A laser radar detection system and detection method thereof

Abstract

The present invention relates to the field of radar detection technology, and specifically to a laser radar detection system and a detection method thereof. In the present application, first, after a light source emits a linearly polarized laser beam, it is transmitted or reflected to a scanning element through a spectroscopic element, so that the laser beam is deflected to a target detection surface, and then an echo beam is generated on the target detection surface, and the echo beam is guided to the spectroscopic element through the scanning element. At this time, the spectroscopic element reflects the echo beam to the beam splitting element, and divides the echo beam into a first echo beam and a second echo beam according to the polarization state, which are respectively received by a first detection element and a second detection element to generate first detection data and a second detection data, and finally, the control element generates a detection result for the target detection surface according to the detection data. By adopting the scheme of the present application, by comparing data of different polarization states to obtain detection and identification of different types of obstacles, the detection dimension of the target detection surface is increased, and the detection accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the field of radar detection technology, and in particular to a laser radar detection system and a detection method thereof. Background Art

[0002] LiDAR is a radar system that works in the near-infrared band and was first seen in the field of remote sensing. In recent years, with the development of autonomous driving technology, LiDAR has gradually developed in the automotive field as a high-precision detection method. When LiDAR is working, it emits a modulated laser beam to detect the target. When the target is irradiated by the laser beam, it will produce some reflected light. The reflected light is received by the LiDAR detector and converted into an electrical signal input into the processing circuit.

[0003] As the application of laser radar products becomes more and more extensive, such as in AGV, unmanned robots for logistics, automobiles and other fields, higher requirements are put forward for the detection accuracy of laser radar products. Therefore, the detection accuracy of laser radar products needs to be improved. Summary of the invention

[0004] The present invention provides a laser radar detection system and a detection method thereof, which effectively solve the problems of the existing laser radar detection system having a single detection dimension and low recognition accuracy.

[0005] According to the first aspect, an embodiment provides a laser radar detection system, including a light source, a light splitting element, a scanning element, a beam splitting element, a first detection element, a second detection element, and a control element;

[0006] The light source is used to emit a linearly polarized laser beam;

[0007] The beam splitter is arranged on the optical path of the laser beam, and is used to split the laser beam into a transmission beam and a reflection beam; the optical path where the transmission beam is located is the transmission optical path, and the optical path where the reflection beam is located is the reflection optical path;

[0008] The scanning element is arranged on the transmission light path and / or the reflection light path; the scanning element is used to deflect the transmission light beam and / or the reflection light beam to different areas of the target detection surface; the scanning element is also used to guide the echo light beam reflected by the target detection surface to the spectroscopic element;

[0009] The beam splitter element is further used to reflect the echo light beam of the transmission light path to the beam splitter element; and / or, the beam splitter element is further used to transmit the echo light beam of the reflection light path to the beam splitter element;

[0010] The beam splitting element is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state; the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam;

[0011] The first detection element is used to receive the first echo light beam and generate first detection data according to the first echo light beam;

[0012] The second detection element is used to receive the second echo light beam and generate second detection data according to the second echo light beam;

[0013] The control element is electrically connected to the first detection element and the second detection element, and is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source, and generate a detection result for the target detection surface according to the difference.

[0014] In an achievable implementation, a first light path shaping element is provided on the light path between the light source and the beam splitting element, and the first light path shaping element is used to collimate the laser beam.

[0015] In an achievable implementation, a second optical path shaping element is provided on the optical path between the optical splitting element and the beam splitting element, and the second optical path shaping element is used to focus the echo light beam reflected or transmitted by the optical splitting element.

[0016] In a feasible implementation manner, the first echo light beam and the second echo light beam emitted by the beam splitting element are parallel to or perpendicular to each other.

[0017] In an achievable embodiment, the system further includes a first polarization element and a second polarization element;

[0018] The first polarizing element is disposed on the optical path between the light source and the beam splitting element, and is used to transmit the laser beam in the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source;

[0019] The second polarization element is arranged on the optical path between the splitting element and the scanning element. The second polarization element is used to convert the laser beam in the main polarization direction transmitted or reflected by the splitting element into a circularly polarized laser beam, and is also used to convert the circularly polarized echo beam into a linearly polarized echo beam.

[0020] In an achievable implementation, the first polarization element includes a polarizer or a polarization beam splitter cube, and the second polarization element includes a quarter wave plate.

