CN118068292A - Lidar system and vehicle - Google Patents

Abstract

The present disclosure provides a lidar system and a vehicle. The lidar system includes: an emission device configured to emit an emission light beam having a uniform energy distribution, the emission light beam being divergent in a first direction perpendicular to an optical axis of the emission device, having a corresponding first divergence angle, and being either parallel or divergent and having a corresponding second divergence angle smaller than a preset threshold in a second direction perpendicular to the optical axis of the emission device and perpendicular to the first direction; a scanning device configured to rotate about a rotational axis oriented in a first direction to direct an emitted light beam to scan a target object within a field of view; and a receiving device configured to receive and detect the reception light beam returned from the target object.

Description

Lidar system and vehicle

Technical Field

The present disclosure relates to lidar systems, and more particularly to lidar systems and vehicles.

Background

The lidar system measures information of a position, a velocity, and the like of a target object by emitting a laser beam toward the target object and receiving the laser beam returned from the target object. The laser radar has the advantages of high resolution, good concealment, strong active interference resistance, small volume, light weight and the like.

Conventional scanning lidars implement laser scanning of the entire field of view through a rotating mirror or other scanning device. In contrast, flash lidar does not have a scanning structure, but emits a large laser light at the same time to illuminate the entire field of view at once, and receives and detects reflected light using a plurality of sensors.

Disclosure of Invention

One aspect of the present disclosure relates to a lidar system comprising: an emission device configured to emit an emission light beam having a uniform energy distribution, the emission light beam being divergent in a first direction perpendicular to an optical axis of the emission device, having a corresponding first divergence angle, and being either parallel or divergent and having a corresponding second divergence angle smaller than a preset threshold in a second direction perpendicular to the optical axis of the emission device and perpendicular to the first direction; a scanning device configured to rotate about a rotational axis oriented in a first direction to direct an emitted light beam to scan a target object within a field of view; and a receiving device configured to receive and detect the reception light beam returned from the target object.

Another aspect of the present disclosure relates to a vehicle including a lidar system according to an embodiment of the present disclosure, the lidar system configured to provide sensory information to the vehicle.

Drawings

The foregoing and other objects and advantages of the disclosure are further described below in connection with the following detailed description of the embodiments, with reference to the accompanying drawings. In the drawings, the same or corresponding technical features or components will be denoted by the same or corresponding reference numerals.

FIG. 1 shows a schematic composition diagram of a lidar system according to an embodiment of the disclosure;

FIG. 2 illustrates a top view of an example of a scanning device in a lidar system according to an embodiment of the disclosure;

FIG. 3 illustrates a side view of an example of a scanning device in a lidar system according to an embodiment of the disclosure;

FIG. 4 is a schematic diagram explaining the directional characteristics of respective reflecting surfaces in an example of a scanning device in a lidar system according to an embodiment of the disclosure;

FIG. 5 shows a schematic view of a scan field of view of a lidar system according to an embodiment of the disclosure;

FIG. 6 shows a schematic partial enlarged view of a scan field of view of a lidar system according to an embodiment of the disclosure;

fig. 7 shows a composition schematic of a vehicle according to an embodiment of the present disclosure.

Detailed Description

The following detailed description is made with reference to the accompanying drawings and is provided to assist in a comprehensive understanding of various example embodiments of the disclosure. The following description includes various details to aid in understanding, but these are to be considered merely examples and are not intended to limit the disclosure, which is defined by the appended claims and their equivalents. The words and phrases used in the following description are only intended to provide a clear and consistent understanding of the present disclosure. In addition, descriptions of well-known structures, functions and configurations may be omitted for clarity and conciseness. Those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the disclosure.

In various schemes of the laser radar system, the Flash laser radar has a large field of view (for example, the whole field of view) in a single irradiation, so that the energy density is low, the Flash laser radar is not suitable for remote detection, and the sensing point density is low under the condition that the number of sensors is fixed. In addition, the transmitting module and the receiving module in the conventional scanning lidar need to be arranged in pairs so that light emitted from one transmitting module is received by a corresponding one of the receiving modules paired therewith, and thus the paired transmitting module and receiving module must be strictly tuned to each other to achieve one-to-one correspondence of the transmitting points and receiving points. Moreover, if a plurality of pairs of transmitting and receiving modules are used, different transmitting or receiving modules need to be arranged at equal intervals to achieve a fixed angular interval of the scanning lines, which also requires accurate adjustment. In particular, the transmission and reception of the same channel need to be kept parallel with high precision, and the transmission-reception of different channels need to be kept in a specific high-precision angular positional relationship, which brings great inconvenience to the assembly and adjustment, especially in terms of automated production. Meanwhile, due to the volume limitation of each transmitting-receiving module and the difficulty in accurately controlling the transmitting angles among different channels, higher spatial resolution cannot be realized.

