3D-LIDAR-SENSOR

Description

[0001] The invention relates to a 3D LIDAR sensor, in particular for motor vehicles, comprising a laser beam source, an optical receiver and a scanning system for deflecting a laser beam generated by the laser beam source in two mutually perpendicular scanning directions. State of the art

[0002] Such a 3D LIDAR sensor is known from DE 10 2015 200 224 A1, which originates from the applicant. Laser beams with a wavelength between 850 and 1500 nm of suitable intensity are used, for example, to avoid endangering people. A micromirror actuator or a MEMS (micro-electro-mechanical system), for example, is used to deflect the laser beam in the desired direction. If a time-of-flight measurement of the emitted laser beam, reflected by an object, and received by the optical receiver, is also performed, a three-dimensional image of the surroundings can be captured and interpreted using appropriate evaluation devices and / or driver assistance systems. This can, among other things, alert a motor vehicle driver to stationary or moving obstacles in the path of travel in order to avoid a collision.Typically, such a 3D LIDAR sensor is arranged in a housing that is equipped with an exit opening in the form of a disc or lens for the laser beam.

[0003] A LIDAR sensor is known from US 2004 / 0 257 556 A1 in which an additional scanning device is used to detect deviations from normal operation. The additional scanning device is configured to evaluate sensor data to determine whether it lies within or outside a predefined error range.

[0004] From the document DE 43 40 756 A1 a LIDAR sensor is known in which an additional light-emitting diode and an additional receiving diode for the light of the light-emitting diode can be used to detect contamination of the sensor. Disclosure of the invention

[0005] The object of the invention is to provide a 3D LIDAR sensor with improved functionality and reliability, which is particularly suitable for motor vehicles, as set out in claim 1.

[0006] Likewise, a corresponding method for operating the 3D LIDAR sensor is to be specified, as shown in claim 6.

[0007] This object is achieved according to the invention by providing an additional detection device for deviations from normal operation in or on the 3D LIDAR sensor. The detection device can be configured in any desired manner, but is preferably as described below. This detection device can also be referred to as an "intelligent plane," which is arranged in or on the sensor, for example, in the transmission and / or reception path of the sensor's laser beam. This plane can be arranged, for example, inside a housing of the sensor or at the exit opening.

[0008] The emission direction of the laser beam is detected at reference points. Additional light sensors are arranged at an intermediate level and / or at the exit opening. These do not need to be illuminated during normal operation of the laser or the scanning system. If this does happen, however, it can be automatically detected that the laser or the scanning system is misaligned and a corresponding error message can be issued or a self-calibration of the entire system is carried out. Similarly, it can be provided that the light sensors must be illuminated during normal operation. If this does not happen, a misalignment can be automatically detected. This can be implemented in the form of laser light detectors that are arranged at the edge of the exit opening or in the area of ​​a so-called intermediate level.This makes it possible to determine whether the emitted laser beam is actually being directed in the desired direction. This direction can be altered by mechanical / thermal influences, such as thermal expansion of the 3D LIDAR sensor housing or the distance between the micromirrors and a microlens array. Mechanical misalignment of the entire sensor can also occur, for example, due to a collision with a motor vehicle. The laser itself can also exhibit thermal drift during continuous operation, such as a laser delay after a trigger pulse.

[0009] Advantageous further developments and embodiments of the invention are specified in the subclaims.

[0010] Furthermore, irradiation from ambient light or the light of other LIDAR sensors on motor vehicles can be detected and suppressed, for example, based on different frequencies, pulse durations, or the like. Bandpass filters and / or corresponding coatings, for example, on the exit aperture, which are only permeable to light of a specific wavelength, are used for this purpose. In principle, data transmission between the sensors of different vehicles would also be possible, for example, to improve traffic flow.

[0011] If an unusual deviation is detected in the backscattered laser light received by the optical receiver or an additional scattered light sensor, for example a back reflection by fog, spray or retroreflection by solar radiation, this can be detected by an additional detection device and taken into account in the evaluation.

[0012] Ambient light detection can also be provided, for example in the form of a brightness sensor, in order to take into account the changed lighting conditions when entering a tunnel or an underground car park, for example.

