Lidar device

Abstract

The present invention relates to a lidar device comprising the following: a laser (24, 34, 44) designed to emit laser light, at least one optical head (20, 30, 40) for emitting the laser light into the environment and for receiving laser light reflected from the environment, at least one detector (26, 36, 46) designed to convert received laser light into electrical signals. A lidar central unit (14) is provided, in which the laser and detector are arranged and which evaluates the electrical signals. An optical fiber connection (22, 32, 42) is arranged between the optical head and the lidar central unit to guide emitted laser light from the laser to the optical head and / or received laser light from the optical head to the detector.

Description

[0001] The present invention relates to a lidar device according to the preamble of claim 1.

[0002] A lidar device of this type is used to scan the area surrounding a vehicle. Known lidar devices emit pulsed or continuous laser beams and receive laser beams reflected from the environment, which are then converted into electrical signals by a detector. The distance between the lidar device and an object in the environment can be calculated from the travel time of the laser beams. Reflection points are compiled into a lidar point cloud, which is stored as a representation of the environment in the vehicle's computer and is continuously updated by a cyclical scanning process of the lidar device.

[0003] A lidar device of this type therefore comprises at least one laser that emits laser light. Such lidar devices also include an optical head that emits the laser light into the environment and receives laser light reflected from the environment. This optical head may also include a scanning device for performing the cyclic scanning process.

[0004] In a lidar device of this type, at least one detector is arranged which is designed to convert the received (reflected from the environment) laser light into electrical signals.

[0005] In known lidar devices, both the laser and the detector are integrated into the optical head. Electronic processing of the acquired electrical signals also takes place within the optical head.

[0006] A suitable optical sensor can be positioned facing forward in the upper area of ​​a windshield, or in a body area below the windshield. Naturally, such optical sensors can also be mounted laterally or in other positions on a vehicle.

[0007] However, the actual integration position of known optical heads is not freely selectable and therefore cannot be optimized with regard to the technical requirements of the lidar device. Known lidar devices of this type exhibit various problems. For example, the installation space required for known optical lidar heads is relatively large, as it must accommodate the laser, detector, and signal processing circuitry. An ideal installation position from an optical perspective may not be achievable. Furthermore, the heat generated by known optical lidar heads with laser, detector, and signal processing circuitry is significant, leading to heating of the installation space, which in turn causes the lidar head to heat up, potentially exceeding its maximum operating temperature.The maximum permissible operating temperature for an optical lidar head is limited to typically 85°C within the installation space by the temperature limits of semiconductor components. Exceeding the maximum operating temperature of semiconductor components can lead to thermal destruction of the semiconductors, so manufacturers of such components define operating temperature ranges that must not be exceeded. Maximum permissible operating temperature ranges are typically between 70 and 125°C.

[0008] This limits the operating conditions of known lidar devices in a vehicle. When determining the installation position in a vehicle, the placement of known lidar devices is often primarily based on integration requirements, maximum installation temperatures, or space requirements, rather than being optimized from an optical perspective. Optical considerations refer to how the optical head of a lidar device would ideally be installed to achieve an ideal range with an ideal "viewing direction" and an ideal detection area. In known lidar devices of this type, the optical head contains not only the beam deflection unit but also the light source and the detectors, which increases the required installation space and also the heat generated within the optical head.

[0009] In known systems, data preprocessing is at least partially integrated into the lidar head, which necessitates very fast electrical data lines from the optical heads of a lidar device to a vehicle computer. Such data lines represent a speed-limiting factor and require complex shielding measures.

[0010] It is therefore the object of the present invention to create a lidar device in which these problems are solved.

[0011] This problem is solved by a lidar device according to the characterizing feature of claim 1.

[0012] In a lidar device according to the invention as defined in claim 1, a lidar central unit is provided in which the at least one laser and the at least one detector are arranged. The lidar central unit is further configured to evaluate the electrical signals generated by the detector.

[0013] At least one optical fiber connection is arranged between the optical head of the lidar device and the lidar central processing unit. Such an optical fiber connection, also called a fiber optic cable, is a light guide that can transmit light in one or, more commonly, several optical fibers. This optical fiber connection is designed to guide laser light emitted by the laser to the optical head and / or received laser light from the optical head to the detector. A corresponding fiber optic connection will therefore guide laser light either in one direction or, preferably, in both directions. Along the paths of the laser light between the laser and the optical head and between the optical head and the detector, additional light-guiding elements can be provided—particularly within the lidar central processing unit—so that the fiber optic connection does not necessarily have to run directly from the laser to the optical head or from the optical head to the detector in a single piece.