[0021] In an achievable implementation, the system further includes a third polarization element, a fourth polarization element, and a fifth polarization element;

[0022] The third polarization element and the fourth polarization element are sequentially arranged on the optical path between the light source and the beam splitter, the third polarization element is used to transmit the laser beam in the main polarization direction; the fourth polarization element is used to convert the laser beam in the main polarization direction into a circularly polarized laser beam; the main polarization direction is the polarization direction of the laser beam emitted by the light source;

[0023] The fifth polarization element is arranged on the optical path between the second optical path shaping element and the beam splitting element, and the fifth polarization element is used to convert the circularly polarized echo light beam into a linearly polarized echo light beam.

[0024] In an achievable implementation, the third polarization element includes a polarizer or a polarization beam splitter cube, and the fourth polarization element and the fifth polarization element both include a quarter wave plate.

[0025] In an achievable implementation, the preset value of the light source is a preset polarization extinction ratio of the light source; the control element is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source, and generate a detection result for the target detection surface according to the difference, including:

[0026] Obtaining an actual polarization extinction ratio of a light source according to the first detection data and the second detection data;

[0027] Comparing the actual polarization extinction ratio of the light source with the preset polarization extinction ratio of the light source;

[0028] If the difference between the actual polarization extinction ratio of the light source and the preset polarization extinction ratio of the light source is less than a preset threshold, the final distance information is output based on the detection data output by the detector of the received echo light beam consistent with the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source.

[0029] In an achievable implementation, when the first echo beam received by the first detection element is an echo beam consistent with the main polarization direction, the second echo beam received by the second detection element is a noise echo beam; or,

[0030] When the second echo beam received by the second detection element is an echo beam with a main polarization direction consistent with that of the first detection element, the first echo beam received by the first detection element is a noise echo beam.

[0031] In one possible implementation, the control element is further used for:

[0032] When the difference between the actual polarization extinction ratio of the light source and the preset polarization extinction ratio of the light source is greater than a preset threshold, outputting first distance information and second distance information according to the first detection data and the second detection data respectively;

[0033] Comparing the actual polarization extinction ratio of the light source with a preset light source polarization information list table to determine the type of the target detection surface;

[0034] One of the first distance information and the second distance information is selected as final distance information according to the type of the target detection surface.

[0035] In an achievable implementation, the preset light source polarization information list table includes a correspondence between multiple groups of detection surface types and selection rules; and selecting one of the first distance information and the second distance information as the final distance information according to the type of the target detection surface includes:

[0036] According to the type of the target detection surface, a selection rule corresponding to the type of the target detection surface is matched in the preset light source polarization information list table;

[0037] One of the first distance information and the second distance information is selected as the final distance information according to the matched selection rule; the selection rule is divided into two types: selecting closer distance information and selecting farther distance information.

[0038] According to the second aspect, an embodiment provides a laser radar detection method, including:

[0039] Controlling the light source to emit a linearly polarized laser beam;

[0040] Control the scanning element to deflect the transmitted light beam and / or the reflected light beam split by the beam splitting element to different areas of the target detection surface; and control the scanning element to guide the echo light beam reflected by the target detection surface to the beam splitting element; the beam splitting element is arranged on the optical path of the laser beam, and is used to split the laser beam into a transmitted light beam and a reflected light beam; the optical path where the transmitted light beam is located is the transmission light path, and the optical path where the reflected light beam is located is the reflection light path; the beam splitting element is also used to reflect the echo light beam of the transmission light path to the beam splitting element; and / or, the beam splitting element is also used to transmit the echo light beam of the reflection light path to the beam splitting element; the beam splitting element is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state; the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam;

[0041] Acquire first detection data generated by a first detection element due to receiving the first echo light beam, and acquire second detection data generated by a second detection element due to receiving the second echo light beam;

[0042] The difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source is determined, and a detection result for the target detection surface is generated according to the difference.

[0043] According to a laser radar detection system / laser radar detection method of the above embodiment, first, after the light source is controlled by the control element to emit a linearly polarized laser beam, it is divided into a transmitted beam and a reflected beam by the beam splitter element. Specifically, the scanning element deflects the transmitted beam or the reflected beam to the target detection surface, and then the target detection surface generates an echo beam, which is guided to the beam splitter element by the scanning element. At this time, the beam splitter element reflects or transmits the echo beam to the beam splitter element; then, the beam splitter element divides the echo beam into a first echo beam and a second echo beam of different polarization states according to the polarization state, wherein the first echo beam generates first detection data after being received by the first detection element, and the second echo beam generates second detection data after being received by the second detection element. Finally, the control element generates a detection result for the target detection surface according to the difference by judging the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source. By adopting the above scheme of the present application, by comparing different polarization state data to obtain different types of obstacle detection and identification, the detection dimension of the target detection surface can be increased, and the detection accuracy can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the first structure of the laser radar detection system of this embodiment;

[0045] Figure 2 is a schematic diagram of a second structure of the laser radar detection system of this embodiment;

[0046] Figure 3 Schematic diagram of the third structure of the laser radar detection system of this embodiment;

[0047] Figure 4 is a schematic diagram of a fourth structure of the laser radar detection system of this embodiment;

[0048] Figure 5 is a fifth structural schematic diagram of the laser radar detection system of this embodiment;

[0049] Figure 6 is a sixth structural schematic diagram of the laser radar detection system of this embodiment;

[0050] Figure 7Flow chart of the laser radar detection method of this embodiment.