Thus, it is desirable for lidar systems to increase detection distance, increase resolution, increase field of view, and reduce tuning difficulty for automated production.

Therefore, the inventor of the present application proposes a laser radar system capable of increasing a detection distance, improving resolution, increasing a field of view, and reducing an adjustment difficulty. In the lidar system according to the embodiment of the present disclosure, a beam of light having a rectangular shape that is linear or narrow in cross section is emitted, so that single-step angle of view energy is more concentrated, the detection distance is longer, the resolution is higher, and the accuracy requirement of the emission-reception alignment is reduced. In addition, the scanning device provided with a plurality of reflecting surfaces with different inclination angles is used for realizing two-dimensional scanning, so that the number of moving devices is reduced, and meanwhile, the laser radar field of view is greatly improved. Further, the plane reflecting mirror with the holes is utilized to realize the receiving and transmitting coaxiality, so that tedious calibration caused by receiving and transmitting separation is avoided, and the automatic production is facilitated.

A lidar system 100 according to an embodiment of the present disclosure is described below with reference to fig. 1. For illustration purposes only, the XYZ coordinate system is labeled in fig. 1 and the subsequent fig. 2-4. Fig. 1 shows a schematic composition diagram of a lidar system 100 according to an embodiment of the disclosure. The lidar system 100 may be used to detect the distance and speed of a target object, etc.

In an embodiment of the present disclosure, lidar system 100 may include a transmitting device 110, a scanning device 120, and a receiving device 130.

In various embodiments, the emitting device 110 may be configured to emit an emission beam having a uniform energy distribution. Here, a uniform energy distribution may also be interpreted as a uniform illuminance or light intensity. In some embodiments, such an emitted light beam with a uniform energy distribution may be obtained by shaping (homogenizing) using an emission optical system 112, which will be discussed in detail later.

In various embodiments, the emission beam is divergent in a first direction perpendicular to the optical axis of the emission device 110, with a corresponding first divergence angle.

Furthermore, in various embodiments, the emission light beam is either parallel in a second direction perpendicular to the optical axis of the emission device and perpendicular to the first direction, or diverges and the corresponding second divergence angle is less than a preset threshold.

In practical applications, the first direction (Y-axis direction shown in fig. 1) may generally refer to a vertical direction (V-direction), while the second direction (Z-axis direction shown in fig. 1) may generally refer to a horizontal direction (H-direction). For ease of understanding, the description below is given by taking a case where the first direction corresponds to the vertical direction and the second direction corresponds to the horizontal direction as an example. Those skilled in the art will readily appreciate that the present application is not so limited. For example, the first direction may also refer to a horizontal direction, while the second direction may refer to a vertical direction.

In one aspect, the emitted light beam is divergent in the vertical direction, and the corresponding first divergence angle is defined as Δθ _V. That is, the emission beam is emitted in a fan-shaped beam of an angle Δθ _V in the vertical direction.

On the other hand, the emitted light beams may be parallel in the horizontal direction. Or the emitted light beam may be divergent in the horizontal direction, but the corresponding second divergence angle is smaller than the preset threshold. I.e. the emitted light beam is emitted in parallel light or at a small angle in the horizontal direction. The selection of the preset threshold will be discussed in detail later.

I.e. the emitted beam is a uniform linear or narrow rectangular beam. Thus, the spot projected in the field of view may appear as a narrow rectangle, even a line. The long side of the rectangle corresponds to the vertical direction, and the short side corresponds to the horizontal direction. Here, "narrow" may refer to a rectangle having an aspect ratio greater than a preset aspect ratio threshold. Advantageously, by using a rectangular shaped emission beam in a line or a narrow shape, the lidar system 100 of the present disclosure may achieve a more focused angular of view energy, a more distant detection, and a higher resolution.

The inventors of the present application have realized that an emitted light beam having the above-mentioned specific illumination distribution can be obtained by shaping a laser beam emitted from a common light source.

Thus, in some embodiments, the emitting device 110 includes a light source 111 and an emitting optical system 112. Wherein the emission optical system 112 is configured to shape the laser beam emitted from the light source 111 to convert it into the above-described emission light beam.

In some embodiments, the light source 111 may be a laser, such as a solid state laser (such as a Vertical-Cavity Surface-emitting laser (EMITTING LASER, VCSEL), an edge-emitting laser (EDGE EMITTING LASER, EEL), an External-Cavity semiconductor laser (ECDL)), a laser diode, a fiber laser. In some embodiments, the light source 111 may also include a light emitting Diode (LIGHT EMITTING Diode, LED). However, those skilled in the art will readily understand that the device type of the light source 111 is not particularly limited in the present application, as long as the output power of the light source 111 is sufficiently large.

