Method for operating lidar sensor system

Abstract

The invention relates to a method for operating a lidar sensor system (10) having a transmitting unit (26) and a receiving unit (28) and at least one mirror (30), comprising the following method steps: a) emitting transmitted radiation (20) by means of the transmitting unit (26); b) in a first operating mode (measuring mode 50), orienting the at least one mirror (30) in such a way that the direction of the reflected radiation (22) is influenced in such a way that the reflected radiation is reflected to the receiving unit (28); c) in a second operating mode (self-test mode 52), orienting the at least one mirror (30) in such a way that the transmitted radiation (20) of the transmitting unit (26) is directed along a direct radiation path (44) to the receiving unit (28).

Description

Technical Field

[0001] The invention relates to a method for operating a lidar sensor system having a transmitting unit, a receiving unit and at least two reflectors. The invention also relates to the use of the method in a lidar sensor system of a vehicle or a lidar sensor system of a consumer electronic device. Background Art

[0002] Laser radar (LiDAR) sensors play an important role in realizing driving functions in automated driving. LiDAR sensors emit temporally structured light, which is reflected on objects and detected by the sensor again. Based on the measurement of the light propagation time, the distance to the object can be determined. Due to the requirements derived from the safety standard ISO 26262, there is a need to continuously monitor the functionality of the LiDAR sensor in order to avoid not only direct damage caused by the system, but also damage caused by erroneous measured values ​​that may lead to erroneous reactions of the superior system. Independent of the use of sensors in the automotive field, IEC 60825 (eye safety of laser systems) needs to be considered in addition. In order to comply with it, various monitoring mechanisms need to be set up, which detect or prevent functional failures as early as possible. At present, self-monitoring of the laser light source is achieved, for example, by internal reflections in the LiDAR housing, whether for clearly set elements or with the help of "undefined scattered light".

[0003] WO 2019 / 197894 A1 relates to a laser radar system and a method for internal light calibration. At least one processor of the laser radar system controls at least one light source. A first set of input signals related to light projected by the first light source and reflected by an object outside the laser radar system is obtained by a group of detectors. The distance to the object is calculated based on the first number of input signals. A second number of input signals related to light projected internally onto a laser radar system having at least one light source is received by the group of detectors. Based on the second number of input signals, it is determined to what extent a performance degradation of at least one detector in the group of detectors has occurred. Remedial measures are taken based on the determined performance degradation.

[0004] DE 10 2017 223 340 A1 relates to an object detection device. The object detection device includes a light sensor and a light receiver, and also includes a rotating scanner, which has a reflector, and by rotating the reflector, the light from the light transmitter is reflected by the reflector, so as to scan the reflected light over a predetermined area, and so that the light reflected by the target is reflected by the reflector and the reflected light is guided to the light receiver. In addition, an object detector is provided, which detects whether a target exists based on a light reception signal. There is also a light guide, which guides the light from the light transmitter to the light receiver, and a failure detector (Versagensdetektor), which detects whether there is a failure based on the light emission state of the light transmitter and the light reception state of the light receiver. The light guide receives the light transmitted by the light transmitter and reflected by the reflector, and reflects the light from the reflector, so as to guide the reflected light to the light receiver.

[0005] DE 10 2015 222 061 A1 relates to a laser radar sensor for a motor vehicle. The laser radar sensor comprises a beam source that emits light in the visible range or in the infrared range, a receiver for receiving light reflected from the beam source on a surface in the surroundings of the vehicle, and an electronic analysis device for analyzing the propagation time of the emitted and received light. The light source is configured to emit light at at least two different wavelengths. The analysis device has a spectral analysis channel for analyzing the intensity of the received light at different wavelengths. Summary of the invention

[0006] According to the invention, a method for operating a lidar sensor system is proposed, wherein the lidar sensor system comprises a transmitting unit and a receiving unit and at least one reflector and runs through at least the following method steps:

[0007] a) emitting the transmitted radiation by means of a transmitting unit;

[0008] b) in a first operating mode (measuring mode), orienting at least one reflector in such a way that the direction of the reflected radiation is influenced in such a way that the reflected radiation is reflected to a receiving unit;

[0009] c) In a second operating mode (self-testing mode), the at least one reflector is oriented in such a way that the transmitted radiation of the transmitting unit is directed along a direct radiation path to the receiving unit.

