LiDAR system, method for operating a LiDAR system, and computer program

Abstract

A lidar system (1, 1a) for a vehicle, which is used to scan the surrounding environment area of the vehicle by means of laser beams. The lidar system includes: a transmitting device (3) having a laser beam source (4), the laser beam source being configured to emit laser beams into the surrounding environment area of the vehicle; a receiving device (5) having at least one detector (6) for detecting the laser beams reflected in the surrounding environment area and having at least one first filter that can be connected in front of the detector (6), wherein at least one first filter is a strength filter (7) configured to selectively absorb background radiation. The invention also relates to a method for operating the lidar system and a computer program.

Description

Technical Field

[0001] The present invention relates to a lidar system for a vehicle, which is used to scan the surrounding environment area of the vehicle by means of laser beams. The lidar system includes: a transmitting device having a laser beam source, the laser beam source being configured to emit laser beams into the surrounding environment area of the vehicle; a receiving device having at least one detector and at least one first filter, the at least one detector being used to detect the laser beams reflected in the surrounding environment area, and the at least one first filter being connectable in front of the detector. Background Art

[0002] Lidar sensors will be established in the next few years to achieve highly automated driving functions. Current lidar systems consist of a transmitting and a receiving device for laser beams. The laser beam source of the transmitting device emits laser beams into the surrounding environment. If this light hits a moving or stationary object, such as a moving or stationary vehicle or pedestrian, the light is reflected and reflected back in the direction of the receiving device. The backscattered light converges in the detector of the receiving device. However, not only the photons of the imaging laser beam source are imaged, but also background photons / background light / environmental light. Only a very small part of this can be filtered out by a narrowband static optical filter in front of the detector. The unfiltered background photons are also detected and cause background noise, which impairs the performance of the lidar system. The photon stream generated by environmental light / background light generates noise, which deteriorates the measurement results. This especially causes damage in lidar systems with significant saturation characteristics, which leads to the failure of the lidar system.

[0003] DE 102017205685 A1 discloses a lidar device and a method having a dynamic filter. The lidar device includes a dynamic optical filter, which can compensate for the angle-of-incidence-related wavelength shift of the incident beam by matching at least one filter to at least one incident electromagnetic beam. Summary of the Invention

[0004] The object of the present invention is to provide a lidar system with high availability even in the case of high solar radiation.

[0005] This object is solved by describing a lidar system. In addition, this object is solved by describing a motor vehicle. In addition, this object is solved by describing a method and a computer program.

[0006] Other advantageous measures are listed in the following description, and these measures can be arbitrarily combined with each other to achieve other advantages.

[0007] According to one aspect of the present invention, a lidar system for a vehicle is provided. The lidar system is configured to scan a surrounding area of the vehicle by means of laser beams, and the lidar system includes:

[0008] A transmitting device having a laser beam source configured to emit laser beams into the surrounding area of the vehicle.

[0009] A receiving device having at least one detector and at least one first filter. The at least one detector is configured to detect the laser beams reflected in the surrounding area, and the at least one first filter can be connected in front of the detector.

[0010] Wherein, the at least one first filter is an intensity filter configured to selectively absorb background radiation.

[0011] The present invention is based on the following recognition: when using a filter, it is necessary to ensure the optimal function of the lidar system both in countries with high solar radiation or in midsummer and in countries with low solar radiation.

[0012] According to the present invention, the at least one first filter is an intensity filter configured to selectively absorb background radiation. Thereby, even in the case of high solar radiation, higher availability of the lidar system is obtained and damage to the lidar system by sunlight is prevented. Thereby, targeted absorption, preferably regulated absorption, of background light can be achieved. Thereby, the amount of interfering background light can be reduced. Thereby, the performance of the lidar system in the case of high external light radiation can be significantly improved.

[0013] By an intensity filter configured to selectively absorb, the amount of interfering background light can be reduced, thereby improving the availability of the lidar system.

[0014] The lidar system may include a plurality of transmitting devices and (corresponding) receiving devices.

[0015] Preferably, the intensity filter is configured as a static intensity filter. Such a filter can be, for example, a gray filter or a reflection filter. Thereby, the function of the lidar system can be ensured in countries with high solar radiation.