In some embodiments, the light source 111 may be an array light source. For example, the light source 111 may be a VCSEL array including a plurality of VCSELs. In a non-limiting example, the plurality of VCSELs may be configured to light up all at the same time at the time of measurement, rather than being lit up in zones and/or time-sharing.

Or in some embodiments, the light source 111 may be a single point light source. Those skilled in the art will readily understand that the arrangement of the light sources 111 is not particularly limited by the present application.

In some embodiments, the light source 111 may emit light beams of different forms, including pulsed light, continuous Wave (CW), and quasi-continuous light. The operating wavelength of the light source may be 650nm to 1150nm, 800nm to 1000nm, 850nm to 950nm, or 1300nm to 1600nm. In some embodiments, the light source 111 may further include an optical assembly optically coupled to the light source 111 for collimating or focusing the light beam emitted by the light source 111. Each emitted light beam emitted by the light source 111 may be continuous light for a certain time or may be one or more light pulses.

In some embodiments, the emission optical system 112 may include a diffusing unit configured to diffusion shape the input laser beam. For example, the diffusing unit may diffusion-shape the light beam based on diffraction and/or refraction or the like to emit the above-described uniform linear or narrow rectangular light beam. Those skilled in the art will readily appreciate that the present application may be used to obtain the above-described emitted light beams by other shaping processes.

In some embodiments, the diffusion unit may include at least one of the following optics: an optical Diffuser (Diffuser), a diffractive optical element (DIFFRACTIVE OPTICAL ELEMENTS, DOE), and an aspherical cylindrical mirror. Those skilled in the art will readily appreciate that the above devices are merely examples of diffusion cells and the present application is not limited thereto.

In case of performing diffusion shaping using an optical diffuser or DOE, the emission optical system 112 may further comprise a collimation unit. Wherein the collimation unit may be configured to collimate the laser beam emitted from the light source to obtain a collimated laser beam to be input into the diffuser or DOE.

In some embodiments, the collimation unit may include at least one of the following optics: microlenses or collimating lenses. For example, the collimating unit may be an array of micro lenses. It will be readily appreciated by those skilled in the art that the above-described devices are merely examples of collimating units and the present application is not limited thereto.

In some embodiments, lidar system 100 also includes a planar mirror 140 having an aperture 141. Specifically, the plane mirror 140 transmits the emitted light beam using the hole 141 to guide the emitted light beam to the scanning device 120, and reflects the received light beam using the mirror surface to guide the received light beam to the receiving device 130. That is, the emitted light beam exiting the emitting device 110 may be directly transmitted through the plane mirror 140 via the hole 141, and the reflected received light beam may be reflected by a mirror surface in the plane mirror 140. That is, the reverse receive path may be separated from the forward transmit path at the planar mirror 140. Thus, lidar system 100 may achieve both transmit and receive coax by means of apertured planar mirror 140. Advantageously, the coaxial transmission and reception can avoid the problem of deviation of the imaging position of the short-distance and long-distance detection return light spots caused by the separation of the optical axes of the transmission and the reception, thereby avoiding the extra calibration caused by the problem and being beneficial to the mass production of products. Those skilled in the art will readily appreciate that the present application may also be used with non-coaxial lidar systems.

The inventors of the present application have realized that the precision requirements for hole fabrication and adjustment of a planar mirror with a hole are relatively relaxed, so long as the passing of the emitted beam is ensured. On this basis, by reducing the size of the holes, the loss of reflected light can be reduced.

Thus, in some embodiments, the emitted light beam is brought into focus as it passes through the aperture. For example, by designing the beam characteristics of the emitted beam and/or adjusting the position of the planar mirror relative to the emitting device, it is ensured that the emitted beam is in focus when passing through the aperture. Advantageously, by focusing the emitted light beam at the aperture, aperture minimization can be achieved with the emitted light beam passing through the aperture ensured, thereby minimizing losses of reflected light and further reducing the precision requirements for aperture fabrication and adjustment. Those skilled in the art will readily appreciate that the present application is not so limited.

The aperture is typically centered in the planar mirror, but the application is not so limited. In addition, to reduce the loss of reflected light, the shape of the aperture may correspond to the cross-sectional shape of the emitted light beam as it passes through the aperture, and thus is not necessarily circular.

Those skilled in the art will readily appreciate that the present application may also be used to achieve transmit and receive coax in other ways. However, the provision of the apertured plane mirror in the present disclosure may reduce light loss and improve efficiency compared to other approaches such as beam splitters.

