CN115877396A - Laser radar ranging method and laser radar system - Google Patents
Laser radar ranging method and laser radar system Download PDFInfo
- Publication number
- CN115877396A CN115877396A CN202111141316.9A CN202111141316A CN115877396A CN 115877396 A CN115877396 A CN 115877396A CN 202111141316 A CN202111141316 A CN 202111141316A CN 115877396 A CN115877396 A CN 115877396A
- Authority
- CN
- China
- Prior art keywords
- distance
- receiving
- laser
- determining
- alternative
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000002592 echocardiography Methods 0.000 claims abstract description 38
- 238000002310 reflectometry Methods 0.000 claims description 48
- 238000001914 filtration Methods 0.000 claims description 19
- 230000005540 biological transmission Effects 0.000 claims description 16
- 230000000007 visual effect Effects 0.000 claims description 13
- 238000005259 measurement Methods 0.000 abstract description 26
- 238000013461 design Methods 0.000 abstract description 18
- 230000006872 improvement Effects 0.000 abstract description 3
- 238000012545 processing Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 9
- 230000008094 contradictory effect Effects 0.000 description 3
- 230000002452 interceptive effect Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
- G01S17/14—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Abstract
The invention discloses a laser radar ranging method and a laser radar system. The method mainly comprises the following steps: the emitting system emits laser beams according to the emitting intervals; the nth receiving system receives echoes of the (N + N) th laser beam emitted by the emitting system in a receiving window which is larger than the emitting interval and not larger than N emitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; m is a natural number; and finally, determining a distance measurement result according to the echo receiving results of the N receiving systems. The invention realizes the improvement of the maximum measurement distance and the reduction of the design complexity of a radar system on the premise of not reducing the resolution ratio and the frame rate of the point cloud.
Description
Technical Field
The invention relates to the technical field of radars, in particular to a laser radar ranging method and a laser radar system.
Background
In the laser radar system, from the aspect of system design, the maximum measurement distance of each scanning point is limited by the resolution and the number of frames of the point cloud, the total number of lasers and the like, wherein the maximum measurement distance is basically in an inverse relation with the resolution and the number of frames of the point cloud, and therefore the laser radar system has the problem that the maximum measurement distance is contradictory to the resolution and the frame rate of the point cloud.
In the prior art, although the maximum measurement distance can be increased under the condition of not changing the resolution ratio of point clouds and not reducing the number of frames by increasing the number of lasers, the complexity of system design can be increased, and meanwhile, difficulty is brought to later-stage point cloud splicing and calibration.
Disclosure of Invention
Based on the above reasons, embodiments of the present invention provide a laser radar ranging method and a laser radar system, which solve the problem in the prior art that the number of lasers is increased to increase the maximum measurement distance, which increases the complexity of system design.
A first aspect of this embodiment provides a laser radar ranging method, including:
the emitting system emits laser beams according to the emitting intervals;
the nth receiving system receives the echo of the nth + N x m laser beams transmitted by the transmitting system in a receiving window which is larger than the transmitting interval and not larger than N transmitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; m is a natural number;
and determining a ranging result according to the echo receiving results of the N receiving systems.
Optionally, the receiving view angle of the receiving system is set according to the emitting view angle of the laser beam, wherein different receiving view angles receive echoes of the laser beam at different emitting view angles.
Optionally, the determining a ranging result according to the echo receiving results of the N receiving systems includes:
determining a corresponding alternative distance according to each echo signal received by the nth receiving system;
determining whether each alternative distance meets a preset condition;
and filtering the alternative distance which does not meet the preset condition to obtain a ranging result in the receiving time window of the nth receiving system.
Optionally, the determining whether each candidate distance satisfies a preset condition includes:
performing difference operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance difference value, and performing sum operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance sum value;
determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: the reflectivity of laser emitted by the laser radar passing through the alternative distance;
determining a second upper limit according to the alternative distance and the maximum reflectivity of the laser, and determining a second lower limit according to the alternative distance and the minimum reflectivity of the laser;
and if the signal intensity corresponding to the alternative distance is between the first upper limit and the first lower limit, and the signal intensity corresponding to the alternative distance is between the second upper limit and the second lower limit, determining the signal intensity corresponding to the alternative distance to meet the preset condition.
Optionally, the laser parameters of the laser beams of two adjacent emission points are different;
the determining a ranging result according to the echo receiving results of the N receiving systems includes:
filtering echoes different from the laser parameters received by the nth receiving system according to the laser parameters of the (N + N) th laser beam to obtain residual echoes received by the nth receiving system;
and determining a ranging result according to the residual echo received by the nth receiving system.
Optionally, the laser parameter includes at least one of:
the number of pulses contained in a single emission of a laser beam;
the pulse time interval of adjacent pulses in the laser beam.