[0016] Preferably, the intensity filter is configured to be movable so that the intensity filter is at least partially arranged in the reflected laser beam in front of the detector. This intensity filter dynamically matched according to the present invention (which can be movably used for partial arrangement, i.e., arranged to be introduced and introduced into the reflected laser beam) results in improved performance - in particular, improved accuracy in object localization and improved regulation depending on the absorption of background light.

[0017] Preferably, the intensity filter can move steplessly (stufenlos) so as to arrange the intensity filter at least partially steplessly in the reflected laser beam in front of the detector. Thus, the intensity filter can be smoothly (i.e., without transitions) introduced / withdrawn into the reflected laser beam in front of the detector. Thereby, a stepless arrangement of the intensity filter is possible, which results in improved characteristics / performance of the lidar system.

[0018] Preferably, the intensity filter can move according to the ambient light incident on the intensity filter. Thereby, a targeted improvement in the performance of the lidar system can be achieved.

[0019] Preferably, an actuator and / or a linear system are provided to move the intensity filter. Other systems for introducing / withdrawing the intensity filter are also possible.

[0020] Preferably, the intensity filter can be selected from a selection unit. Such an intensity filter dynamically matched according to the invention (selected, for example, in terms of its characteristics) results in an improvement in performance, in particular in an increase in the range of the lidar system and in improved usability. Background light can be absorbed particularly targeted.

[0021] Preferably, the selection unit includes a color filter (especially a black-and-white filter) and / or a neutral density filter (especially a gray filter) and / or a gradient filter (especially a gradient mask and / or a gray gradient filter / color gradient filter). Particularly preferably, the selection of the intensity filter from the selection unit can be achieved according to the distance to the object detected in the surrounding area.

[0022] Compared with the laser beam reflected by an object in the far region (Fernbereich), the laser beam reflected by an object in the near region (Nahbereich) irradiates the detector at different positions. Additionally, more signal photons reaching the detector are obtained from the target in the near region. Therefore, by selecting the filter, the ideal signal relative to the background light can be adjusted according to the distance. Thus, for example, a black-and-white filter can be used in a lidar system with a horizontally polarized laser beam, while a gradient mask can be used in a lidar system with a vertically polarized laser beam.

[0023] In a preferred configuration, at least one second filter is provided, wherein the at least one second filter is also configured as an intensity filter for targeted absorption of background radiation. However, the lidar system according to the invention is not limited to two intensity filters, but can include a plurality of intensity filters.

[0024] Preferably, the detector is configured as a SPAD (single photon avalanche diode) detector, characterized by a very high amplification factor for individual photons for providing a detection signal. Thus, a small number of photons are sufficient to achieve a signal. Therefore, with the lidar system according to the present invention, it is possible to arrange a filter even in a SPAD system where usually no filter can be installed. Thus, in a SPAD-based lidar system, there is no longer the risk that the lidar system collects too much background light in the case of strong solar radiation and thus can no longer operate properly.

[0025] Preferably, a rotor with a rotor axis is provided, wherein the rotor is configured to rotate the transmitting device and the receiving device around the rotor axis. Preferably, a plurality of transmitting devices and a plurality of receiving devices corresponding to the transmitting devices are provided, wherein the rotor is configured to rotate the plurality of transmitting devices and the plurality of receiving devices corresponding to the transmitting devices around the rotor axis. With this arrangement on the rotor, different direction information and distance information can be covered by emitting laser beams at different angles, and then the direction information and distance information can be combined into overall information.

[0026] According to another aspect of the present invention, a motor vehicle is provided, which is configured with a lidar system as described above. The vehicle is in particular a car or a truck. The lidar system can also be used in other vehicles, such as rail transit vehicles.

[0027] According to another aspect of the present invention, a method for operating a lidar system of a vehicle is proposed, the lidar system being used to scan a surrounding area of the vehicle with a laser beam, the method having the following steps:

[0028] Emitting a laser beam into the surrounding area through a laser beam source in the transmitting device,

[0029] Detecting the laser beam reflected in the surrounding area by a detector in the receiving device,

[0030] Providing at least one first filter, wherein the at least one first filter is configured as an intensity filter,

[0031] Targetedly absorbing background radiation through the at least one first filter configured as an intensity filter.