In various embodiments, a scanning device 120, such as a turning mirror, may be configured to rotate about a rotational axis oriented in a vertical direction (first direction, Y-axis direction in the figures) to direct an emitted light beam to scan a target object within a field of view. The target object may be any object within the scanning field of view of the lidar system capable of reflecting the scanning laser light, such as a vehicle, a pedestrian, an animal, a guideboard, an obstacle, a tree, a shelf, furniture, etc.

The transmitted beam is scattered back after impinging on the target object, a portion of which is returned to the lidar system 100 as a received beam and received by the receiving device 130.

In various embodiments, the receiving device 130 may be configured to receive and detect a received light beam returned from the target object. For example, the received light beam scattered back by the target object may be returned to the scanning device 120 along the original path, then guided by the scanning device 120 to the plane mirror 140, and then reflected by the plane mirror 140 to the receiving device 130.

In some embodiments, the receiving means 130 may comprise a photodetector 131. The photodetector 131 may measure the power, phase, or time characteristics of the received light and generate a corresponding current output.

In some embodiments, as shown in fig. 1, the photodetector 131 may include a plurality of photodetector cells 1310 arranged along one direction. Wherein different photo-detection units 1310 are configured to receive and detect optical signals returned from target objects at different relative angles in the vertical direction in the field of view. The photodetector 131 may also include a receiving circuit (not shown) associated with each of the photodetector units 1310. Each receiving circuit may be used to process the output electrical signal of a corresponding photo-detection unit 1310.

The photo-detection unit 1310 may comprise various forms of photo-detection devices or one-or two-dimensional arrays of photo-detection devices, and accordingly, the receiving circuit may be a circuit or an array of circuits. In various embodiments, the photodetector device may be an avalanche diode (AVALANCHE PHOTODIODE, APD), a single photon avalanche diode (Single Photon Avalanche Diode, SPAD), a PN-type photodiode, or a PIN-type photodiode.

For example, the photo-detection unit 1310 may be a photo-detection device SPAD or a one-dimensional or two-dimensional array thereof, and thus the photo-detector 131 is an array of SPADs. Advantageously, spatial resolution can be greatly improved due to the very small pitch and close arrangement of SPADs. Furthermore, different SPADs can simultaneously and independently measure the Flight time (DIRECT TIME-of-Flight, dToF), and the time resolution can be greatly improved without dividing and time-sharing lighting the light source.

In some embodiments, the receiving device 130 may also include a receiving optical system 132. The receiving optical system 132 may be configured to image the received light onto the photodetector 131. For example, in some embodiments, the receiving optical system 132 may include a receiving lens and a stop. The receiving lens and diaphragm are located upstream of the photodetector 131 on the receiving path. For example, the receiving lens may comprise an imaging system lens such that the focal point of the receiving beam is in front of or behind or just above the receiving surface of the photodetector. In some cases, instead of being present as a separate component, the receiving lens may also be integrated into the photodetector 131. The aperture is used to limit the angle of incident light on the photodetector 131, block stray light, and the like.

As described above, the spot projected into the field of view by the lidar system 100 may be a uniform line or a narrow rectangle extending in the vertical direction, so that the received beam returning from the target object will form a similar pattern on the receiving surface of the photodetector 131. By arranging a plurality of photo-detecting units 1310 correspondingly along the direction of the long side of the line or rectangle, and imaging light returned from the target object at different opposite angles in the vertical direction in the field of view to the different photo-detecting units 1310 with the receiving optical system 132, it is possible to make these photo-detecting units 1310 correspond to the target object at different opposite angles in the vertical direction in the field of view, respectively. That is, different photo-detection units 1310 are configured to receive and detect optical signals returned from target objects at different relative angles in the vertical direction in the field of view. Accordingly, the relative angle of the corresponding target object can be precisely calculated according to the arrangement information of the photo detection unit 1310, the parameter information of the optical system, and the like.

Since a uniform line-shaped (or narrow rectangular) emitted beam is used, only a simple adjustment of the lidar system 100 is required, so that the receiving light spot imaged by the receiving optical system 132 on the photodetector 131 can cover the receiving surfaces of the photodetecting units 1310 (i.e., the photosensitive surfaces of all the photodetecting units 1310), and no separate alignment of the emitting module and the receiving module needs to be performed. Here, a receiving spot "covers" a receiving surface is understood to mean that the receiving spot at least partially overlaps the receiving surface, so that the respective photo detection unit can receive the optical signal returned from the target object. For example, in some embodiments, the size of the receive spot may be made relatively small and only a portion of the receive surface may be covered, whereby the returned optical signal can be received by the photo detection unit as much as possible with reduced waste. Therefore, the scheme provided by the disclosure can greatly simplify the difficulty of assembly and adjustment, and is beneficial to realizing automatic production.

