Laser radar system

Abstract

The application is a laser radar system having a light source for emitting light pulses along an optical axis, a steering device for deflecting the optical axis in a first direction and a second direction, a control unit for activating and deactivating the light source, the steering device being configured to oscillatingly deflect the optical axis in a first spatial direction and in a second spatial direction such that the optical axis repeatedly traverses a two-dimensional scan pattern, wherein the oscillating deflection in the first spatial direction is effected by a first sub-motion and a second sub-motion opposite thereto, wherein the oscillating deflection in the second spatial direction is effected by a third sub-motion and a fourth sub-motion opposite thereto, wherein the control unit is configured to control the light source to emit one light pulse each at predefined positions, i.e. pixels, of the scan pattern, the control unit being further configured to control the light source to emit light pulses at different pixels during the first sub-motion and / or the third sub-motion than during the second sub-motion and / or the fourth sub-motion, respectively.

Description

Technical Field

[0001] This invention relates to a lidar system. More particularly, it relates to a vehicle equipped with such a lidar system. Background Technology

[0002] Lidar systems for distance measurement are known from existing technology. The core of such a lidar system is a light source, such as a laser source, which emits a time-structured light signal. This light signal is reflected at the object and detected by a receiving unit. By receiving the reflected signal, the distance from the object (where the reflection occurs) to the lidar system can be determined, for example, based on the signal propagation time. Lidar systems can perform one-dimensional measurements, i.e., the light pulse is emitted at only a single location. Similarly, two-dimensional measurements can be achieved, in which the light pulse illuminates a two-dimensional measurement area. Different areas of the eye. Pre-defined guidelines regarding eye safety must be followed under all circumstances. This means allowing only a pre-defined amount of light to enter the human eye. This is especially important in laser devices to avoid eye damage caused by excessive light energy. Summary of the Invention

[0003] The lidar system according to the present invention is constructed as a two-dimensional measurement system. Here, a scanning mode is implemented that covers the largest possible measurement area while simultaneously meeting pre-defined requirements for eye safety. Specifically, the lidar system can emit high-energy light pulses, but simultaneously poses absolutely no risk of eye damage. This is achieved by illuminating different pixels of the scanning mode at different times.

[0004] The lidar system according to the invention has at least one light source for emitting light pulses. The light pulses are emitted along the optical axis of the lidar system. The optical axis can be deflected by a steering device of the lidar system. The steering device is configured to deflect the optical axis in at least one first spatial direction and one second spatial direction. Here, the spatial directions are preferably independent of each other, i.e., particularly perpendicular to each other, but at least not parallel to each other. Two-dimensional scanning can be achieved in this way because each point in a two-dimensional measurement area can be illuminated by the steering device, wherein the measurement area is spread out by two spatial directions. Finally, the lidar system has a control unit. This control unit is used to activate and deactivate the light source, thereby allowing the control unit to manipulate the light source for emitting light pulses.

[0005] The steering mechanism is configured to oscillate the optical axis in both a first and a second spatial direction. This implies a two-dimensional scanning mode that traverses the optical axis. The scanning mode is specifically configured such that it covers the entire measurement area in a sinusoidal or zigzag pattern.

[0006] The oscillating deflection of the optical axis in the first spatial direction is achieved by repeating a first sub-motion and a second sub-motion opposite to the first sub-motion. The first and second sub-motions differ only in their directions of motion, not in their deflection distance. Similarly, the oscillating deflection of the optical axis in the second spatial direction is achieved by repeating a third sub-motion and a fourth sub-motion opposite to the third sub-motion (8). Again, the difference between the third and fourth sub-motions is only in their directions, not in their deflection distance.

[0007] The control unit is configured to manipulate the light source to emit light pulses at predefined locations within a scanning pattern. These predefined locations are also referred to hereinafter as pixels. In particular, pixels are predefined such that the entire measurement area to be inspected is covered by the pixels. Therefore, the control unit can detect the entire measurement area by emitting light pulses at the corresponding predefined locations within the scanning pattern. The light pulses at the pixels are selected in such a way that they meet predefined requirements for eye safety and minimize eye strain as much as possible.

[0008] The control unit is configured such that, during the first and / or third sub-movements, light pulses are emitted from a light source at a pixel different from those emitted during the second and / or fourth sub-movements. This achieves the time interval between the emission of a light pulse at the first pixel and the emission of a light pulse at the second pixel. Particularly preferably, this allows the light source to be manipulated to illuminate all pixels in the measurement area, wherein the illumination is performed at increased temporal and spatial intervals, particularly at maximum temporal and spatial intervals.

[0009] The following shows a preferred extension of the present invention.