[0013] It is proposed that a close-meshed grid of photosensitive resistance filaments be arranged either at the exit aperture or at an intermediate level to verify that the laser beam actually covers all desired observation areas during continuous operation. This allows for detection of any gaps in the detection area.

[0014] In principle, it is possible, for example, to induce a change in the thickness of the disc or lens of the exit opening or of a disc in an intermediate plane using a piezoelectric effect in order to alter the transmission behavior. This can also be a Fabry-Perot filter effect. Thus, only the desired wavelength can be received, even if the laser wavelength drifts, and other wavelengths are suppressed. This can also be done with a very narrow band. Likewise, it is possible to use a reverse piezoelectric effect at the exit opening to detect and compensate for influences caused by gusts of wind, other sound signals, or the like on the transmission or reception directions of the laser beams, depending on the vehicle's speed.

[0015] Furthermore, an ultrasonic sensor can be provided in, on, or in addition to the 3D LIDAR sensor to enable further monitoring of the vehicle's surroundings.

[0016] A temperature sensor can also be provided, which, for example, measures the ambient and / or road surface temperature in order to take this into account when evaluating the signal.

[0017] Similarly, a detector for radioactive radiation could also be provided, which could influence the measurement results.

[0018] Preferably, the disc or lens at the exit opening is designed to be dirt-repellent, for example with a lotus-effect coating.

[0019] The 3D LIDAR sensor can also be combined with a fog sensor to detect fogging caused by rainwater, haze or fog, for example, and to take this into account when evaluating the measurement results.

[0020] It is also recommended that the disc or lens at the exit opening be designed to be particularly impact- and scratch-resistant, for example, to withstand stone chips. This can be achieved, for example, by a diamond coating.

[0021] Finally, damage detection can be carried out, for example, using integrated resistance or strain gauges to detect damage to the disc or lens of the exit opening.

[0022] Inside the 3D LIDAR sensor, an expanding and / or focusing optic, e.g. in the form of a microlens array, can also be arranged for the emitted and / or backscattered laser beams in order to increase the angle of view.

[0023] A chemical detector can also be provided, which detects, for example, the use of road salt, smog or other environmental influences in order to take these into account when evaluating the measurement results.

[0024] In the following, embodiments of the invention are explained in more detail with reference to the drawing.

[0025] They show: Fig. 1 shows the schematic structure of a 3D LIDAR sensor, Fig. 2 shows the 3D LIDAR sensor with additional sensors, Fig. 3 shows a disc or lens in cross section, Fig. 4 shows the scan path of a laser beam, Fig. 5 shows a disc or lens with photosensitive resistance wires, Fig. 6 shows a disc or lens in cross section, Fig. 7 shows an intermediate plane and Fig. 8 shows an expanding optic.

[0026] The Fig. 1 The 3D LIDAR sensor 10 shown on the left has a laser beam source 11 which, as indicated by the various arrows, is designed to emit laser beams 20 in at least two mutually perpendicular spatial directions. Together with an optical receiver (not shown here to simplify the illustration), the surroundings of a motor vehicle can thus be monitored, in particular. The 3D LIDAR sensor comprises a housing 12 and is arranged, for example, on or in a body of a motor vehicle. It is understood that it is equipped with an electrical power supply and with data transmission means in order to forward measurement signals to a control device of the motor vehicle for further processing. Furthermore, a disk or lens 13 is arranged on the housing in order to allow the laser beams 20 to exit and, if necessary, to enter again.According to the invention, a further detection device 14, arranged here between the laser beam source 11 and the disk or lens 13, is provided to increase the functionality of the 3D LIDAR sensor 10. As shown in . Fig. 1 As shown on the right, this detection device 14 can also be integrated into the disc or lens 13.

[0027] A temperature sensor 28 can also be provided which detects the ambient temperature or which is designed to detect a mirage effect, since in particular mirages on hot road surfaces could influence the measurement results or their evaluation.

