CN114442116A - Detection method and detection system - Google Patents
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Abstract
The invention discloses a detection method, which comprises the following steps: the device comprises a light emitting module, a processing module and a light receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; at least part of the receiving areas in the light receiving module receive the return light which is input by at least two transmitting areas and has different polarization angles and is reflected by the detected object, the receiving module corresponds to at least part of areas of the return light with different polarization angles, and the return light is excited by the return light with at least one polarization angle or the return light after being completely filtered out to generate a photo-generated electric signal; the processing module processes the photo-generated electric signal excited by the return light filtered by the receiving module to obtain the final target information of the detected object, so that the effect of reducing or eliminating the multipath interference phenomenon is realized, and the accuracy of the detection result is ensured.
Description
Technical Field
The present application relates to the field of laser radar detection technologies, and in particular, to a detection method and a detection system.
Background
With the technical development of Laser radar, Time of flight (TOF) has received more and more attention, the TOF principle is that light pulses are continuously transmitted to a target object, then a sensor is used to receive light returning from the object, and the distance to the target object is obtained by detecting the flight (round trip) Time of the light pulses, at present, many methods are adopted including direct Time-of-flight detection (mainly, the target distance is obtained by using the direct Time difference between transmitted Laser light and returned Laser light) and indirect Time-of-flight detection (mainly, the phase difference between the transmitted light and returned light is obtained, so that the final Time-of-flight is obtained by using the phase difference to calculate the distance to the target), at present, many Vertical-Cavity Surface-Emitting lasers (VCSEL for short) are adopted in a detection system, the Laser emission sources are a plurality of Laser emission units arranged in an array type, the laser source emits detection light, the detection light enters the detection unit after being reflected by a detected object and is further converted into photo-generated charges, and the target distance or the target image of the detected object is obtained through a signal processing circuit at the later stage to complete detection.
In the normal distance measurement process, the distance of the detected object can be obtained without contacting the object by using a direct or indirect flight time measurement method, when multipoint detection is adopted, the shape profile of the object can also be obtained through multipoint measurement, and the output of a three-dimensional image and the like can be realized by matching and post-processing, however, in the actual detection process, particularly in the distance measurement process, the emitted light of an array type light source needs to have a certain diffusion angle to ensure that the field range is sufficient, while the emitted light projected by the light source has a larger diffusion angle when the field range is ensured, in this case, the detected object in the field will be more complex, for example, the complex components of a road surface, obstacles, people and the like exist in the market in automatic driving, and for example, the ground, a wall corner, obstacles and the like exist in the market in the sweeping robot application, and for example, the field of a security camera exists on the ground, corner characters, etc., although the application scenarios are merely exemplary and not limited thereto. In this case, there is a possibility that there is a case where an obstacle a and an object B exist in the field of view, and there is a case where detection laser light emitted from a light source is reflected by the object B partially and returns to a detector, but there is a case where part of the emission light is reflected by the obstacle a and returns to the detector without being directly reflected by the object B, but returns to the detector after being reflected by the object B, and this phenomenon is particularly serious when a detection object of high reflection characteristics exists in the field of view, or when a detector carrier is located near a corner, and this phenomenon causes a false value of distance detection in an output result in a detector array, and interference of the detection result due to this phenomenon belongs to multipath interference in detection, and this phenomenon has a very serious constraint on application of the detector and realization of accurate detection, "CN 205621076U, a size marking system with multipath interference reduction' provides a method for improving and restricting the multipath interference phenomenon, which is realized by designing a self-adaptive adjusting structure of a light beam scene, such as an adjustable lens, detecting in a self-adaptive manner to obtain basic information of a field of view and further adjust a projection light beam of emitted light, so that the projection light output by a light source defines a diffusion angle, and projecting an object or an object of interest in a focused manner to obtain an accurate detection result, thereby eliminating the influence of the multipath phenomenon, the method has certain practicability, but has certain limitation on scenes in which multiple objects are concerned in the field of view, and meanwhile, when an image acquisition or processing method is required to be matched with a diffusion angle adjusting scheme, the complexity of the whole scheme is higher, and how to realize the realization that under the premise that the diffusion angle is enough to ensure that the field of view is enough, and the targeted emitted light can be output only for a specific area in a targeted manner, so that the constrained light beam in the prior art can perform the key projection on the interested article, and the scheme for reducing or eliminating the multipath phenomenon is a problem to be solved urgently.