[0032] With the method according to the present invention, the performance of the lidar system can be improved. The method is not limited to the first filter, but can include multiple filters.

[0033] Preferably, the method includes additional steps: configuring the intensity filter as a static intensity filter, or moving the intensity filter so that the intensity filter is at least partially disposed in the reflected laser beam before the detector, and / or selecting the intensity filter from the selection unit. Thus, improved adjustment of the lidar system can be achieved.

[0034] The various measures according to the invention can be implemented alternatively or in combination, as long as they are not mutually exclusive.

[0035] In a preferred configuration, the intensity filter is moved according to the ambient light incident on at least one first filter. In another preferred configuration, the selection of the intensity filter from the selection unit can be achieved according to the distance to the object detected in the surrounding area.

[0036] The method is particularly suitable for implementation on a lidar system according to the invention.

[0037] Another aspect of the invention provides a computer program comprising instructions that cause the lidar system as described above to perform the method as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, characteristics, and advantages of the invention result from the following description with reference to the drawings. These are schematically shown:

[0039] Figure 1 A lidar system according to the invention is shown in a first configuration;

[0040] Figure 2 An intensity filter according to the invention is shown;

[0041] Figure 3 A selection unit with different filters is shown;

[0042] Figure 4 A lidar system according to the invention is shown in a second configuration;

[0043] Figure 5 A method according to the invention is shown;

[0044] Figure 6 A lidar system according to the invention with a rotor is shown. DETAILED DESCRIPTION

[0045] Although the invention has been shown and described in detail by way of preferred embodiments, the invention is not limited by the disclosed examples. Those skilled in the art can arrive at variant solutions of the invention without departing from the scope of protection of the invention.

[0046] Figure 1The lidar system 1 according to the present invention is shown in a first configuration. The lidar system 1 is configured to determine the direction and / or distance of an object 2. The lidar system 1 is particularly configured to scan the surrounding area of a motor vehicle. The orientation of the object 2 and the distance of the object 2 with respect to the lidar system can be determined by the lidar system 1. Here, the object 2 may include other traffic participants or traffic objects that can move or are stationary (such as road closure signs).

[0047] The lidar system 1 includes a transmitting device 3 having a laser beam source 4. The laser beam source 4 may include one or more lasers. The laser beam source 4 is configured to be swingable. The laser beam source 4 emits a laser beam to scan the object 2. The laser beam is reflected on the object 2. According to the emission angle of the emitted laser beam, the orientation of the object 2 relative to the vehicle can be determined; the distance to the object 2 can be obtained according to the propagation time of the laser beam.

[0048] In addition, the transmitting device 3 may have other components (such as a polarizer for polarization, a grating spectrometer, etc.), which are not shown here.

[0049] The lidar system 1 further includes a receiving device 5 having a detector 6, which can be configured as a photon detector. The detector 6 is particularly configured as a SPAD (single photon avalanche diode) detector. The SPAD detector enables a very high amplification of individual photons in order to provide a detection signal. The detector 6 converts the power of the laser beam into an electrical signal through a possibly subsequent amplifier.

[0050] An intensity filter 7 is arranged in front of the detector 6, and the intensity filter is configured as a movable filter in order to be at least partially in the reflected laser beam in front of the detector.

[0051] The intensity filter 7 is moved according to the ambient light incident on the intensity filter 7. The adjustment of the intensity filter 7 can be carried out by analyzing the background light, which can be determined by the receiving device 5. Thereby, a targeted absorption of the background light can be achieved. Therefore, in countries with high solar radiation, the function of the lidar system 1 can be ensured without loss of performance in terms of the effective distance of object recognition, for example.

[0052] As a supplement or alternative to the above-mentioned movable filter, the intensity filter 7 can be adjusted in terms of different filters / selected from different filters.

[0053] To this end, the lidar system 1 has a selection unit 9 for selecting the intensity filter 7. Preferably, the intensity filter 7 is selected from the selection unit 9 according to the distance of the object 2 to the vehicle. Since the reflected light from the object 2 in the near region of the vehicle irradiates the detector 6 at different positions from the reflected light from the object 2 in the far region of the vehicle, and the reflected laser beam from the object 2 in the near region irradiates the detector more, the selection of the filter can be adjusted accordingly, thereby achieving better absorption of the background light.