[0051] Figure numerals: 10, light source; 20, spectroscopic element; 30, scanning element; 40, target detection surface; 50, beam splitting element; 60, first detection element; 70, second detection element; 80, first optical path shaping element; 90, second optical path shaping element; 110, first polarization element; 120, second polarization element; 130, third polarization element; 140, fourth polarization element; 150, fifth polarization element. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0053] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0054] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0055] The current laser radar products have a single detection dimension and may have recognition errors for highly reflective targets such as glass, smooth ground, and water. When the incident light is irradiated to the target surface, different intensities of reflectivity will be generated in different polarization states due to differences in interface materials and incident angles. However, existing radar products are unable to analyze the reflectivity deviations of different polarization states and can only obtain single reflection information, which causes the reflected light intensity of highly reflective targets or targets at special angles to exceed the expected range, ultimately leading to distance analysis errors. In view of this, the present application proposes a laser radar detection system and a detection method thereof.

[0056] refer to Figure 1-Figure 4 The present embodiment provides a laser radar detection system, comprising a light source 10, a spectroscopic element 20, a scanning element 30, a beam splitting element 50, a first detection element 60, a second detection element 70 and a control element. The light source 10 is used to emit a linearly polarized laser beam; the spectroscopic element 20 is arranged on the optical path of the laser beam, and the spectroscopic element 20 is used to split the laser beam into a transmitted beam and a reflected beam; the optical path where the transmitted beam is located is the transmitted optical path, and the optical path where the reflected beam is located is the reflected optical path; the scanning element 30 is arranged on the transmitted optical path and / or the reflected optical path; the scanning element 30 is used to deflect the transmitted optical path and / or the reflected optical path to different areas of the target detection surface 40, and the scanning element 30 is also used to guide the echo beam reflected by the target detection surface 40 to the spectroscopic element 20; the spectroscopic element 20 is also used to reflect the echo beam generated by the target detection surface 40 of the transmitted optical path to the beam splitting element 50; and / or, the spectroscopic element 20 is also used to reflect the echo beam generated by the target detection surface 40 of the reflected optical path to the beam splitting element 50. Transmitted to the beam splitting element 50; the beam splitting element 50 is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state; the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam; the first detection element 60 is used to receive the first echo light beam, and generate first detection data according to the first echo light beam; the second detection element 70 is used to receive the second echo light beam, and generate second detection data according to the second echo light beam; the control element is electrically connected to the first detection element 60 and the second detection element 70, and the control element is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source, and generate the detection result for the target detection surface 40 according to the difference.

[0057] In this embodiment, the light source 10 is a polarized laser light source, for example, it can be a VCSEL (Vertical Cavity Surface Emitting Laser) light source to emit a linearly polarized laser beam, and the polarization extinction ratio of the VCSEL chip output light is >16dB. The beam splitting element 20 adopts a non-polarizing beam splitter, which is used to reflect a part of the laser beam and transmit another part of the laser beam, wherein the ratio of the reflected beam to the transmitted beam can be 1:1; the scanning element 30 adopts a scanning galvanometer, for example, it can be a MEMS or a mechanical rotating mirror. The beam splitting element 50 adopts a polarization beam splitter. In the following embodiments, the laser beam transmitted when the laser beam is incident on the beam splitter and the laser beam reflected when the laser beam is incident on the beam splitter are used as examples to illustrate respectively:

[0058] Specifically, when the non-polarized beam splitter transmits the laser beam to the scanning galvanometer, the scanning galvanometer deflects the transmitted beam to different areas of the target detection surface 40 to achieve detection of different areas of the target detection surface 40. Since the reflectivity of the target detection surface 40 to light of different polarization states is different, the polarization state of the reflected light (echo beam) deviates from the polarization state of the incident light. At this time, the echo beam generated by the target detection surface 40 is guided to the beam splitter through the scanning galvanometer. At this time, the beam splitter reflects the echo beam to the polarization beam splitter. After passing through the polarization beam splitter, the light beams of different polarization states enter the corresponding first detection element 60 or second detection element 70. After the detection data of the first detection element 60 and the second detection element 70 are obtained by the control element, the detection data is processed to obtain target polarization characteristic information other than conventional laser radar energy information, determine the difference between the target polarization characteristic information and the preset value of the light source, and accurately calculate the distance information of the detection target according to the difference.

