OBJECT DETECTION BY AN ACTIVE OPTICAL SENSOR SYSTEM

Description

[0001] The invention is defined by the appended claims. The present invention relates to a method for object detection by an active optical sensor system, wherein light reflected by means of a detector unit of the sensor system and an object in the vicinity of the sensor system is detected, and a sensor signal is generated based on the detected light, and a first pulse width of a signal pulse of the sensor signal is determined by means of a processing unit, wherein the first pulse width is defined by a predetermined first limit value for an amplitude of the sensor signal. The invention further relates to a method for at least partially automatic control of a motor vehicle, an active optical sensor system, an electronic vehicle guidance system for a motor vehicle, computer programs, and a computer-readable storage medium.

[0002] Active optical sensor systems, such as lidar systems, can be mounted on motor vehicles to implement a wide range of functions for electronic vehicle guidance systems or driver assistance systems. These functions include distance measurement, distance control algorithms, lane keeping assist, object tracking, object detection, object classification, and so on.

[0003] The detected light results in an analog signal pulse with a temporal profile that reflects the intensity of the detected light. To represent this information discretely, the signal pulse can, for example, be described by a specific pulse width, defined by the time the pulse remains above a certain threshold.

[0004] The choice of threshold value for determining the pulse width generally influences various qualitative aspects of the resulting point cloud. The higher the threshold value, the lower the sensitivity or effective range of the active optical sensor system, since the typical maximum amplitude of the sensor signal decreases with increasing distance from the sensor system. If the threshold value is set too high, only objects relatively close to the sensor system will be represented in the point cloud. Conversely, the influence of noise becomes more pronounced as the threshold value decreases. At very low threshold values, signal pulses that do not correspond to reflections from real objects in the vicinity of the sensor system can potentially lead to entries in the point cloud.

[0005] Document EP 1 557 694 B1 describes a method for classifying objects. In this method, the area around a motor vehicle is scanned with a laser scanner, and the echo pulse width of the received reflected light pulse is evaluated. A threshold value is defined that the light pulse must exceed, and the time interval between exceeding the threshold and subsequently falling below it is defined as the echo pulse width of the light pulse.

[0006] In US 2004 / 257556 A1 (SAMUKAWA YOSHIE [JP] ET AL) December 23, 2004 (2004-12-23) the creation of a point cloud is described, whereby points of tracked objects are entered into the point cloud.

[0007] Against this background, it is an object of the present invention to provide an improved concept for object recognition by means of an active optical sensor system, which can reduce or minimize the influence of noise effects, while simultaneously increasing or maintaining the same sensitivity of the sensor system.

[0008] According to the invention, this problem is solved by the respective subject matter of the independent patent claims. Advantageous further developments and embodiments are the subject matter of the dependent claims.

[0009] The improved concept is based on the idea of ​​generating a hybrid point cloud by identifying one of at least two categories for each signal pulse and, depending on the category, creating an entry for the signal pulse in the point cloud that corresponds to either a first pulse width or a second pulse width of the signal pulse, with the different pulse widths corresponding to different limit values ​​for the amplitude of the sensor signal.

[0010] According to the improved concept, a method for object detection by an active optical sensor system, in particular an active optical sensor system of or for a motor vehicle, is described. Light reflected from an object in the vicinity of the sensor system is detected by a detector unit of the sensor system, and a sensor signal is generated based on the detected light by the detector unit. A first pulse width of a signal pulse of the sensor signal is determined by a processing unit, in particular of the sensor system or the motor vehicle, wherein the first pulse width is defined by a predetermined first limit value for the amplitude of the sensor signal. A second pulse width of the signal pulse is determined by the processing unit, wherein the second pulse width is defined by a predetermined second limit value, which is in particular different from the first limit value, for the amplitude of the sensor signal.The processing unit assigns the signal pulse to one of at least two predefined categories, specifically exactly one, based on at least one predefined parameter of the signal pulse. The processing unit then generates a point cloud for object recognition, containing exactly one entry for each signal pulse. Depending on the category assigned to the signal pulse, the entry corresponds to either the first pulse width or the second pulse width.

[0011] Here and in the following, an active optical sensor system can be defined as having an emitter unit with a light source, in particular for emitting light, for example in the form of light pulses. The light source can be designed, in particular, as a laser. Furthermore, an active sensor system has a detector unit with at least one optical detector, in particular for detecting light or light pulses, especially reflected components of the emitted light.