[0010] The steering mechanism is preferably configured to deflect the optical axis along a scanning pattern during forward and reverse motion, wherein the forward and reverse motions are oriented in opposite directions. Therefore, the scanning pattern during forward motion is the same as the scanning pattern during reverse motion. In other words, there exists a unique scanning pattern that is traversed not only during forward motion but also during reverse motion, so the motion is the same, only the direction is different. Forward motion is a superposition of multiple first sub-motions, multiple second sub-motions, and a single third sub-motion. In this way, forward motion is particularly configured as sinusoidal or sawtooth-shaped. Reverse motion is a superposition of multiple first sub-motions, multiple second sub-motions, and a single fourth sub-motion. Preferably, the control unit is additionally configured such that light pulses are emitted only at the first pixel during forward motion. This means that the control unit is configured to manipulate the light sources such that they emit light pulses only at the first pixel during forward motion. Conversely, no light pulses are emitted at the second pixel, so the control unit is configured to skip the second pixel when emitting light pulses during forward motion. Conversely, the opposite manipulation is performed during the reverse motion. Therefore, the control unit is configured to manipulate the light source to emit light pulses at the second pixel during the reverse motion. In this case, the first pixel is skipped, so no light pulses are emitted at the first pixel. Particularly advantageously, the first and second pixels together form the entire measurement area. Therefore, particularly advantageously, during the first and second sub-motions, only every second swept pixel is illuminated in the first spatial direction. To still illuminate all pixels, the illuminated pixels are switched when switching from the third sub-motion in the second spatial direction to the fourth sub-motion in the second spatial direction. This achieves that only the first pixel is illuminated during the forward motion, and only the second pixel is illuminated during the reverse motion.

[0011] Preferably, the first pixel and the second pixel are arranged spatially adjacent to each other. This specifically means that the first pixel and the second pixel are advantageously arranged adjacent to each other along the scanning pattern. Therefore, adjacent pixels are illuminated at different times, where there is, in particular, the maximum possible interval between the illumination times of adjacent pixels. This results in a significant reduction in eye strain, thereby avoiding eye damage.

[0012] Furthermore, the control unit is preferably configured to manipulate the light source to emit light pulses only at the first group of pixels during the first and / or third sub-movements. Conversely, during the second and / or fourth sub-movements, the control unit manipulates the light source to emit light pulses only at the second group of pixels. The pixels of the first and second groups are arranged staggered from each other, especially adjacent to each other. This type of manipulation specifically achieves that after the combined first and second sub-movements or the combined third and fourth sub-movements, all pixels swept by these movements have been illuminated, wherein temporal and spatial offsets (Versatz) of illumination are achieved. In particular, adjacent pixels are not directly and sequentially illuminated, but only a few pixels, especially every second pixel, are illuminated during the initial sub-movement. During the subsequent opposite sub-movements, the skipped pixels are illuminated. This allows for a longer time interval between light pulses, and thus reduces the power reaching the eye in a short period of time.

[0013] Preferably, the light source has a first sub-unit and a second sub-unit. Preferably, the first and second sub-units can be independently controlled by a control unit. Furthermore, preferably, the illumination of the first and second sub-units is performed via the same steering mechanism, meaning that the optical axes of the first and second sub-units can be deflected via the same steering mechanism. Therefore, the first and second sub-units are preferably configured independently to illuminate two pixels. Thus, it is particularly possible to illuminate two adjacent pixels independently. Therefore, especially, it is always possible to simultaneously illuminate a group of two pixels along the scanning mode during different sub-movements. Consequently, less oscillating motion is required in the first and second spatial directions to completely cover the predetermined measurement area. Therefore, the requirements for the dynamics of the steering mechanism are lower.

[0014] Particularly advantageously, the illumination of the first and second sub-units occurs during different movements along the optical axis. This means that the control unit is configured to manipulate the first sub-unit to emit light pulses only during the first and / or third sub-movements. Furthermore, the control unit is configured to manipulate the second sub-unit to emit light pulses only during the second and / or fourth sub-movements. This thus achieves further temporal and spatial separation of pixel illumination.

[0015] The steering mechanism is advantageously configured as a micromirror actuator. The micromirror actuator allows steering by tilting the mirror surface. Therefore, the deflection of the optical axis of the light source can be achieved. In particular, the micromirror actuator can be easily and with low overhead, and high dynamics can be achieved especially when manipulating the micromirror actuator.

[0016] In another advantageous configuration, the steering mechanism is constructed as a single mirror that can tilt around two different axes. Therefore, deflection in a first spatial direction and deflection in a second spatial direction can be achieved using this single mirror.