[0059] When the non-polarized beam splitter reflects the laser beam to the scanning galvanometer, the reflected beam is deflected to different areas of the target detection surface 40 by the scanning galvanometer to detect different areas of the target detection surface 40. Since the reflectivity of the target detection surface 40 to light of different polarization states is different, the polarization state of the reflected light (echo beam) deviates from the polarization state of the incident light. At this time, the echo beam generated by the target detection surface 40 is guided to the beam splitter by the scanning galvanometer. At this time, the beam splitter transmits the echo beam to the polarization beam splitter. After passing through the polarization beam splitter, the light beams of different polarization states enter the corresponding first detection element 60 or second detection element 70. After the detection data of the first detection element 60 and the second detection element 70 are obtained by the control element, the detection data is processed to obtain the target polarization characteristic information other than the conventional laser radar energy information, determine the difference between the target polarization characteristic information and the preset value of the light source, and accurately calculate the distance information of the detection target according to the difference.

[0060] refer to Figure 2 and Figure 4 In this scheme, a beam splitter is used to divide a laser beam into a transmission beam and / or a reflection beam. The light path where the transmission beam is located is called a transmission light path, and the light path where the reflection beam is located is called a reflection light path, so that both the transmission light path and the reflection light path can detect different target detection surfaces. The detection of different target detection surfaces or the same target detection surface can be realized at the same time to improve the utilization rate of energy and increase the scanning speed. In addition, the detection of different target detection surfaces can also be realized separately according to actual needs.

[0061] By adopting the laser radar detection system of this embodiment, not only can the polarization information of obstacles be obtained and the detection dimension be increased, but also the recognition and detection of different types of obstacles can be effectively improved by comparing different polarization state data.

[0062] For further reference, Figure 1-Figure 6 A first optical path shaping element 80 is arranged on the optical path between the light source 10 and the beam splitting element 20, and the first optical path shaping element 80 is used to collimate the laser beam.

[0063] In this embodiment, the first optical path shaping element 80 uses a collimating lens group to collimate the laser beam emitted by the light source 10, so as to collimate and project the light source 10 array onto the target detection surface 40, or image onto the detection array.

[0064] Furthermore, a second optical path shaping element 90 is provided on the optical path between the beam splitting element 20 and the beam splitting element 50, and the second optical path shaping element 90 is used to focus the echo light beam reflected or transmitted by the beam splitting element 20. Specifically, when the laser beam is transmitted to the target detection surface 40 by the beam splitting element 20, the second optical path shaping element 90 is used to focus the echo light beam reflected by the beam splitting element 20; or, when the laser beam is reflected to the target detection surface 40 by the beam splitting element 20, the second optical path shaping element 90 is used to focus the echo light beam transmitted by the beam splitting element 20. The second optical path shaping element 90 may be a single lens; or may be an imaging lens composed of multiple lenses, such as a classic Cooke three-piece lens.

[0065] Furthermore, the first echo light beam and the second echo light beam emitted by the beam splitting element 50 are parallel to or perpendicular to each other.

[0066] In this embodiment, specifically, since the polarization beam splitter can split the reflected light into the first echo beam and the second echo beam according to the polarization state, in the actual setting, the polarization beam splitter can make the first echo beam and the second echo beam emit in parallel. At this time, the first detection element 60 receiving the first echo beam and the second detection element 70 receiving the second echo beam can be set on the same circuit board (such as Figure 1 and Figure 2 As shown), the space of the system can be saved. In addition, the first echo light beam and the second echo light beam can also be emitted in two different directions according to different requirements. In this case, the first detection element 60 and the second detection element 70 can be set at different positions according to the corresponding light beams (such as Figure 3-Figure 6 Different optical path structures can be set according to actual needs to increase flexibility.

[0067] As an optical path structure of a detection system, Figure 5 As shown, the system further includes a first polarization element 110 and a second polarization element 120; the first polarization element 110 is disposed on the optical path between the light source 10 and the beam splitter 20, and the first polarization element 110 is used to transmit the laser beam in the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source 10; the second polarization element 120 is disposed on the optical path between the beam splitter 20 and the scanning element 30, and the second polarization element 120 is used to convert the laser beam in the main polarization direction transmitted or reflected by the beam splitter 20 into a circularly polarized laser beam, and also used to convert the circularly polarized echo beam into an echo beam in the main polarization direction. Further, the first polarization element 110 includes a polarizer, and the second polarization element 120 includes a quarter wave plate.