[0012] Here and in the following, the term "light" can be understood to encompass electromagnetic waves in the visible, infrared, and / or ultraviolet ranges. Accordingly, the term "optical" can also be understood to refer to light as defined in this way.

[0013] The light emitted by the active optical sensor system can include infrared light, for example, with a wavelength of 905 nm, approximately 905 nm, 1200 nm, or approximately 1200 nm. These wavelength specifications can each refer to a broader wavelength range, as is typical for the respective light source.

[0014] In the present case of the active optical sensor system, the light source can, for example, be a laser light source. The wavelengths mentioned can, within normal tolerances, correspond, for example, to peak wavelengths of the laser spectrum.

[0015] In particular, light is emitted towards the object by means of an emitter unit of the sensor system, and the reflected detected light consists of components of the emitted light reflected by the object.

[0016] A point cloud can be understood, for example, as a set of data points with a multitude of entries, where each entry corresponds to a corresponding signal pulse of a sensor signal generated by the detector unit. Different entries can originate from the same sensor signal if the sensor signal contains multiple signal pulses, also known as echoes. However, each entry is assigned to exactly one signal pulse.

[0017] Each entry can contain multiple parameters, properties, or other information for the corresponding signal pulse. For example, an entry might include coordinates in two or three dimensions for a specific point in the vicinity of the sensor system, from which the light was reflected and, after being detected by the detector unit, resulted in the corresponding signal pulse. The coordinates could be in the form of polar or Cartesian coordinates, for example. The entry might also include an echo number for the corresponding signal pulse. This echo number would then correspond to the position of the signal pulse within a series of successive signal pulses from the same sensor signal.

[0018] Furthermore, the entry can generally contain information regarding a pulse width or a maximum signal amplitude of the signal pulse. However, according to the improved concept, each entry in the point cloud contains precisely the value relating to the pulse width, namely either a value for the first pulse width or a value for the second pulse width, but not both.

[0019] However, it is also possible that no entry is generated for individual or different signal pulses.

[0020] The fact that the entry corresponds to either the first or the second pulse width can be understood to mean that the entry contains a value that is proportional to or equivalent to the first or second pulse width. The fact that the point cloud contains exactly one entry for the signal pulse is to be understood, in particular, to mean that the point cloud contains no further entries for the same signal pulse. Of course, the point cloud can contain further entries for other signal pulses belonging to the same sensor signal or to a different sensor signal.

[0021] The point cloud can be used by the processing unit or another processing unit for object recognition, and in particular for classifying the object. Therefore, the point cloud can be referred to as a point cloud for object recognition.

[0022] According to the improved concept, as described, different pulse widths or different threshold values ​​for the signal amplitude are used depending on the parameter of the signal pulse. This prevents signal pulses that do not correspond to reflections from real objects, but rather arise from noise, for example, from being considered in the further processing of the point cloud. At the same time, it ensures that as few signal pulses as possible that originate from a real reflection from a real object are disregarded.

[0023] In other words, this reduces the influence of noise effects, which corresponds to higher reliability of object detection according to the improved concept, and also results in high sensitivity or effective range of the sensor system.

[0024] Furthermore, the improved method saves storage space for the point cloud, as it contains only one entry for each signal pulse. If, for example, two point clouds were generated—one for the first threshold and its corresponding first pulse width, and one for the second threshold and its corresponding second pulse width—the storage requirement would be significantly higher. This is especially true if the entries contain information regarding the assigned category, such as a flag or an identifier.

[0025] According to at least one embodiment of the improved method, the processing unit determines the radial distance of the object from the sensor system based on the signal pulse. The processing unit then assigns the signal pulse to one of at least two categories based on this radial distance.

[0026] The radial distance can be determined, for example, by measuring the time-of-flight (ToF). The longer the time between the emission of the light and the detection of the corresponding signal pulse, the greater the time of flight and the greater the corresponding radial distance.

[0027] The radial spacing is particularly well-suited as a parameter for categorizing signal pulses, since it becomes increasingly unlikely that a signal pulse will exceed a certain amplitude as the radial spacing increases. In other words, the maximum amplitude of the signal pulses decreases with increasing radial spacing. Therefore, it may be advantageous to use a smaller threshold value for determining the pulse width at large radial spacings and a larger threshold value at smaller radial spacings, especially to reduce the influence of noise.