A second aspect of the present embodiment provides a lidar system comprising: a transmitting system and N receiving systems;
the emission system is used for emitting laser beams according to emission intervals;
the nth receiving system is used for receiving the echo of the nth + N x m laser beams emitted by the emitting system in a receiving window which is larger than the emitting interval and not larger than N emitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; m is a natural number;
and the nth receiving system is also used for determining a distance measuring result according to the echo receiving result.
Optionally, the receiving view angle of the receiving system is set according to the emitting view angle of the laser beam, wherein different receiving view angles receive echoes of the laser beam at different emitting view angles.
Optionally, the nth receiving system is specifically configured to:
determining a corresponding alternative distance according to each echo signal received by the nth receiving system;
determining whether each alternative distance meets a preset condition;
and filtering the alternative distance which does not meet the preset condition to obtain a ranging result in the receiving time window of the nth receiving system.
Optionally, the nth receiving system is specifically configured to:
performing difference operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance difference value, and performing sum operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance sum value;
determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: the intensity of laser light emitted by the laser radar reflected back through the alternative distance;
determining a second upper limit according to the alternative distance and the maximum reflectivity of the laser, and determining a second lower limit according to the alternative distance and the minimum reflectivity of the laser;
and if the signal intensity corresponding to the alternative distance is between the first upper limit and the first lower limit, and the signal intensity corresponding to the alternative distance is between the second upper limit and the second lower limit, determining the signal intensity corresponding to the alternative distance to meet the preset condition.
Optionally, the laser parameters of the laser beams of two adjacent emission points are different;
the nth receiving system is specifically configured to:
filtering echoes different from the laser parameters received by the nth receiving system according to the laser parameters of the (N + N) th laser beam to obtain residual echoes received by the nth receiving system;
and determining a ranging result according to the residual echo received by the nth receiving system.
Optionally, the laser parameter includes at least one of:
the number of pulses contained in a single emission of a laser beam;
the pulse time interval of adjacent pulses in the laser beam.
The invention has the advantages of
In the laser radar ranging method of the embodiment, the transmitting system transmits laser beams according to transmitting intervals, the nth receiving system receives echoes of the (N + N) th laser beams transmitted by the transmitting system in receiving windows which are larger than the transmitting intervals and not larger than the N transmitting intervals, and further the measuring time of ranging is prolonged, so that a single laser beam can still be detected after being reflected by an object at a far position, and the maximum measuring distance of the laser radar is increased; in addition, the embodiment does not need to increase the number of emitting devices or lasers, that is, under the condition of not changing the resolution and the frame rate of the point cloud, the problem that the maximum measurement distance and the resolution and the frame rate of the point cloud are contradictory to each other in the laser radar system is solved, the maximum measurement distance is increased, and the complexity of system design is reduced.
Drawings
Fig. 1 is a schematic diagram of an implementation process of a laser radar ranging method according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a specific implementation flow of step S13 in fig. 1.
Fig. 3 is a schematic diagram of a specific implementation flow of step S22 in fig. 2.
Fig. 4 is a schematic diagram of another specific implementation flow of step S13 in fig. 3.
Fig. 5 is a schematic diagram of signal reception performed by a conventional lidar system according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of signal reception performed by the laser radar ranging method according to the embodiment of the present invention.
Fig. 7 is a schematic diagram of an overlapping area in a signal of a receiving system according to an embodiment of the present invention.
Fig. 8 is a schematic structural diagram of a laser radar system according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems and methods consistent with certain aspects of the invention, as detailed in the appended claims.
Fig. 1 is a flow chart illustrating a lidar ranging method according to an exemplary embodiment, as shown in fig. 1, including the following steps.
In step S11, the emission system emits a laser beam at emission intervals.
The laser radar ranging method of the embodiment may be applied to any laser radar, such as a laser radar for scanning by a Micro-Electro-Mechanical System (MEMS) and Mechanical rotation scanning.
In designing a lidar system, the maximum measurement distance of each scanning point in the lidar is limited by the resolution of the point cloud, the number of frames of the point cloud, and the total number of lasers. For example, if the frame number of the laser radar point cloud is M frames/second, the resolution of the point cloud is L a ·L e When the total number of the lasers is K, the point cloud number responsible for the single laser is K
It can then be calculated that the maximum measurement time period for each point is ^ greater than>
Second, so that the maximum measurement distance is
Wherein L is a Is the number of upward points of the scanning point, L e The number of azimuth points of the scanning point is C, and the speed of light is C. It can be seen that, when designing a radar system, the frame number and resolution ratio of the farthest distance measurement and the point cloud are basically in an inverse relation, although the maximum measurement distance can be increased by increasing the number of lasers under the condition of not changing the resolution ratio of the point cloud and reducing the frame number, the complexity increase in the system design can be brought, and meanwhile, difficulties are brought to the later point cloud splicing, calibration and the like.
