EP3841402A1 - Lidar sensor for optically detecting a field of view, working apparatus or vehicle having a lidar sensor, and method for optically detecting a field of view - Google Patents

Abstract

The invention relates to a LIDAR sensor (100, 300) for optically detecting a field of view (106), having: a transmitting unit (101, 301) with a laser pattern generating unit (102), the laser pattern generating unit (102) being designed to generate an illumination pattern (218) in the field of view (106); a receiving unit (110, 310) with at least one detector unit (112) for receiving secondary light (109, 309) which was reflected in the field of view (106) by an object (107), the at least one detector unit (112) having a plurality of image points (401-m,n; 500), and at least some of the image points (401-m,n; 500) each having a plurality of activatable single-photon avalanche diodes (402, 501-1 to 501-4); and at least one rotor unit (116) rotatable about a rotation axis (221, 321), the transmitting unit (101, 301) and the receiving unit (110, 310) being arranged at least in part on the rotor unit (116). The LIDAR sensor (100, 300) also has at least one linker (502), which is designed to link detection signals of at least two single-photon avalanche diodes (402, 501-1 to 501-4) of an image point (401-m,n; 500) via a combinatorial logic.

Description

 description

title

 LIDAR sensor for optical detection of a field of view, work device or vehicle with a LIDAR sensor and method for optical detection of a field of view

The present invention relates to a LIDAR sensor for the optical detection of a field of view, a working device or a vehicle with a LIDAR sensor and a method for the optical detection of a field of view according to the preamble of the independently formulated claims.

State of the art

DE 10 2016 219 955 A1 discloses a transmitter unit for illuminating an environment, in particular a vehicle, with a

 Laser pattern generation unit, a deflection unit and a control unit. The laser pattern generation unit is set up to generate an illumination pattern in a field of view, the illumination pattern having a first direction and a second direction, the first direction and the second direction being arranged orthogonally to one another, an extension of the

Illumination pattern along the first direction is greater than one

Expansion of the illumination pattern along the second direction, the illumination pattern being in particular a check pattern, and the control unit being set up to move the deflection unit at least along the second direction, so that the illumination pattern is moved at least along the second direction.

US 2017/0176579 A1 discloses an electro-optical device which comprises a laser light source which emits at least one beam of light pulses, a beam steering device which transmits the at least one beam over a target Scene sends and scans, and includes an array of sensor elements. Each sensor element outputs a signal which indicates an incidence time of a single photon on the sensor element. A light collecting optics images the target scene scanned by the transmitted beam onto the array. The circuit is coupled to actuate the detection elements only in a selected area of the array and to guide the selected area over the array in synchronism with the scanning of the at least one beam. A scanning system is thus disclosed which successively activates detector pixels in order to increase the signal-to-noise ratio of the sensor. It is apparent to the person skilled in the art from this teaching that it is a micromirror-based one

Implementation of a LiDAR system. The detector pixels are activated in a so-called “region of interest” (ROI).

US 2018/0003821 A1 discloses an object detector which comprises a light-emitting system and a light-receiving system. The light-emitting system includes a light source with a plurality of light-emitting elements arranged in a uniaxial direction. The light-emitting system emits light. The light-emitting elements are individually and sequentially controllable laser diodes. The light receiving system receives the light emitted by the light emitting system and reflected by an object. The plurality of light-emitting elements emits a plurality of light beams to a plurality of areas that differ in the uniaxial direction. The amount of light for illuminating some of the plurality of areas differs from the amount of light for illuminating an area other than some of the plurality of areas. It is disclosed that each light-emitting element is exactly one

Receiving element is assigned.

