LiDAR receiving unit

Abstract

The invention relates to a laser radar receiving unit (16) arranged in a focal plane array, comprising: a plurality of sensor elements (24) for receiving light pulses of a laser radar transmitting unit (18); and a plurality of routing channels (32) for transmitting signals of the sensor elements (24) to an edge region (R) of the laser radar receiving unit (16), wherein the plurality of sensor elements are arranged in macrocells (26, 26') assigned to a transmitting element (22) of the laser radar transmitting unit (18); the plurality of macrocells (26, 26') form a macrocell cluster (30), and the plurality of macrocell clusters (30) are arranged in a plurality of rows (Z1, Z2, Z3); the routing channels (32) pass through the plurality of rows (Z1, Z2, Z3) between adjacent macrocell clusters (30) in a row, and are used to transmit signals in a direction orthogonal to the rows (Z1, Z2, Z3). The invention also relates to a laser radar measuring device (10) for detecting an object (12) in an environment of a vehicle (14).

Description

Technical Field

[0001] The invention relates to a laser radar receiving unit arranged in a focal plane array. The invention also relates to a laser radar measuring device for detecting objects in the environment of a vehicle. Background Art

[0002] Modern vehicles (cars, transporters, trucks, motorcycles, driverless transport systems, etc.) include a number of systems which provide information to the driver or to the operator and / or control the functions of the vehicle in a partially or fully automated manner. The vehicle's surroundings and, if applicable, other road users are detected by means of sensors. Based on the detected data, a model of the vehicle's environment can be generated and changes in this vehicle environment can be reacted to. With the continued development of the field of autonomous and partially autonomous vehicles, the impact and scope of activities of advanced driver assistance systems (ADAS) and autonomously operated transport systems are becoming increasingly greater. By developing ever more precise sensors, it is possible to detect the environment and control vehicle functions completely or partially without driver intervention.

[0003] An important sensor principle for detecting the environment here is LiDAR technology (Light Detection and Ranging). LiDAR sensors are based on the emission of light pulses and the detection of reflected light. By measuring the propagation time, the distance to the reflection location can be calculated. By evaluating the received reflections, the destination can be detected. With regard to the application of the technology of the corresponding sensors, a distinction needs to be made between scanning systems, which usually work based on micromirrors, and non-scanning systems, in which a plurality of transmitting and receiving elements are arranged statically next to each other (in particular a so-called focal plane array arrangement).

[0004] In this regard, a method and device for optical distance measurement are described in WO 2017 / 081294 A1. A transmitting matrix is ​​disclosed for transmitting measurement pulses, and a receiving matrix is ​​disclosed for receiving measurement pulses. When transmitting the measurement pulses, a subset of the transmitting elements of the transmitting matrix is ​​activated.

[0005] One challenge in the field of non-scanning LiDAR measurement systems is the arrangement of the sensor elements in the receiving array and the routing of the sensor elements' signals to the edge of the receiving array. On the one hand, the highest possible density of sensor elements of the array should be achieved. On the other hand, it should be possible to efficiently route the signals to the edge of the array for further processing. Furthermore, a high resolution or a good detection should be ensured. Summary of the invention

[0006] Based on this, the object of the present invention is to provide a method for effectively reading an array of sensor elements. In particular, it should be achieved that blind areas of the array are avoided to the greatest extent possible. In addition, a high resolution should be achieved.

[0007] To achieve this object, in a first aspect, the present invention relates to a laser radar receiving unit arranged in a focal plane array, comprising:

[0008] A plurality of sensor elements for receiving light pulses from a lidar transmitting unit; and

[0009] A plurality of routing channels for transmitting the signal of the sensor element to the edge region of the lidar receiving unit, wherein

[0010] A plurality of sensor elements are arranged in a macro unit assigned to a transmitting element of the laser radar transmitting unit;

[0011] The plurality of macrocells form a macrocell cluster, and the plurality of macrocell clusters are arranged in a plurality of rows; and

[0012] The routing channel passes through a plurality of rows between adjacent macro cell clusters in a row and is used to transmit the signal in a direction orthogonal to the row.