[0010] In a special embodiment of the invention, at least the following method steps are carried out in the method for operating a lidar sensor system:

[0011] a) emitting the transmitted radiation by means of a transmitting unit;

[0012] b) in a first operating mode (measuring mode), at least one reflector is oriented in such a way that the direction of the reflected radiation is influenced and at least one further reflector receives the reflected radiation and reflects it to a receiving unit;

[0013] c) In a second operating mode (self-testing mode), at least one reflector is oriented in such a way that the transmitted radiation of the transmitting unit is directed along a direct radiation path via at least one further reflector to the receiving unit.

[0014] Compared to the first variant, at least one additional reflector is required in this variant of the invention.

[0015] The solution proposed according to the invention advantageously enables a self-testing operation of the lidar sensor system which is extremely simple and enables monitoring of the functionality of the laser diode of the radiation source, so that degradation, failure or other malfunctions can be detected at an early stage. This can be achieved directly by means of components already installed in the lidar sensor system, without having to install new elements or use scattered light.

[0016] In a development of the method proposed according to the invention, different external angular ranges are measured by the lidar sensor system by rotating at least one mirror, in particular a polygon mirror.

[0017] In an advantageous embodiment of the method according to the invention, the change from the operating mode "measuring operation" to the operating mode "self-test operation" and vice versa is carried out according to the rotation of the polygonal reflector. As a result, there is the possibility of switching from the mode "measuring operation" to the mode "self-test operation" at any time, thereby achieving freedom from fixed intervals.

[0018] In a further advantageous embodiment of the method proposed according to the invention, in the operating mode “measuring operation” the light / radiation is guided to the receiving unit substantially via reflection as reflected radiation from the object.

[0019] In a development of the method proposed according to the invention, in the operating mode "self-test operation", light / radiation, in particular in a direct light path or radiation path, is guided to the receiving unit as transmitted radiation. In this case, the intended functionality can be checked without installing further separate components in the lidar sensor system.

[0020] In the method proposed according to the invention, a reception range is created corresponding to the rotational position of the polygon mirror relative to the transmitting unit, so that the transmitted radiation does not reach the receiving unit directly from the transmitting unit.

[0021] In an advantageous embodiment of the method according to the invention, the radiation transmitted by the transmitting unit extends substantially in the form of a vertical line. In addition, in the method according to the invention, the receiving unit is designed substantially to receive radiation in the form of a vertical line.

[0022] In an advantageous embodiment of the method proposed according to the invention, the receiving unit used is designed such that it either comprises a detector or a corresponding detector is assigned to the receiving unit, wherein the detector is advantageously designed as a line detector.

[0023] Furthermore, the invention relates to the use of the method in a lidar sensor system of a vehicle or a lidar sensor system of a consumer electronic device.

[0024] Advantages of the present invention

[0025] The solution proposed according to the invention makes it possible to carry out very simple monitoring of functionality, for example of the functionality of the laser diode of the transmitting unit, so that degradation, impending failure or other malfunctions that may occur at an early stage can be recognized in a timely manner. Within the framework of the operating mode "self-test operation" proposed according to the invention, such diagnosis can be carried out in the lidar sensor system without the use of separate test elements or devices or without the use of scattered light. The solution proposed according to the invention makes it possible to provide a direct optical path that extends from the transmitting unit (laser or laser diode group) to the detector, i.e. the receiving unit, so that the receiving unit can be used not only for the actual measurement of the object to be detected, but also at the same time within the framework of the self-test operation for monitoring the lidar sensor system with respect to impending damage.

[0026] The solution proposed according to the invention makes it possible to avoid self-monitoring of the laser source, for example by internal reflections in the lidar housing, as is known, for example, from WO 19 / 197894 A1 or DE 10 2017 223 340 A1.