Therefore, the design method of multiple sets of independent receiving systems is adopted in the embodiment, the problem that the maximum measuring distance is shortened due to the fact that the distance measuring time period of a single point is not long enough in distance measuring is avoided, and meanwhile complexity of the laser radar in design is reduced. Specifically, the transmitting system can transmit a plurality of laser beams to form a point cloud when performing laser scanning on a target, and the laser beams are transmitted according to the transmitting period according to the sequence of laser transmitting points in the embodiment, so that the laser radar system does not need to design a plurality of transmitting systems, and the complexity of radar system design is reduced.
Here, the emission interval refers to an emission time interval of adjacent laser beams, and for example, the emission system emits one laser beam every 0.01 second. The laser emission points may be illuminated in the sequence 1,2,3,4 … …, as in fig. 5 to 7, according to the emission interval; the 1,2,3,4 … … can be understood as a point number on a point cloud of a laser radar, namely, a point number marked according to a light emitting sequence, and a laser emitting sequence is directly related to a resolution.
The laser beam of this embodiment may be light pulses, with the emission system emitting light pulses at emission intervals.
In step S12, the nth receiving system receives echoes of the (N + N × m) th laser beam emitted by the emitting system in a receiving window which is greater than the emitting interval and not greater than N emitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; and m is a natural number.
Here, the receiving window greater than the transmitting interval and not greater than N transmitting intervals refers to a time length in which the nth receiving system receives the echo of the N + N × m laser beams transmitted by the transmitting system, where m is the number of the time length, and optionally, the time length of the receiving window may be N transmitting intervals.
Illustratively, the radar system includes one transmitting system and 4 receiving systems. The transmitting point of the transmitting system is 100, that is, the transmitting system transmits 100 beams of laser according to the transmitting interval, and 4 receiving systems receive the 100 beams of laser, so that for the number 1-100 transmitting points, the receiving system corresponding to each point respectively circulates in sequence 1,2,3,4,1,2,3,4. For another example, as shown in fig. 6 and 7, the radar system includes 2 receiving systems, the laser beam at point 1 is received by receiving system a, the laser beam at point 2 is received by receiving system B, the laser beam at point 3 is received by receiving system a, and the laser beam at point 4 is received by receiving system B, and the operations are sequentially cycled, that is, the laser beams at adjacent transmitting points are received by different receiving systems.
Here, the time window of the N-th receiving system for receiving the N + N × m laser beam is determined according to the start time of the N + N × m laser beam. For example, to ensure successful reception of the echo of the (N + N) th laser beam, the start of the time window is equal to or earlier than the time required for the emission of the (N + N) th laser beam. This ensures that objects 0m from the lidar system are successfully measured.
Optionally, if the number of the transmitting points and the number of the receiving systems are not in a multiple relationship, when the number of the last N laser beams is not enough, the following steps are still performed: the nth receiving system receives the echo of the nth + N x m laser beams; wherein N is the number of receiving systems, and N is more than or equal to 2; n is a positive integer less than or equal to N; m is a natural number, that is, the transmitting point is matched with N as a divisor, and different point numbers are allocated with respective receiving systems to process according to different remainders, for example, a radar system includes 6 receiving systems, the transmitting point of the transmitting system is 100, and then for transmitting points 1 to 100, the receiving systems corresponding to each point are respectively used for receiving in the sequence of 1,2,3,4,5,6,1,2,3,4,5,6 and … … 1,2,3,4,5,6,1,2,3,4.
In step S13, a ranging result is determined according to echo reception results of the N reception systems.
For example, referring to fig. 8, the radar system may include a transmitting system and N receiving systems, where the transmitting system transmits laser beams according to a transmitting interval, the nth receiving system receives echoes of an N + N × m laser beam transmitted by the transmitting system in a receiving window that is greater than the transmitting interval and not greater than N transmitting intervals, N is a positive integer less than or equal to N, and m is a natural number; and then the nth receiving system determines a ranging result according to the echo receiving result. It should be understood that the number of the receiving systems is not limited in particular in this embodiment, and is at least two, so that adjacent laser beams are received by different receiving systems.
This embodiment is under the prerequisite that does not change transmitting system hardware configuration, only carry out many sets of redundant receptions to the system of receiving terminal, through the system mapping that changes the receiving terminal, adopt many sets of independent receiving system to carry out the echo of independent receipt difference promptly, can realize that every point measuring time on the point cloud prolongs, so single laser beam still can be detected after being reflected back by the object of remote department, and then realize promoting the maximum measuring distance under the condition of not changing point cloud resolution ratio and reducing the frame number, complexity in the radar system design is reduced.
Further, as shown in fig. 5, the original transmitting and receiving logic of the conventional laser imaging radar is that after each point is transmitted, the corresponding echo starts receiving processing, and the receiving window continues until the light-emitting time of the next point, so that the measuring time is short. Although the method of this embodiment prolongs the measurement time, the measurement start time and the measurement end time between the points may have time overlap, so the logic of the control transmitting system and the algorithm improvement of the data processing end are needed to realize the distance resolution of the adjacent points, and the problem of the range finding ambiguity caused by the time overlap is solved.