[0068] In practical applications, the first polarizing element 110 may be a polarizing plate or a polarization beam splitter cube, and the second polarizing element 120 may be a quarter wave plate. The polarized laser beam emitted by the light source 10 is screened by the polarizing plate to allow the laser beam in the main polarization direction to pass through, and to block the light in other polarization directions, and at the same time, to isolate the reverse incident linear polarized light. The laser beam in the main polarization direction passing through the beam splitter is converted into a circularly polarized laser beam by the quarter wave plate, and at the same time, the polarization state of the echo beam reflected by the target detection surface 40 can be converted from a circularly polarized state to a linearly polarized echo beam again. In addition, combining a 1 / 4 wave plate with a polarizer can act as an isolator to increase the life of the light source 10. Specifically, after the laser beam in the main polarization direction emitted by the spectroscopic element 20 passes through the 1 / 4 wave plate, the polarization state of the laser beam changes from a linear polarization state to a circular polarization state. After the circularly polarized laser beam is reflected by the target detection surface 40, the echo light beam will be transformed into a linearly polarized light beam after passing through the 1 / 4 wave plate again. At this time, the polarization state of the echo light beam will be orthogonal to the polarization state of the incident light beam (i.e., the laser beam in the main polarization direction), and thus will be blocked by the polarizer so that it cannot irradiate the light source, thereby acting as an isolator.

[0069] As another optical path structure of the detection system, Figure 6As shown, the system further includes a third polarization element 130, a fourth polarization element 140 and a fifth polarization element 150; the third polarization element 130 and the fourth polarization element 140 are sequentially arranged on the optical path between the light source 10 and the beam splitter 20, the third polarization element 130 is used to transmit the laser beam in the main polarization direction; the fourth polarization element 140 is used to convert the laser beam in the main polarization direction into a circularly polarized laser beam; the main polarization direction is the polarization direction of the laser beam emitted by the light source 10; the fifth polarization element 150 is arranged on the optical path between the second optical path shaping element 90 and the beam splitter 50, the fifth polarization element 150 is used to convert the circularly polarized echo beam into a linearly polarized echo beam. Further, the third polarization element 130 includes a polarizer, and the fourth polarization element 140 and the fifth polarization element 150 both include a 1 / 4 wave plate.

[0070] In practical applications, the third polarization element 130 may be a polarizer or a polarization beam splitter cube, the fourth polarization element 140 may be a quarter wave plate, and the fifth polarization element 150 may also be a quarter wave plate. The third polarization element 130 is used to emit the light beam in a polarization state (i.e., the main polarization state) consistent with the polarizer; the fourth polarization element 140 is used to convert the polarization state of the emitted laser beam into a circularly polarized laser beam; the fifth polarization element 150 is used to convert the polarization state of the emitted echo light beam from a circularly polarized state into a linearly polarized state, and the linearly polarized state is orthogonal to the polarization direction of the polarizer.

[0071] Furthermore, the preset value of the light source is a preset polarization extinction ratio of the light source; the control element is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source, and generate a detection result for the target detection surface according to the difference, including:

[0072] Obtaining an actual polarization extinction ratio of the light source 10 according to the first detection data and the second detection data;

[0073] Comparing the actual polarization extinction ratio of the light source 10 with the preset polarization extinction ratio of the light source 10;

[0074] If the difference between the actual polarization extinction ratio of the light source 10 and the preset polarization extinction ratio of the light source 10 is less than a preset threshold, the final distance information is output based on the detection data output by the detector of the received echo light beam consistent with the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source 10.

[0075] Specifically, since the first detection element 60 and the second detection element 70 respectively receive echo light beams of two polarization states, the actual polarization extinction ratio after the light source 10 irradiates the target detection surface 40 can be calculated based on the first detection data and the second detection data. Then, the actual polarization extinction ratio is compared with the preset polarization extinction ratio of the light source 10. When the difference between the actual polarization extinction ratio of the light source 10 and the preset polarization extinction ratio of the light source 10 is less than the preset threshold value, in actual application, when the actual polarization extinction ratio of the light source 10 is substantially consistent with the preset polarization extinction ratio of the light source 10, the detection data output by the detection element receiving the echo light beam in the main polarization direction is used as the calculation basis, and the distance information is calculated using the ITOF (Indirect Time-of-Flight, indirect time flight laser radar technology) or DTOF (Direct Time-of-Flight, direct time flight laser radar technology) detection principle, and the distance information is output as the final distance information.

[0076] Among them, when the first echo beam received by the first detection element 60 is an echo beam consistent with the main polarization direction, the second echo beam received by the second detection element 70 is a noise echo beam; or, when the second echo beam received by the second detection element 70 is an echo beam consistent with the main polarization direction, the first echo beam received by the first detection element 60 is a noise echo beam.