Disclosure of the invention

The present invention is based on a LIDAR sensor for optically detecting a field of view, comprising a transmission unit with a

Laser pattern generation unit for emitting primary light into the field of vision. The laser pattern generation unit has in particular at least one laser. The laser pattern generation unit is designed, an illumination pattern to generate in the field of view, wherein the illumination pattern has a first direction and a second direction, the first direction and the second direction being arranged orthogonally to one another. The first direction and the second direction are arranged essentially orthogonally to one another. This means that slight deviations from the right angle are also included. For example, deviations that occur due to a laser alignment error are also included. An expansion of the illumination pattern along the first direction is greater than one

Extend the illumination pattern along the second direction. The illumination pattern is in particular designed as a line, a rectangle or a check pattern. The LIDAR sensor still has one

Receiving unit with at least one detector unit for receiving secondary light which was reflected and / or scattered in the field of view by an object. The at least one detector unit has a large number of pixels, at least some pixels each having a plurality of activatable single-photon avalanche diodes. The LIDAR sensor also has a rotor unit that can be rotated about an axis of rotation. The transmission unit of the LIDAR sensor is at least partially arranged on the rotor unit. The receiving unit of the LIDAR sensor is at least partially on the

Rotor unit arranged.

According to the invention, the LIDAR sensor has at least one link which is designed to detect at least two detection signals

Link single-photon avalanche diodes of a pixel using combinatorial logic.

The LIDAR sensor also has in particular at least one

Evaluation unit on. The at least one evaluation unit is designed to determine a light transit time of the emitted primary light and of the secondary light received again. The distance between the LIDAR sensor and an object in the field of view can be based on a time of flight (TOF) or on the basis of a frequency-modulated continuous wave signal

(Frequency Modulated Continuous Wave, FMCW) can be determined. The time-of-flight methods include pulse methods that determine the time of reception of a reflected laser pulse or phase methods that determine a Send out the amplitude-modulated light signal and determine the phase offset to the received light signal.

The detector unit has a plurality of activatable ones

Single-photon avalanche diodes (SPAD). A single-photon avalanche diode can be referred to as a sub-pixel. By linking at least two

So-called single-photon avalanche diodes of a pixel arise

Macro pixels. The pixels of the detector unit can be referred to as macropixels. A single photon avalanche diode triggers an electrical pulse when a minimal amount of light hits a light-intensive area of the

Single photon avalanche diodes fall. The amount of light can be achieved with a single photon. A single photon avalanche diode can accordingly be very sensitive. After the electrical pulse has been provided, the single photon avalanche diode takes a fixed time to be ready to provide another electrical pulse in response to the minimum amount of light. No light can be registered during this time. This time can be called dead time.

The advantage of the invention is that the dynamic range of the

Detector unit can be increased. The pixels, i.e. macropixels, enable the use, which is otherwise usually too sensitive

Single photon avalanche diodes. The performance of a pixel can be optimized regardless of the optically necessary size. In the case of a defective single-photon avalanche diode of a pixel, the complete pixel does not fail. The light yield of a pixel is thus increased in the event of a defective single-photon avalanche diode. With a flexible assignment of the

Pixels for evaluation units of the LIDAR sensor can be made possible to adapt the area of the detector unit to be evaluated in the sub-pixel area. This allows the detector unit to be easily adapted to the transmitter unit of the LIDAR sensor. The adjustment of the sending unit and the receiving unit are facilitated.

In an advantageous embodiment of the invention, it is provided that the link is an OR link or an exclusive OR link. in the In the case of an OR link, the time of reception of a photon is encoded in the rising edge of the output signal of a subpixel. The logically active phase of the output signal reflects the dead time of the subpixel. In the case of an exclusive OR gate, the subpixel is switched to a toggle flip-flop. Each photon detection of a subpixel therefore leads to a change in the state of the output signal. In other words, it is

Receiving time of a photon is now encoded in the rising and falling edge of the output signal. The advantage of this embodiment is that an evaluation unit does not have to be assigned to each subpixel.

In a further advantageous embodiment of the invention, the

Linker is an OR-linker, the LIDAR sensor also has at least one pulse shortener in order to shorten a digital signal generated by a single photon avalanche diode. The dead time between individual signals can be reduced. The advantage of this configuration is that the signal throughput can be increased. It can be elevated

Photon count rate can be achieved.