[0027] In the method proposed according to the invention, the rotation adjustment of the polygon mirror can advantageously be carried out in the operating mode "self-test mode" in such a way that it either allows or interrupts the direct light path from the laser source to the detector. In the case of a light path through a laser diode or a transmission unit comprising a plurality of grouped laser diodes, a check of the time signal can be carried out within the framework of the self-test mode. For example, if the transmission unit consists of different laser diodes or groups of laser diodes, different groups of laser diodes can be pulsed so that it can be checked whether the expected functionality is present, to what extent it is present, and whether preliminary damage is already present that could lead to a possible stoppage of operation.

[0028] Advantageously, the method proposed according to the invention is implemented in such a way that it can function properly without further reflective elements in the lidar sensor housing, since a direct beam path is used. In contrast, in known assemblies, the mode of operation depends, for example, on the aging-related decrease in the reflectivity of the disk of the housing, and in particular only specific materials are conceivable for their selection, which accordingly necessitates higher costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present invention are explained in more detail based on the drawings and the following description.

[0030] The accompanying drawings show:

[0031] Figure 1 A lidar sensor system with self-monitoring capabilities according to the prior art;

[0032] Figure 2 A lidar sensor system comprising a polygonal mirror operable to carry out a first variant of the method according to the invention;

[0033] Figure 3 In the operating mode "Self-test operation" Figure 2 A lidar sensor system according to a first variant;

[0034] Figure 4 An embodiment variant of the lidar sensor system, in which a measuring operation is performed;

[0035] Figure 5 An embodiment variant of the lidar sensor system, in which the method proposed according to the invention is implemented for carrying out the “self-test operation” operating mode;

[0036] Figure 6A lidar sensor system comprising a polygonal mirror operable to carry out a second variant of the method according to the invention;

[0037] Figure 7 In the operating mode "Self-test operation" Figure 2 A lidar sensor system according to a second variant. DETAILED DESCRIPTION

[0038] From the basis Figure 1 The illustration of FIG. 1 shows a lidar sensor system 10, the components of which are essentially arranged in a housing 12. The housing 12 includes a transparent cover 14, which can be designed, for example, as a glass disk or a glass cover. The inner side thereof is denoted by reference numeral 16, while the outer side of the transparent cover 14 is denoted by reference numeral 18. Figure 1 In the housing 12 of the lidar sensor system 10 shown in FIG. 1 , there is a transmitting unit 26 which radiates emitted radiation 20 which is partially reflected at the inner side 16 of the transparent cover 14 as scattered light 24. This scattered light 24 at least partially reaches a receiving unit 28 which is also arranged in the housing 12. Figure 1 The embodiment variant shown in , which represents the prior art, carries out a self-test of lidar sensor system 10 shown there, based on an evaluation of scattered light 24 in receiving unit 28 .

[0039] Embodiments of the present invention

[0040] In the following description of embodiments of the invention, identical or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is omitted in individual cases. The figures merely schematically illustrate the subject matter of the invention.

[0041] From the basis Figure 2 From the illustration of , a lidar sensor system 10 can be seen, in whose housing 12 a transmitting unit 26 is arranged, which transmitting unit has a plurality of laser diodes or a plurality of laser diode groups. In addition, a receiving unit 28 is present in the housing 12 of the lidar sensor system 10, which receiving unit serves as a detector or comprises such a detector. The housing 12 is closed by a transparent cover 14, the inner side of which is denoted by reference numeral 16 and the outer side of which is denoted by reference numeral 18. In the housing 12, in addition to a first deflection mirror 46 which is arranged essentially fixedly, there is also a second deflection mirror 48 which is arranged opposite thereto. Between the two deflection mirrors 46, 48, a further reflector, in particular a polygonal reflector 30, is arranged which is rotatable about a rotation axis 32, for example in a rotation direction 34. The polygonal reflector 30 in the above case comprises at least two facets or at least two reflector surfaces. From the Figure 2As can be seen from the figure, in this embodiment variant, the polygonal reflector 30 has a substantially square cross section and includes a first reflector surface 36, a second reflector surface 38, a third reflector surface 40 and a fourth reflector surface 42. The reflector surfaces 36, 38, 40, 42 are oriented at 90° relative to each other.