Illustratively, taking two independent receiving systems as an example, the two independent receiving systems receive the laser light of the transmitting point in a differentiated manner, for example, an odd-even point manner is used to map different receiving systems for data processing and analysis, an odd point is processed by the receiving system a, and an even point is processed by the receiving system B, as shown in fig. 6, the laser light of point 1 is received by the receiving system a, the laser light of point 2 is received by the receiving system B, the laser light of point 3 is received by the receiving system a, and the laser light of point 4 is received by the receiving system B, and the process is cycled in sequence, that is, under the condition that the light emitting time sequence does not change, the distribution of the receiving systems at different points is adjusted to realize the extension of the measuring time of each point, thereby realizing the extension of the maximum measuring distance.
However, the system may have a problem of distance ambiguity in processing, that is, a plurality of distances may be measured according to the echo of each receiving system, as shown in fig. 6, the measurement of point 1 is responsible for receiving system a, and the measurement of point 2 is responsible for receiving system B, but within the measurement time window of point 1, there may be a time when point 2 is emitted, that is, the measurement time window of point 2 and the measurement time window of point 1 overlap, and the overlapping region is shown in fig. 7. In the receiving overlapping area, echoes of point 1 and point 2 exist at the same time, and for this case, the present embodiment may adopt a plurality of methods to avoid or distinguish.
In one embodiment, the receiving view angle of the receiving system is set according to the emitting view angle of the laser beam, wherein different receiving view angles receive echoes of the laser beam of different emitting view angles.
The receiving visual angles of the receiving systems are set according to the transmitting visual angles of the laser beams, so that the receiving visual angles of the adjacent receiving systems are different, the different receiving systems receive the echoes of the laser beams at different transmitting visual angles, and the situation that each receiving system receives the echoes of the laser beams at other transmitting visual angles can be avoided. Illustratively, the radar system comprises 2 receiving systems, the size and the range of a receiving FOV (field of view) of each receiving system are set, spatial isolation is realized between an echo of a laser beam of the No. 1 transmitting point received by the receiving system 1 and an echo of a laser beam of the No. 2 transmitting point received by the receiving system 2, so that echo distinction between the No. 1 point and the No. 2 point is realized, although time is overlapped, the echoes of the No. 1 point and the No. 2 point do not appear on the same receiving system, so that echo distinction between the No. 1 point and the No. 2 point is realized, a distance ambiguity phenomenon is eliminated, the method is simple, and the realization cost is low.
Optionally, in this embodiment, the receiving angle of each receiving system may be set according to parameters such as the number of the transmitting points and/or the maximum scanning angle of the transmitting system, for example, the transmitting angle of each transmitting point may be determined according to the number of the transmitting points and the maximum scanning angle of the transmitting system, so that the reflection angle may be determined, and further the receiving angle of the receiving system may be determined. The embodiment can also directly set the receiving angle of view of each receiving system according to the transmitting angle of each transmitting point.
According to the embodiment, the echo spaces of the laser beams with different emission angles are isolated, and meanwhile, the space information is fully utilized, so that the number of receiving systems can be reduced, and the size of a radar system is further reduced.
In one embodiment, as shown in fig. 2, the determining a ranging result according to echo receiving results of N receiving systems includes:
in step S21, a corresponding candidate distance is determined from each echo signal received by the nth receiving system. In this embodiment, the receiving angles of the receiving systems may be the same or different, and the receiving angles of the receiving systems do not need to be considered, thereby reducing the design complexity of the receiving systems.
When designing a radar system, the farthest measuring distance and the number of frames of point cloud, the resolution ratio is basically in an inverse relation, although the maximum measuring distance can be improved under the condition of not changing the resolution ratio of the point cloud and reducing the number of frames by increasing the number of lasers, a plurality of sets of transmitting devices are used, lasers with different wavelengths are used, meanwhile, the receiving ends carry out matching processing on the transmitting devices with different wavelengths, an independent filter plate needs to be designed to shield the lasers with other wavelengths, the difficulty of large complexity and engineering practice exists in system design, and uncontrollable factors exist. Therefore, the embodiment adopts a design method of multiple sets of independent receiving systems, so that the problem of shortening the maximum measuring distance caused by insufficient ranging time sequence of a single point during ranging is avoided, and meanwhile, a special system design method is adopted for echoes among the multiple sets of receiving systems to avoid the problem of distance ambiguity.
In the embodiment, the relationship between the signal intensity and the distance is distinguished on the basis of a processing algorithm, and it can be known from a laser radar equation that the echo intensity of the target is inversely proportional to the square of the distance where the target is located, so that the judgment of the overlapping area can be performed through the echo signal received by the receiving system. Specifically, the nth receiving system may receive an interference echo outside the nth + N × m laser beam while receiving the echo of the nth + N × m laser beam, and in this embodiment, the corresponding candidate distance is determined according to each echo signal received by the nth receiving system, and the interference echo may be filtered according to the candidate distance.