[0014] Such a lidar device of this type offers a variety of advantages. Firstly, the optical head of the lidar device is radically miniaturized in terms of the installation space required for vehicle integration, since the laser light source and the detector are no longer housed within the optical head itself. These components are relocated to the lidar central unit. In addition to the reduction in installation space, numerous heat sources are also moved away from the optical head. These heat sources include, in particular, the laser light source, the driver circuits for operating the laser and detector, and circuits for preprocessing the electrical data derived from the reflected laser light.

[0015] Even if a beam deflection unit can be provided in the optical head of the lidar device, the necessary electronics for controlling such a beam deflection unit can also be moved to the lidar central unit.

[0016] Since the useful signals are transmitted optically between the optical head and the lidar central unit, the requirements for EMC (Electromagnetic Compatibility) shielding are reduced. Furthermore, fewer high-speed data connections are needed for transmitting high-frequency electrical data. In contrast to the use of high-speed data connections, there is also practically no upper limit to the length of the fiber optic connection used in a lidar device according to the invention.

[0017] Preferred embodiments of the present invention are set forth in the dependent claims.

[0018] In a first preferred embodiment of a lidar device according to the invention, each optical head has a scanning device for scanning the surroundings. Such a scanning device can be implemented in various ways. As with known lidar devices, movable mirrors can be provided, which can be moved, for example, by a galvanometer drive. Microelectromechanical mirrors (MEMS) can also be used and offer, in particular, the advantage of a very small form factor. Such MEMS systems still contain moving parts, namely the individual mirrors.

[0019] To avoid any moving parts, a phased array can be used, in which a composite signal can be directed in a specific direction by controlling the phase of (in this case, optical) antennas. A phased array can also be used as a detector. However, such solid-state lidar units require that all individual emitters emit coherent light, which can be achieved, for example, by powering all emitters from the same laser source.

[0020] In a further preferred embodiment of the present invention, the lidar central unit is configured to control the scanning device. This offers the advantage that the electrical circuits used to control the scanning device, which, in addition to the laser, also represent a significant heat source, can be relocated away from the optical head. This also reduces the form factor of the optical head of the lidar device, both by eliminating electronic components that must be housed within the head and by reducing the thermal power that needs to be dissipated from the optical head.

[0021] In a further preferred embodiment of the present invention, several lasers, each with an associated detector, are provided, wherein the lasers and the associated detectors are arranged in the central unit. In particular, several optical heads can also be provided, with each optical head then being assigned a laser and a detector. This offers the advantage that different optical heads with different detection ranges can be arranged on a vehicle, so that the detection ranges complement each other. All lasers and detectors necessary for operating the optical heads are, in turn, relocated away from the optical heads to the lidar central unit. The signal transmission between the lasers and detectors on the one hand and the various optical heads on the other hand is realized by optical fiber connections, with each optical head being assigned a laser, a detector, and a fiber optic connection.

[0022] The optical fiber connection between an optical head and its associated laser or detector can be implemented in various ways. In a first embodiment of the present invention, a first optical fiber connection is provided between each optical head and its associated laser, which is configured to guide emitted laser light from the laser to the optical head. A second optical fiber connection is also provided between each optical head and its associated detector, which is configured to guide received light from the optical head to the detector. In other words, a fiber optic connection is provided for both the forward and return transmission of the light.

[0023] Alternatively, and particularly preferred, is an embodiment in which each optical head is connected to only one optical fiber connection, which is designed to guide both the laser light emitted by the associated laser to the optical head and the laser light received by the optical head to the associated detector. It must be ensured that laser light emitted by the laser and transmitted via the optical head, and after reflection in the environment, collected again by the optical head and returned via the fiber optic connection, also reaches the detector. Polarizing or other beam splitters, which may be arranged within the lidar central unit, can be used to separate emitted and reflected light.This can take advantage of the fact that the emitted laser light is emitted with a defined polarization, for example linearly polarized in a plane, while the received reflected laser light assumes other polarization states.

[0024] A lidar device is further preferred in which at least one optical fiber connection includes a connectable optical connector. Such connectors, in this case fiber optic connectors, serve to detachably connect optical fibers or fiber optic cables to each other or to other elements such as the lidar central processing unit or the optical heads. They offer the possibility of easily establishing a connection, for example, between the fiber optic connection and the laser or the lidar central processing unit on the one hand and / or the optical head on the other, with low signal attenuation. The detector can also be connected via such a connector.In addition to simplified assembly, such a design of the present invention also offers the further advantage that damaged parts, such as lasers, detectors or the fiber optic connection itself, can be very easily disassembled and replaced by disconnecting the plug connection.