[0017] In an alternative configuration, the steering device has a first mirror and a second mirror. Here, the optical axis can be deflected in a first spatial direction by the first mirror, and in a second spatial direction by the second mirror. The first and second mirrors are arranged sequentially, so that the light pulse emitted by the light source first hits the first mirror and then the second mirror, or alternatively, first hits the second mirror and then the first mirror. Therefore, it is possible to deflect the optical axis in both spatial directions.

[0018] The light source is advantageously a laser source. Therefore, the light pulse is a laser pulse. Consequently, distance can be measured effectively and reliably.

[0019] Advantageously, all pixels are close to each other. This achieves the goal of all pixels forming a connected network. Two-dimensional measurement area. Therefore, this measurement area can be illuminated by light pulses from a light source.

[0020] The present invention also relates to a vehicle. This vehicle has a lidar system as described above. Therefore, it enables the vehicle to determine the distance to objects in the surrounding environment. Particularly advantageously, the vehicle can determine the distance to objects in the direction of travel ahead of the vehicle, especially for identifying traffic traveling ahead. Attached Figure Description

[0021] Embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings show:

[0022] Figure 1 A schematic diagram of a lidar system according to an embodiment of the present invention is shown;

[0023] Figure 2 A schematic diagram showing an alternative steering device for a lidar system according to an embodiment of the present invention;

[0024] Figure 3 A schematic view showing the time-varying process of deflection in the first spatial direction;

[0025] Figure 4 A schematic view showing the time-varying process of deflection in the second spatial direction;

[0026] Figure 5 A schematic view showing a pulse pattern that can be generated during a first operating mode by means of a lidar system according to an embodiment of the present invention;

[0027] Figure 6 Showing via from Figure 5 A schematic view of the pixel-by-pixel coverage of the measurement area by the scanning mode;

[0028] Figure 7 A schematic view showing a scanning pattern that can be generated during a second operating mode using a lidar system according to an embodiment of the present invention;

[0029] Figure 8 Showing via from Figure 7 A schematic view of the pixel-by-pixel coverage of the measurement area by the scanning mode;

[0030] Figure 9 A schematic view of a vehicle having a lidar system according to an embodiment of the present invention is shown. Detailed Implementation

[0031] Figure 1 A lidar system 1 according to an embodiment of the present invention is schematically shown. The lidar system 1 has a light source 2, a steering device 3, and a control unit 4. The light source 2 is used to emit light along an optical axis 100. In the illustrated embodiment, the light source 2 has a first subunit 2a and a second subunit 2b, wherein the first subunit 2a emits light pulses along a first optical axis 100a. The second subunit 2b emits light pulses along a second optical axis 100b. In an alternative configuration, there may be only one light source 2, which emits a single light pulse along a single optical axis 100. By using two subunits 2a, 2b, two adjacent positions can be illuminated independently of each other, wherein a single steering device 3 can be used for this purpose. Because the first optical axis 100a and the second optical axis 100b are therefore coupled in their deflection and are therefore immutable relative to each other, the optical axis 100 will be used only for the purpose of describing the deflection below, in order to cover several cases in which only one pixel 12, 13 can be illuminated by the light source 2, and two pixels 12, 13 can be illuminated by the light source 2.

[0032] The steering device 3 is used for deflecting the optical axis 100 or optical axes 100a, 100b in the first spatial direction X and the second spatial direction Y. The spatial directions X and Y are oriented perpendicularly to each other and correspond in particular to the coordinate axes in the Cartesian coordinate system.

[0033] exist Figure 1 The diagram schematically illustrates that the steering device 3 has a first mirror 3a and a second mirror 3b. The first mirror 3a enables deflection in a first spatial direction X, while the second mirror 3b enables deflection in a second spatial direction Y. Alternatively, it can be used in... Figure 2The exemplary mirror element shown in the diagram has a steering device 3 configured as a single mirror that can tilt around two different axes. In this way, changes in the first spatial direction X and the second spatial direction Y can also be achieved.

[0034] The steering device 3 allows for the deflection of the optical axis 100 by correspondingly manipulating the mirrors used. For this purpose, a particular manipulation mode is employed where the optical axis deflects oscillatingly in both the first spatial direction X and the second spatial direction Y. Figure 3 and Figure 4 The corresponding control mode is displayed. Thus, Figure 3 The diagram schematically illustrates the variation of deflection in the first spatial direction X with time t. This is particularly evident in the sinusoidal deflection. For example... Figure 4 As schematically shown, preferably, there is a sawtooth-shaped change process over time in the second spatial direction Y. Therefore, in any case, the deflection in the first spatial direction X and the second spatial direction Y consists of oscillating motion. There is a first sub-motion 5 in the first spatial direction X, wherein a second sub-motion 6 is subsequently implemented. The first sub-motion 5 and the second sub-motion 6 in the first spatial direction X are oriented in opposite directions. The same applies to the second spatial direction Y. There are also opposite sub-motions here, wherein multiple third sub-motions 7 and opposite fourth sub-motions 8 are implemented. Scanning mode 9 can be achieved through the superposition of these sub-motions 5, 6, 7, and 8. Figures 5 to 8 It is shown schematically in the diagram.