[0013] In another aspect, the invention relates to a lidar measuring device for detecting objects in an environment of a vehicle, having:

[0014] A laser radar receiving unit according to one of the preceding aspects;

[0015] a lidar transmitting unit having a plurality of transmitting elements for transmitting light pulses; and

[0016] A control unit for controlling the lidar transmitting unit and for evaluating the signals of the sensor elements in order to detect objects.

[0017] Preferred embodiments of the invention are also described. It should be understood that the features mentioned above and the features still to be explained further below can be used not only in the respectively indicated combination but also in other combinations or alone without departing from the scope of the present invention. In particular, the lidar measuring device or the lidar transmitting unit can be implemented according to the preferred embodiments described for the lidar receiving unit.

[0018] The sensor elements of a lidar receiving unit receive light pulses of a corresponding lidar transmitting unit. A plurality of sensor elements together form a macrocell. A plurality of macrocells together form a macrocell cluster. The macrocell clusters of a lidar receiving unit are arranged in rows. In order to evaluate the signals generated by the sensor elements when receiving the light pulses, these signals must be transmitted from the sensor elements to an edge region of the lidar receiving unit via routing channels. According to the invention, the routing channels are arranged orthogonally to the rows. A routing channel runs between two adjacent macrocell clusters in a row. In particular, the lidar receiving unit is a microchip on which the sensor elements are arranged and the signals must be routed into an edge region of the chip, where the corresponding evaluation electronics are located.

[0019] Due to the arrangement of the routing channels according to the present invention, the signal of the sensor element is effectively delivered to the edge area of ​​the laser radar receiving unit. By designing the laser radar receiving unit and the laser radar transmitting unit row by row, or by controlling the laser radar transmitting unit row by row, it is possible to route the signal orthogonally to the row. Therefore, high performance can be ensured at long distances. At close range, although there are gaps due to routing and the resolution is therefore reduced, the spatial resolution is effectively improved because the laser radar measuring device operates at a constant angular resolution. Efficient routing is achieved. High resolution can be achieved. Due to the use of a focal plane array arrangement, high robustness against vibration is generated. The service life of the laser radar measuring device is improved. In addition, there are advantages in manufacturability. Low-cost implementation becomes possible.

[0020] In a preferred embodiment, every two macrocells form a macrocell cluster. The two macrocells of the macrocell cluster are preferably arranged parallel to the row. Since the routing channel runs between two adjacent macrocell clusters in a row, the two macrocells of the macrocell cluster can be read from both sides. Effective readability is obtained. Since the macrocells are arranged parallel to the row, good contact is obtained.

[0021] In a preferred embodiment, the macrocell clusters of the first row are arranged offset relative to the macrocell clusters of the second row adjacent to the first row. Due to the offset arrangement (staggered structure), vertical blind areas (orthogonal to the row) where detection is not possible are avoided. Object detection is improved.

[0022] In a preferred embodiment, the routing channels run parallel to the rows in the channel sections between the rows. At least in some sections, the channels may run parallel to the rows. Nevertheless, the signals are transmitted out of the array orthogonally to the rows. In this case, channel sections running parallel to the rows are advantageous, especially if the macrocell clusters of two adjacent rows are arranged offset from each other.

[0023] In a preferred embodiment, the distance between adjacent macrocell clusters of a row is greater than the distance between adjacent macrocell clusters in an adjacent row. Additionally or alternatively, preprocessing elements are arranged between adjacent rows to read the sensor elements. In this case, the preprocessing elements preferably comprise transistors. The distance is preferably selected so that the highest possible density of sensor elements of the lidar receiving unit can be obtained. As many sensor elements as possible should be arranged on the chip. Routing is performed between adjacent macrocell clusters of a row. The preprocessing elements are arranged between the rows, which in most cases requires relatively little space.

