Lidar sensor

Abstract

A lidar sensor, in particular a vertical flash lidar sensor, is described, which has a laser source, which is arranged to emit a laser signal into a transmission path, and a pixel detector, which has at least one macro-pixel array (1, 2), which is arranged to detect a reflected laser signal in a reception path. Here, the pixel detector is arranged to analyze at least two macro-pixel arrays (1, 2) in each of its measurement points.

Description

TECHNICAL FIELD

[0001] The present application relates to a laser radar sensor, in particular a vertical flash laser radar sensor, having a laser source which is arranged to emit a laser signal into a transmission path, and a pixel detector having at least one macro-pixel array which is arranged to detect a reflected laser signal in a reception path. BACKGROUND

[0002] In the coming years, the use of highly automated or fully automated driving (level 3 to 5) of motor vehicles will increasingly occur in road traffic. This automation of the driving of motor vehicles is achieved by different concepts. Common to all these concepts is that they require sensors in order to detect the surroundings of the autonomously driving motor vehicle. For this purpose, different sensors can be used, for example video cameras, sensors or ultrasonic sensors. Here, a special type of sensor should play an increasingly important role. This relates, for example, to laser radar sensors. These are optical sensors which, by means of a laser source, emit a laser signal into a reception path. The emitted laser signal is reflected at objects in the surroundings of the laser radar sensor and reflected back into the laser radar sensor. There, the reflected laser signal is typically detected in a pixel detector. As a result, a 3D point cloud of the surroundings is generated. Here, the laser radar sensor can be configured as a vertical flash macro scanner. This type of laser radar sensor generates a horizontal deflection of the emitted laser signal by means of a rotating scanner, for example a rotating mirror or a rotating transmission and reception module, and a vertical deflection by emitting a vertically diverging laser signal. This vertically emitted laser signal is mapped onto a pixel detector in the reception path. This pixel detector can have at least one micro-pixel array. The micro-pixel array can be realized, for example, by means of a plurality of diodes. These micro-pixel arrays are typically synthesized and jointly analyzed in order to improve the statistics. A macro-pixel array is then mentioned. Thus, the pixel detector can have at least one macro-pixel array. Especially when using binary pixel detectors such as single-photon avalanche diodes (SPADs), it makes sense to improve the statistics by combining micro-pixels. SUMMARY

[0003] According to the application, a laser radar sensor is provided, wherein the pixel detector is arranged to analyze at least two macro-pixel arrays in each of its measurement points.

[0004] ADVANTAGES OF THE INVENTION

[0005] In a laser radar sensor, there are typically two requirements for the mapping of the surroundings. On the one hand, the laser radar sensor should have a large range of action. Thereby, objects can already be detected at a large distance from the laser radar sensor at an early stage. On the other hand, it is important that in the surroundings directly next to the laser radar sensor a position determination and a size determination of the present objects is carried out as precisely as possible. For this, a high angular resolution of the laser radar sensor is required. However, these two requirements of the laser radar sensor are typically contrary, so that a compromise has to be found between them. According to the application, it is now proposed that in each measuring point of the pixel detector at least two macro pixel arrays are analyzed. Thereby, the requirement of a large range of action of the laser radar sensor and the requirement of a high angular resolution of the laser radar sensor can be distributed to at least two different macro pixel arrays. The two contrary requirements can be fulfilled at the same time. A large range of action and a high angular resolution can be achieved. For this, no additional hardware is required in the laser radar sensor, but only a corresponding configuration of the macro pixel arrays. Such a laser radar sensor can be provided correspondingly cost advantageously.

[0006] It is also possible that the at least two analyzed macro pixel arrays have different widths.

[0007] The different widths of the two analyzed macro pixel arrays provide two macro pixel arrays with different configurations. A "narrow" macro pixel array can be provided. This narrow macro pixel array achieves a high angular resolution of the laser radar sensor. Within the macro pixel, a uniform distribution of the intensity of the reflected laser signal occurs. A precise determination of the position and size of objects in the vicinity of the laser radar sensor is possible. On the other hand, a "wide" macro pixel array is provided. This wide macro pixel array achieves a maximization of the range of action in the case of objects with low reflection. Objects at a large distance from the laser radar sensor can be detected at an early stage. This different configuration of the at least two analyzed macro pixel arrays can also result in an increase in the dynamic range of the signal intensity for the laser radar sensor. Strongly reflecting objects can saturate the narrow macro pixel array, for example, because the intensity of the reflected laser signal is too high. A correct intensity measurement is no longer possible thereby. However, if the same measuring point is now also analyzed via the wide macro pixel array, the intensity of the laser signal can still be resolved.