[0025] In a further particularly preferred embodiment of the lidar device according to the invention, the lidar central unit is integrated together with a vehicle computer in an ECU (Electronic Control Unit). This offers the advantage of further increasing integration, since a separate lidar central unit in the vehicle is no longer necessary. Furthermore, by eliminating the spatial separation between the vehicle computer and the lidar central unit, the data exchange between the lidar central unit and subunits in the vehicle computer that rely on lidar data is improved.A corresponding ECU can be arranged in an installation area within the vehicle, since, due to the provision of optical fiber connections according to the invention between the optical head or optical heads of the lidar and the lidar central unit or, in this case, the ECU, spatial proximity between the lidar central unit and the optical head is no longer necessary.

[0026] The lidar central unit is therefore preferably installed spatially separate from the at least one optical head in the vehicle. This allows the lidar central unit to be installed in any area inside the vehicle body.

[0027] The invention will be explained in more detail below using the figures as examples.

[0028] This shows: Fig. 1: a schematic representation of a vehicle which has a lidar device according to the invention, and Fig. 2: a lidar central unit.

[0029] Fig. Figure 1 shows a vehicle 10, which includes a vehicle computer 12 that is connected via a data line 18 to a lidar central unit 14 installed in the vehicle 10. A vehicle computer 12 is understood to be a central computer of the vehicle 10, which can, among other things, control various assistance systems and other functions of the vehicle 10.

[0030] The data line 18 is not necessarily designed as a shielded, high-speed data connection in a cable-like configuration. Instead, in a highly integrated version of the present invention, the vehicle computer 12 and the lidar central unit 14 are integrated together in an ECU (Electronic Control Unit) 16. This reduces the installation space required for the vehicle computer 12 and the ECU 16. Furthermore, it significantly increases the speed at which data is exchanged between the lidar central unit 14 and the vehicle computer 12.

[0031] Vehicle 10 is equipped with a first optical head 20 of the lidar device as well as another optical head 30.

[0032] The first optical head 20 is located in an area of ​​the upper edge of the windshield of the vehicle 10, and the second optical head 30 is located in a front area of ​​the vehicle. Both optical heads 20 and 30 can be similarly or identically designed, but they detect different areas of the vehicle 10's surroundings.

[0033] A fiber optic connection 22 is provided between the first optical head 20 and the ECU 16, in particular the lidar central unit 14 integrated in the ECU 16. A further fiber optic connection 32 is provided between the second optical head 30 and also the lidar central unit 14. These two optical fiber connections 22 and 32 serve to transmit laser light, which is generated within the lidar central unit 14 and emitted into the environment via the optical heads 20 and 30.

[0034] Each of the optical heads 20 and 30 is equipped with a scanning device (not shown in detail) by which the direction of emission of the laser light can be varied by means of the lidar central unit 14, thus enabling cyclic scanning of the detection area of ​​the respective laser head 20, 30. Simultaneously, the lidar central unit 14 also controls the direction from which the optical heads 20 and 30 receive laser light reflected from the environment and transmit it back to the lidar central unit 14 via the associated fiber optic connections 22 and 32. In addition to the fiber optic connections 22 and 32, electrical connections (not shown in detail) to the lidar central unit 14 can be provided to control such scanning devices in the optical heads 20 and 30.Since the bandwidth for the electrical signals to control the scanning device is lower than that of the optical signals to be processed, the realization of the electrical connection between the lidar central unit 14 and the optical heads 20 and 30 is less critical than in known lidar devices, where the received laser light is already converted in the optical heads into high-frequency electrical signals that must be transmitted to the lidar central unit.

[0035] The lidar central unit 14 will be described below using the Fig. 2 explained in more detail. As in the Fig.Figure 2 schematically depicts the lidar central unit 14, which is a subunit of the ECU 16, comprising several light sources in the form of lasers 24, 34, and 44. The dotted lines indicate that, of course, additional lasers and detectors can also be provided. The present invention offers the advantage that optical heads 20, 30, and 40 can be provided at different installation positions on the vehicle 10, thus achieving an overlapping detection range of 360° around the vehicle 10. Each optical head within the lidar central unit 14 is assigned a laser 24, 34, or 44. Likewise, each optical head 20, 30, or 40 within the lidar central unit 14 is assigned a detector 26, 36, or 46. The connection between the lasers 24, 34 and 44 as well as the detectors 26, 36 and 46 and the optical heads 20, 30 and 40 is made particularly outside the lidar central unit 14 via fiber optic connections 22, 32 and 42.These fiber optic connections 22, 32, and 42 serve for the bidirectional exchange of optical signals. At one end, each is connected to the lidar central unit 14 via a first optical connector 28, 38, and 48, respectively. At a second end, the fiber optic connections 22, 32, and 42 are also connected to the optical heads 20, 30, and 40 via further connectors 29, 39, and 49, respectively. The provision of such optical connectors 28, 38, 48, 29, 39, and 49 offers the advantage of easy assembly and disassembly of the system, allowing, for example, the simple replacement of defective components. These known optical connectors also exhibit low attenuation of the transmitted light signal.