[0024] In a preferred embodiment, an integer multiple of the diameter of the sensor element differs from the distance between the midpoints of the assigned transmitting elements of the laser radar transmitting unit. Since multiple sensor elements receive the light pulses of the transmitting element, alignment errors can lead to poor detection. These errors can be balanced or averaged by correspondingly selecting the diameter of the sensor element or the distance between the midpoints of the assigned transmitting elements. It can therefore be said that the leveling of the errors leads to at least one macro unit not completely matching the assigned transmitting element in terms of its imaging position on the receiving array. Since the availability of the sensor data is increased, the detection of the object is improved.

[0025] In a preferred embodiment, sensor elements with reduced sensitivity are arranged between the macrocells of a macrocell cluster. In particular, emitting elements can be used which have metallization on their openings and therefore receive fewer photons. This makes the boundaries between adjacent macrocells of a macrocell cluster more distinct. The detection of objects is improved.

[0026] In a preferred embodiment, the lidar receiving unit comprises evaluation electronics for reading out the sensor elements line by line. Preferably, the evaluation electronics are also arranged on the chip. The signals of the sensor elements are evaluated to enable object detection.

[0027] In a preferred embodiment, one macrocell cluster includes 14 to 34 sensor elements.

[0028] A focal plane array arrangement can be understood to mean a configuration of sensor elements (or respectively transmitting elements) essentially in a plane. The lidar receiving unit is in particular a microchip with corresponding sensor elements. The lidar transmitting unit is likewise in particular a microchip with corresponding transmitting elements. The receiving unit and the transmitting unit can be arranged together on a microchip. The sensor elements are arranged in a matrix on the chip. The sensor elements are distributed on the surface of the chip of the lidar receiving unit. The light pulses of the lidar transmitting unit can be understood as in particular laser pulses. The environment of the vehicle includes in particular the area visible from the vehicle in the surroundings of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is described and explained in more detail below with the help of some selected exemplary embodiments in conjunction with the accompanying drawings. In the accompanying drawings:

[0030] Figure 1 A schematic diagram showing a laser radar measuring device for detecting objects in the environment of a vehicle according to the present invention;

[0031] Figure 2 A schematic diagram showing a laser radar transmitting unit for transmitting light pulses;

[0032] Figure 3 A schematic diagram showing a laser radar receiving unit according to the present invention; and

[0033] Figure 4 A schematic diagram showing a macro unit of a laser radar receiving unit according to the present invention. DETAILED DESCRIPTION

[0034] exist Figure 1 , a lidar measuring device 10 according to the invention for detecting an object 12 in the environment of a vehicle 14 is schematically shown. In the exemplary embodiment shown, the lidar measuring device 10 is integrated into the vehicle 14. The object 12 in the environment of the vehicle 14 can be, for example, another vehicle or also a stationary object (traffic sign, house, tree, etc.) or another road user (pedestrian, cyclist, etc.). The lidar measuring device 10 is preferably installed in the area of ​​the bumper of the vehicle 14 and can in particular evaluate the environment of the vehicle 14 in front of the vehicle. For example, the lidar measuring device 10 can be integrated into the front bumper.

[0035] The LiDAR measuring device 10 according to the invention comprises a LiDAR receiving unit 16 and a LiDAR transmitting unit 18. Furthermore, the LiDAR measuring device 10 comprises a control unit 20 for controlling the LiDAR transmitting unit 18 and for evaluating the signals of the sensor elements of the LiDAR receiving unit 16.

[0036] Preferably, both the laser radar receiving unit 16 and the laser radar transmitting unit 18 are designed to be configured in a focal plane array. The elements of each device are basically arranged in a plane on the corresponding chip. The chip of the laser radar receiving unit 16 or the chip of the laser radar transmitting unit 18 is arranged in the focus of the corresponding optical device (transmitting optical device or receiving optical device). In particular, the sensor elements of the laser radar receiving unit or the transmitting elements of the laser radar transmitting unit 18 are respectively arranged in the focus of the respective receiving optical device or transmitting optical device. These optical devices can be configured, for example, by an optical lens system.