[0054] Therefore, by selecting a suitable intensity filter 7 in front of the detector 6, the background light can be absorbed targeted according to the distance, and thus the disturbing background light can be significantly reduced.

[0055] Figure 2 The movement of the intensity filter 7 in front of the detector 6 is schematically shown by the arrow 8. This can be achieved, for example, by means of an actuator (not shown) or a linear system (not shown). The intensity filter 7 is configured to be able to move steplessly so as to be arranged in front of the detector 6 steplessly until it is fully introduced in front of the detector 6 / withdrawn from in front of the detector. Here, "steplessly" means that the intensity filter 7 can be adjusted / tuned arbitrarily and steplessly. The intensity filter 7 is configured as a gradient filter in Figure 2 this case.

[0056] Therefore, the intensity filter 7 can be introduced and withdrawn from the area in front of the detector 6 steplessly as needed.

[0057] Figure 3 The selection unit 9 with different intensity filters is shown in detail. The selection unit 9 includes, without limitation, neutral density filters (especially the gray filter 11), gradient filters (especially the gray mask 13 or the gray / color gradient filter 14), and color filters (especially the black-and-white filter 12). In the case of the gradient filter, a continuously varying filtering effect is achieved on the filter surface. Now, the intensity filter 7 can be selected from the selection unit 9.

[0058] Here, the black-and-white filter 12 can preferably be used for the lidar system 1 with horizontally polarized light ( Figure 1 ), and the gradient mask 13 can be used for the lidar system 1 with vertically polarized light ( Figure 1 ).

[0059] Figure 4 Another configuration of the lidar system 1a is shown. Here, a second filter 10 can be arranged in the reflected laser beam in front of the detector 6. The second filter can be configured similarly to the intensity filter 7.

[0060] Figure 5shows a method according to the present invention. Here, in a first step S1, a laser beam source 4 of the transmitting device 3 ( Figure 1 ) emits a laser beam.

[0061] In a second step S2, these laser beams are incident on an object 2 ( Figure 1 ) and are reflected at the object. In a third step S3, the reflected laser beams are received by a receiving device 5 ( Figure 1 ).

[0062] Then, in step S4, an intensity filter 7 ( Figure 1 ) is moved according to the ambient light incident on it. According to the determined incident ambient light, the intensity filter 7 ( Figure 1 ) is introduced in front of a detector 6 ( Figure 1 ). The incident ambient light can be determined / calculated in the receiving device 5 ( Figure 1 ). Figure 1

[0063] Instead of step S4, in step S5, an intensity filter 7 ( Figure 1 ) is selected from a selection unit 9 according to the distance to an object 2 ( Figure 1 ) detected in the surrounding area. The distance can be calculated by the receiving device 5 ( Figure 1 ). According to the calculated distance, an intensity filter 7 ( Figure 1 ) can be selected from the selection unit 9 ( Figure 1 ).

[0064] Figure 1 Alternatively, in step S6, an intensity filter 7 ( Figure 1 ) is selected according to the distance to an object 2 ( Figure 1 ) detected in the surrounding area. Additionally, the incident ambient light ( Figure 1 ) is calculated / determined in the receiving device 5. According to the determined incident ambient light, the selected intensity filter 7 ( Figure 1 ) is at least partially arranged in front of the detector 6 ( ).

[0065] Figure 6 ​A lidar system having a rotor 15 according to the present invention is shown. The rotor 15 is rotatably supported (arrow 16) about a rotor axis (not shown) herein. The rotor 15 may have one or more of the transmitting devices 3 as described above and the corresponding receiving devices 5. The rotor 15 is preferably driven by a drive device (not shown). Thereby, the transmitting device 3 and the corresponding receiving device 5 rotate. With this arrangement on the rotor 15, different direction information and distance information can be covered by emitting laser beams at different angles, and then the direction information and the distance information can be combined into overall information.

[0066] The present invention is not limited to one intensity filter 7. Two or more intensity filters 7 according to the present invention may also be provided.

[0067] In addition, the intensity filter 7 may also be configured as a static intensity filter - for example, a gray filter or a reflection filter.