The angular resolution δθ _V＝Δθ_V/Q of the lidar system 100 according to the embodiment of the present disclosure in the vertical direction, where Q is the number of photo-detection units 1310 included in the photo-detector 131. By decreasing the emission angle Δθ _V and/or increasing the number Q of photo-detection units 1310 in the photo-detector 131, the value of the angular resolution δθ _V in the vertical direction may be decreased, thereby increasing the angular resolution in the vertical direction.

It is noted that in some embodiments, each of the photo-detection units 1310 may include a plurality of photo-detection devices (such as SPADs) arranged along a direction, wherein the arrangement direction of the plurality of photo-detection devices is perpendicular to the arrangement direction of the plurality of photo-detection units 1310. With this arrangement, the number of photo-detection devices in each photo-detection unit 1310 can be increased without affecting the pitch of the photo-detection units 1310, thereby improving the accuracy of detection without affecting the spatial resolution.

Examples of scanning devices in a lidar system according to embodiments of the present disclosure are described below with reference to fig. 2-4. Fig. 2 to 3 are schematic structural views of examples of a scanning device in a lidar system according to an embodiment of the present disclosure, and fig. 4 illustrates orientation characteristics of respective reflection surfaces in examples of the scanning device.

Fig. 2 shows a top view of the scanning device 120 viewed from the vertical direction (first direction, Y-axis direction in the drawing). Fig. 3 shows a side view of the scanning device 120 from the horizontal direction (second direction, Z-axis direction in the drawing). Note that the scanning device 120 shown in fig. 3 can be obtained by rotating the scanning device 120 shown in fig. 1 by 180 ° on the paper surface.

In some embodiments, as shown in fig. 2-4, the scanning device 120 is provided with a plurality of reflective surfaces. These reflection surfaces are configured to sequentially perform deflection scanning in the horizontal direction (second direction) as the scanning device 120 rotates. In the case where the number of reflection surfaces is N and the deflection angle of each reflection surface is the same, the respective reflection surfaces can deflect and scan in the horizontal direction over an angle range θ _H =720°/N. For example, in the example shown in fig. 2-4, the scanning device 120 is provided with 5 reflective surfaces: the 1 st reflection surface, the 2 nd reflection surface, the 3 rd reflection surface, the 4 th reflection surface, and the 5 th reflection surface, i.e., n=5. Therefore, the angular range in which each reflecting surface can be deflected and scanned in the horizontal direction is 144 ° theoretically. However, it will be readily appreciated by those skilled in the art that the value of this angular range is a theoretical maximum and will vary in practice with the particular configuration of the scanning device.

During scanning, as the scanning device 120 rotates about the rotation axis, the reflective surfaces of the scanning device 120 sequentially direct the emitted light beam to deflect in a horizontal direction. During the deflection scanning of the same reflecting surface, the receiving light beams sequentially detected by the receiving device return from the target object at adjacent angles in the horizontal direction in the field of view. Wherein the angular interval Δθ _H in the horizontal direction corresponding to the two front and rear detections may be regarded as the angular resolution of the lidar system 100 in the horizontal direction.

Therefore, the angular resolution of the lidar system 100 according to the embodiment of the present disclosure in the horizontal direction corresponds to the product of the detection period of the receiving device and the rotational angular velocity of the scanning device. The detection period of the receiving device can be generally determined according to the accumulated laser emission times and the laser emission time interval of single detection. Specifically, the angular resolution of lidar system 100 in the horizontal direction may be represented by the following equation: Δθ _H＝θ_speed ×Δtq, where θ _speed is a rotation angular velocity of the scanning device, Δt is a laser emission time interval, and q is a laser emission number accumulated by a single detection. That is, the value of the angular resolution Δθ _H in the horizontal direction is proportional to the rotational angular velocity θ _speed of the scanning device, the laser emission time interval Δt, and the number q of laser emissions accumulated by a single detection. By reducing at least one of the rotational angular velocity θ _speed of the scanning device, the laser emission time interval Δt, and the number q of laser emission times accumulated by a single detection, the value of the angular resolution Δθ _H in the horizontal direction can be reduced, thereby improving the angular resolution in the horizontal direction.

The inventors of the present application have appreciated that the second divergence angle of the emitted beam in the horizontal direction may not exceed the angular resolution Δθ _H of the lidar system 100 in the horizontal direction in order to avoid unnecessary energy losses. Accordingly, in some embodiments, the preset threshold is set equal to or less than the angular resolution Δθ _H of the lidar system 100 in the horizontal direction, such that the second divergence angle does not exceed Δθ _H.