[0037] The sensor element of the laser radar receiving unit 16 is preferably configured as a SPAD (single photon avalanche diode). The laser radar transmitting unit 18 includes a plurality of transmitting elements for transmitting lasers or laser pulses. The transmitting element is preferably configured as a VCSEL (vertical cavity surface emitting laser). The transmitting elements of the laser radar transmitting unit 18 are distributed on the surface of the transmitting chip. The sensor elements of the laser radar receiving unit 16 are distributed on the surface of the receiving chip.

[0038] The transmitting optics are assigned to the transmitting chip, and the receiving optics are assigned to the receiving chip. The optics image the light arriving from the spatial area onto the corresponding chip. The spatial area corresponds to the observation range of the laser radar measuring device 10, which is inspected or scanned for the object 12. The spatial area of ​​the laser radar receiving unit 16 or the spatial area of ​​the laser radar transmitting unit 18 is basically the same. The transmitting optics forms a transmitting element with a solid angle representing a partial area of ​​the spatial area. The transmitting element emits laser light into the solid angle accordingly. The transmitting elements cover the entire spatial area together. The receiving optics maps the sensor element to the solid angle of the partial area constituting the spatial area. The number of all sensor elements covers the entire spatial area. Considering the same solid angle, the transmitting elements and sensor elements are mapped to each other and correspondingly assigned or paired with each other. The laser of the transmitting element usually always irradiates the associated sensor element. Advantageously, a plurality of sensor elements are arranged within the solid angle of the transmitting element.

[0039] In order to determine or detect an object 12 in a spatial area, the laser radar measuring device 10 performs a measuring process. Depending on the structural design of the measuring system and its electronics, this measuring process includes one or more measuring cycles. Preferably, the TCSPC method (time-correlated single photon counting method) is used in the control unit 20 here. In this case, the individual impinging photons are detected, in particular by a SPAD, and the activation time (detection time) of the sensor element is stored in a storage element. The detection time is related to the reference time of the laser emission. From this difference, the propagation time of the laser can be determined, from which the distance to the object 12 can be determined.

[0040] The sensor elements of the lidar receiving unit 16 can be activated by laser light on the one hand and by ambient radiation on the other hand. The laser light at a certain distance from the object 12 always irradiates at the same time, while ambient radiation at any time can also activate the sensor elements. With multiple executions of the measurement, in particular the execution of multiple measurement cycles, the activation of the sensor elements accumulates over the detection time, which corresponds to the propagation time of the laser light relative to the distance of the object. In contrast, the activation by ambient radiation is evenly distributed over the measurement duration of the measurement cycle. The measurement corresponds to the emission of the laser light and the subsequent detection. The data of the individual measurement cycles of the measurement process stored in the storage element make it possible to evaluate the detection times determined multiple times in order to infer the distance of the object 12.

[0041] The sensor element is advantageously connected to a TDC (time to digital converter). The TDC stores the time at which the sensor element was activated in a storage element. Such a storage element can be, for example, a short-term memory or a long-term memory. For a measurement process, the TDC fills the storage element with the time at which the sensor element detected the impinging photon. This can be represented graphically in a histogram based on the data of the storage element. In the histogram, the duration of a measurement cycle is divided into very short time periods (so-called bins). When the sensor element is activated, the TDC increases the value of the bin by 1. The bin corresponding to the propagation time of the laser pulse (i.e. the difference between the detection time and the reference time) is filled.

[0042] exist Figure 2 The structure of the laser radar transmitting unit 18 is schematically shown in FIG. The chip includes a plurality of transmitting elements 22 arranged in an array (matrix). For example, several thousand transmitting elements can be used. The transmitting elements 22 are controlled row by row. For greater clarity, only one transmitting element 22 is marked with a reference numeral.

[0043] In the exemplary embodiment shown, rows 0..ny-1 each include a plurality of emitting elements 0..nx-1. For example, 100 rows (ny=100) and 128 emitting elements per row (nx=128) may be provided. The row spacing A1 between the rows may be in the range of a few micrometers, for example 40 μm. The element spacing A2 between the emitting elements 22 in the same row may be of a similar order of magnitude.