[0008] In one particular embodiment, the first analyzed macro pixel array has a width which is coordinated with the width of the reflected laser signal.

[0009] The first analyzed macro-pixel array is a narrow macro-pixel array. The scan step of the laser radar sensor can thus correspond exactly to the width of the narrow macro-pixel array. The vertical flash laser radar sensor can here for example be the horizontal width of the laser signal. The narrow macro-pixel array then allows a higher horizontal resolution. The angular resolution is increased. The position and size of the object can be determined exactly.

[0010] It is also advantageous if the first analyzed macro-pixel array is configured to detect the reflected laser signal in a plateau of the reflected laser signal.

[0011] In this way, in addition to the higher horizontal resolution in the vertical flash laser radar sensor, a uniform distribution of the intensity of the laser signal over the width of the first analyzed macro-pixel array is also achieved. In this way, the object can be detected everywhere in the first analyzed macro-pixel array with the same intensity.

[0012] It is then advantageous if the second analyzed macro-pixel array has a greater width than the width of the first analyzed macro-pixel array.

[0013] The second analyzed macro-pixel array corresponds to a wide macro-pixel array. In addition to the detection of the laser signal in the plateau of the laser signal, the edge of the intensity of the laser signal laterally falling away from the plateau of the laser signal is also measured here. In this way, a uniform distribution of the intensity of the laser signal can no longer be achieved. However, the sensitivity of the second analyzed macro-pixel array is increased. The uniform distribution is ensured, however, by the simultaneous analysis of the first macro-pixel array.

[0014] It is advantageous if the width of the second analyzed macro-pixel array can be configured to cover at least 85% of the width of the reflected laser signal.

[0015] In this way, the signal-to-noise ratio of the second analyzed macro-pixel array can be optimized. At least 85% of the width of the laser signal is thus covered. The best possible signal-to-noise ratio is set. The sensitivity of the laser radar sensor is increased. A large range of action of the laser radar sensor is achieved.

[0016] Finally, it is advantageous if the measurement data of the at least two analyzed macro-pixel arrays are output into a point cloud in parallel, or if the measurement data of one of the at least two analyzed macro-pixel arrays are output depending on a predetermined condition.

[0017] Depending on the case, the best signal for the analysis of each reflected laser signal can be selected. The predetermined condition for the output of the measurement data of one of the at least two macro-pixel arrays can be predefined by means of an algorithm.

[0018] Advantageous refinements of the application are specified in the dependent claims and described in the description. BRIEF DESCRIPTION OF DRAWINGS

[0019] Embodiments of the application are further explained with reference to the drawings and the following description. The drawings show:

[0020] Figure 1a diagram of the correlation of the intensity of the laser signal and the width of the macro-pixel array;

[0021] Figure 1b diagram of the correlation of the signal-to-noise ratio and the width of the macro-pixel array;

[0022] Figure 2 diagram of the first and second analyzed macro-pixel array and the associated profile of the laser signal in cross-section. DETAILED DESCRIPTION

[0023] The application relates to a laser radar sensor, in particular a vertical flash laser radar sensor, having a laser source, which is arranged to emit a laser signal into a transmission path, and a pixel detector, which has at least one macro-pixel array 1, 2, which is arranged to detect a reflected laser signal in a reception path, wherein the pixel detector is arranged to analyze at least two macro-pixel arrays 1, 2 in each of its measurement points. The at least two macro-pixel arrays 1, 2 can be provided by a first analyzed macro-pixel array 1 and a second analyzed macro-pixel array 2. Here, the second analyzed macro-pixel array 2 has a greater width 3 than the width 4 of the first analyzed macro-pixel array 1.

[0024] Detecting the reflected laser signal can include determining the intensity 5 of the laser signal. Likewise, the signal-to-noise ratio 6 of the reflected laser signal can be detected.

[0025] A diagram (Diagramm) 7 is shown in Figure 1a which shows the intensity 5 of the laser signal as a function 8 of the width 3 of the second analyzed macro-pixel array 2. Here, the width 3 of the second analyzed macro-pixel array 2 is given in units of the width σ of the laser signal. This is exemplarily based on the following assumptions. It is assumed that the laser signal has the shape of a "Gauβ-Glocke". This Gauβ-Glocke has a width σ. It is further assumed that the noise of the background light follows and is governed by a Poisson distribution.