As described above, the emission beam of the lidar system 100 according to the embodiment of the present disclosure diverges in the vertical direction in a fan shape at an angle Δθ _V. Thus, lidar system 100 may acquire a "column" of data corresponding to a field of view having an angular range Δθ _V in the vertical direction and an angular range Δθ _H in the horizontal direction in each measurement.

In performing deflection scanning using a single reflection surface, the number of times m=θ _H/Δθ_H that the reception device can perform detection, that is, M columns of data can be acquired.

Since the spot projected into the field of view by lidar system 100 may appear as a uniform line or a narrow rectangle extending in the vertical direction, the angle of view of lidar system 100 in the horizontal direction may be considered to be approximately equal to the angular range θ _H of the deflection scan of the various reflective surfaces of scanning device 120 in the horizontal direction, i.e., approximately equal to 720 °/N. The angle of view of lidar system 100 in the vertical direction is related not only to the first divergence angle of the emitted light beam in the vertical direction, but also to the range of angles of the normal of the respective reflecting surfaces of scanning device 120 with respect to a reference plane perpendicular to the rotation axis (e.g., the end face of scanning device 120 shown in fig. 3), because the angles can reflect the angles of incidence of the chief rays of the emitted light beam with respect to the respective reflecting surfaces. For example, when the angles of the two reflecting surfaces relative to the end surfaces are different, the spatial pitch angles of the chief rays of the emitted light beams when reflected by the two reflecting surfaces are different, and therefore will be directed to positions in the field of view at which the relative angles in the vertical direction are different, thereby achieving scanning of different "rows" in the field of view.

Thus, in some embodiments, the plurality of reflective surfaces are oriented such that the angles of normals of at least two of the reflective surfaces with respect to the reference plane are different. Thus, lidar system 100 may scan at least two lines of field of view such that the field of view of lidar system 100 in the vertical direction is not limited to first divergence angle Δθ _V. Advantageously, a large field of view may be achieved with a smaller first divergence angle Δθ _V. As analyzed above, decreasing the first divergence angle Δθ _V can increase the angular resolution in the vertical direction.

For example, in some embodiments, the plurality of reflective surfaces are oriented such that the angles of the normals of all reflective surfaces relative to the reference plane form an arithmetic progression after being ordered by numerical size. In this way, the chief rays of the emitted light beams when reflected by the plurality of reflecting surfaces can be equally spaced, so that the field of view of N rows can be scanned.

As shown in fig. 4, the respective reflection surfaces may be oriented such that the angles of the normals of the first to fifth reflection surfaces with respect to the reference plane sequentially vary by a difference Δθ _mirror-step. However, the present application is not limited thereto, and each angle may be formed into an arithmetic progression after being ordered according to the numerical values. For example, in some embodiments, to solve the problem of center of gravity placement of the scanning device, the included angles are avoided from being sequentially changed according to the arrangement order of the reflective surfaces.

It is noted that if the difference Δθ _mirror-step＜Δθ_V/2, there will be field overlap between different rows during scanning, resulting in repeated scanning. On the other hand, if Δθ _mirror-step＞Δθ_V/2, the fields of view of the different rows appear to be blank in the vertical direction, resulting in a missed scan.

Thus, in some embodiments, the difference Δθ _mirror-step may be set equal to half the first divergence angle Δθ _V, i.e., Δθ _mirror-step＝Δθ_V/2. In this way, the set of fields of view of different rows can cover the complete area without overlapping when scanning. Alternatively, the difference Δθ _mirror-step may be set to be less than half the first divergence angle Δθ _V to ensure that the scan covers the complete area at the cost of repeatedly scanning a small number of areas. That is, in some embodiments, the difference Δθ _mirror-step may be set to be less than or equal to half the first divergence angle.

As described above, the emission beam of the lidar system 100 according to the embodiment of the present disclosure diverges in the vertical direction in a fan shape at an angle Δθ _V. Thus, by deflection scanning in the horizontal direction, the lidar system 100 can achieve scanning of a field of view with a projection angle range θ _H in the horizontal direction and a projection angle range Δθ _V in the vertical direction. On this basis, by setting the inclination angle of the reflecting surface to scan different rows when switching the reflecting surface, the lidar system 100 can realize scanning of a field of view having a projection angle range θ _H in the horizontal direction and a projection angle range nΔθ _V in the vertical direction.