[0028] In particular, a signal pulse can be assigned to a first category of at least two categories if the radial distance is greater than a predefined limit. Conversely, a signal pulse can be assigned to a second or third category of at least two, or optionally at least three, categories if the radial distance is less than the limit.

[0029] According to at least one embodiment, the second limit is greater than the first limit.

[0030] According to at least one embodiment, the signal pulse is assigned to the first category of at least two categories by the processing unit if the radial distance is greater than the predefined limit distance. The point cloud is generated by the processing unit with the entry corresponding to the first pulse cloud if the signal pulse was assigned to the first category.

[0031] In such embodiments, the radial distance corresponds to one of the parameters for the signal pulse.

[0032] If the radial distance is greater than the limiting distance, it can be assumed with a high degree of probability that the signal pulse did not originate from noise. Accordingly, it is advantageous to consider the lower first limiting distance and, consequently, the first pulse width for generating the point cloud in order to represent objects that are as far away as possible. This, in turn, increases the sensitivity of the optical sensor system.

[0033] According to at least one embodiment, the signal pulse is assigned to a second category of at least two categories, particularly by means of the processing unit, if the radial distance is smaller than the limiting distance and the second pulse width is greater than zero. The point cloud is generated by the processing unit with the entry corresponding to the second pulse width when the signal pulse has been assigned to the second category.

[0034] In such embodiments, the second pulse width also corresponds to one of the parameters of the signal pulse.

[0035] If the radial distance is smaller than the limiting distance, it can be assumed with a high degree of probability that pulses originating from reflections of real objects will have maximum amplitudes greater than the second limiting distance. In other words, it can be assumed that those signal pulses whose maximum amplitude does not reach the second limiting distance, for which the second pulse width is therefore zero, are due to noise effects. Accordingly, it is advantageous to use the second pulse width to generate the point cloud for such small radial distances. This reduces the influence of noise.

[0036] According to at least one embodiment, the at least two categories contain at least three categories or exactly three categories. In particular, the at least two categories contain the first category, the second category, and a third category. The signal pulse is assigned, in particular by means of the processing unit, to the third category of the at least three categories if the radial distance is smaller than the limiting distance and the second pulse width is zero. The point cloud is generated, in particular by means of the processing unit, with the entry corresponding to the first pulse width when the signal pulse has been assigned to the third category.

[0037] In this case, only the first pulse width is relevant, since the second pulse width is zero. Accordingly, the entry is generated using the first pulse width. If the radial distance is smaller than the limiting distance and the second pulse width is zero, it can be assumed with a high degree of probability that the corresponding signal pulse is due to signal noise or other noise effects.

[0038] This information can, for example, be stored in the point cloud using an identifier, so that entries of third-category signal pulses are not considered further for certain subsequent applications.

[0039] According to at least one embodiment, the entry contains an identifier that indicates the category to which the signal pulse has been assigned.

[0040] The identifier can therefore be understood as a flag that can take on as many different values ​​as there are different categories for the signal pulses.

[0041] Subsequent applications, for example for object classification or the like, can use the identifier to determine which pulse width the entry concerns and use it accordingly.

[0042] Storing the identifier requires very little storage space. For two categories, only one bit per entry is needed; for three or four categories, only two bits per entry are required. This results in a significant saving of storage space, especially compared to storing two complete entries, for example, if two different point clouds were stored.

[0043] According to at least one embodiment, the object is automatically classified based on the point cloud, taking the entry into account, particularly by means of the computing unit.

[0044] The classification is based in particular on the first pulse width or the second pulse width, depending on which of the two pulse widths the entry corresponds to.

[0045] According to at least one embodiment, the classification depends on the identifier of the entry.

[0046] For example, entries whose identifier points to the third category cannot be used for classification. Since the entries in the third category, as described above, indicate the influence of noise effects, this can reduce their impact on the classification, potentially leading to a more reliable or accurate classification.

[0047] According to at least one embodiment, the second limit value is greater than the first limit value and the first limit value is greater than a predetermined noise level of the detector unit.

[0048] This can advantageously prevent signal noise from being misinterpreted. The reliability of the method is thereby further increased.

[0049] According to at least one embodiment, the method includes determining the predetermined noise level based on test measurements.