As shown in fig. 6 or 7, when the receiving system a receives the echo of the laser beam of the transmitting point 3 and the echo of the laser beam of the transmitting point 2 in the overlapping region, it is necessary to determine the alternative distance R2 of the transmitting point 2 and the alternative distance R3 of the transmitting point 3, and determine whether there is an interference echo in the receiving system a according to the alternative distances R2 and R3, so that the ranging result of the receiving system a is more accurate. For another example, the number of the transmitting points is 100, the number of the receiving systems is 5, the receiving system 2 receives the 2 nd transmitting point, the 7 th transmitting point, the 12 th transmitting point … …, the 47 th transmitting point and the 52 th transmitting point … …, for example, while receiving the echo of the laser beam of the 52 th transmitting point, it may also receive the echoes of the laser beams of the number 48, 49, 50 and 51 transmitting points, at this time, it is necessary to determine a corresponding candidate distance according to the echoes of the laser beams of the number 48, 49, 50, 51 and 52 transmitting points, and determine whether the receiving system 2 has an interfering echo according to the corresponding candidate distance, so that the ranging result of the receiving system 2 is more accurate and the range ambiguity is avoided. Optionally, in this embodiment, the echo signals whose signal strengths do not meet the condition may be filtered according to the signal strength of each echo signal in the receiving system; if the distance value does not meet the distance condition, filtering the corresponding echo signal which does not meet the distance condition; and interference signals can be filtered according to the pulse number of the echo signals in the receiving system, the time sequence information of the received echo signals and other information.
In step S22, it is determined whether each of the candidate distances satisfies a preset condition.
If the candidate distances do not meet the preset condition, filtering the candidate distances which do not meet the preset condition to obtain the remaining candidate distances, namely the ranging result in the receiving time window of the nth receiving system; if the alternative distances all meet the preset condition, filtering is not needed, namely, the distances determined by the echo signals of the nth receiving system are all target distances.
As shown in fig. 7, the determination of the interference echo can be performed in the receiving overlapping area of point No. 1 and point No. 2, and the echo signal strength should be small for point No. 1 because the overlapping area belongs to the end of the ranging time window, that is, the long-distance target, and the signal strength should be high for point No. 2 because the overlapping area belongs to the front end of the ranging time window, that is, the short-distance target. Therefore, in this embodiment, by determining whether the candidate distance satisfies the preset condition, the candidate distance that does not satisfy the preset condition is filtered from the nth receiving system, so as to filter the echo interference signal of the receiving system, and remove the interference echo signal, that is, remove the candidate distance obtained by the interference echo signal.
Optionally, the preset conditions corresponding to each receiving system are different. As shown in fig. 7, for point No. 1, the overlapping region belongs to the end of the ranging time window, that is, a long-distance target, and for point No. 2, the overlapping region belongs to the front end of the ranging time window, that is, a short-distance target, so that the alternative distances determined by each receiving system according to the interference echoes are different, the alternative distances of some receiving systems may be large, the alternative distances of some receiving systems may be small, for example, the alternative distances determined by the overlapping region of point No. 1 are large, the corresponding preset conditions are also large, for example, the alternative distances determined by the overlapping region of point No. 2 are small, and the corresponding preset conditions are also small.
Optionally, as shown in fig. 3, the determining whether each alternative distance satisfies a preset condition includes:
in step S31, a difference operation between the candidate distance and the distance determined according to the transmission interval is performed to obtain a distance difference, and a sum operation between the candidate distance and the distance determined according to the transmission interval is performed to obtain a distance sum value.
Here, the emission interval may also be said to be timing information of adjacently emitted laser light, and as described in the above embodiments, the distance difference may be expressed as
The distance and value may be expressed as->
Wherein R is an alternative distance, T N Is the emission interval between the emission moments of adjacently emitted laser light, C is the speed of light, and->
Is a distance determined according to the transmission interval.
In step S32, determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: reflectivity of laser light emitted by the lidar through the alternative distance.
The embodiment determines the strength of the echo signal according to the distance and the reflectivity of the target, and the distance and the signal strength are in inverse proportion. Specifically, a first upper limit is determined based on the distance difference and the target reflectivity, and is expressed as
According to the sum of distancesThe value and target reflectivity determine a first lower limit, expressed as @>
In step S33, a second upper limit is determined according to the candidate distance and the maximum reflectance of the laser light, and a second lower limit is determined according to the candidate distance and the minimum reflectance of the laser light.