Advantageously, by implementing two-dimensional scanning using scanning devices in which the angles of the respective reflecting surfaces with respect to the end surfaces are all different, the lidar system proposed by the present disclosure can reduce the number of moving devices while greatly improving the field of view.

The scanning process of lidar system 100 according to embodiments of the present disclosure is schematically illustrated below in connection with the scanning field diagrams in fig. 5 and 6. Fig. 5 shows a schematic view of the scan field of view of lidar system 100, and fig. 6 shows a schematic partial magnified view of the scan field of view. For the sake of simplicity, the following description will be given by taking an example in which the angles of the normals of the first to fifth reflecting surfaces with respect to the end surfaces are sequentially changed by the difference Δθ _V/2. But this is merely an example and the present application is not limited thereto.

The emitted light beam is first projected onto the 1 st reflecting surface of the scanning device 120, and the angle range of the reflected light beam in the vertical direction is θ ₀～θ₀+Δθ_V, where θ ₀ is the spatial pitch angle of the emitted light beam at the lower edge of the light beam reflected by the 1 st reflecting surface. The emitted light beam is scattered after being irradiated to the target object, a part of the emitted light beam returns to the scanning device 120 along the original path, is reflected to the plane mirror 140 by the 1 st reflecting surface, is reflected by the plane mirror 140, enters the receiving optical system 132, and is imaged on the array of Q photoelectric detection units 1310, so that Q ranging data corresponding to the 1 st row and the 1 st column are obtained. As the scanning device 120 rotates, the emitted light beam is deflected by an angle Δθ _H, so Q ranging data corresponding to the 1 st row and the 2 nd column are obtained similarly to the above-described process, then Q ranging data are measured one column after each deflection by the angle Δθ _H, and so on until Q ranging data of the 1 st row and the M-th column are measured.

Subsequently, when the scanning device 120 is rotated to the 2 nd reflecting surface, the angle of the normal line of the reflecting surface with respect to the end surface increases by Δθ _V/2, and the angle range of the emitted light beam in the vertical direction becomes θ ₀+Δθ_V～θ₀+2·Δθ_V after being reflected by the 2 nd reflecting surface. First, Q ranging data of row 2 and column 1 are measured, and then so on until Q ranging data of row 2 and column M are measured.

By analogy, when the scanning device 120 finally rotates to the nth (e.g., n=5) reflecting surface, the included angle of the normal line of the reflecting surface with respect to the end surface increases by (N-1) ·Δθ _V/2, and the angle range of the emitted light beam in the vertical direction becomes θ ₀+(N-1)·Δθ_V～θ₀+N·Δθ_V after being reflected by the nth reflecting surface, so as to perform ranging data detection of the nth row and M columns in total.

To this end, lidar system 100 completes a full frame scan. And then back to the first reflective surface for a second frame scan. The number of measurement points detected in total per frame is N M Q. In each frame, the projection angle range of the reflected light beam in the vertical direction after being reflected by the N reflection surfaces of the scanning device is θ _V＝N·Δθ_V, and the projection angle range in the horizontal direction is θ _H. That is, the field of view in the vertical direction of the lidar is θ _V, and the field of view in the horizontal direction is θ _H.

Therefore, the laser radar system provided by the disclosure emits a light beam which is linear or narrow in cross section, so that single-step angle of view energy is more concentrated, the detection distance is longer, the resolution is higher, and the accuracy requirement of emission-receiving alignment is reduced. In addition, the scanning device provided with a plurality of reflecting surfaces with different inclination angles is used for realizing two-dimensional scanning, so that the number of moving devices is reduced, and meanwhile, the laser radar field of view is greatly improved. Further, the plane reflecting mirror with the holes is utilized to realize the receiving and transmitting coaxiality, so that tedious calibration caused by receiving and transmitting separation is avoided, and the automatic production is facilitated.

The disclosed embodiments also provide a vehicle. The vehicle uses the lidar system in the above-described embodiments to provide the sensing information.

Fig. 7 schematically illustrates a configuration of a vehicle 700 including the above-described lidar system according to an embodiment of the present disclosure.

Lidar system 702 may be used as a sensor in vehicle 700 to provide sensory information to the vehicle. For example, lidar system 702 may be implemented using lidar system 100 in fig. 1. Here, a detailed description of the specific configuration of the lidar system 702 is not repeated here.

In some embodiments, in addition to lidar system 702 functioning as a sensor, vehicle 700 also includes a vehicle controller 704 and a motorized system 706. Wherein vehicle controller 704 may adjust motorized system 706 based on the sensing results of lidar system 702.

The functions included in one unit in the above embodiments may be implemented by separate devices. Alternatively, the functions realized by the plurality of units in the above embodiments may be realized by separate devices, respectively. In addition, one of the above functions may be implemented by a plurality of units. Such configurations are included within the technical scope of the present disclosure.