[0077] It should be noted that, for linearly polarized light, the polarization state and polarization direction are consistent, because the direction of the electric field vector is constant. Specifically, when the polarization state of the echo light beam is consistent with the main polarization state of the laser beam, the detection element receiving the echo light beam of this polarization state has a photoelectric signal output; when the polarization state of the echo light beam is inconsistent with the main polarization state of the laser beam, the detection element receiving the echo light beam of this polarization state has no photoelectric signal output or the output signal has no obvious change. In this embodiment, for different detection systems, such as Figure 1 and Figure 2 In the optical path structure of the detection system shown in FIG. 1 , the first detection element 60 outputs a photoelectric signal, and the output signal of the second detection element 70 does not change significantly. Therefore, the first detection element 60 receives an echo beam consistent with the main polarization state, and the second detection element 70 receives an echo beam of other polarization directions. Figure 3 and Figure 4 In the optical path structure of the detection system shown, the second detection element 70 has a photoelectric signal output, and the output signal of the first detection element 60 has no obvious change. Therefore, the second detection element 70 receives an echo beam consistent with the main polarization state, and the first detection element 60 receives an echo beam of other polarization directions. At this time, the control element only selects the detection data output by the detection element that receives the echo beam consistent with the main polarization direction, and calculates the final distance information based on the data.

[0078] Furthermore, the control element is also used for: when the difference between the actual polarization extinction ratio of the light source 10 and the preset polarization extinction ratio of the light source 10 is greater than a preset threshold, outputting the first distance information and the second distance information according to the first detection data and the second detection data respectively; comparing the actual polarization extinction ratio of the light source 10 with the preset polarization information list of the light source 10 to determine the type of the target detection surface 40; and selecting one of the first distance information and the second distance information as the final distance information according to the type of the target detection surface 40.

[0079] In this embodiment, when the difference between the actual polarization extinction ratio of the light source 10 and the preset polarization extinction ratio of the light source 10 is greater than the preset threshold value, the first detection data output by the first detection element 60 and the second detection data output by the second detection element 70 are both involved in the calculation, that is, the first distance information is calculated according to the first detection data, and the second distance information is calculated according to the second detection data. Then, the actual polarization extinction ratio of the light source 10 is compared with the preset light source 10 polarization information list table to determine the type of the target detection surface 40. Finally, the corresponding selection rule is selected according to the type of the target surface, and the accurate distance information is finally calculated.

[0080] The preset light source 10 polarization information list table includes a correspondence between multiple sets of detection surface types and selection rules. Specifically, the selection rule corresponding to the type of the target detection surface 40 is matched in the preset light source 10 polarization information list table according to the type of the target detection surface 40; one of the first distance information and the second distance information is selected as the final distance information according to the matched selection rule; the selection rule is divided into two types: selecting closer distance information and selecting farther distance information.

[0081] For example, the type of the detection surface can be a highly reflective detection surface such as a water surface, a glass surface, a smooth ground, a transparent plastic surface, etc. Each detection surface will correspond to a selection rule. For example, by comparing the actual polarization extinction of the light source 10 with the preset light source 10 polarization information list table, it is determined that the target detection surface 40 is a water surface. Then, when the laser beam is irradiated to the water surface, the first part of the laser beam is reflected by the water surface (corresponding to the shorter distance information), and the second part passes through the water surface and encounters an obstacle and then reflects (corresponding to the longer distance information). At this time, two polarization states of echo beams are generated. The two polarization states of echo beams are received by the first detection element 60 and the second detection element 70, respectively, and the first detection data and the second detection data are generated. At this time, the detection data of the detection element that receives the second part of the reflected echo beam can be selected as the calculation basis according to the water surface selection rule, and the final distance information is calculated according to the detection data (that is, the longer distance information is selected as the final distance information).

[0082] It should be noted that the detection unit in this embodiment can adopt an existing detector, the control element can adopt a control device such as a single-chip microcomputer or FPGA, and calculating the detection distance based on the detection data is also an existing mature technology, and this embodiment does not make too many requirements here.

[0083] refer to Figure 7 An embodiment provides a laser radar detection method, which specifically includes the following steps:

[0084] Step 100: Control the light source 10 to emit a linearly polarized laser beam.

[0085] The light source 10 is turned on by a control element so that the light source 10 emits a polarized laser beam, and the laser beam is irradiated onto the target detection surface 40 through the optical path structure of the detection system.