[0035] Figure 5 and 6 A first exemplary operating mode of the lidar system 1 according to an embodiment of the present invention is shown. A scanning mode 9 in the form of a sine curve is achieved by superimposing the aforementioned sub-motions 5, 6, 7, and 8, wherein the optical axis 100 moves along the scanning mode 9, which has a forward motion 10 and a reverse motion 11. This is achieved in particular by the fact that the oscillating motion in the first spatial direction X has a higher frequency than the oscillating motion in the second spatial direction Y. Therefore, the same scanning mode 9 first moves back and forth along the forward motion 10 and then along the reverse motion 11.

[0036] The control unit 4 is configured to emit light pulses from the light source 3 at predefined positions on the scanned pattern. These predefined positions are hereinafter referred to as pixels 12 and 13. By illuminating pixels 12 and 13, it is particularly possible to achieve complete coverage of the two-dimensional measurement area by the lidar system 1.

[0037] To achieve the greatest possible spatial and temporal separation in the illumination of individual pixels 12 and 13, the following configuration is adopted: during forward motion 10, a light pulse is emitted only at the first pixel 12, while the second pixel 13 is not illuminated. Conversely, during reverse motion 11, the second pixel 13 is illuminated, while the first pixel 12 is not illuminated. The first pixel 12 and the second pixel 13 are arranged alternately along scanning pattern 9, such that every second pixel is skipped during both forward and reverse motions. This achieves illumination of all existing pixels 12 and 13 simultaneously, with increased temporal and spatial intervals. In this way, eye safety of the lidar system 1 can be improved.

[0038] Scanning mode 9 can be implemented using either light source 2 or light source 3. Light source 2 emits only a single light pulse, while light source 3 has the aforementioned subunits 2a and 2b and is therefore capable of emitting two light pulses. Figure 5 The diagram schematically illustrates how to emit only a single light pulse. Figure 6 The diagram schematically illustrates how two sub-units 2a and 2b simultaneously emit optical pulses for better coverage. Figure 5 In the process, pixels 12 and 13 are illuminated during both the first sub-motion 5 and the second sub-motion 6. That is, pixel 12 is illuminated during the simultaneous third sub-motion 7, and pixel 13 is illuminated during the simultaneous fourth sub-motion 8. However, in the case of... Figure 6 When using two sub-units 2a and 2b, illumination is performed only during the first sub-motion 5, but not during the second sub-motion 6. This is because during the first sub-motion 5, two adjacent pixels 12 and 13 in the second spatial direction Y are always illuminated, so this illumination is no longer needed during the second sub-motion 6. This method specifically produces full-area illumination of the measurement region, where each pixel 12 and 13 is illuminated at different times, both spatially and temporally.

[0039] Figure 7 and Figure 8 Show Figure 1 The second operating mode of the lidar system 1 is shown. In this operating mode, the control unit 4 independently operates the first sub-unit 2a and the second sub-unit 2b of the light source 2. Therefore, during forward movement, only the first sub-unit 2a emits light pulses, which in turn applies only to the first pixel 12. The second sub-unit 2b remains completely inactive during forward movement 10. Conversely, during reverse movement 11, only the second sub-unit 2b of the light source 2 is used to illuminate pixels 12 and 13, where, as described above, only the second pixel 13 is illuminated. Furthermore, illumination occurs during both the first sub-movement 5 and the second sub-movement 6. Thus, in... Figure 7The diagram schematically illustrates that if a third sub-motion 7 is superimposed simultaneously, the first subgroup 12a of the first pixel is illuminated during the first sub-motion 5, and the second subgroup 12b of the first pixel is illuminated during the second sub-motion 6. Conversely, if a second sub-motion 8 is superimposed, the first subgroup 13a of the second pixel is illuminated during the first sub-motion 5, and the second subgroup 13b of the second pixel is illuminated during the second sub-motion 6. All these pixel groups 12a, 12b, 13a, and 13b are staggered, and their entirety completely covers the measurement area to be detected. However, due to the different manipulation times of the first subunit 2a and the second subunit 2b, a maximum temporal and spatial interval of illumination is achieved.