The signal intensity determined by the alternative distance is also constrained according to the reflectivity of the laser, so that the screening precision of the alternative distance is further improved, the ranging result of the receiving system is more accurate, and the reflectivity of the embodiment can be understood as the reflection intensity or the reflectivity intensity. Specifically, a second upper limit, denoted as p (R, ρ), is determined based on the candidate distance and the maximum reflectivity of the laser light 100 ) A second lower limit, denoted as p (R, ρ), is determined from the sum of distances and the minimum reflectivity 1 ) Where ρ is 1 Is the minimum reflectivity of the laser, e.g. reflectivity of 1, p 100 The maximum reflectance of the laser light is, for example, 100.
In step S34, if the signal strength corresponding to the candidate distance is located between the first upper limit and the first lower limit, and the signal strength corresponding to the candidate distance is located between the second upper limit and the second lower limit, the signal strength corresponding to the candidate distance is determined to meet the preset condition.
Specifically, if the signal strength obtained according to the alternative distance is between the first upper limit and the first lower limit, the alternative distance does not need to be filtered, that is, the distances determined by the echo signal of the nth receiving system are all target distances; if the signal strength obtained according to the alternative distance is not located between the first upper limit and the first lower limit, the alternative distance needs to be filtered out to obtain a remaining alternative distance, and the remaining alternative distance is used as a ranging result in the receiving time window of the nth receiving system.
Or, if the signal strength obtained according to the candidate distance is located between the second upper limit and the second lower limit, the candidate distance does not need to be filtered, and if the signal strength obtained according to the candidate distance is not located between the second upper limit and the second lower limit, the candidate distance needs to be filtered, so as to obtain the remaining candidate distance.
Or, if the signal strength obtained according to the alternative distance is between the first upper limit and the first lower limit, and the signal strength obtained according to the alternative distance is between the second upper limit and the second lower limit, the alternative distance does not need to be filtered; if the signal strength obtained according to the alternative distance is not located between the first upper limit and the first lower limit, and the signal strength obtained according to the alternative distance is not located between the second upper limit and the second lower limit, the alternative distance needs to be filtered out to obtain a remaining alternative distance, and the remaining alternative distance is used as a ranging result in the receiving time window of the nth receiving system.
Exemplarily, referring to fig. 7, assume that the laser emission interval of the dot No. 1 and the dot No. 2 is T N And the alternative distance determined by the echo which is corresponding to the point 1 and appears in the overlapping region is R 1 I.e. the alternative distance determined from the interfering echoes of the receiving system a with respect to the unknown target, the alternative distance determined for the echo occurring in the overlap region corresponding to point 2 being R 2 I.e. the alternative distance to an unknown object is determined from the interfering echoes of the receiving system B. Then the intensity of the reflectivity is p for the receiving systems a and B r (ρ 1 ＜ρ r ＜ρ 100 Where ρ is 1 Representing an object with a reflectivity of 1, p 100 Representing an object with a reflectivity of 100) and an object located at a distance R (a candidate distance) have a reflected signal strength p (R, ρ) r )。
Further, the reflected signal strength p (R, p) is determined from the candidate distance and the reflectivity r ) Determining the reflected signal strength p (R, p) r ) Whether it is between the first upper limit and the first lower limit. In particular, the reflected signal strength p (R, ρ) r ) Should satisfy
If the above condition is not satisfied, the reflection will be generatedSignal strength p (R, ρ) r ) The corresponding candidate distance R is filtered out. Illustratively, if R 1 Reflected signal strength p (R) determined from the reflectivity of a corresponding unknown target 1 ,ρ r ) If the above condition is not satisfied, R is added 1 Filtering, i.e. receiving the signals in system A and R 1 Filtering out corresponding echoes; or, if R 2 Reflected signal strength p (R) determined from the reflectivity of a corresponding unknown target 2 ,ρ r ) If the above condition is not satisfied, R is added 2 Filtering, i.e. receiving both the signals in the system B and R 2 The corresponding echoes are filtered out.
According to the embodiment, the alternative distance is determined according to each echo signal through the relation between the distance and the signal strength, then the alternative distance which does not meet the preset condition is filtered, the filtering efficiency is better, the phenomenon of distance repetition is avoided, and the ranging precision of the radar system is greatly improved.
In one embodiment, the laser parameters of the laser beams of two adjacent emission points are different.
Here, the laser parameters refer to various parameters of the laser beam output by the emission system, such as the number of pulses of the laser beam of a single emission point, timing information of adjacent laser beams, and the like.
Further, referring to fig. 4, the determining a ranging result according to echo receiving results of N receiving systems includes:
in step S41, according to the laser parameter of the N + N × m laser beam, the echo that is received by the nth receiving system and is different from the laser parameter is filtered, so as to obtain the residual echo that is received by the nth receiving system.
In step S42, a ranging result is determined according to the remaining echoes received by the nth receiving system.
In this embodiment, through improvement of control logic of the transmitting system, transmitting logic with different laser parameters of laser beams of two adjacent transmitting points is adopted, so that each receiving system receives echoes of the laser beams of different transmitting logic, and simultaneously, according to laser parameters of an N + N × m laser beam, echoes different from the laser parameters received by the N receiving system are filtered out, and the residual intensity of the receiving intensity of the N receiving system is obtained.