[0086] Step 200: Control the scanning element 30 to deflect the transmission light beam and / or the reflected light beam split by the beam splitting element 20 to different areas of the target detection surface 40; and control the scanning element 30 to guide the echo light beam reflected by the target detection surface 40 to the beam splitting element 20. The beam splitting element 20 is arranged on the optical path of the laser beam, and is used to split the laser beam into a transmission light beam and a reflection light beam; the optical path where the transmission light beam is located is the transmission light path, and the optical path where the reflection light beam is located is the reflection light path; the beam splitting element 20 is also used to reflect the echo light beam generated by the target detection surface 40 of the transmission light path to the beam splitting element 50; and / or, the beam splitting element 20 is also used to transmit the echo light beam generated by the target detection surface 40 of the reflection light path to the beam splitting element 50; the beam splitting element 50 is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state, wherein the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam.

[0087] When the laser beam is irradiated to the target detection surface, it will pass through the scanning element 30. The control element can control the scanning element 30 to deflect the transmitted light beam to different areas of the target detection surface 40, or deflect the reflected light beam to different areas of the target detection surface 40, and control the scanning element 30 to guide the echo light beam reflected by the target detection surface 40 to the beam splitting element 20, and then the beam splitting element 20 emits the echo light beam to the beam splitting element 50. The beam splitting element 50 splits the echo light beam into a first echo light beam and a second echo light beam according to the polarization state, wherein the first echo light beam is received by the first detection element 60, and the second echo light beam is received by the second detection element 70.

[0088] Step 300: Acquire first detection data generated by the first detection element 60 due to receiving the first echo light beam, and acquire second detection data generated by the second detection element 70 due to receiving the second echo light beam.

[0089] The first detection element 60 and the second detection element 70 will generate a detection data respectively, and send the generated first detection data and second detection data to the control element, and the control element will perform the calculation process of step 400 according to the detection data.

[0090] In addition, before calculating the distance information based on the detection data, the detection data needs to be denoised and filtered.

[0091] Step 400: Determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset value of the light source, and generate a detection result for the target detection surface 40 according to the difference.

[0092] In this step, in view of the fact that the laser radar detection method of this embodiment adopts the laser radar detection system in the above-mentioned embodiment, and the specific implementation scheme of the control element generating the detection result of the target detection surface 40 according to the first detection data and the second detection data has been described in detail in the above-mentioned embodiment, this embodiment will not be elaborated here.

[0093] In addition, the control element scans the target detection surface 40 point by point by controlling the scanning element 30 on the transmitted light path, or the control element scans the target detection surface 40 point by point by controlling the scanning element 30 on the reflected light path; the detection data of each point is calculated by the above method, and finally the point cloud data is output.

[0094] By adopting the laser radar detection method of this embodiment, not only the probability of recognition errors is reduced and the detection dimension is increased, but also the recognition and detection of different types of obstacles can be effectively improved by comparing different polarization state data.

[0095] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A laser radar detection system, characterized in that: It includes a light source, a light splitting element, a scanning element, a beam splitting element, a first detection element, a second detection element and a control element; The light source is used to emit a linearly polarized laser beam; The beam splitter is arranged on the optical path of the laser beam, and is used to split the laser beam into a transmission beam and a reflection beam; the optical path where the transmission beam is located is the transmission optical path, and the optical path where the reflection beam is located is the reflection optical path; The scanning element is arranged on the transmission light path and / or the reflection light path; the scanning element is used to deflect the transmission light beam and / or the reflection light beam to different areas of the target detection surface; the scanning element is also used to guide the echo light beam reflected by the target detection surface to the spectroscopic element; The beam splitting element is also used to reflect or transmit the echo light beam to the beam splitting element; The beam splitting element is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state; the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam; The first detection element is used to receive the first echo light beam and generate first detection data according to the first echo light beam; The second detection element is used to receive the second echo light beam and generate second detection data according to the second echo light beam; The control element is electrically connected to the first detection element and the second detection element. The control element is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset polarization extinction ratio of the light source, and generate a detection result for the target detection surface according to the difference.

2. The laser radar detection system according to claim 1, characterized in that: A first optical path shaping element is arranged on the optical path between the light source and the beam splitting element, and the first optical path shaping element is used to collimate the laser beam.

3. The laser radar detection system according to claim 1 or 2, characterized in that: A second optical path shaping element is arranged on the optical path between the optical splitting element and the beam splitting element, and the second optical path shaping element is used to focus the echo light beam reflected or transmitted by the optical splitting element.

4. The laser radar detection system according to claim 1, characterized in that: The first echo light beam and the second echo light beam emitted by the beam splitting element are parallel to or perpendicular to each other.