[0028] In Fig.2 a laser beam source 11 with a mirror 16 is depicted which, as indicated by the double arrow, can be pivoted in two mutually perpendicular spatial directions in order to illuminate the surroundings of the motor vehicle. The laser beams 20 exit the 3D LIDAR sensor 10 through a disk or lens 13. Here, additional light sensors 15 are arranged at the corners of the disk or lens 13. If a misalignment of the direction of the laser beams 20 occurs due to thermal and / or mechanical and / or temporal changes, the laser light is no longer directed directly through the disk or lens 13 but strikes a surrounding edge of the housing 12. This is detected by the light sensors 15 and self-adjustment can be carried out or an error message can be issued.

[0029] It is understood that the light sensors 15 can be arranged not only at the corners but also around the entire edge of the disc or lens 13.

[0030] A scattered light sensor 25 is also shown. This can detect, for example, that a laser beam 20 is directly reflected by a contamination 17 on the pane or lens 13. The laser beam 20 is then no longer used to detect the surroundings, and an error message can be output.

[0031] In Figur 3 1 shows a cross-section of a disk or lens 13 of a 3D LIDAR sensor. Alternatively or additionally, light sensors 15 are arranged not only around the disk or lens 13 but also at the edge of the disk or lens 13. If a laser beam 20, for example, encounters contamination 17, it can be reflected within the disk or lens 13 as scattered light 18. The same applies to damage 19 to the disk or lens 13. This can be detected by the light sensors 15 at the edge of the disk or lens 13. Contamination 17 can also be formed and detected by water droplets, dew, fogging, or the like. Likewise, temperature influences, chemical or radioactive influences from the environment can be recorded and taken into account in the evaluation. For this purpose, the 3D LIDAR sensor 10 can be equipped or networked with appropriate sensors.

[0032] A drop of rain or water or fog or dew can also be considered as contamination 17, which affects the transmission behavior of incoming and outgoing laser beams.

[0033] In addition, a photoresistor 27 can also be provided to detect the ambient light, so that the 3D LIDAR sensor 10 can automatically detect that a tunnel, a parking garage or the like is being entered in order to take the changed lighting conditions into account.

[0034] In addition or alternatively to the photoresistor 17, a scratch-resistant and / or lotus coating may also be provided.

[0035] Furthermore, an environmental influence such as road salt contamination can be detected additionally or alternatively using a chemically sensitive coating.

[0036] Likewise, the thickness of the disc or lens 13 can be adjusted, for example, by means of a piezoelectric effect, as indicated by the double arrow 28, in order to achieve a desired transmission behavior for laser beams 20, for example, depending on temperature and / or air pressure. Likewise, the influence of sound waves, wind, and the like on the lens or disc 13 can be detected by piezoelectric detection and taken into account in the evaluation.

[0037] Additionally, scintillating atoms or molecules, for example, can be incorporated into the disc or lens 13, as indicated by box 28. These would be excited by radioactive radiation and emit light, which would be detected by appropriate detectors, for example, at the edge of the disc or lens 13. Thus, the influence of radioactive radiation can be determined and taken into account in the evaluation.

[0038] In Fig. 4 It shows how a scan path 21 of a laser beam 20 across the disk or lens 13 can be shifted by any influence. This is then detected by, for example, the light sensors 15 and then readjusted accordingly.

[0039] It is understood that the pane or lens 13 can be equipped, for example, with a lotus coating, a scratch-resistant coating, and / or a coating that allows only certain wavelengths to pass through. The same applies to a component arranged inside the 3D LIDAR sensor 10. Likewise, a bandpass filter and / or a photoresistor can be provided, for example, as an additional coating. This can prevent, for example, the entry of laser beams from other motor vehicles to avoid interference or other disturbances.

[0040] In Fig. 5 A disc or lens 13 is depicted, on or in which photosensitive resistance wires 22 are arranged, for example, in a grid-like manner. If a laser beam 20 strikes such a wire 22, an electrical pulse is triggered, illustrated by the circle 23. If, for example, a mechanical fault has occurred in the mirror 16 and an area 24 is not covered by the laser beam, the electrical signal remains absent, and an error message can be output.

[0041] In Fig. 6 A disc or lens 13 is shown in cross-section. A bandpass filter is preferably arranged around its edge to filter out light beams 26 of an undesirable wavelength, for example, from sensors of other motor vehicles, so that the measurement results are not distorted. Only the laser beams 20 of the vehicle's own 3D LIDAR sensor 10 are to be detected.