[0050] According to the improved concept, a method for at least partially automatic control of a motor vehicle is also specified. A point cloud for object recognition is generated using an object recognition method according to the improved concept, and the motor vehicle is controlled at least partially automatically depending on the point cloud, in particular on a result of the object classification based on the point cloud, taking the entry into account.

[0051] According to at least one embodiment, the second limit value is greater than the first limit value and the second limit value is greater than a predetermined saturation limit value of the detector unit.

[0052] The saturation limit can, for example, correspond to a maximum detector current, so that the sensor signal is cut off at the saturation limit, regardless of any higher intensity of the incident light.

[0053] Above the saturation limit, a pulse width is therefore not meaningful or is identically zero.

[0054] According to at least one embodiment, the saturation limit is determined in advance by further test measurements in the method.

[0055] According to at least one embodiment of the method for at least partially automatic control of the motor vehicle according to the improved concept, generating the point cloud for object recognition by means of an object recognition method according to the improved concept includes the automatic classification of the object based on the point cloud, taking the entry into account. The motor vehicle is controlled at least partially automatically depending on the result of the classification.

[0056] According to the improved concept, an active optical sensor system, particularly for a motor vehicle, is also described. The sensor system comprises a detector unit configured to detect light reflected from an object in the sensor system's environment and to generate a sensor signal based on the detected light. The sensor system includes a processing unit configured to determine a first pulse width of a signal pulse from the sensor signal, the first pulse width being defined by a predetermined first limit value for the sensor signal's amplitude. The processing unit is configured to determine a second pulse width of the signal pulse, the second pulse width being defined by a predetermined second limit value for the sensor signal's amplitude.The processing unit is configured to assign the signal pulse to one of at least two categories based on at least one predefined parameter of the signal pulse and to generate a point cloud for object detection. The point cloud contains exactly one entry for the signal pulse, where the entry corresponds to either the first pulse width or the second pulse width, depending on the category of the signal pulse.

[0057] In particular, the active optical sensor system has an emitter unit that is configured to emit light in the direction of the object, and the detector unit is configured to detect portions of the emitted light reflected by the object and to generate the sensor signal based on this.

[0058] Further embodiments of the active optical sensor system according to the improved concept follow directly from the various configurations of the object detection method according to the improved concept, and vice versa. In particular, an active optical sensor system according to the improved concept can be configured or programmed to perform a method according to the improved concept, or it can perform such a method.

[0059] According to the improved concept, an electronic vehicle guidance system for a motor vehicle is also specified. The vehicle guidance system includes an active optical sensor system according to the improved concept, and the vehicle guidance system includes a control unit configured to generate at least one control signal based on the point cloud in order to control the motor vehicle at least partially automatically.

[0060] The control unit can, for example, include the processing unit of the active optical sensor system.

[0061] According to the improved concept, a motor vehicle is also specified as having an electronic vehicle guidance system according to the improved concept or an active optical sensor system according to the improved concept.

[0062] According to the improved concept, an initial computer program with initial commands is specified. When these initial commands, or the initial computer program, are executed by an active optical sensor system according to the improved concept, the initial commands cause the sensor system to perform an object detection procedure according to the improved concept.

[0063] According to the improved concept, a second computer program with second instructions is also specified. When the second instructions are executed by an electronic vehicle guidance system according to the improved concept, or when the second computer program is executed by the vehicle guidance system, the second instructions cause the vehicle guidance system to carry out a procedure for at least partially automatic control of a motor vehicle according to the improved concept.

[0064] According to the improved concept, a computer-readable storage medium is also specified on which a first computer program according to the improved concept and / or a second computer program according to the improved concept is stored.

[0065] The computer programs based on the improved concept, as well as the computer-readable storage medium, can be considered as respective computer program products with the corresponding first and / or second instructions.

[0066] Further features of the invention are evident from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the description of the figures and / or shown in the figures alone, are not only usable in the combinations specified but also in other combinations without departing from the scope of the invention. Thus, embodiments that are not explicitly shown and explained in the figures but can be derived and generated from the explained embodiments by separate combinations of features are also to be considered disclosed. Embodiments and combinations of features that do not exhibit all the features of an originally formulated independent claim are also to be considered disclosed.Furthermore, embodiments and combinations of features, in particular those set out above, are to be considered disclosed which go beyond or deviate from the combinations of features set out in the cross-references of the claims.

