DE102020211151A1 - LiDAR sensor with increased detection area - Google Patents

Abstract

The present invention relates to a LiDAR sensor (1) having a housing (2) with a window (3), a transmitting and receiving unit (4) fixed in the housing (2) for emitting and receiving laser light, and an am Housing (2) rotatably mounted mirror device (5) which is designed to deflect a light path (100) from the transmitting and receiving unit (4) in different first directions (100) directly through the window (3), with the housing (2nd ) an additional mirror unit (6) is arranged in a stationary manner, so that the light path (100) can be deflected from the mirror device (5) to the additional mirror unit (6) and from the additional mirror unit (6) in different second directions (300) through the window (3). is.

Description

State of the art

The present invention relates to a LiDAR sensor. In particular, this is a rotating measuring LiDAR sensor. The LiDAR sensor advantageously has an enlarged detection range.

Various types of rotating LiDAR sensors are known from the prior art. On the one hand, an entire transmission and reception unit can be mounted on a rotor in order to emit light in different directions and receive it from different directions. However, such systems have the disadvantage that it is difficult to feed in power supply lines and data transmission lines due to the rotation of the transmitting and receiving unit. Cooling the transmitting and receiving unit can also only be achieved with great effort. LiDAR sensors that have a rotating mirror are therefore known from the prior art. The transmitter and receiver units are fixed in place, so that the problems mentioned above are avoided. The detection range of the LiDAR sensor is thus predetermined by the arrangement and design of the rotating mirror.

Disclosure of Invention

The LiDAR sensor according to the invention has an enlarged detection range in which dead areas are avoided in the measurement period. An additional mirror unit is provided, by means of which a measurement is also possible if a rotating mirror device would not steer the field of view into the surroundings. In other words, the additional mirror unit avoids or at least reduces the occurrence of such cases in which the field of view of a transmitting and receiving unit is directed at a housing part of the LiDAR sensor and not at the surroundings due to the rotating mirror device. This means that an enlarged detection area is available, which can either be used to increase the spatial field of view of the LiDAR sensor or to scan a specific area multiple times, i.e. with a higher sampling rate.

The LiDAR sensor has a housing with a window attached. A transmitter and receiver unit is fixed in the housing. In particular, this means that no relative movement between the housing and the transmitter and receiver unit is possible. The transmitting and receiving unit is used to emit and receive laser light.

A pivoted mirror assembly is also attached to the housing. The mirror device can thus rotate relative to the housing. This also allows rotation with respect to the transmitting and receiving unit fixedly attached to the housing. A light path from the transmitting and receiving unit is directed onto the mirror device, so that the mirror device is designed to deflect said light path in different first directions directly through the window. This enables the LiDAR sensor to carry out measurements in the first directions in order to thus capture a spatial field of view. These measurements are in particular time-off-flight measurements, i.e. the runtime of a transmitted, reflected and received laser signal is determined. This transit time can be used to determine a distance to an object in the vicinity of the LiDAR sensor. As a result of the rotating mirror device, the deflected light path sweeps over a predefined area that is defined by the arrangement of the mirror device. This swept area corresponds to the first directions previously described. All first directions lead from the mirror device directly through the window. Directly means that there is no further deflection between the mirror device and the window.

If the mirror device is in an orientation in which the light path is not deflected in one of the first directions, the window cannot be penetrated and the field of view of the transmitting and receiving unit is directed in particular at a part of the housing. In this case, there would be a dead zone in which the LiDAR sensor cannot take measurements. In order to minimize such dead zones, an additional mirror unit is stationarily arranged on the housing. Thus, in turn, a relative movement between the housing and the additional mirror unit is avoided. In a particularly advantageous manner, only the mirror device remains as the only movable element. The additional mirror unit is arranged in particular in such a way that the light path can be deflected from the mirror device to the additional mirror unit. The additional mirror unit in turn deflects it in different second directions through the window. Instead of the light path thus being directed from the mirror device to a part of the housing, it is preferably deflected to the additional mirror unit, which also makes it possible to penetrate the window. Thus, the mirror device can continue to perform a rotational movement, wherein dead areas during this rotational movement, ie those areas in which the light path, with or without additional deflection, cannot penetrate through the window, are minimized. With that he stands LiDAR sensor per revolution of the mirror device available for measurements for a longer period of time. This increased period of time can be used to increase the spatial detection range of the LiDAR sensor and/or to scan a sub-area of the detection range of the LiDAR sensor multiple times. The LiDAR sensor can thus be used for improved measurement.

The dependent claims relate to preferred developments of the invention.