[0042] From the basis Figure 2 It can also be seen from the diagram that in the operating mode "measuring operation" 50 shown there, the radiation 20 transmitted by the transmitting unit 26 is deflected by 90° by the first deflection mirror 46 and irradiates the second reflector surface 38 of the polygonal reflector 30 parallel to the transparent cover 14. The transmitted radiation 20 reaches the outside from there. The radiation 22 reflected by the detected object, i.e. the reflected light, is incident again on the housing 12 of the lidar sensor system 10 via the transparent cover 14, is deflected at the third reflector surface 40, irradiates the upper surface of the second deflection mirror 48 arranged in the housing 12, and from there irradiates the receiving unit 28 used as a detector. Figure 2 In the operating mode “measuring operation” 50 shown in the figure, the optical path between a first deflection mirror 46 fixedly arranged in the housing 12 and a second deflection mirror 48 arranged essentially fixedly opposite thereto is interrupted due to the rotational position shown here of the polygonal reflector 30 rotatable about its rotational axis 32, so that the transmitted light, i.e. the emitted radiation 20, is emitted only from the housing 12 of the lidar sensor system 10.

[0043] From the basis Figure 3 As can be seen from the diagram, Figure 2 Compared to the operating mode "measurement operation" 50 shown in Figure 3 In the operating mode “self-test operation” 52 shown in FIG. 1 , polygon mirror 30 arranged between two deflecting mirrors 46 , 48 is pivoted into a rotational position in which a direct beam path 44 between first deflecting mirror 46 and second deflecting mirror 48 in housing 12 is permitted.

[0044] From the basis Figure 3 It can be seen from the diagram that in the operating mode "self-test operation" 52 of the lidar sensor system 10, the radiation 20 emitted by the transmitting unit 26 is also deflected by 90° at the first deflecting mirror 46 and, due to the rotational position of the polygonal reflector 30, directly strikes the upper surface of the second deflecting mirror 48 in the housing 12 parallel to the transparent cover 14. From there, the emitted radiation 20 now strikes the receiving unit 28 used as a detector in a deflected manner and can be evaluated there.

[0045] exist Figure 3In the operating mode "self-test operation" 52 shown in the figure, a check of the time signal can be performed. In the operating mode "self-test operation" 52, for example, in the case where the transmission unit 26 is composed of different laser diodes or groups of laser diodes, it is possible to test and verify whether the expected functionality is given by pulse-controlling different groups of laser diodes, or whether possible initial damage has occurred in the laser diodes, which may cause the lidar sensor system 10 to stop functioning soon. By the possibility of realizing a self-test operation in the lidar sensor system 10 proposed by the present invention, it is possible to omit the pre-setting (Vorhalten) of corresponding test elements according to the prior art or to use scattered light to test the functionality. By the solution proposed according to the present invention, in the operating mode "self-test operation" 52 of the lidar sensor system 10, the functionality of the laser diode of the transmission unit 26 can be monitored very simply, so that degradation, stoppage or other possible functional failures can be recognized at an early stage.

[0046] From the basis Figure 3 As can be seen from the diagram of FIG, the provision of a direct optical path 44 from the transmitting unit 26 via the first deflection mirror 46 and the second deflection mirror 48 and from there to the receiving unit 28 used as a detector enables a double utilization of the components present in the housing 12. For the actual measurement of the object, it can be selected Figure 2 The operating mode "measuring operation" 50 shown in FIG. 1 and the polygon mirror 30 can be switched to the operating mode "measuring operation" 50 when a corresponding rotation of the polygon mirror 30 about its rotation axis 32 is performed, for example in the rotation direction 34 (here in the clockwise direction). Figure 3 The operating mode “self-test operation” 52 is shown in FIG.