[0067] The figures show: Fig. 1 a schematic representation of a motor vehicle with an exemplary embodiment of an electronic vehicle guidance system according to the improved concept; Fig. 2 a schematic representation of sensor signals of a detector unit of an exemplary embodiment of an active optical sensor system according to the improved concept; Fig. 3 a schematic representation of further sensor signals of a detector unit of another exemplary embodiment of an active optical sensor system according to the improved concept; Fig. 4 a schematic representation of further sensor signals of a detector unit of another exemplary embodiment of an active optical sensor system according to the improved concept; Fig. 5 a schematic representation of a camera image and a point cloud generated by another exemplary embodiment of an active optical sensor system according to the improved concept; Fig.6 a schematic representation of a camera image and a point cloud; and Fig. 7 a schematic representation of a camera image and a point cloud.

[0068] In the Fig. 1 The figure schematically depicts a motor vehicle 1 which has an exemplary embodiment of a vehicle guidance system 6 according to the improved concept.

[0069] The electronic vehicle guidance system 6 features, in particular, an active optical sensor system 2 according to the improved concept. Optionally, the vehicle guidance system 6 can also include a control unit 7.

[0070] The active optical sensor system 2 comprises an emitter unit 2a, which may contain, for example, an infrared laser. Furthermore, the sensor system 2 comprises a detector unit 2b, which may contain, for example, one or more optical detectors, such as APDs.

[0071] The sensor system 2 also includes a processing unit 2c. The functions of the processing unit 2c described below can also be taken over by the control unit 7 in various configurations, or vice versa.

[0072] The emitter unit 2a emits laser pulses 3a into the environment of the vehicle 1, where they are partially reflected by an object 4 and, as reflected pulses 3b, are at least partially reflected back towards the sensor system 2 and, in particular, the detector unit 2b. The detector unit 2b, in particular the optical detectors of the detector unit 2b, detect the reflected components 3b and, based on this, generate a time-dependent sensor signal that has an amplitude proportional to the radiant intensity or radiant power of the detected light 3b. Fig. 2 und Fig. 3 Examples of different signal pulses are shown.

[0073] The processing unit 2c determines a first time interval during which the sensor signal 5a, 5b, 5c, 5d exceeds a first threshold value G1. This first time interval then corresponds to the first pulse width D1 of the corresponding signal pulse. In the same way, the processing unit 2c determines a second pulse width D2 by comparing the sensor signal 5a, 5b, 5c, 5d with a second threshold value G2, which is greater than the first threshold value G1.

[0074] The computing unit 2c or the control unit 7 can then determine a property of the object 4 based on the first pulse width D1 and the second pulse width D2, for example a reflectivity or an extent of the object 4.

[0075] In particular, the computing unit 2c or the control unit 7 can classify the object 4 depending on the property or on the pulse widths D1, D2.

[0076] Based on a result of the classification or based on the property of the object, the control unit 7 then generates, for example, control signals to control the motor vehicle 1 at least partially automatically.

[0077] In Fig. 2 Two exemplary sensor signals, 5a and 5b, are shown. While the signal pulse of sensor signal 5a reaches a saturation limit GS, meaning its amplitude exceeds the second limit G2, this is not the case for the signal pulse of sensor signal 5b. However, both sensor signals exceed the first limit G1. Consequently, the first pulse width D1 is greater than zero for both sensor signals 5a and 5b. The second pulse width D2, on the other hand, is greater than zero only for sensor signal 5a and is zero for sensor signal 5b.

[0078] For example, if APDs are used as optical detectors, the saturation limit GS can be on the order of several hundred mV, for example between 100 mV and 1000 mV.

[0079] In Fig. 3 Another example of two further sensor signals 5c, 5d is shown. Here, both the first pulse width D1 and the second pulse width D2 are greater than zero for both sensor signals 5c, 5d.

[0080] The processing unit 2c generates a point cloud based on the signal pulses, specifically based on either the first pulse width D1 or the second pulse width D2. For this purpose, the signal pulses are assigned to one of three categories I, II, III as described in Fig. 4 is shown schematically.

[0081] If the radial distance r, determined for the signal pulse based on the time-of-flight measurement, is greater than a predefined limit distance R, it is unlikely that an object 4 in the vicinity of the vehicle 1 will reflect light with sufficiently high intensity to exceed the second limit G2 and, consequently, for the second pulse width D2 to be greater than zero. Therefore, in this case, the signal pulse is assigned to a first category I. For signal pulses of category I, the corresponding entry for the signal pulse is generated such that it represents the first pulse width D1.