[0044] Figure 3A laser radar receiving unit 16 according to the invention is schematically shown. The laser radar receiving unit 16 comprises a plurality of sensor elements 24. The sensor elements are arranged in macrocells 26, 26', wherein the macrocells 26, 26' comprise those sensor elements 24 which are jointly assigned to the individual transmitting elements 22 of the laser radar transmitting unit. Two macrocells 26, 26' are arranged in a macrocell cluster 30. A plurality of macrocell clusters 30 are arranged in a plurality of rows Z1, Z2, Z3. Routing channels 32 are arranged between two adjacent macrocell clusters 30, which pass through the rows Z1, Z2, Z3 and transmit the signals of the sensor elements 24 to the edge region R of the laser radar receiving unit 16.

[0045] exist Figure 3 Also schematically marked in the illustration are two exemplary light spot positions 28 , 28 ′, which correspond to the positions of transmitting elements in the array of the lidar receiving unit 16 which are assigned to the lidar transmitting unit.

[0046] It should be understood that in order to visualize the arrangement of sensor elements 24, routing channels 32, macrocells 26, and macrocell clusters 30, Figure 3 Only a part of the chip structure of the laser radar receiving unit 16 is shown in detail. The chip further extends upward to the side in the figure. Preferably, the number of macro cells 26 corresponds to the number of transmitting elements 22 of the laser radar transmitting unit 18. For greater clarity, not all sensor elements 24 or macro cells 26, 26' and macro cell clusters 30 are marked with reference numerals.

[0047] As shown, the routing channel 32 in the exemplary embodiment shown travels between adjacent macrocell clusters 30 and transmits signals in a direction orthogonal to the routes of rows Z1, Z2, and Z3. In the exemplary embodiment shown, in this case, the routing channel 32 has a channel section 34 that travels parallel to rows Z1, Z2, and Z3 in the area between rows Z1, Z2, and Z3. Therefore, the macrocell clusters 30 of the first row can be arranged offset relative to the macrocell clusters 30 of the second row adjacent to the first row. The effect is that in the vertical direction, no vertical blind area is generated. In this regard, the macrocell clusters 30 are arranged in a staggered structure. The sensor elements 24 or light spots of adjacent rows are arranged in the gaps of a row.

[0048] Furthermore, as shown in the exemplary embodiment shown, the distance A3 between adjacent macrocell clusters 30 of a row Z1, Z2, Z3 is greater than the distance A4 between adjacent macrocell clusters 30 in adjacent (neighboring) rows Z1, Z2, Z3. Routing channels 32 run within the distance A3 or between macrocell clusters 30. Furthermore, pre-processing elements (preferably transistors) may be arranged between rows Z1, Z2, Z3.

[0049] Evaluation electronics 38 , which are designed to read out sensor elements 24 line by line or to further process the signals of sensor elements 24 , may be provided in edge region R of the chip of lidar receiving unit 16 .

[0050] exist Figure 4 A single macrocell cluster 30 is schematically shown in FIG. 1 . In the exemplary embodiment shown, the macrocell cluster 30 includes a total of 28 sensor elements 24 and includes two macrocells 26, 26'. In the exemplary embodiment shown, two sensor elements 36, 36' with reduced sensitivity are arranged between the two macrocells 26, 26' or at the edges of one or both of the two macrocells 26, 26'. For example, the sensor elements 36, 36' with reduced sensitivity can be sensor elements with metallization on the opening so that fewer photons can be received. The sensor elements 36, 36' with reduced sensitivity can also be referred to as aperture SPADs. It will be appreciated that a different number of sensor elements 36, 36' with reduced sensitivity can also be used.