In a further advantageous embodiment of the invention it is provided that the pixels are arranged in a grid with a predetermined number of lines and a predetermined number of columns. The pixels of at least one row and / or the pixels of at least one column can be activated in parallel. When receiving secondary light, each pixel in a column can be active. Each individual photon avalanche diode of these pixels can also be active in the corresponding column. When receiving secondary light, each pixel in one line can be active. Anyone can do this

Single photon avalanche diode of these pixels must be active in the corresponding line. The advantage of this embodiment is that improved detection of the secondary light caused by the emitted illumination pattern can be achieved. For example, when using multiple lasers in the laser pattern generation unit, it is not necessary to have a specific laser in the laser pattern generation unit exactly one

Assign single photon avalanche diode to the detector unit. In a further advantageous embodiment of the invention, the LIDAR sensor also has at least one control unit which is designed to move the rotatable rotor unit at least along the second direction, so that the illumination pattern is moved at least along the second direction. The laser pattern generation unit thus generates an illumination pattern that is scanned orthogonally to the first direction. The illumination pattern is therefore not scanned pixel by pixel, but as a whole. It is therefore a combination of the flash and the scan principle, which are known from known LIDAR sensors. The advantage of this

Design consists in that the required pulse power of the

Laser pattern generation unit can be kept low. The required pulse power of the at least one laser of the laser pattern generation unit can be kept low. The pulse power can be kept lower compared to a LIDAR sensor that works according to the flash principle. The combination of the flash and the scanning principle also enables

Increase the pulse number of the at least one laser

Laser pattern generation unit per measurement. This is particularly advantageous when using a detector unit that has single-photon avalanche diodes. The eye safety of the LIDAR sensor can also be increased. At the same time, the measuring time can be increased compared to a LIDAR sensor that works according to the scanning principle. By creating the

Illumination pattern in the field of view, the resolution in one direction is no longer limited by a number of laser units and detector diodes. The resolution along the first direction depends on the receiving unit of the LIDAR sensor. The resolution along the first direction can be dependent on the receiving optics of the receiving unit. The resolution along the first direction depends on the number of pixels of the detector unit. The resolution along the second direction depends on the scanning unit of the LIDAR sensor. The rotor unit rotatable about an axis of rotation can be referred to as a scanning unit.

In a further advantageous embodiment of the invention, it is provided that the transmitting unit and the receiving unit are arranged one above the other or next to one another along the axis of rotation of the rotatable rotor unit. The advantage of this configuration is that the requirements for example can be taken into account when installing the LIDAR sensor in a vehicle. For example, the requirements regarding the height of the LIDAR sensor can be taken into account.

The invention is also based on a working device or a vehicle with a LIDAR sensor described above.

The invention is also based on a method for optically detecting a field of view by means of a described LIDAR sensor. The method includes generating an illumination pattern in a field of view, the illumination pattern having a first direction and a second direction. The first direction and the second direction are arranged essentially orthogonally to one another. An extension of the illumination pattern along the first direction is greater than an extension of the

Illumination pattern along the second direction. Furthermore, the method comprises the control of a rotor unit for rotation about one

Rotation axis by means of a control unit, so that the illumination pattern is moved at least along the second direction. Furthermore, the method comprises receiving secondary light that was reflected and / or scattered by an object in the field of view by means of at least one

Detector unit. The at least one detector unit has a large number of pixels. At least some pixels each have a plurality of activatable single-photon avalanche diodes. Furthermore, the method comprises linking the detection signals of at least two

Single photon avalanche diodes of a pixel via combinatorial logic using a link.

drawings

Exemplary embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. The same reference symbols in the figures denote the same or equivalent elements. Show it:

FIG. 1 top view of a first embodiment of a LIDAR

sensor; Figure 2 side view of the first embodiment of a LIDAR sensor;

 Figure 3 side view of a second embodiment of a LIDAR sensor;

 Figure 4 shows a schematic representation of an embodiment of a

 Detector unit of the LIDAR sensor;

 Figure 5 shows a schematic representation of an embodiment of a

 Pixel of the detector unit of the LIDAR sensor and a link;

 Figure 6 embodiment of a method for optical detection of a field of view by means of a LIDAR sensor.