[0082] However, if the radial distance r is smaller than the limiting distance R, it can be assumed that pulses that do not reach the second limit G2 are due to noise effects or are unreliable for other reasons.

[0083] Accordingly, signal pulses for which the specified radial distance is smaller than the limiting distance R and whose second pulse width D2 is greater than zero are assigned to a second category II, and those signal pulses for which the radial distance r is smaller than the limiting distance R and for which the second pulse width D2 is equal to zero are assigned to a third category III.

[0084] For signal pulses of category II, the entry of the point cloud relates to the second pulse width D2, and for signal pulses of category III, the entry relates to the first pulse width D1.

[0085] In Fig. 5 A schematic representation of point cloud 9 is shown, generated based on the improved concept as described. Point cloud 9 only displays points corresponding to category I or category II. Category III signal pulses are not shown. This is achieved by assigning an identifier or flag to each entry, or by storing such an identifier for each entry, indicating the corresponding category I, II, or III.

[0086] In this way, the points in category III can be hidden, as these are highly likely to be due to noise effects.

[0087] However, by taking into account signal pulses with a radial distance r greater than the limit distance R with the second pulse width D2, points are also shown in the point cloud 9 for relatively large distances from the sensor system.

[0088] Schematically, in Fig. 5 A corresponding camera image 8 is also shown.

[0089] In Fig. 6 Another point cloud is shown schematically. In the point cloud of Fig. 6 The same signal pulses were used as those for generating point cloud 9. Fig. 5 were used as a basis. For the Fig. 6 However, the second pulse width D2 was used for each entry. As can be seen from a comparison of Fig. 5 and Fig. 6 As can be seen, the effective range in the point cloud of the Fig. 6 less than for point cloud 9 of the Fig. 5 .

[0090] In Fig. 7 Another point cloud is shown, which is again based on the same signal pulses. For Fig. 7 However, the first pulse width D1 was used for all signal pulses. Accordingly, it can be seen that the range is comparable to that shown by point cloud 9 of the Fig. 5 is given. In the immediate vicinity, the point cloud contains the Fig. 7 However, there are additional points that are highly likely due to noise.

[0091] As described, the improved concept makes it possible to specify a point cloud for object detection or object classification that exhibits both less noise and reflects the high sensitivity of the sensor system. Furthermore, the improved concept saves storage space, especially compared to storing two full point clouds.

[0092] In various iterations of this improved concept, a hybrid point cloud is generated to convert the analog signal pulses into the discrete domain. For example, each point can be assigned a flag depending on its radial distance from the sensor system and the maximum amplitude of the signal pulse. In this way, points with small radial distances and small maximum amplitudes can be filtered out, as these are likely due to interference or noise.

Claims

1. Method for object detection by an active optical sensor system (2), wherein - by means of a detector unit (2b) of the sensor system (2), light (3b) reflected from an object (4) in an environment of the sensor system (2) is captured and a sensor signal (5a, 5b, 5c, 5d, 5e, 5f) is generated based on the captured light (3b); - by means of a computing unit (2c), a first pulse width (D1) of a signal pulse of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f) is determined, wherein the first pulse width (D1) is defined by a predetermined first threshold value (G1) for an amplitude of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f); wherein by means of the computing unit (2c) - a second pulse width (D2) of the signal pulse is determined, wherein the second pulse width (D2) is defined by a predetermined second threshold value (G2) for the amplitude of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f); - the signal pulse is assigned to one of at least two categories depending on at least one predefined parameter of the signal pulse; - a point cloud (9) is generated for object detection, which can contain different entries for signal pulses, wherein the point cloud contains exactly one entry for the same signal pulse and the entry corresponds to either the first pulse width (D1) or the second pulse width (D2) depending on the category of the signal pulse wherein by means of the computing unit (2c), a radial distance of the object (4) from the sensor system (2) is determined depending on the signal pulse; and the signal pulse is assigned to one of at least two categories depending on the radial distance, wherein the second threshold value (G2) is greater than the first threshold value (G1); wherein the signal pulse is assigned to a first category of the at least two categories if the radial distance is greater than a predefined boundary distance (R); and the point cloud (9) is generated with the entry corresponding to the first pulse width (D1) if the signal pulse was assigned to the first category, and wherein the signal pulse is assigned to a second category of the at least two categories if the radial distance is less than the boundary distance (R) and the second pulse width (D2) is greater than zero; and the point cloud (9) is generated with the entry corresponding to the second pulse width (D2) if the signal pulse was assigned to the second category.