[0051] In the illustration, two exemplary light spot positions 28, 28' are marked, which represent the positions of the transmitting elements assigned to the macro-units 26, 26'. S The integer multiple of is different from the distance D between the midpoints of the assigned transmitting elements of the lidar transmitting unit at positions P1 and P2 A , thus achieving a balance of alignment errors. The highest photon density is always received at the center of the spot position 28, 28' of the transmitting element on the macro unit cluster. In other words, the receiving element located at the center of the spot position 28, 28' always receives the highest photon density. Since the spot position 28, 28' cannot be precisely aligned with the array of the laser radar receiving unit, the distance D A (corresponding to the distance D S Integer multiples of ) will result in both spot positions 28, 28' being hit well or poorly. S and D A , thus avoiding this situation and achieving error correction in the case of imprecise alignment.

[0052] The invention is fully described and explained with the aid of the drawings and the specification. The description and explanation are to be understood as illustrative and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will occur to those skilled in the art in the application of the invention and in a careful analysis of the drawings, the disclosure and the appended claims.

[0053] In the claims, the words "comprising" and "having" do not exclude the presence of other elements or steps. The indefinite article "a" or "an" does not exclude the presence of a plurality. A single element or a single unit may perform the functions of a plurality of units defined in the claims. Elements, units, interfaces, devices and systems may be implemented partly or completely in hardware and / or software. The mere limitation of some provisions in a plurality of different dependent claims should not be understood as meaning that a combination of these provisions cannot be used with equal advantage. The reference signs in the claims should not be understood as being restrictive.

[0054] Reference numerals

[0055] 10 LiDAR measurement device

[0056] 12 Objects

[0057] 14 Vehicles

[0058] 16 LiDAR receiving unit

[0059] 18 LiDAR transmitter unit

[0060] 20 Control unit

[0061] 22 Transmitter

[0062] 24 Sensor element

[0063] 26 Macrocells

[0064] 28 Light spot position

[0065] 30 macrocell clusters

[0066] 32 Routing Channels

[0067] 34 Channel Segment

[0068] 36, 36' Sensor element with reduced sensitivity.

Claims

1. A laser radar receiving unit arranged in a focal plane array, having: a plurality of sensor elements for receiving light pulses from a laser radar transmitting unit; and A plurality of routing channels, the plurality of routing channels being used to transmit the signal of the sensor element to the edge area of ​​the laser radar receiving unit, wherein A plurality of sensor elements are arranged in a macro unit assigned to a transmitting element of the laser radar transmitting unit; The plurality of macrocells form a macrocell cluster, and the plurality of macrocell clusters are arranged in a plurality of rows; and The routing channel passes through the plurality of rows between adjacent macro cell clusters in a row and is used to transmit the signal in a direction orthogonal to the row. in, The macrocell clusters of a first row are arranged offset relative to the macrocell clusters of a second row adjacent to the first row so that the macrocell clusters are arranged in a staggered structure, and Wherein the routing channels run in channel sections between and parallel to the rows.

2. The laser radar receiving unit according to claim 1, wherein The two macrocells form a macrocell cluster; and The two macrocells of the macrocell cluster are arranged parallel to the row.

3. The laser radar receiving unit according to claim 1, wherein The distance between adjacent macrocell clusters in one row is greater than the distance between adjacent macrocell clusters in an adjacent row; and / or The pre-processing elements for reading the sensor elements are arranged between adjacent rows, respectively, wherein: The pre-processing element includes a transistor.

4. The laser radar receiving unit according to claim 1, wherein: The integer multiples of the diameter of the sensor element are different from the distances between the center points of the associated transmitting elements of the lidar transmitting unit.

5. The laser radar receiving unit according to claim 1, wherein: Sensor elements of reduced sensitivity are arranged between the macrocells of the macrocell cluster.

6. The lidar receiving unit according to claim 1 has evaluation electronics for reading out the sensor elements line by line.

7. The laser radar receiving unit according to claim 1, wherein: A macrocell cluster includes 14 to 34 sensor elements.

8. A laser radar measuring device for detecting an object in an environment of a vehicle, the laser radar measuring device comprising: The laser radar receiving unit according to any one of claims 1 to 7; a laser radar transmitting unit having a plurality of transmitting elements for transmitting light pulses; and A control unit for controlling the lidar transmitting unit and for evaluating the signals of the sensor element in order to detect the object.

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