Disclosure of Invention
The present application aims to provide a detection method and a detection system to design a technique capable of performing specific projection for different areas and using the technique to weaken or eliminate the multipath interference in the background art, in order to overcome the above-mentioned shortcomings in the prior art.
In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:
in a first aspect, an embodiment of the present application provides a detection method, including an optical transmitting module, a processing module, and an optical receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; at least part of the receiving areas in the light receiving module receive the return light which is input by at least two transmitting areas and has different polarization angles and is reflected by the detected object, the receiving module corresponds to at least part of areas of the return light with different polarization angles, and the return light is excited by the return light with at least one polarization angle or the return light after being completely filtered out to generate a photo-generated electric signal; and the processing module is used for processing according to the photo-generated electric signal excited by the filtered return light of the receiving module to obtain the final target information of the detected object.
Optionally, the emission light of the N emission regions corresponds to each region within the field of view, and there is an overlap region between at least part of two adjacent emission lights.
Optionally, the emission light of the N emission regions corresponds to a plurality of regions within a field of view, and at least part of the time period, one of the detected objects of one region within the field of view reflects at least part of the emission light having the first polarization angle to another detected object of another region.
Optionally, the filtered polarized angle returned light energy accounts for no less than 20% of the total polarized angle returned light energy.
Optionally, characterized in that the number N of light emitting mode emitting areas is an even number equal to or greater than 2.
Optionally, the number N of light emitting mode emitting regions is 4, and the polarization angles of the light emitted by the two diagonally arranged emitting regions are different by 90 °.
Optionally, the number N of light emitting mode emitting regions is 4, and the polarization angles of the light emitted by the two diagonally arranged emitting regions are different by 45 °.
In a second aspect, an embodiment of the present application provides a detection system, which is applied to the detection method in the first aspect, where the detection system includes:
the device comprises a light emitting module, a processing module and a light receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; at least part of the receiving areas in the light receiving module receive the return light which is input by at least two transmitting areas and has different polarization angles and is reflected by the detected object, the receiving module corresponds to at least part of areas of the return light with different polarization angles, and the return light is excited by the return light with at least one polarization angle or the return light after being completely filtered out to generate a photo-generated electric signal; and the processing module is used for processing according to the photo-generated electric signal excited by the filtered return light of the receiving module to obtain the final target information of the detected object.
Optionally, the emission light of the N emission regions corresponds to a plurality of regions within the field of view, and at least part of the time period, one of the detected objects of one region within the field of view reflects at least part of the emission light having the first polarization angle to another detected object of another region.
Optionally, the filtered polarized angle returned light energy accounts for no less than 20% of the total polarized angle returned light energy.