[0047] based on Figure 4 and Figure 5 A possible embodiment variant of the lidar sensor system 10 proposed according to the invention is described.

[0048] From the basis Figure 4 From the diagram, we can see that Figure 2 and Figure 3 The described lidar sensor system 10 is different in that Figure 4 In the embodiment variant of , there is no first deflection mirror 46. Figure 2 and Figure 3 Compared to the embodiment variant of the lidar sensor system 10, the transmitting unit 26 is displaced so that the transmitted radiation 20 directly strikes the second mirror surface 38 of the polygonal mirror 30 which is rotatable about its rotation axis 32 and leaves there as the transmitted radiation 20 according to Figure 4 The housing is not shown in the illustration. Figure 4As shown in FIG. , in this embodiment variant, the radiation 22 reflected by the detected object impinges on the third mirror surface 40 , is deflected therein in the direction of the second deflection mirror 48 , and as reflected radiation 22 impinges on the receiving unit 28 used as a detector.

[0049] As according to Figure 4 As can be seen from the illustration of , in this embodiment variant, the polygonal reflector 30 can also be rotated about its rotation axis 32, for example in a rotation direction 34. Here, the polygonal reflector 30 is also designed essentially with a square cross section, so that a first reflector surface 36, a second reflector surface 38, a third reflector surface 40 and a fourth reflector surface 42 are formed on its outer side, which are each oriented with a 90° offset relative to each other.

[0050] By selecting the receiving range 54 relative to the transmitting unit 26, light cannot reach the receiving unit 28 used as a detector from the transmitting unit 26 in a direct path when the polygonal reflector 30 is in an inclined position. Figure 4 As is known from , emitted radiation 20 can leave the housing of lidar sensor system 10 and radiation 22 reflected by an object can enter lidar sensor system 10 again.

[0051] From the basis Figure 5 It can be seen from the diagram that in this embodiment variant, similar to the Figure 3 In a variant embodiment of the lidar sensor system 10, the polygonal reflector 30 is rotated about its rotation axis 32 in a rotation direction 34 (here in a clockwise direction) such that the second reflector surface 38 is oriented parallel to the transmitted radiation 20. This results in a direct beam path 44 from the transmitting unit 26 to the second deflecting mirror 48, from which the transmitted radiation 20 impinges on the receiving unit 28 serving as a detector. Therefore, when the polygonal reflector 30 is rotated accordingly about its rotation axis 32, whether in the direction of rotation 34 or in the clockwise direction, the second reflector surface 38 is oriented parallel to the transmitted radiation 20. Figure 5 Whether rotating in the direction of rotation 34 shown in FIG. 1 or in the opposite direction of rotation, a direct beam path 44 between the transmitting unit 26 on the one hand and the receiving unit 28 serving as a detector on the other hand can be permitted.

[0052] Similar to Figure 3 The diagram, according to Figure 5In a variant embodiment, via the position of the polygonal reflector 30 about its rotation axis 32, an operating mode "self-test operation" 52 can also be implemented, within the framework of which, for example, a check of the time signal can be carried out or the light source, i.e. the sending unit 26 (which, for example, includes different laser diodes or groups of laser diodes), can be pulse-controlled with different pulses, so that the expected functionality can be checked and degradation and malfunctions can be identified at an early stage.

[0053] based on Figure 2 and Figure 3 as well as Figure 4 and Figure 5 The two illustrated embodiments of the lidar sensor system 10 have in common that they comprise a rotatable polygonal mirror 30 which interrupts a direct beam path 44 between the transmitting unit 26 and the receiving unit 28 either by means of one of the mirror surfaces 36, 38, 40, 42 or by means of a rotatable polygonal mirror 30. Figure 2 and Figure 4 The operating mode "measurement operation" 50 shown in FIG. Figure 3 and Figure 4 The diagram in FIG. 4 allows a direct optical path 44 between the transmitting unit 26 and the receiving unit 28 used as a detector, thereby enabling the “self-test operation” operating mode 52. Advantageously, the “measuring operation” operating mode 50 or the “self-test operation” operating mode 52 can be performed on the lidar sensor system 10 without having to pre-set a separate test component in the lidar sensor system 10.