2. Method according to claim 1, characterized in that - the at least two categories include at least three categories; - the signal pulse is assigned to a third category of the at least three categories if the radial distance is less than the boundary distance (R) and the second pulse width (D2) is equal to zero; and - the point cloud (9) is generated with the entry corresponding to the first pulse width (D1) if the signal pulse was assigned to the third category.

3. Method according to any one of the preceding claims, characterized in that - the entry contains an identifier indicating the category to which the signal pulse was assigned.

4. Method according to any one of the preceding claims, characterized in that - the object (4) is automatically classified based on the point cloud (9) taking into account the entry.

5. Method according to any one of the preceding claims, characterized in that - the second threshold value (G2) is greater than the first threshold value (G1) and the first threshold value (G1) is greater than a predetermined noise level of the detector unit (2b); and / or - the second threshold value (G2) is greater than the first threshold value (G1) and the second threshold value (G2) is greater than a predetermined saturation threshold value (GS) of the detector unit.

6. Method for at least partially automatic control of a motor vehicle (1), characterized in that - a point cloud (9) for object detection is generated by means of a method according to any one of the preceding claims; and the motor vehicle (1) is at least partially automatically controlled depending on the point cloud (9).

7. Method according to claim 6, characterized in that - the point cloud (9) is generated by means of a method according to claim 4; and the motor vehicle (1) is at least partially automatically controlled depending on a result of the classification.

8. Active optical sensor system (2), comprising - a detector unit (2b) configured to capture light (3b) reflected from an object (4) in an environment of the sensor system (2) and to generate a sensor signal (5a, 5b, 5c, 5d, 5e, 5f) based on the captured light (3b); a computing unit (2c) configured to determine a first pulse width (D1) of a signal pulse of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f), wherein the first pulse width (D1) is defined by a predetermined first threshold value (G1) for an amplitude of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f); the computing unit (2c) is configured to determine a second pulse width (D2) of the signal pulse, wherein the second pulse width (D2) is defined by a predetermined second threshold value (G2) for the amplitude of the sensor signal (5a, 5b, 5c, 5d, 5e, 5f); assign the signal pulse to one of at least two categories depending on at least one predefined parameter of the signal pulse; generate a point cloud (9) for object detection, which can contain different entries for signal pulses, wherein the point cloud contains exactly one entry for the same signal pulse and the entry corresponds to either the first pulse width (D1) or the second pulse width (D2) depending on the category of the signal pulse wherein the computing unit (2c) is configured to determine a radial distance of the object (4) from the sensor system (2) depending on the signal pulse; and assign the signal pulse to one of at least two categories depending on the radial distance, wherein the second threshold value (G2) is greater than the first threshold value (G1); wherein the computing unit (2c) is configured to assign the signal pulse to a first category of the at least two categories if the radial distance is greater than a predefined boundary distance (R); and generate the point cloud (9) with the entry corresponding to the first pulse width (D1) if the signal pulse was assigned to the first category, assign the signal pulse to a second category of the at least two categories if the radial distance is less than the boundary distance (R) and the second pulse width (D2) is greater than zero; and generate the point cloud (9) with the entry corresponding to the second pulse width (D2) if the signal pulse was assigned to the second category.

9. Electronic vehicle guidance system for a motor vehicle (1), characterized in that the vehicle guidance system (6) comprises an active optical sensor system (2) according to claim 8; and the vehicle guidance system (6) comprises a control unit (7) configured to generate at least one control signal depending on the point cloud (9) to at least partially automatically control the motor vehicle (1).

10. Computer program with instructions which, when executed by an active optical sensor system (2) according to claim 8, cause the sensor system (2) to perform a method according to any one of claims 1 to 5.

11. Computer program with instructions which, when executed by an electronic vehicle guidance system (6) according to claim 9, cause the vehicle guidance system (6) to perform a method according to any one of claims 6 or 7.

12. Computer-readable storage medium storing a computer program according to any one of claims 10 or 11.