[0036] Within the lidar central unit 14, the fiber optic connections 22, 32 and 42 are optically coupled to the lasers 24, 34 and 44, as well as to the detectors 26, 36 and 46, taking into account the assignment of lasers and detectors to the optical heads.

[0037] This coupling within the lidar central unit 14 can be achieved through additional fiber optic connections 23, 33, and 43 or other light-guiding elements. To differentiate between emitted and reflected laser light during detection, polarizing beam splitters 25, 35, and 45 can be provided. This utilizes the fact that the emitted laser light from lasers 24, 34, and 44 is linearly polarized in a defined polarization state, for example, in a defined plane. Upon reflection in the surrounding environment, the polarization state changes, so that light with a rotated polarization direction or with, for example, elliptically polarized components reaches the optical heads 20, 30, and 40. However, alternative methods, such as time-division multiplexing, can also be used to distinguish between emitted and reflected laser light.Time-dependent beam splitters can be used here. Intensity-dependent beam splitters can also be employed to differentiate between emitted laser light (with high intensity) and reflected laser light (with lower intensity). Reference symbol list 10 vehicles 12 vehicle computers 14 Lidar central unit 16 ECU 18 data lines 20 first optical head 22 fiber optic connections 23 Fiber optic connection 24 lasers 25 beam splitters 26 Detector 28 first optical connector 29 second optical connector 30 more optical heads 32 fiber optic connections 33 fiber optic connections 34 lasers 35 beam splitters 36 Detector 38 first optical connector 39 second optical connector 40 optical heads 42 fiber optic connections 43 Fiber optic connection 44 lasers 45 beam splitters 46 Detector 48 first optical connector 49 second optical connector

Claims

[1] Lidar device for detecting the surroundings of a vehicle (10), wherein the lidar device comprises: at least one laser (24, 34, 44) designed to emit laser light, at least one optical head (20, 30, 40) for emitting the laser light into the environment and for receiving laser light that has been reflected from the environment, at least one detector (26, 36, 46) designed to convert received laser light into electrical signals, characterized by , that: a lidar central unit (14) is provided in which the at least one laser (24, 34, 44) and the at least one detector (26, 36, 46) are arranged, and which is configured to evaluate the electrical signals, wherein at least one optical fiber connection (22, 32, 42) is arranged between the optical head (20, 30, 40) and the lidar central unit (14), which is configured to guide emitted laser light from the laser (24, 34, 44) to the optical head (20, 30, 40) and / or received laser light from the optical head (20, 30, 40) to the detector (26, 36, 46). [2] Lidar device according to claim 1, characterized by , that each optical head (20, 30, 40) has a scanning device for spatial scanning of the environment. [3] Lidar device according to claim 2, characterized by , that the lidar central unit (14) is designed to control the scanning device. [4] Lidar device according to any of the preceding claims, characterized by , that several lasers (24, 34, 44) are provided, each with an associated detector (26, 36, 46), and the lasers and the detectors are arranged in the central unit (14). [5] Lidar device according to claim 4, characterized by , that several optical heads (20, 30, 40) are provided and each optical head is assigned a laser (24, 34, 44) and a detector (26, 36, 46). [6] Lidar device according to any of the preceding claims, characterized by , that between each optical head and the laser associated with it a first optical fiber connection is arranged, which is designed to guide emitted laser light from the laser to the optical head, and between each optical head and the detector associated with it a second optical fiber connection, which is designed to guide received laser light from the optical head to the detector. [7] Lidar device according to any one of the preceding claims 1 to 5, characterized by, that each optical head (20, 30, 40) is connected to an optical fiber connection (22, 32, 42) which is configured to guide both emitted laser light from the laser (24, 34, 44) associated with the optical head to the optical head, and received laser light from the optical head to the detector (26, 36, 46) associated with the optical head, wherein beam splitters (25, 35, 45) are preferably provided within the lidar central unit (16) to separate emitted laser light from reflected laser light. [8] Lidar device according to any of the preceding claims, characterized by , that at least one optical fiber connection (22, 32, 42) includes a connectable optical connector (28, 38, 48). [9] Lidar device according to any of the preceding claims, characterized by , that the lidar central unit (14) is integrated together with a vehicle computer (12) in an ECU (16). [10] Lidar device according to any of the preceding claims, characterized by , that the lidar central unit (14) is spatially separated from the at least one optical head (20, 30, 40) in an area within a vehicle body of the vehicle (10).

Images