It should be understood that, in this embodiment, specific values of the laser parameters are not limited, and the number of the receiving systems is not limited, and is at least two, as long as the laser parameters of the laser beams of two adjacent emitting points are different, and different receiving systems receive echoes of the laser beams of different laser parameters.
Above-mentioned embodiment realizes when extension measuring time, and through laser parameter filtering interference callback, the filtering effect is better, and is more accurate, has avoided the interference between the signal, and the method implements more easily, and then has eliminated the range repetition as far as possible, has improved the precision of range finding result, has prolonged range finding distance simultaneously.
Optionally, the laser parameter of this embodiment includes at least one of: the single emission laser beam comprises the number of pulses and the pulse time interval of the adjacent pulses in the laser beam, but is not limited to the encoding combination method of the number of pulses and the pulse time interval.
In this embodiment, a multi-pulse emission system may be adopted, and the light emitting logic (laser parameters) of adjacent points may adopt different numbers of pulses included in a single laser beam, or adopt pulse time intervals of adjacent pulses in different laser beams, or any two of them may be combined. Different data processing modes are adopted in different receiving systems, and targets can be distinguished. For example, for the transmission point No. 1, two pulses are used with a pulse interval of N 2 For the No. 2 transmitting point, three pulses are adopted, and the pulse interval is N 2 And N 3 The emission system can be analogized in turn, so that the receiving system A can be screened by adopting a two-pulse data processing mode, and the receiving system B can be screened by adopting a three-pulse data processing mode, so that the adjacent points can be distinguished in an overlapping area, the precision is high, the distance fuzzy phenomenon is avoided, and the distance measurement precision is improved.
In the embodiment, for the distance ambiguity problem caused by the echo interference in the overlapping area, the multi-pulse transmission system is adopted by the method for improving the control logic of the transmission system, and different receiving systems are mapped to perform data processing at the same time, so that the echoes of different point numbers in the overlapping area can be distinguished, and the echo distinction of different point numbers in different receiving systems is realized.
The embodiment solves the problem that the maximum measurement distance, the point cloud resolution and the frame rate are contradictory in the existing laser radar system, and under the premise of not reducing the point cloud resolution and the frame rate, the measurement time is prolonged, the maximum measurement distance is improved and the design complexity of the system is reduced by improving the receiving relation between the transmitting system and the receiving system and using one transmitting system and a plurality of receiving systems; meanwhile, in order to solve the problem of distance ambiguity, processing optimization is carried out on system design, multiple transmitting systems do not need to be designed by changing transmitting logic of transmitting laser beams, complexity of radar system design is reduced, adjacent laser beams are received by different receiving systems, and distance ambiguity is avoided.
FIG. 8 is a block diagram illustrating a lidar system according to an exemplary embodiment. Referring to fig. 8, the system includes: one transmitting system 100 and N receiving systems 200.
The emission system 100 emits laser beams at emission intervals. The nth receiving system 200 receives the echo of the (N + N) th laser beam emitted by the emitting system in a receiving window which is larger than the emitting interval and not larger than N emitting intervals; wherein N is the number of receiving systems; n is a positive integer less than or equal to N; m is a natural number. Nth receiving system 200 determines a ranging result based on the echo reception result.
Optionally, the receiving angle of view of the receiving system 200 is set according to the emitting angle of view of the laser beam, where different receiving angles of view 200 receive echoes of laser beams of different emitting angles of view.
Optionally, the nth receiving system 200 is specifically configured to:
determining a corresponding alternative distance according to each echo signal received by the nth receiving system;
determining whether each alternative distance meets a preset condition;
and filtering the alternative distance which does not meet the preset condition to obtain a ranging result in the receiving time window of the nth receiving system.
Optionally, the nth receiving system 200 is specifically configured to:
performing difference operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance difference value, and performing sum operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance sum value;
determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: the reflectivity of laser emitted by the laser radar passing through the alternative distance;
determining a second upper limit according to the alternative distance and the maximum reflectivity of the laser, and determining a second lower limit according to the alternative distance and the minimum reflectivity of the laser;
and if the signal strength corresponding to the alternative distance is between the first upper limit and the first lower limit, and the signal strength corresponding to the alternative distance is between the second upper limit and the second lower limit, determining the signal strength corresponding to the alternative distance to meet the preset condition.
Optionally, the laser parameters of the laser beams of two adjacent emission points are different; the nth receiving system 200 is specifically configured to:
filtering echoes different from the laser parameters received by the nth receiving system according to the laser parameters of the (N + N) th laser beam to obtain residual echoes received by the nth receiving system;
and determining a ranging result according to the residual echo received by the nth receiving system.