Provision is preferably made for the mirror device to run through at least a first angular range and a second angular range during a rotation. The mirror device is designed to deflect the light path directly through the window during the first angular range and to deflect the light path onto the additional mirror unit during the second angular range. In other words, the light path is deflected through the window in the first directions. During the first angular range and deflecting the light path through the window in the second directions during the second angular range. In order to realize the second directions, an additional deflection takes place via the additional mirror unit.

The first angular range and the second angular range together preferably amount to at least 270°, preferably at least 300°. In this way, the dead zone can be minimized in a particularly advantageous manner, as described above.

The first directions and the second directions are preferably at least partially identical. In this case, it is thus possible to scan the identical area of the first directions and second directions multiple times, i.e. the identical area of the first directions and second directions is scanned twice per revolution of the mirror device. In this way, relevant areas around the LiDAR sensor can be recorded better. For example, the LiDAR sensor can be used as an environmental sensor of an autonomous or at least automated vehicle, so that, for example, an area immediately in front of the vehicle is scanned several times per revolution of the mirror device to detect vehicles driving ahead.

Provision is also preferably made for the first directions and the second directions to be at least partially different. In this way, an entire field of view of the LiDAR sensor can be enlarged. A larger area of the environment can thus be scanned using a LiDAR sensor than would be possible with a corresponding LiDAR sensor from the prior art. This reduces the number of LiDAR sensors with the same or at least a similar overall detection range.

In a preferred embodiment, the additional mirror unit has a plurality of individual mirrors. The plurality of individual mirrors are at least two individual mirrors, so that there is at least one first individual mirror and at least one second individual mirror. In this case, the light path is deflected by the mirror device onto the first individual mirror of the additional mirror unit. Deflection takes place from the first individual mirror directly or via a further individual mirror element to the second individual mirror. Finally, the second individual mirror is used for deflection through the window. Any number of further individual mirrors can thus be inserted between the first individual mirror and the second individual mirror. The use of a plurality of individual mirrors means that, on the one hand, the dead areas during the rotation of the mirror device are further minimized and, on the other hand, the second directions can be set easily and flexibly.

Provision is preferably made for the window to have a curvature or a kink. In this way, it is achieved in particular that the window is arranged over an angular range of at least 60°, in particular at least 90°, of the rotation of the mirror device. As a result, the window extends over an area that enables a large detection field for the first directions and/or the second directions.

Provision is also preferably made for the additional mirror unit to be tilted with respect to an axis of rotation of the mirror device. Thus, the additional mirror unit is not oriented parallel to the axis of rotation. In this way, the second directions can be angled relative to the first directions, with the first directions all being arranged in a plane perpendicular to the axis of rotation, while the angling causes the second directions to be angled relative to said plane perpendicular to the axis of rotation. A spatial field of view of the LiDAR sensor can thus be enlarged. In particular, the axis of rotation is oriented vertically, so that a vertical field of view of the LiDAR sensor is increased by the corresponding bending of the additional mirror unit.

In a further preferred configuration, the additional mirror unit has a curved mirror surface. In this way, LiDAR properties such as a resolution or an opening angle of the first directions and/or second directions can be modified.

Finally, it is preferably provided that the transmitting and receiving unit has a laser light source and a detector. Laser light source and detector can be separate components, alternatively these elements can also be implemented in a single unit. The laser light source is designed to emit laser light onto the mirror device along the light path. The detector is designed to detect laser light reflected from surroundings of the LiDAR sensor at least via the mirror device. The reflected laser light is thus also guided by the mirror device along the light path to the detector. Thus, using the transmitter and receiver unit, distance measurements can be carried out, which are based in particular on the propagation time of the emitted laser light.

character list

• 1 eine erste schematische Abbildung eines LiDAR-Sensors gemäß einem ersten Ausführungsbeispiel der Erfindung,
• 2 eine zweite schematische Abbildung des LiDAR-Sensors gemäß dem ersten Ausführungsbeispiel der Erfindung,
• 3 eine schematische Abbildung eines LiDAR-Sensors gemäß einem zweiten Ausführungsbeispiel der Erfindung, und
• 4 eine schematische Abbildung eines LiDAR-Sensors gemäß einem dritten Ausführungsbeispiel der Erfindung.

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing is:

• 1 a first schematic image of a LiDAR sensor according to a first embodiment of the invention,
• 2 a second schematic image of the LiDAR sensor according to the first exemplary embodiment of the invention,
• 3 a schematic illustration of a LiDAR sensor according to a second exemplary embodiment of the invention, and
• 4 a schematic illustration of a LiDAR sensor according to a third embodiment of the invention.