In the present disclosure, the steps described in the flowcharts include not only processes performed in time series in the order described, but also processes performed in parallel or individually, not necessarily in time series. Further, even in the steps of time-series processing, the order may be appropriately changed.

The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The term "or" in this disclosure means an inclusive "or" rather than an exclusive "or". References to a "first" component do not necessarily require the provision of a "second" component. Furthermore, unless explicitly indicated otherwise, reference to "a first" or "a second" component does not mean that the referenced component is limited to a particular order. The term "based on" means "based at least in part on.

Claims (20)

1. A lidar system, comprising:

An emission device configured to emit an emission light beam having a uniform energy distribution, the emission light beam being divergent in a first direction perpendicular to an optical axis of the emission device, having a corresponding first divergence angle, and being either parallel or divergent and the corresponding second divergence angle not exceeding a preset threshold in a second direction perpendicular to the optical axis of the emission device and perpendicular to the first direction;

A scanning device configured to rotate about a rotational axis oriented in a first direction to direct an emitted light beam to scan a target object within a field of view; and

And a receiving device configured to receive and detect the reception light beam returned from the target object.

2. The lidar system according to claim 1, which is a coaxial lidar system.

3. The lidar system of claim 2, further comprising:

A planar mirror having an aperture configured to transmit the emitted light beam with the aperture to direct the emitted light beam to a scanning device and reflect the received light beam with a mirror to direct the received light beam to a receiving device.

4. The lidar system of claim 3, wherein the laser radar system comprises a laser beam,

The emitted light beam is in focus when passing through the aperture.

5. The lidar system according to claim 1, wherein the transmitting means comprises:

A light source; and

An emission optical system configured to shape a laser beam emitted from a light source to convert it into the emission light beam.

6. The lidar system of claim 5, wherein the light source is a VCSEL array comprising a plurality of vertical cavity surface emitting laser VCSELs configured to all illuminate simultaneously at the time of measurement.

7. The lidar system according to claim 5, wherein the transmitting optical system comprises:

a diffusing unit configured to diffusion shape an input laser beam, wherein the diffusing unit includes at least one of the following optics: optical diffusers, diffractive optical elements, and aspherical cylindrical mirrors.

8. The lidar system according to claim 7, wherein in case of diffusion shaping using an optical diffuser or a diffractive optical element, the transmitting optical system further comprises:

A collimation unit configured to collimate the laser beam emitted from the light source to obtain a collimated laser beam to be input to the diffuser or the diffractive optical element.

9. The lidar system according to claim 8, wherein the collimation unit comprises at least one of the following optics: microlenses or collimating lenses.

10. The lidar system according to claim 1, wherein the scanning device is provided with a plurality of reflective surfaces configured to perform deflection scanning in the second direction in sequence as the scanning device rotates.

11. The lidar system according to claim 10, wherein the plurality of reflecting surfaces are oriented such that the angle between the normals of at least two reflecting surfaces with respect to a reference plane perpendicular to the rotation axis is different.

12. The lidar system according to claim 11, wherein the plurality of reflecting surfaces are oriented such that the angles of the normals of all reflecting surfaces with respect to the reference plane form an arithmetic series after being ordered by numerical size.

13. The lidar system according to claim 12, wherein the tolerance of the series of arithmetic is less than or equal to half the first divergence angle.

14. The lidar system according to claim 1, wherein the preset threshold is equal to or smaller than the angular resolution of the system in the second direction.

15. The lidar system according to claim 1, wherein the angular resolution of the system in the second direction corresponds to the product of the detection period of the receiving device and the rotational angular velocity of the scanning device.

16. The lidar system according to claim 1, wherein the receiving device comprises:

A photodetector includes a plurality of photodetector units arranged along one direction,

Wherein the different photo detection units are configured to receive and detect optical signals returned from target objects at different relative angles in a first direction in the field of view.

17. The lidar system according to claim 16, wherein the receiving device further comprises:

and a receiving optical system configured to image the received light onto the photodetector.

18. The lidar system according to claim 16, wherein in case the number of photo detection units is Q, the angular resolution of the system in the first direction corresponds to 1/Q of the first divergence angle.

19. The lidar system according to claim 16, wherein each of the photodetection units comprises a plurality of photodetection devices arranged along a direction, wherein an arrangement direction of the plurality of photodetection devices is perpendicular to an arrangement direction of the plurality of photodetection units.

20. A vehicle comprising a lidar system according to any of claims 1-19, the lidar system being configured to provide sensory information to the vehicle.