[0054] Figure 6 and Figure 7 A particularly advantageous variant of the invention is shown in FIG. Figure 2 and Figure 3 The difference is that due to the connection between the receiving unit 28 and the transmitting unit 26 Figure 2 and Figure 3 Compared to the changed position, the deflection mirrors 46 and 48 can be omitted here. This is particularly advantageous because a very compact design of the laser radar can be achieved in this way. Depending on the position of the reflector 30, the emitted radiation is measured directly by the receiving unit 28 (self-test operation, Figure 7 ), or, during a measurement run ( Figure 6 ), the reflector 30 is adjusted so that the receiving unit 28 detects the radiation reflected by the object to be detected.

[0055] The invention is not limited to the embodiments described herein and the aspects emphasized therein. On the contrary, many modifications are possible within the scope of the art within the scope of the claims.

Claims

1. A method for operating a lidar sensor system (10), the lidar sensor system having a transmitting unit (26) and a receiving unit (28) and at least one reflector (30), the method comprising at least the following method steps: a) emitting the transmitted radiation (20) by means of a transmitting unit (26); b) in a first operating mode (measuring operation 50), orienting the at least one reflector (30) in such a way that the direction of the reflected radiation (22) is influenced in such a way that the reflected radiation is reflected to the receiving unit (28); c) In a second operating mode (self-test operation 52), the at least one reflector (30) is oriented in such a way that the emitted radiation (20) of the transmitting unit (26) is directed along a direct radiation path (44) to the receiving unit (28).

2. The method according to claim 1, characterized in that According to method step c), the operating mode "self-test operation" (52) of the lidar sensor system (10) is carried out by checking the wavelength of the time signal, the laser diode or the laser diode group on the transmission unit (26) with respect to the expected functionality.

3. The method according to claims 1 and 2, characterized in that By rotating the at least one reflector (30), in particular the at least one polygonal reflector (30), different external angular ranges are measured by the lidar sensor system (10).

4. The method according to claim 3, characterized in that Depending on the rotation of the polygonal reflector (30), a change is made from the operating mode "measuring operation" (50) to the operating mode "self-test operation" (52), and vice versa.

5. The method according to claims 3 and 4, characterized in that In the operating mode "measuring operation" (50), light is guided to the receiving unit (28) essentially via reflection as reflected radiation (22) from an object.

6. The method according to claims 3 and 4, characterized in that In the operating mode "self-test operation" (52), light is guided to the receiving unit (28) essentially in a direct beam path (44) as transmitted radiation (20).

7. The method according to any one of claims 1 to 6, characterized in that A receiving range (54) is provided in accordance with a rotational position of the at least one polygonal reflector (30) relative to the transmitting unit (26), so that the transmitted radiation (20) does not directly reach the receiving unit (28) from the transmitting unit (26).

8. The method according to any one of claims 1 to 7, characterized in that The radiation (20) transmitted by the transmitting unit (26) extends substantially in the form of at least one vertical line.

9. The method according to any one of claims 1 to 8, characterized in that The receiving unit (28) is designed essentially for receiving radiation in the form of at least one vertical line.

10. The method according to any one of claims 1 to 9, characterized in that The receiving unit (28) comprises a detector or a detector is assigned to the receiving unit, wherein the respective detector is designed as a line detector.

11. The method according to claim 1, characterized in that: In a first operating mode (measuring operation 50), the at least one reflector (30) is oriented in such a way that the direction of the reflected radiation (22) is influenced and at least one further reflector (48) receives the reflected radiation (22) and reflects it to the receiving unit (28); In a second operating mode (self-test operation 52), the at least one reflector (30) is oriented in such a way that the transmitted radiation (20) of the transmitting unit (26) is directed along a direct radiation path (44) via the at least one further reflector (48) to the receiving unit (28).

12. Application of the method according to any one of claims 1 to 11 in a lidar sensor system (10) of a vehicle or a lidar sensor system of a consumer electronic device.

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