[0026] Correspondingly, a diagram (Diagramm) 9 is shown in Figure 1bIn Fig. 9 a curve diagram is shown which illustrates the dependency of the signal-to-noise ratio 6 on the width 3 of the second analyzed macro-pixel array 2 as a function 10. The width 3 is again given in units of the width sigma of the laser signal. Therein it can be recognized that there is a line 11 which intersects the maximum of the signal-to-noise ratio 6. This line 11 is at a width 3 of the second analyzed macro-pixel array 2 which corresponds approximately to 1.4 times the width sigma of the laser signal. At this maximum 85% of the laser signal have been covered.

[0027] In other words, if the width 3 of the second analyzed macro-pixel array 2 is chosen such that 85% of the laser signal are covered, the best signal-to-noise ratio 6 can be achieved. Here, however, it should be noted that at this point there is no longer a uniform intensity 5 of the laser signal within the second analyzed macro-pixel array 2, since the Gaussian bell has fallen too much. However, for the second analyzed macro-pixel array 2 a high sensitivity can be achieved due to the best signal-to-noise ratio 6. The second analyzed macro-pixel array 2 can achieve a large range of the lidar sensor which ensures an early detection of objects at a large distance.

[0028] Now, in Figure 2 In Fig. 12 the first analyzed macro-pixel array 1 is shown next to the second analyzed macro-pixel array 2. It can be recognized that the width 3 of the second analyzed macro-pixel array 2 is larger than the width 4 of the first analyzed macro-pixel array 1. Additionally, in the curve diagram 12 the laser profile 13 is mapped over the macro-pixel arrays 1, 2 as a function 14 of the position 15. The position 15 is presented in units of the width sigma of the laser signal. Here, also the widths 3, 4 of the first analyzed macro-pixel array 1 and the second analyzed macro-pixel array 2 are mapped.

[0029] As mentioned above, the width 3 of the second analyzed macro-pixel array 2 is chosen to be 1.4 times the width sigma of the laser signal. In this way, with the second macro-pixel array 2 again 85% of the laser signal can be covered. The best signal-to-noise ratio 6 is achieved. The sensitivity and the range of the lidar sensor are increased. An early detection of objects at a large distance is possible. On the other hand, as can be recognized here, the width 4 of the first analyzed macro-pixel array 1 is chosen such that it comprises a plateau or maximum of the function 14. At the same time, with this a uniform distribution of the intensity 5 is also achieved. Everywhere on the first analyzed macro-pixel array 1 the object to be detected is detected with the same intensity. In this way a high angular resolution of the first analyzed macro-pixel array 1 is generated. A precise position determination and size determination of the object is possible.

[0030] Thus, in total, a lidar sensor can be provided which has a large range and a high angular resolution.

[0031] Although the application has been further illustrated and described by means of preferred embodiments, it is not intended to be limited to the disclosed examples, and other variations to the preferred embodiments can be derived from the application without departing from the scope of the application.

Claims

1. A laser radar sensor comprising a laser source and a pixel detector, wherein the laser source is configured to emit a laser signal into a transmission path, and the pixel detector comprises at least two macro pixel arrays (1, 2) configured to detect reflected laser signals in a reception path, wherein: The pixel detector is configured to evaluate at least two macropixel arrays (1, 2) in each of its measuring points, wherein a first evaluated macropixel array (1) has a width (4) that is coordinated with the width of the reflected laser signal, and wherein a second evaluated macropixel array (2) has a width (3) that is greater than the width (4) of the first evaluated macropixel array (1).

2. The laser radar sensor according to claim 1, wherein: The first evaluated macropixel array (1) is provided for detecting the reflected laser signal in a plateau of the reflected laser signal.

3. The laser radar sensor according to claim 1 or 2, wherein: The width (3) of the second analyzed macropixel array (2) covers at least 85% of the width of the reflected laser signal.

4. The laser radar sensor according to claim 1 or 2, wherein: The measurement data of the at least two analyzed macropixel arrays (1, 2) are output in parallel to a point cloud, or the measurement data of one of the at least two analyzed macropixel arrays (1, 2) are output according to predetermined conditions.

5. The laser radar sensor according to claim 1 or 2, wherein: The lidar sensor is a vertical flash lidar sensor.

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