5. The laser radar detection system according to claim 3, characterized in that: The system also includes a first polarization element and a second polarization element; The first polarizing element is disposed on the optical path between the light source and the beam splitting element, and is used to transmit the laser beam in the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source; The second polarization element is arranged on the optical path between the splitting element and the scanning element. The second polarization element is used to convert the laser beam in the main polarization direction transmitted or reflected by the splitting element into a circularly polarized laser beam, and is also used to convert the circularly polarized echo beam into a linearly polarized echo beam.

6. The laser radar detection system according to claim 5, characterized in that: The first polarization element includes a polarizer or a polarization beam splitter cube, and the second polarization element includes a quarter wave plate.

7. The laser radar detection system according to claim 3, characterized in that: The system further comprises a third polarizing element, a fourth polarizing element, and a fifth polarizing element; The third polarization element and the fourth polarization element are sequentially arranged on the optical path between the light source and the beam splitter, the third polarization element is used to transmit the laser beam in the main polarization direction; the fourth polarization element is used to convert the laser beam in the main polarization direction into a circularly polarized laser beam; the main polarization direction is the polarization direction of the laser beam emitted by the light source; The fifth polarization element is arranged on the optical path between the second optical path shaping element and the beam splitting element, and the fifth polarization element is used to convert the circularly polarized echo light beam into a linearly polarized echo light beam.

8. The laser radar detection system according to claim 7, characterized in that: The third polarization element includes a polarizer or a polarization beam splitter cube, and the fourth polarization element and the fifth polarization element each include a quarter wave plate.

9. The laser radar detection system according to claim 1, characterized in that: The control element is used to determine the difference between the detection signal value formed by the first detection data and the second detection data and the preset polarization extinction ratio of the light source, and generate a detection result for the target detection surface according to the difference, including: Obtaining an actual polarization extinction ratio of a light source according to the first detection data and the second detection data; Comparing the actual polarization extinction ratio of the light source with the preset polarization extinction ratio of the light source; If the difference between the actual polarization extinction ratio of the light source and the preset polarization extinction ratio of the light source is less than a preset threshold, the final distance information is output based on the detection data output by the detector of the received echo light beam consistent with the main polarization direction; the main polarization direction is the polarization direction of the laser beam emitted by the light source.

10. The laser radar detection system according to claim 9, characterized in that: When the first echo beam received by the first detection element is an echo beam consistent with the main polarization direction, the second echo beam received by the second detection element is a noise echo beam; or, When the second echo beam received by the second detection element is an echo beam with a main polarization direction consistent with that of the first detection element, the first echo beam received by the first detection element is a noise echo beam.

11. The laser radar detection system according to claim 9, characterized in that: The control element is also used to: When the difference between the actual polarization extinction ratio of the light source and the preset polarization extinction ratio of the light source is greater than a preset threshold, outputting first distance information and second distance information according to the first detection data and the second detection data respectively; Comparing the actual polarization extinction ratio of the light source with a preset light source polarization information list table to determine the type of the target detection surface; One of the first distance information and the second distance information is selected as final distance information according to the type of the target detection surface.

12. The laser radar detection system according to claim 11, characterized in that: The preset light source polarization information list table includes a correspondence between multiple groups of detection surface types and selection rules; The selecting one of the first distance information and the second distance information as the final distance information according to the type of the target detection surface includes: According to the type of the target detection surface, a selection rule corresponding to the type of the target detection surface is matched in the preset light source polarization information list table; One of the first distance information and the second distance information is selected as the final distance information according to the matched selection rule; the selection rule is divided into two types: selecting closer distance information and selecting farther distance information.

13. A laser radar detection method, characterized in that: The method comprises: Controlling the light source to emit a linearly polarized laser beam; Control the scanning element to deflect the transmitted light beam and / or the reflected light beam split by the beam splitting element to different areas of the target detection surface; and control the scanning element to guide the echo light beam reflected by the target detection surface to the beam splitting element; the beam splitting element is arranged on the optical path of the laser beam, and is used to split the laser beam into a transmitted light beam and a reflected light beam; the optical path where the transmitted light beam is located is the transmission light path, and the optical path where the reflected light beam is located is the reflection light path; the beam splitting element is also used to reflect or transmit the echo light beam to the beam splitting element; the beam splitting element is used to split the echo light beam into a first echo light beam with a first polarization state and a second echo light beam with a second polarization state according to the polarization state; the polarization state of one of the first echo light beam and the second echo light beam is consistent with the polarization state of the laser beam; Acquire first detection data generated by a first detection element due to receiving the first echo light beam, and acquire second detection data generated by a second detection element due to receiving the second echo light beam; The difference between the detection signal value formed by the first detection data and the second detection data and the preset polarization extinction ratio of the light source is determined, and a detection result for the target detection surface is generated according to the difference.

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