FIG. 1 shows an example of a top view of a LIDAR sensor 100. The LIDAR sensor 100 according to FIG. 1 has a transmission unit 101 with a laser pattern generation unit 102 for emitting primary light 104 into the field of view 106. The laser pattern generation unit 102 has the laser 103 in the example. The laser 103 can have a line orientation, for example. The emitted primary light 104 can pass through an optical transmission system 105 when it is emitted into the field of view 106. The transmission optics 105 can have, for example, at least one lens or at least one optical filter. The primary light 104 is emitted to detect and / or examine a scene 108 and an object 107 located there. The field of vision

106 is the area of the environment that the transmission unit 101 can illuminate. The field of view 106 preferably extends at a distance of 1 m - 180 m to the transmission unit 101.

 Furthermore, the LIDAR sensor 100 according to FIG. 1 has a receiving unit 110. The receiving unit 110 receives light and in particular from the object

107 light reflected in field of view 106 as secondary light 109 via a

Receiving optics 111. The receiving optics 111 can have, for example, at least one lens or at least one optical filter. The received secondary light 109 is transmitted to a detector unit 112. The LIDAR sensor also has at least one link, not shown in FIG. 1 for the sake of clarity. This linker is described in more detail in the explanation of FIG. 5 in conjunction with FIG. 4. The laser pattern generation unit 102 and the detector unit 112 are controlled via control lines 114 and 115 by means of a control and

Evaluation unit 113. An embodiment of the detector unit 112 is described in more detail in FIG. 4.

 The receiving unit 110 and the transmitting unit 101 are formed on the field of view with essentially biaxial optical axes. The LIDAR sensor 100 also has a rotor unit 116 which can be rotated about an axis of rotation. In the exemplary embodiment, the transmission unit 101 is arranged on the rotor unit 116. The receiving unit 110 is also arranged on the rotor unit 116. The rotatable rotor unit 116 is controlled by means of a control unit 117.

FIG. 2 shows an example of the side view of the LIDAR sensor 100 described in FIG. 1. It can be seen in FIG. 2 that the laser pattern generation unit 102 is designed to generate an illumination pattern 218 in the field of view 106. The illumination pattern 218 has a first direction 219 and a second direction 220. The first direction 219 and the second direction 220 are arranged orthogonally to one another. An extension of the

Illumination pattern 218 along the first direction 219 is greater than an extension of the illumination pattern 218 along the second direction 220. The illumination pattern 218 of the LIDAR sensor 100 shown here is designed as a check pattern. Illumination pattern 218 may alternatively be formed as a line or as a rectangle.

 It can be seen in FIG. 2 that the control unit 117 is designed to rotate the rotatable rotor unit 116 at least along the second direction 220

To move axis of rotation 221. As a result, the illumination pattern 218 is moved at least along the second direction 220. The movement of the illumination pattern 218 can, for example, take place step by step or can be carried out as a continuous scanning movement.

 The transmitting unit 101 and the receiving unit 110 of the LIDAR sensor 100 are arranged alongside one another along the axis of rotation 221 of the rotatable rotor unit 116.

FIG. 3 shows an example of the side view of a LIDAR sensor 300. The LIDAR sensor 300 has the transmitter unit 301 for emitting primary light 304 in a field of view. The primary light is emitted along the transmission direction 322. The LIDAR sensor 300 also has the receiving unit 310 for receiving secondary light 309, which was reflected and / or scattered in the field of view by an object. The secondary light hits under the

Receiving direction 323 to receiving unit 310.

 The LIDAR sensor 300 essentially corresponds to the LIDAR sensor 100 described in FIGS. 1 and 2. The transmission unit 301 corresponds to the transmission unit 101 described in FIGS. 1 and 2. The reception unit 310 corresponds to the reception unit 310 described in FIGS. 1 and 2. The difference to the LIDAR sensor 100 essentially only consists in the fact that in the LIDAR sensor 300 the transmitting unit 301 and the receiving unit 310 along the

Rotation axis 321 of the rotatable rotor unit are arranged one above the other.