The beneficial effect of this application is:
the detection method provided by the embodiment of the application comprises a light emitting module, a processing module and a light receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; further comprising a polarization module located upstream of the light receiving module in a direction of the returning light; the polarization module comprises N polarization filtering areas corresponding to the transmitting module; at least one polarization filtering area in the polarization module receives return light which is output by at least two emission areas and has different polarization angles and is reflected by the detected object, the at least one polarization filtering area filters part or all of the return light with the at least one polarization angle, the receiving module receives the return light filtered by the polarization module and outputs an excited photo-generated electric signal, and the processing module obtains target information of the detected object finally according to the photo-generated electric signal, so that the design can ensure that when the detection method is applied to object distance acquisition, a detector emission light source is divided into N different areas, and emission light of every two adjacent emission areas has different polarization angles, which is equivalent to the division of a light emitting source VCSEL array, and every two adjacent emission areas have different polarization angles, therefore, the light output by the two adjacent light emitting areas has different polarization angles, so that the light emitted by each area has certain recognizable characteristics, which is equivalent to the characteristic that the irradiation area of the emitted light in the comparison file is limited, the emitted light projection field of view of each area can be changed into 1/N of the whole field of view by setting N areas, and meanwhile, the N emitting areas form the complete field of view.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic block diagram of a detection system according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram illustrating an influence of multipath interference on detection according to an embodiment of the present application;
fig. 3 is a schematic diagram illustrating a detection result in the presence of multipath interference according to an embodiment of the present application;
fig. 4 is a schematic diagram of another multipath interference phenomenon provided in the embodiment of the present application;
FIG. 5 is a schematic diagram and a simplified diagram of a polarization structure according to an embodiment of the present disclosure;
fig. 6 is a schematic diagram of a system for implementing multipath mitigation at a transmitting end and a receiving end according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of a system for implementing multipath mitigation by a transmitting end and a polarization part located in at least one image plane according to an embodiment of the present application;
fig. 8 is a schematic diagram of signals received by four regions of the receiving end A, B, C, D when the multipath effect is not considered at all according to the embodiment of the present application;
fig. 9 is a schematic diagram of signals received by four areas of the receiving end A, B, C, D when considering multipath interference according to an embodiment of the present application;
fig. 10 is a schematic diagram of signals received by four regions of the receiving end A, B, C, D after reducing multipath effects by using polarization selective pixels according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Fig. 1 is a schematic block diagram of a detection system according to an embodiment of the present disclosure. As shown in fig. 1, the detecting device includes: the light emitting module 110, the processing module 120, and the light receiving module 130 are described by taking ITOF ranging as an example, the light emitting module 110 emits a sine wave, a square wave, a triangular wave, or the like, in a ranging application, most of the emitted light is laser light with a certain wavelength, for example, infrared laser light with 950nm or the like, the emitted light is projected into a field of view, the projected laser light can be reflected by an object to be detected 150 existing in the field of view to form return light, the return light enters a detection system to be received by the light receiving module 130, the light receiving module may include a photoelectric conversion portion, for example, an array type sensor composed of CMOS, CCD, or the like, and may further include a plurality of lenses capable of forming more than one image plane, that is, the receiving module includes more than one image plane, the photoelectric conversion portion of the receiving module is located at one of the image planes, and the photoelectric conversion portion of the receiving module may be received by a four-phase scheme, which may obtain 0 °, (iii) degree) when the receiving module receives the received by the four-phase scheme, The delayed received signals of 90 °, 180 ° and 270 ° are illustrated here in a sine wave method using a four-phase distance calculation scheme, and the amplitude of the received signal is measured at four equidistant points (e.g., intervals of 90 ° or 1/4 λ):
the ratio of the difference between a1 and A3 to the difference between a2 and a4 is equal to the tangent of the phase angle. ArcTan is in fact a bivariate arctangent function, which can be mapped to the appropriate quadrant, defined as 0 ° or 180 ° when a2 ═ a4 and a1> A3 or A3> a1, respectively.
The distance to the target is determined by the following formula:
the distance measurement is carried out by determining the frequency of the emitted laser, where c is the speed of light,
is the phase angle (measured in radians) and f is the modulation frequency. The above-mentioned solution can achieve the effect of detecting the distance of the detected object in the field of view, that is, the existence of the interference of the light returning to the target through other paths as shown in fig. 2 to the ranging signal, thereby generating the error and interference to the actual ranging result. As shown in fig. 2, the normal path is light source (a) → target (B) → receiving end (C), at which time the waveform, hair are receivedThe temporal relationship between the firing waveforms is shown in fig. 2. When other objects near the target B reflect the signal light for multiple times, an extra path is generated, i.e., light source (a) → reflector (D) → target (B) → receiving end (C) in fig. 2. Fig. 3 illustrates the multi-path and the influence on the waveform, in which (1) is the signal light emitted by itself, (2) the echo received by the normal path (a → B → C), (3) the echo generated by the extra path (a → D → B → C), and (4) the echo effect received by the normal path and the extra path. In the scenario of fig. 1, since there is a plurality of reflections in the moving path of the light and the optical path is increased by a distance, an echo signal with a relatively low intensity and a relatively late timing sequence is generated at the received signal end. When the test is performed by the integration method, certain interference is generated on the charge quantity obtained by different integrations through integration, so that interference is generated on the actual ranging result, and the accuracy of the result is influenced.