Embodiments of the invention

1 FIG. 1 schematically shows a LiDAR sensor 1 according to a first exemplary embodiment of the invention. The LiDAR sensor 1 has a rotating mirror device 5 . The same LiDAR sensor 1 is also in 2 shown where 1 and 2 differ only in the orientation of the rotating mirror device 5, ie show different points in time during the rotation of the mirror device 5.

The LiDAR sensor 1 according to the first exemplary embodiment of the invention has a housing 2 . The housing 2 in turn has a window 3 through which the laser light can be emitted from the LiDAR sensor 1 to an environment and through which the laser light can reach the LiDAR sensor 1 from the environment. A transmitting and receiving unit 4 is also arranged in a stationary manner on the housing 2 and said rotating mirror device 5 is rotatably mounted. The mirror device 5 is designed in such a way that it can be rotated about an axis of rotation 400, with the axis of rotation 400 preferably being aligned vertically when the LiDAR sensor 1 is in operation.

The transmitting and receiving unit 4 has a laser light source and a detector. The laser light source is used to emit laser light along a light path 100 to the mirror device 5. The detector is used to detect reflected laser light, reflected laser light being guided from the mirror device 5 along the light path 100 to the detector. The exact structure and the exact arrangement of the light source and detector are not relevant to the invention, which is why they are summarized below by the transmission and reception unit 4 .

During the rotation of the mirror device 5 about the axis of rotation 400, the mirror device 5 runs through different angular ranges, with a first angular range in 1 is shown. This first angular range enables the light path 100 to be deflected by the mirror device 5 in order to thus pass directly through the window 3 . In other words, the transmitting and receiving unit 4 emits laser light onto the mirror device, which directs said laser light directly through the window 3 into the environment. The same applies vice versa for reflected laser light, which impinges directly on the mirror device 5 through the window 3 and is guided by it to the transmitting and receiving unit 4 . The light path 100 is thus deflected directly through the window 3 along first directions 200 .

The first directions 200 thus correspond to an area that can arise as a result of the deflection of the mirror device 5 in the different orientations of the mirror device 5 during the rotation.

Dead areas can also occur during the rotation of the mirror device 5 , in which it is not possible for the light path 100 to be deflected through the window 3 , so that the light path 100 would be deflected onto a housing part of the housing 2 . In order to minimize such dead areas, an additional mirror unit 6 is provided. In particular 2 the operation of the additional mirror unit 6 is shown.

2 FIG. 1 shows an orientation of the mirror device 5 that would lead to a dead zone in conventional LiDAR sensors 1, since the light path 100 would be directed through the mirror device 5 directly onto a housing area of the housing 2. However, the additional mirror unit 6 means that the light path 100 nevertheless can be deflected through the window 3. For this purpose, the mirror device 5 directs the light path 100 onto the additional mirror unit 6, with deflection from there through the window 3 in second directions 300 taking place. In the first exemplary embodiment, the first directions 200 and the second directions 300 are advantageously different at least in certain areas, so that a visual range of the LiDAR sensor 1 is increased overall. On the one hand, this avoids dead areas and, on the other hand, the performance of the LiDAR sensor is improved.

In order to enable a maximum detection range of the LiDAR sensor 1, it is preferably also provided that the window 3 covers an angular range of at least 60°, in particular of at least 90°, with respect to the rotation of the mirror device 5. In other words, the window 3 is curved and extends with respect to the axis of rotation 400 by the previously described angular range. Alternatively, the window can also be kinked, with the curvature being advantageous in order to avoid optical influences at the kinks.

The additional mirror unit 6 can, as in 1 and 2 shown to be a planar mirror element. It is also possible to provide the additional mirror unit 6 with a curved mirror surface, in particular to adjust parameters of the LiDAR sensor such as a resolution or a detection range.

In the 1 and 2 an alternative is also shown in which the first directions 200 and the second directions 300 all lie in the same plane, namely in a plane perpendicular to the axis of rotation 400. The mirror unit 6 can also be oriented tilted with respect to said axis of rotation 400, so that the additional mirror unit 6 is not arranged in a plane parallel to the axis of rotation 400 . In this case, the first directions 200 and the second directions 300 have a difference with regard to the vertical orientation, at least in regions. While the first directions 200 continue to be within the plane of the drawing, ie the plane perpendicular to the axis of rotation 400, the second directions 300 are oriented at an angle to said plane. A vertical detection range of the LiDAR sensor 1 can thus be increased.