In the figures described, the first direction 219 and the second direction 220 can be interchanged, so that this

Illumination pattern 218 extends along the second direction and is scanned along the first direction, i. H. the greater extent of the

Illumination pattern extends in the horizontal direction and is scanned in the vertical direction. The illumination pattern is designed, for example, as a laser line or in the form of a check pattern.

FIG. 4 schematically and exemplifies the detector unit 112 as it has a LIDAR sensor 100, 300. The detector unit 112 has a large number of pixels 401-m, n. In the example, the pixels are arranged in a grid with a predetermined number of m rows and a predetermined number of n columns. The number m is an integer. The number m can be an integer 1 to i. The number n is an integer. The number n can be an integer 1 to j. The value of the number i and / or the value of the number j can be limited in a specific embodiment by the requirements regarding eye safety for a given range of the LIDAR sensor. The value of the number i and / or the value of the number j can be in a concrete

Embodiment through cost specifications or specifications regarding the

Producibility may be limited. Here, at least the number m or at least the number n is not equal to 1. It has at least one row or a column at least two pixels. As shown in the example in FIG. 4, both the number m of rows and the number n of columns should be greater than 1. The detector unit is designed as an array of a plurality of pixels 401-m, n.

In the detector unit 112 shown in the example, the pixels 401-m, n each have a plurality of activatable single-photon avalanche diodes 402 (for the sake of clarity, only one is per pixel 401-m, n

Single photon avalanche diode 402 provided with a reference number). A single-photon avalanche diode 402 can be referred to as a sub-pixel. The pixels 401-m, n of at least one row and / or the pixels 401-m, n of at least one column can be activated in parallel.

 The single-photon avalanche diodes 402 of a pixel 401-m, n are linked via a link not shown in FIG. 4. Each of the pixels 401-m, n of the detector unit 112 shown in FIG. 4 can have one

Linkers, as shown by way of example in FIG. 5, can be assigned. Linking at least two individual photon avalanche diodes 402 of a pixel 401-m, n creates so-called macropixels. The pixels 401-m, n of the detector unit 112 can be referred to as macropixels.

FIG. 5 schematically shows an exemplary embodiment of a pixel 500 of a detector unit 112, as it has a LIDAR sensor 100, 300 shown in FIGS. 1 to 3, and a linker 502, like that of a LIDAR sensor 100 shown in FIGS. 1 to 3 , 300 has. The pixel 500 can be part of a detector unit 112 described in the previous figures.

 The pixel 500 shown shows the four by way of example

 Single photon avalanche diode 501-1 to 501-4. The linker 502 links the four single-photon avalanche diodes 501-1 to 501-4 to one another. The

Linker 502 is designed to link detection signals of at least two of the four individual photon avalanche diodes 501-1 to 501-4 of pixel 500 using combinatorial logic. The link 502 can in particular be an OR link or an exclusive OR link. In the event that the link 502 is an OR link, the LIDAR sensor can optionally also have at least one pulse shortener 503. By means of the

A digital signal generated by a single photon avalanche diode 501-1 to 501-4 can be shortened in time. FIG. 6 shows an example of a method for optically detecting a field of view using a LIDAR sensor. The method begins with step 601. In step 602, an illumination pattern is generated in a field of view. The

Illumination pattern has a first direction and a second direction. The first direction and the second direction are arranged orthogonally to one another, an extension of the illumination pattern along the first direction being greater than an extension of the illumination pattern along the second direction. In step 603, a rotor unit is controlled for rotation about an axis of rotation by means of a control unit. The

Illumination pattern is thus moved at least along the second direction. In step 604, secondary light that was reflected and / or scattered in the field of view by an object is received by means of at least one detector unit. The at least one detector unit has a large number of pixels. At least some pixels each have a plurality of activatable single-photon avalanche diodes. In step 605, the

Detection signals of at least two single photon avalanche diodes of a pixel are linked via combinatorial logic by means of a linker. The method ends in step 606. The LIDAR sensors 100 and 300 and the method 600 can both be used for

Detection of a field of view of a vehicle as well as detection of a field of view of a working device can be used.