According to the scheme mentioned in the background technology, the key projection is carried out through the pre-identification of the key area, so that the interference area can be prevented from being projected to identify the multipath interference, and further the detection result with the multipath interference eliminated can be obtained. However, there are problems of efficiency and complexity in the comparison file. Therefore, a scheme capable of targeted transmission is designed to be beneficial to reducing or eliminating multipath interference, a partition transmission scheme is provided in the previous research to solve the problem, the submitted Chinese patent '202011040936.9-a flight time distance measuring device and method' describes a scheme for forming distance information of a detected object with a complete view field by partitioning a transmitting terminal, then performing time-division transmission and then combining the distance information of the detected object with the complete view field in a synthesis mode, the scheme overcomes the characteristic of a comparison file of the background technology on the limitation of the view field, and the mode is entered by means of manual selection, self-adaptation and the like, so that a feasible scheme for eliminating the multipath interference problem in the requirement of a large view field is realized. In order to further ensure efficient and continuous elimination and reduction of multipath interference, the present invention has made further intensive research, and in the ranging process of a common TOF sensor, if both the transmitting end and the receiving end are actually divided into N regions (where N is an integer greater than or equal to 2), the regions are in conjugate relation in a set of imaging systems, that is, it is necessary to make real images of the light emitted from the region a of the transmitting end on the region a of the receiving end through a receiving system (the receiving system herein includes not only lens imaging, pinhole imaging, etc.). That is to say, when the emitting end is artificially divided into N different regions in the whole field of view, the emitted light of the N emitting end regions will correspond to the N regions in the field of view, and during normal detection, the receiving end will also correspondingly receive the reflected return light in each different field of view due to imaging correspondence, that is, the receiving end is also correspondingly divided into N regions, and if multipath interference is introduced, as further explained in conjunction with fig. 4, the emitting end in fig. 4 is regarded as a combination of A, B, C, D four regions. In this way, the problem of multipath interference is reanalyzed, at this time, if the detector 1 exists in the D region in the field of view and the detector 2 exists in the a region, and the detector 3 exists in the a region, that is, at this time, the laser emitted from the D region at the emitting end is projected to the D region in the field of view, the laser may be emitted from the detector 1, one of the possible directions is the detector 2, and the laser may also be reflected to the detector 3, in this scenario, because the detector 1 and the detector 2 are within the same emitting region D, the interference caused by reflection is weaker, the interference to the distance information that we need to obtain finally is smaller, and at the same time, the difference can be further weakened by the number of more divided emitting regions N, and in this case, the multipath interference across the regions becomes an important reason for affecting the accuracy of the detection result. In this scenario, the original correct reflected return light is <2>, but since the laser light reflected by the detector 1 in the D region enters the a region, the reflected light returned at the same time also includes multi-path interference light <1> caused by the multi-path reflection in the field of view, that is, during at least a part of the time period, the emitted light of at least two different emitting regions is reflected back to the receiving end pointing to the same region, and the technical idea of taking care of the comparison document is that if the regions with different emitting ends are designed as light sources with different characteristics, for example, by using polarization characteristics, each emitting region is set as an emitting region with different polarization angles, and the emitted light of each two adjacent emitting regions has different polarization angles, so that the detection regions in the field of view are distinguished, that is, by setting N regions, the field of projection of the emitted light of each region can be changed to 1/N of the whole field of view, meanwhile, the N emitting areas form a complete field of view, so that the scheme can be used for realizing the aim of projecting on the premise of ensuring the detection field of view range, further, in order to ensure the accuracy of the measurement result, two adjacent areas can be provided with overlapping areas, so that the result of the whole detector array can be ensured to be accurate and integral, a corresponding polarization filtering structure is arranged on a light path between returning light and a receiving end or on the receiving end directly, as shown in figure 