As described, the additional mirror unit 6 can reduce a dead zone during the measurement of the LiDAR sensor. During the rotation of the mirror device 5 there is thus a first angular range in which the first directions 100 are formed and a second angular range in which the second directions 300 are formed. The first angular range and the second angular range together are preferably at least 270°, in particular at least 300°. In this way, the dead zone is advantageously minimized.

3 shows a LiDAR sensor 1 according to a second exemplary embodiment of the invention. In contrast to the first exemplary embodiment, only the additional mirror unit 6 is modified. Due to a different orientation than in the first exemplary embodiment, in the second exemplary embodiment, the second directions 300 are at least partially the same as the first directions 200 . As a result, a certain area of the detection area of the LiDAR sensor 1, namely the area in which the first directions 200 and the second directions 300 overlap, is scanned multiple times per rotation of the mirror device 5 . Thus, an accuracy of detection at this area is increased. Otherwise, the LiDAR sensor is designed analogously to the first exemplary embodiment.

4 finally shows a third exemplary embodiment of the LiDAR sensor 1. The difference to the first exemplary embodiment and to the second exemplary embodiment is again only formed by the additional mirror unit 6, since in contrast to the first exemplary embodiment and the second exemplary embodiment, the LiDAR sensor 1 in the third exemplary embodiment is Additional mirror unit 6 has a first individual mirror 6a and a second individual mirror 6b.

In the third exemplary embodiment, it is therefore provided that the light path 100 travels from the transmitting and receiving unit 4 to the rotating mirror device 5 and is deflected from there to the first individual mirror 6a. A deflection to the second individual mirror 6b takes place at the first individual mirror 6a, with a deflection from there taking place through the window 3 in order to thus realize the second directions 300. The use of several individual mirrors 6a, 6b as additional mirror unit 6 thus enables a flexible arrangement of the additional mirror unit 6 in the housing 2, whereby on the one hand a dead area can be further minimized and on the other hand a flexible orientation of the second directions 300 is made possible.

The LiDAR sensor 1 can be used in particular in autonomous or at least automated vehicles. Because of the minimized dead zone, a more powerful measurement is thus made possible than is the case in the prior art.

Claims (10)

LiDAR sensor (1) having a housing (2) with a window (3), a transmitting and receiving unit (4) fixed in the housing (2) for emitting and receiving laser light, and one rotatable on the housing (2). Mounted mirror device (5) which is designed to deflect a light path (100) from the transmitting and receiving unit (4) in different first directions (100) directly through the window (3), with an additional mirror unit (6 ) is arranged stationary, so that the light path (100) from the mirror device (5) to the additional mirror unit (6) and from the additional mirror unit (6) in different second directions (300) through the window (3) can be deflected. LiDAR sensor (1) after claim 1 , characterized in that the mirror device (5) runs through at least a first angular range and a second angular range during a rotation, wherein the mirror device (5) is designed to deflect the light path (100) directly through the window (3) during the first angular range and to deflect the light path (100) onto the additional mirror unit (6) during the second angular range. LiDAR sensor (1) after claim 2 , characterized in that the first angular range and the second angular range together amount to at least 270°, in particular at least 300°. LiDAR sensor (1) according to one of the preceding claims, characterized in that the first directions (200) and the second directions (300) are at least partially identical. LiDAR sensor (1) according to one of the preceding claims, characterized in that the first directions (200) and the second directions (300) are at least partially different. LiDAR sensor (1) according to one of the preceding claims, characterized in that the additional mirror unit (6) has at least two individual mirrors (6A, 6B), so that the light path (100) from the mirror device (5) onto a first individual mirror (6A ) of the additional mirror unit (6), from the first individual mirror (6A) directly or via other individual mirrors to a second individual mirror (6B) of the additional mirror unit (6) and from the second individual mirror (6B) through the window (3), LiDAR sensor (1) according to one of the preceding claims, characterized in that the window (3) is arranged over an angular range of at least 60°, in particular at least 90°, of the rotation of the mirror device (5). LiDAR sensor (1) according to one of the preceding claims, characterized in that the additional mirror unit (6) is tilted relative to an axis of rotation (400) of the mirror device (5), so that the additional mirror unit (6) is not parallel to the axis of rotation (400) is oriented. LiDAR sensor (1) according to one of the preceding claims, characterized in that the additional mirror unit (6) has a curved mirror surface. LiDAR sensor (1) according to one of the preceding claims, characterized in that the transmitting and receiving unit (4) has a laser light source and a detector, the laser light source being designed to emit laser light onto the mirror device (5) and the detector being designed is to detect laser light reflected from surroundings of the LiDAR sensor at least via the mirror device (5).

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