Claims

1. A lidar system (1, 1a) for a vehicle, the lidar system being configured to scan a surrounding area of the vehicle by means of laser beams, the lidar system comprising: Transmitting device (3), said transmitting device having a laser beam source (4), said laser beam source being configured to emit a laser beam into the surrounding area of the vehicle, receiving device (5), said receiving device having at least one detector (6) and at least one first filter, said at least one detector being used to detect the laser beam reflected in the surrounding area, said at least one first filter being connectable in front of the detector (6), characterized in that said at least one first filter is configured as an intensity filter (7), said intensity filter being used to selectively absorb background radiation, wherein the intensity filter (7) can absorb background radiation in a regulated manner according to the background radiation of the ambient light incident on the intensity filter (7), wherein for higher background radiation and lower background radiation, the intensity filter (7) absorbs background radiation in a differently regulated manner, wherein the intensity filter (7) can be selected from a selection unit (9), and wherein the selection of the intensity filter (7) from the selection unit (9) can be achieved according to the distance to the object (2) detected in the surrounding area.

2. The lidar system (1, 1a) according to claim 1, characterized in that, The intensity filter (7) is configured as a static intensity filter.

3. The lidar system (1, 1a) according to claim 1, characterized in that, The intensity filter (7) is configured to be movable so as to arrange the intensity filter (7) at least partially in the reflected laser beam in front of the detector (6).

4. The lidar system (1, 1a) according to claim 3, characterized in that, The intensity filter (7) can move according to the ambient light incident on the intensity filter (7).

5. The lidar system (1, 1a) according to any one of the above claims 2 to 4, characterized in that, An actuator and / or a linear system is provided to move the intensity filter (7).

6. The lidar system (1, 1a) according to claim 1, characterized in that, The selection unit (9) includes a color filter and / or a neutral density filter and / or a gradient filter.

7. The lidar system (1, 1a) according to any one of the above claims, characterized in that, The detector (6) is configured as a SPAD detector.

8. The lidar system (1, 1a) according to any one of the above claims, characterized in that, A rotor (15) with a rotor axis is provided, wherein the rotor (15) is configured to rotate the transmitting device (3) and the receiving device (5) around the rotor axis.

9. The lidar system (1, 1a) according to claim 8, characterized in that, A plurality of transmitting devices (3) and a plurality of receiving devices (5) corresponding to the transmitting devices are provided, wherein the rotor (15) is configured to rotate the plurality of transmitting devices (3) and the plurality of receiving devices (5) corresponding to the transmitting devices around the rotor axis.

10. The lidar system (1, 1a) according to claim 3, characterized in that, The intensity filter (7) is configured to be movable steplessly so as to arrange the intensity filter (7) steplessly in the reflected laser beam in front of the detector (6).

11. The lidar system (1, 1a) according to claim 6, characterized in that, The color filter is a black-and-white filter (12).

12. The lidar system (1, 1a) according to claim 6, characterized in that, The neutral density filter is a gray filter (11).

13. The lidar system (1, 1a) according to claim 6, characterized in that, The gradient filter is a gradient mask (13) and / or a gray gradient filter / color gradient filter (14).

14. A motor vehicle, said motor vehicle being configured with a lidar system (1, 1a) according to any one of the above claims 1 to 13.

15. A method for operating a lidar system (1, 1a) according to any one of claims 1 to 13, the method having the following steps: emitting a laser beam into the surrounding area by means of a laser beam source (4) in the transmitting device (3), detecting the laser beam reflected in the surrounding area by means of a detector (6) in the receiving device (5), providing at least one first filter, wherein, The at least one first filter is configured as an intensity filter (7), and the at least one first filter configured as an intensity filter (7) selectively absorbs background radiation.

16. A method for operating a lidar system (1, 1a) according to claim 15, characterized in that, The intensity filter (7) is configured as a static intensity filter (7), or the intensity filter (7) is moved so as to at least partially arrange the intensity filter (7) in the reflected laser beam in front of the detector, and / or the intensity filter (7) is selected from the selection unit (9).

17. A computer program product, the computer program product comprising instructions that cause a lidar system (1, 1a) according to any one of claims 1 to 13 above to perform the method according to claim 15 or 16.

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