Claims

Expectations 1. LIDAR sensor (100, 300) for optical detection of a field of view (106),  comprising:  • a transmission unit (101, 301) with a laser pattern generation unit (102) for emitting primary light (104, 304) into the field of view (106);  • wherein the laser pattern generation unit (102) is formed  Generate illumination patterns (218) in the field of view (106), the illumination pattern (218) having a first direction (219) and a second direction (220), the first direction (219) and the second direction (220) being orthogonal to one another are arranged, an extension of the  Illumination pattern (218) along the first direction (219) is greater than an extent of the illumination pattern (218) along the second direction (220); and still showing  • a receiving unit (110, 310) with at least one detector unit (112) for receiving secondary light (109, 309) which was reflected and / or scattered in the field of view (106) by an object (107); in which  • the at least one detector unit (112) has a plurality of pixels  (401-m, n; 500), and at least some pixels (401-m, n; 500) each having a plurality of activatable single-photon avalanche diodes (402, 501-1 to 501-4); and still showing  • at least one rotor unit (116) rotatable about an axis of rotation (221, 321), wherein  • the transmission unit (101, 301) at least partially on the rotor unit (116)  is arranged; and where  • The receiving unit (110, 310) is at least partially arranged on the rotor unit (116).  characterized in that the LIDAR sensor (100, 300) continues to have • at least one link (502), which is designed to link detection signals of at least two single-photon avalanche diodes (402, 501-1 to 501-4) of a pixel (401-m, n; 500) via combinatorial logic. 2. LIDAR sensor (100, 300) according to claim 1, characterized in that the link (502) is an OR link or an exclusive OR link. 3. LIDAR sensor (100, 300) according to claim 2, wherein the logic device (502) is an OR logic device, further comprising at least one pulse shortener (503) to one of a single photon avalanche diodes (402, 501-1 to 501-4 ) to shorten the generated digital signal. 4. LIDAR sensor (100, 300) according to any one of claims 1 to 3, characterized  characterized in that the pixels (401-m, n; 500) are arranged in a grid with a predetermined number (m) of rows and a predetermined number (n) of columns, the pixels (401-m, n; 500) being at least one Row and / or the pixels (401-m, n; 500) of at least one column can be activated in parallel. 5. LIDAR sensor (100, 300) according to one of claims 1 to 4, further comprising at least one control unit (117) which is designed to move the rotatable rotor unit (116) at least along the second direction (220), so that Illumination pattern (218) is moved at least along the second direction (220). 6. LIDAR sensor (100, 300) according to one of claims 1 to 5, characterized  characterized in that the transmitting unit (101, 301) and the receiving unit (110, 310) along the axis of rotation (221) of the rotatable rotor unit (116)  are arranged one above the other or side by side. 7. Working device or vehicle with a LIDAR sensor (100, 300) according to one of claims 1 to 6. 8. A method (600) for optically detecting a field of view by means of a LIDAR sensor according to one of claims 1 to 6, comprising the steps:  • Generate (602) an illumination pattern in a field of view, wherein the Illumination pattern has a first direction and a second direction, the first direction and the second direction being arranged orthogonally to one another, with an expansion of the illumination pattern along the first direction is greater than an extension of the illumination pattern along the second direction;  • Control (603) of a rotor unit for rotation about an axis of rotation  by means of a control unit (117), so that the illumination pattern is moved at least along the second direction;  • Receiving (604) secondary light, which was reflected and / or scattered in the field of view by an object, by means of at least one detector unit, the at least one detector unit having a multiplicity of picture elements, and wherein at least some picture elements each have a plurality of activatable single-photon avalanche diodes; and  Linking (605) the detection signals of at least two  Single photon avalanche diodes of a pixel via combinatorial logic using a linker.