5, so that the key identification of the reflected returning light corresponding to the directional emitting light is realized, the key object detection of a key area is realized, the technical effect of multi-path interference can be weakened or even eliminated, the effect of synthesizing the result by multiple detection is avoided, and the scheme can be used with the prior subarea emitting scheme without limitation, of course, the above-mentioned figures are also only exemplary, in practical implementation, 4 regions may be used, 8 regions may be used, 6 regions may be used, and the like, and N is an even number greater than or equal to 2, so that the reliability of the partition is achieved, it is not limited that the arrangement rule is that the emergent light of two adjacent emission regions has different polarization angles, and further, the polarization angle difference between the emergent light of two adjacent emission regions is not less than 45 °.
Fig. 6 is a polarizer structure, which cooperatively divides the light source into four different regions, and the array type emitting end system is collectively referred to as a VCSEL + diffuser light emitting system, a polarizer with the size of diffuser can be placed on the diffuser, N regions are divided on the polarizer according to the requirement of the emitting end region, each region has a different polarization direction, the polarization direction of the different regions of the polarizer is the same as the system design, of course, the polarizer can be designed into a changeable type, for example, the polarizer can be output with different polarization angles by voltage control, or can be arranged according to the actual requirement under the condition that the polarization angles of the emitted light from the two diagonally arranged emitting regions are different by 90 degrees or the polarization angles of the emitted light from the two diagonally arranged emitting regions are different by 45 degrees, or the polarization angles of the different regions can be set or adaptively adjusted when the polarization module has an adjustable function, the implementation mode of polarization is not limited here, and certainly, the polarization setting does not necessarily adopt four combinations of 0 °, 45 °, 90 ° and 180 °, and the other polarization angles can also achieve the effect of the present invention, and it is necessary to ensure that the proportion of the filtered return light energy of the polarization angle to the total return light energy of the polarization angle is not less than 20%, so as to achieve the effect of reducing the influence on polarization.
The polarization processing at the receiving end is a way to distinguish the multipath influence by matching with the transmitting end, the processing of the pixel is to add a layer of line grating on the pixel, and other parameters such as the material, period, groove width and the like of the grating are determined according to the wavelength used by the signal light. The line grating has the main function of completely or partially filtering out light which is not matched with the polarization direction of the emitted light in the corresponding area, namely at least one of the receiving modules receives the returned light which is output by at least two emitting areas and has different polarization angles, and interference light caused by the multipath phenomenon of the polarization angles which are not corresponding to the area can be completely or partially filtered out by utilizing the grating.
Fig. 6 shows that the receiving end and the transmitting end are divided into four regions by matching with the polarization of the transmitting end, the same N regions are also arranged at the receiving end, the polarization angles of every two adjacent regions are different, wherein the polarization directions of the four regions are as shown in fig. 6, it can be seen that the four regions respectively adopt four different polarized emissions, then the corresponding four regions also adopt corresponding polarized reception, certainly, a polarization part can be arranged in the light path from the returning light to the receiving end, in the receiving optical system, one or more image planes capable of forming real images are formed between the object to be measured and the photoelectric sensor array by optical elements (including elements or modes such as lenses, lens groups, zone plates, fresnel lenses, pinhole imaging, etc.), the relationship of the image planes is as shown in fig. 7, one of the image planes is selected as a polarization selection, a sub-area polarization filter (including but not limited to a polarizer, an 1/2 wavelength plate, a liquid crystal light modulator, etc.) is placed on the image plane to match the sub-area position and direction of the emitted light modulation polarization. When the received light passes through the polarization filter, the light component different from the polarization direction of the filter is greatly reduced. The method can effectively reduce the light which is not emitted from the transmitting terminal subarea corresponding to the area on the photoelectric detector, effectively reduce the error of the multipath effect on the ITOF ranging, and ensure the original setting without performing various special treatments on the receiving terminal.