[0040] at last, Figure 9 Vehicle 14 is shown. Vehicle 14 has a lidar system 1 according to an embodiment of the present invention. Therefore, lidar system 1 is capable of emitting light pulses along a deflectable optical axis 100. Due to the above-described operating mode, improved eye safety of lidar system 1 can be achieved.

Claims

1. A lidar system (1), the lidar system having: At least one light source (2), said at least one light source being used to emit light pulses along the optical axis (100), At least one steering device (3) is configured to deflect the optical axis (100) in at least one first spatial direction (X) and a second spatial direction (Y). Control unit (4), which is used to activate and deactivate the light source (2). in, The steering device (3) is configured to oscillate the optical axis (100) in the first spatial direction (X) and the second spatial direction (Y), such that the optical axis (100) repeatedly traverses the two-dimensional scanning pattern (9). The oscillating deflection of the optical axis (100) in the first spatial direction (X) is achieved through repeated first sub-motions (5) and second sub-motions (6) opposite to the first sub-motions (5). The oscillating deflection of the optical axis (100) in the second spatial direction (Y) is achieved through repeated third sub-motions (7) and fourth sub-motions (8) opposite to the third sub-motions (7). The control unit (4) is configured to control the light source (2) to emit light pulses at a predefined position in the scanning mode (9), the predefined position being referred to as pixel (12, 13). The control unit (4) is configured to manipulate the light source (2) to emit light pulses at different pixels (12, 13) during the first sub-movement (5) and / or the third sub-movement (7) than during the second sub-movement (6) and / or the fourth sub-movement (8).

2. The lidar system (1) according to claim 1, characterized in that, The steering device (3) is configured to deflect the optical axis (100) along the scanning pattern (9) in forward motion (10) and reverse motion (11). The forward motion (10) is a superposition of multiple first sub-motions (5), multiple second sub-motions (6), and a single third sub-motion (7). The reverse motion (11) is a superposition of multiple first sub-motions (5) and multiple second sub-motions (6) with a single fourth sub-motion (8). The control unit (4) is configured to manipulate the light source (2) to emit light pulses only at the first pixel (12) during the forward movement (10) and skip the second pixel (13), and to manipulate the light source (2) to emit light pulses only at the second pixel (13) and skip the first pixel (12) during the reverse movement (11).

3. The lidar system (1) according to claim 2, characterized in that, The first pixel (12) and the second pixel (13) are arranged close together in space, especially along the scanning pattern (9).

4. The lidar system (1) according to any one of claims 1 to 3, characterized in that, The control unit (4) is configured to manipulate the light source (2) to emit light pulses only at the first group of pixels (12a, 13a) during the first sub-movement (5) and / or the third sub-movement (7), and to manipulate the light source (2) to emit light pulses only at the second group of pixels (12b, 13b) during the second sub-movement (6) and / or the fourth sub-movement (8), wherein the first group of pixels (12a, 13a) and the second group of pixels (12b, 13b) are arranged staggered from each other, especially adjacent to each other.

5. The lidar system (1) according to any one of claims 1 to 3, characterized in that, The light source (2) has a first sub-unit (2a) and a second sub-unit (2b), wherein the first sub-unit (2a) and the second sub-unit (2b) are configured to illuminate two pixels, especially two adjacent pixels, independently of each other.

6. The lidar system (1) according to claim 5, characterized in that, The control unit (4) is configured to manipulate the first sub-unit (2a) to emit light pulses only during the first sub-movement (5) and / or the third sub-movement (7), and to manipulate the second sub-unit (2b) to emit light pulses only during the second sub-movement (6) and / or the fourth sub-movement (8).

7. The lidar system (1) according to any one of claims 1 to 3, characterized in that, The steering device (3) is configured as a micromirror actuator.

8. The lidar system (1) according to claim 7, characterized in that, The steering device (3) is configured as a single mirror that can tilt around two different axes.

9. The lidar system (1) according to claim 7, characterized in that, The steering device (3) has a first mirror (3a) and a second mirror (3b), wherein the optical axis (100) can be deflected in the first spatial direction (X) through the first mirror (3a), and the optical axis (100) can be deflected in the second spatial direction (Y) through the second mirror (3b).

10. The lidar system (1) according to any one of claims 1 to 3, characterized in that, The light source (2) is a laser light source, so that the light pulse is a laser pulse.

11. The lidar system (1) according to any one of claims 1 to 3, characterized in that, All pixels (12, 13) are placed close to each other, so that all pixels (12, 13) form a connected two-dimensional measurement region.

12. A vehicle (14) having a lidar system (1) according to any one of the preceding claims.

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