on the degradation of the lidar sensor.

[0016] In the following, an embodiment of the present invention will be explained in detail with reference to the drawings. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 illustrates a schematic diagram of a receiver of a LIDAR sensor when an object is detected at a first distance. [Diagram 2] 2 shows a schematic view of the receiver according to FIG. 1 when an object is detected at a second distance which is smaller than the first distance; [Diagram 3] FIG. 2 shows a schematic diagram of a receiver of a lidar sensor when detecting an object. [Figure 4] FIG. 2 shows a schematic diagram of the failure rate of the receiver of a LIDAR sensor as a function of the distance to a detected object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In all the drawings, the same reference numerals are used to designate corresponding parts.

[0019] In Fig. 1 a receiver 1 of a lidar sensor is shown diagrammatically when an object O is detected at a first distance d. Fig. 2 shows the receiver 1 according to Fig. 1 when the object O is detected at a second distance d, which is smaller than the first distance d. The distance d is shown in more detail in Fig. 4.

[0020] The LIDAR sensor scans its surroundings with light in the infrared range and detects for each measurement point or receiver pixel 1.1-1.n a spacing or distance d and information about the backscattered light, for example the intensity of the backscattered light. Due to the measurement principle, the receiver 1 of the LIDAR sensor measures in polar coordinates, so that the number of measurement points or receiver pixels 1.1-1.n per unit area decreases as the distance d increases.

[0021] As a result, as shown diagrammatically in Fig. 1, on an object O with a large distance d to the receiver 1, for example 150 m, fewer receiver pixels 1.1-1.n will receive a signal than when detecting an object O according to Fig. 2, where the distance d is much smaller. If the object O is measured several times and tracked over time, it is possible to collate how often individual receiver pixels 1.1-1.n fail to receive, even though a signal is expected at the receiver pixels 1.1-1.n based on the existing object dimensions.

[0022] In Fig. 3 the receiver 1 of the lidar sensor is shown when an object O is detected, where the object O is designed to be detected by the receiving pixels 1.3-1.5, 1.12-1.14, 1.21-1.23 and 1.30-1.32. Fig. 4 shows the failure rate a of the various receiving pixels 1.1-1.n of the lidar sensor in dependence on the distance d to the detected object O.

[0023] If an object O is detected for the first time at a first time t_0 and is then tracked continuously over the course of time through another time t_k and up to yet another time t_m, a failure rate a for each receiver pixel 1.1-1.n of the lidar sensor can be determined based on the known geometry. Here, the failure rate a can be combined with a distance d of the object O between said first time t_0 and said another time t_m. Thus, a failure rate a depending on the distance d can be determined for each receiver pixel 1.1-1.n.

[0024] A comparison of the determined failure rates a in dependence on the distance between the different receiver pixels 1.1-1.n allows inferences to be made about possible defects or degradation of the receiver pixels 1.1-1.n, where possible temporary disturbances, such as rain or dirt on the windshield of the lidar sensor, can be identified by different temporal accumulations.

[0025] If the failure rate a is determined in the laboratory as a function of distance d at the beginning of the life cycle of the lidar sensor, these values ​​can be used as the basis for determining temporary or permanent changes.

[0026] Figure 3 shows an example of the discrepancy between receiver pixel 1.13 and defective receiver pixel 1.22 when an object O is detected. A failure rate a of 100% shown in Figure 4 indicates no measurement, i.e. the receiver 1 of the lidar sensor did not recognize any object O.

[0027] Here, the failure rate a determined depending on the distance d allows the following estimation: The relationship between the maximum reach of the lidar sensor and the failure rate a is as follows: When β=f(a), d max =β d(t k ) (1) Here, the factor β can be determined based on laboratory measurements or measurements with previous sensors and depends on the failure rate a.

[0028] So, for example, it would look like this: a(d(t k ))=25% and β=f(a)=f(25%)=1.25, d max =1.25·d(t k ) (2)

[0029] Here, the difference in the failure rate curves between two different receiver pixels 1.1-1.n can be caused permanently by defects or degradation of electronic and / or optical components and / or temporarily by dirt on the windshield of the lidar sensor or external disturbances such as rain or fog, etc. This is illustrated in Fig. 4 for the failure rate a(1.22) of the defective receiver pixel 1.22 and the failure rate a(1.13) of the adjacent receiver pixel 1.13. [Prior art documents] [Patent documents]

[0030] [Patent Document 1] DE 102018008903

Claims

1. 1. A method for detecting degradation of a lidar sensor, comprising: - LIDAR pulses are emitted by said LIDAR sensor, - reflections of the emitted LIDAR pulses are detected by the LIDAR sensor, an object (O) reflecting a LIDAR pulse is detected in the environment of said LIDAR sensor, - said detected object (O) is tracked over a number of time cycles, - determining the LIDAR pulses that will be reflected by the tracked object (O) when tracking said object (O), taking into account the distance (d) of said object to said LIDAR sensor and the geometry of said tracked object (O); A failure rate (a) is determined, which indicates how often an expected reflection is not detected within a given period of time; - based on said failure rate (a) and said distance (d) to said tracked object (O), a degradation of said lidar sensor is inferred; method.

2. A decrease in the coverage area of ​​the lidar sensor is determined as degradation.

2. The method according to claim 1 .

3. The failure rate (a) is determined for each receiver pixel (1.1 to 1.n) of the lidar sensor.

3. The method according to claim 1 or 2.

4. A comparison is performed between the determined failure rate (a) of each receiver pixel (1.1-1.n) and the determined failure rates (a) of adjacent receiver pixels (1.1-1.n) depending on the distance (d) to the tracked object (O) in order to determine defects and / or aging of each of the receiver pixels (1.1-1.n).

4. The method according to claim 3 .

5. The range of the lidar sensor is determined from the reflection intensity of the lidar pulse reflected by an object (O) and the distance (d) of the lidar sensor to the object (O). The method according to any one of claims 1 to 4, characterized in that

6. 1. A method of operating a vehicle and / or a robot, comprising: the surrounding environment of said vehicle and / or robot is detected by at least one lidar sensor, - depending on the data detected by the lidar sensor, an automatic, in particular highly automatic or autonomous operation of the vehicle and / or robot is performed, taking into account the degradation of the at least one lidar sensor detected by the method according to any one of claims 1 to 5, method.

7. In an autonomous driving operation, the driving speed of the vehicle and / or robot is reduced as the deterioration of the at least one lidar sensor progresses.

7. The method according to claim 6 .

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