In a target system as shown in fig. 4, it is assumed that at least one region will have 10% of the light cross-talk to other regions (or each region will have 10% of the light cross-talk to other regions), and the light is reflected back to the region corresponding to the receiving end. In the target system with four regions, the reflectivity and crosstalk ratio correspondence of different regions is shown in table 1.
TABLE 1 transmittance of different polarization selective pixels with different polarizations
| Direction of |
0° | 45° | 90° | 135° |
| 0° | 100％ | 50％ | 1％ | 50％ |
| 45° | 50％ | 100％ | 45％ | 1％ |
| 90° | 1％ | 50％ | 100％ | 50％ |
| 135° | 50％ | 1％ | 50％ | 100％ |
As can be seen from the results in the above table, by the solution of the present invention, the proportion of the polarization angle returning light to other areas of the crosstalk to be filtered, which is caused by the multipath interference phenomenon, to the total polarization angle returning light is not less than 50%, so that the effect of reducing or eliminating the multipath interference problem is achieved.
Assume that 10% of the light in each area will cross-talk to the other areas and reflect back to the area corresponding to the receiving end. When the polarization type receiving end of fig. 5 is adopted or a similar manner of fig. 6 is adopted to arrange a polarization part on at least one phase plane in the optical path, an actual multipath effect result table under the multipath effect as the following table 2 can be obtained.
TABLE 2 reflectivity of different target multipath effects
| Region(s) | A | B | C | D |
| Reflectivity of light | 90％ | 70％ | 80％ | 85％ |
| A | - | 10％ | 10％ | 5％ |
| B | 10％ | - | 5％ | 10％ |
| C | 10％ | 5％ | - | 10％ |
| D | 5％ | 10％ | 10％ | - |
When the return is made after the time delay of the flight is assumed to be 20ns, the area delay results under the influence of the multipath phenomenon in different areas can be obtained, as shown in the following table 3.
TABLE 3 reflectivity of different target multipath effects
| Region(s) | A | B | C | D |
| Optical retardation | 20ns | 20ns | 20ns | 20ns |
| A | - | 4ns | 4ns | 5.66ns |
| B | 4ns | - | 5.66ns | 4ns |
| C | 4ns | 5.66ns | - | 4ns |
| D | 5.66ns | 4ns | 4ns | - |
Further, the measurement results of the whole system are counted to obtain the final statistical result of the optical path difference caused by the multipath as shown in table 4 below.
TABLE 4 optical path difference of multipath in different areas
| Region(s) | A | B | C | D |
| Optical retardation | 3m | 3m | 3m | 3m |
| A | - | 0.6m | 0.6m | 0.85m |
| B | 0.6m | - | 0.85m | 0.6m |
| C | 0.6m | 0.85m | - | 0.6m |
| D | 0.85m | 0.6m | 0.6m | - |
When no crosstalk occurs, the received signals of the four areas of the receiving end A, B, C, D or the four different receiving areas corresponding to the return light filtered by a single image plane polarizer are respectively as shown in fig. 8, and when the multipath crosstalk effect is considered, the total signals received by the four areas of the receiving end A, B, C, D are respectively as shown in fig. 9 (the polarization filtering scheme is not adopted). After the pixels received by polarization are used, the total signals received by the four areas of the receiving end A, B, C, D are respectively as shown in fig. 10, and it can be seen from the results in the above two figures that interference caused by multipath has a certain influence on the waveform, which also provides an identifiable technical scheme for other post-processing schemes, and for different situations, the result is calculated under the existing assumption, and the ranging results after multipath interference is reduced by taking the multipath effect into account, taking the multipath effect into account and adopting polarization selection pixels without performing interference cancellation operation are summarized as shown in table 5.