[0042] In Fig.7 Three different designs of the so-called intelligent intermediate layer are shown. On the left, it is transparent and allows, in particular, the reflected laser beams to pass through unfiltered. In the middle, it is completely darkened and allows, for example, only light of a specific wavelength to pass through. On the right, only a portion is darkened, for example, to specifically block out unwanted light. This can be achieved using microarrays and / or photosensitive, controllable coatings.

[0043] Finally, in Fig. 8 a disk or lens 13 with expanding properties. The laser beams generated by a laser beam source 11 are expanded by the disk or lens 13 in order to capture a larger surrounding area. In principle, a focusing design is also possible.

Claims

1. 3D lidar sensor (10), in particular for motor vehicles, having a laser beam source (11), an optical receiver and a scanning system for deflecting a laser beam (20) created by the laser beam source (11) in two mutually perpendicular scanning directions, wherein a further detection device (14) for deviations from normal operation is provided in the 3D lidar sensor (10), wherein the detection device is arranged inside a housing of the 3D lidar sensor or at an outlet opening, wherein the detection device (14) comprises light sensors (15), wherein either the light sensors (15) are arranged on an intermediate plane and / or at the outlet opening such that the light sensors are not irradiated during normal operation of the laser beam source (11) and the scanning system and this allows detection of whether the emitted laser beam is actually transmitted in the desired direction, wherein the laser beam (20) or the scanning system can be identified as maladjusted in the event of the light sensors (15) being irradiated, or wherein the light sensors (15) are arranged at the edge of the outlet opening or in the region of the intermediate plane such that the light sensors are irradiated during normal operation of the laser beam source (11) and the scanning system and this allows detection of whether the emitted laser beam is actually transmitted in the desired direction, wherein the laser beam (20) or the scanning system can be identified as maladjusted in the event of the light sensors (15) not being irradiated, and wherein an error message is output when the laser beam (20) or the scanning system is recognized as being maladjusted.

2. 3D lidar sensor (10) according to Claim 1, additionally comprising a bandpass filter and / or a coating, characterized in that extraneous light can be suppressed by means of the bandpass filter and / or the coating.

3. 3D lidar sensor (10) according to any of the preceding claims, characterized in that a scattered light sensor (16) is provided.

4. 3D lidar sensor (10) according to any of the preceding claims, characterized in that the 3D lidar sensor (10) is coupled to further sensors such as rain sensors, temperature sensors, ultrasonic sensors, chemical sensors or radioactivity sensors.

5. 3D lidar sensor (10) according to any of the preceding claims, characterized in that an expanding and / or focusing optical unit for the laser beams (20) is provided.

6. Method for operating a 3D lidar sensor (10), in particular for motor vehicles, wherein the 3D lidar sensor (10) is equipped with a laser beam source (11), an optical receiver and a scanning system for deflecting a laser beam (20) created by the laser beam source (11) in two mutually perpendicular scanning directions, wherein a further detection device (14) for deviations from normal operation, which renders deviations from normal operation of the 3D lidar sensor (10) determinable, is provided in the 3D lidar sensor (10), wherein the detection device is arranged inside a housing of the 3D lidar sensor or at an outlet opening, wherein the detection device (14) comprises light sensors (15), wherein either the light sensors (15) are arranged on an intermediate plane and / or at the outlet opening such that the light sensors are not irradiated during normal operation of the laser beam source (11) and the scanning system and this detects whether the emitted laser beam is actually transmitted in the desired direction, wherein the laser beam (20) or the scanning system is identified as maladjusted in the event of the light sensors (15) being irradiated, or wherein the light sensors (15) are arranged at the edge of the outlet opening or in the region of the intermediate plane such that the light sensors are irradiated during normal operation of the laser beam source (11) and the scanning system and this detects whether the emitted laser beam is actually transmitted in the desired direction, wherein the laser beam (20) or the scanning system is identified as maladjusted in the event of the light sensors (15) not being irradiated, and wherein an error message is output when the laser beam (20) or the scanning system is recognized as being maladjusted.