TABLE 5 comparison of ranging results under different conditions
| A | B | C | D | |
| Without multiple paths | 3m | 3m | 3m | 3m |
| With multiple paths | 3.1976m | 3.2467m | 3.2213m | 3.2073m |
| Error rate | 6.56％ | 8.22％ | 7.38％ | 6.91％ |
| Ranging results after polarization selective reduction of multipath | 3.0828m | 3.1040m | 3.0914m | 3.0839m |
| Error rate | 2.76％ | 3.47％ | 3.05％ | 2.80％ |
From the above results, it can be seen that by using the present invention, after filtering at least 50% of the multipath interference light of at least one polarization angle in at least one region, the error due to the multipath phenomenon is significantly reduced, and the multipath interference is not limited to occur in one plane in the actual use process.
In summary, the method of the invention achieves at least the following technical effects:
1) the ranging error caused by the multipath effect can be greatly reduced;
2) redundant modulation operation is not needed to be carried out on the transmitting end and the receiving end;
3) the change can be made by changing the polarizing film of the transmitting end and the receiving end.
It is to be noted that 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 an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A method of probing, comprising:
the device comprises a light emitting module, a processing module and a light receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; at least part of the time period, at least part of receiving areas in the light receiving module receive return light which is input by at least two transmitting areas and has different polarization angles and is reflected by the detected object, and the receiving module corresponds to at least part of areas of the return light with different polarization angles and is excited by the return light with at least one polarization angle or the return light after being completely filtered out to generate a photo-generated electric signal; and the processing module is used for processing according to the photo-generated electric signal excited by the filtered return light of the receiving module to obtain the final target information of the detected object.
2. The detection method according to claim 1, wherein the emission light of the N emission regions corresponds to respective regions within the field of view, and there is an overlapping region of at least some adjacent two emission lights.
3. The detection method according to claim 1, wherein the emission light of the N emission regions corresponds to a plurality of regions within a field of view, and at least part of the time period, one of the detected objects of one of the regions within the field of view reflects at least part of the emission light having the first polarization angle to another detected object of another region.
4. A detection method according to claim 1, wherein the filtered polarized angle return light energy is no less than 20% of the total polarized angle return light energy.
5. The detection method according to claim 1, wherein the number N of the light emission mode emitting regions is an even number equal to or greater than 2.
6. The detection method according to claim 1, wherein the number of the light emitting mode emitting regions N is 4, and the polarization angles of the light emitted from the diagonally arranged two emitting regions are different by 90 °.
7. The detection method according to claim 1, wherein the number of the light emitting mode emitting regions N is 4, and the polarization angles of the light emitted from the diagonally arranged two emitting regions are different by 45 °.
8. A detection system for performing detection using the detection method of claim 1, comprising: the device comprises a light emitting module, a processing module and a light receiving module; the light emitting module comprises N emitting regions (wherein N is an integer greater than or equal to 2), and the emitting light of every two adjacent emitting regions has different polarization angles; at least part of the receiving areas in the light receiving module receive the return light which is input by at least two transmitting areas and has different polarization angles and is reflected by the detected object, the receiving module corresponds to at least part of areas of the return light with different polarization angles, and the return light is excited by the return light with at least one polarization angle or the return light after being completely filtered out to generate a photo-generated electric signal; and the processing module is used for processing according to the photo-generated electric signal excited by the filtered return light of the receiving module to obtain the final target information of the detected object.
9. The detection system according to claim 8, wherein the emission light of the N emission regions corresponds to a plurality of regions within a field of view, one of the detected objects of one of the regions within the field of view reflecting at least part of the emission light having the first polarization angle to another detected object of another region at least part of the time period.
10. The detection system of claim 8, wherein the filtered polarized return light energy is no less than 20% of the total polarized return light energy.
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