Optionally, the laser parameters include at least one of: the number of pulses contained in a single shot of laser beam, and the pulse time interval of adjacent pulses in the laser beam.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (12)
1. A laser radar ranging method, comprising:
the emitting system emits laser beams according to the emitting intervals;
the nth receiving system receives echoes of the (N + N) th laser beam emitted by the emitting system in a receiving window which is larger than the emitting interval and not larger than N emitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; m is a natural number;
and determining a ranging result according to the echo receiving results of the N receiving systems.
2. The lidar ranging method of claim 1,
and setting a receiving visual angle of the receiving system according to the transmitting visual angle of the laser beam, wherein different receiving visual angles receive echoes of the laser beam at different transmitting visual angles.
3. The lidar ranging method of claim 1, wherein the determining a ranging result from echo reception results of N reception systems comprises:
determining a corresponding alternative distance according to each echo signal received by the nth receiving system;
determining whether each alternative distance meets a preset condition;
and filtering the alternative distance which does not meet the preset condition to obtain a ranging result in the receiving time window of the nth receiving system.
4. The lidar ranging method according to claim 3, wherein the determining whether each of the candidate ranges satisfies a preset condition comprises:
performing difference operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance difference value, and performing sum operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance sum value;
determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: the reflectivity of laser emitted by the laser radar passing through the alternative distance;
determining a second upper limit according to the alternative distance and the maximum reflectivity of the laser, and determining a second lower limit according to the alternative distance and the minimum reflectivity of the laser;
and if the signal intensity corresponding to the alternative distance is between the first upper limit and the first lower limit, and the signal intensity corresponding to the alternative distance is between the second upper limit and the second lower limit, determining the signal intensity corresponding to the alternative distance to meet the preset condition.
5. Lidar ranging method according to claim 1, wherein the ranging unit is a radar ranging unit,
the laser parameters of the laser beams of two adjacent emission points are different;
the determining a ranging result according to the echo receiving results of the N receiving systems includes:
filtering echoes different from the laser parameters received by the nth receiving system according to the laser parameters of the (N + N) th beam of laser to obtain residual echoes received by the nth receiving system;
and determining a ranging result according to the residual echo received by the nth receiving system.
6. The lidar ranging method of claim 5, wherein the laser parameter comprises at least one of:
the number of pulses contained in a single emitted laser beam;
the pulse time interval of adjacent pulses in the laser beam.
7. A lidar system, comprising: a transmitting system and N receiving systems;
the emission system is used for emitting laser beams according to emission intervals;
the nth receiving system is used for receiving the echo of the nth + N x m laser beams emitted by the emitting system in a receiving window which is larger than the emitting interval and not larger than N emitting intervals; wherein, N is the number of receiving systems; n is a positive integer less than or equal to N; the m is a natural number;
and the nth receiving system is also used for determining a ranging result according to the echo receiving result.
8. The lidar system of claim 7,
and setting different receiving visual angles of the receiving system according to the transmitting visual angles of the laser beams, wherein the different receiving visual angles receive the echoes of the laser beams with different transmitting visual angles.
9. The lidar system of claim 7, wherein the nth receiving system is specifically configured to:
determining a corresponding alternative distance according to each echo signal received by the nth receiving system;
determining whether each alternative distance meets a preset condition;
and filtering the alternative distance which does not meet the preset condition to obtain a ranging result in the receiving time window of the nth receiving system.
10. The lidar system of claim 9, wherein the nth receiving system is specifically configured to:
performing difference operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance difference value, and performing sum operation between the alternative distance and the distance determined according to the transmission interval to obtain a distance sum value;
determining a first upper limit according to the distance difference and the target reflectivity, and determining a first lower limit according to the distance sum and the target reflectivity; wherein the target reflectivity is: the intensity of laser light emitted by the laser radar reflected back through the alternative distance;
determining a second upper limit according to the alternative distance and the maximum reflectivity of the laser, and determining a second lower limit according to the alternative distance and the minimum reflectivity of the laser;
and if the signal intensity corresponding to the alternative distance is between the first upper limit and the first lower limit, and the signal intensity corresponding to the alternative distance is between the second upper limit and the second lower limit, determining the signal intensity corresponding to the alternative distance to meet the preset condition.
11. The lidar system of claim 7, wherein the lasing parameters of the laser beams of two adjacent emission points are different;
the nth receiving system is specifically configured to:
filtering echoes different from the laser parameters received by the nth receiving system according to the laser parameters of the (N + N) th laser beam to obtain residual echoes received by the nth receiving system;
and determining a ranging result according to the residual echo received by the nth receiving system.
12. The lidar system of claim 11, wherein the laser parameters include at least one of:
the number of pulses contained in a single emitted laser beam;
the pulse time interval of adjacent pulses in the laser beam.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111141316.9A CN115877396A (en) | 2021-09-28 | 2021-09-28 | Laser radar ranging method and laser radar system |
| PCT/CN2022/121526 WO2023051482A1 (en) | 2021-09-28 | 2022-09-27 | Lidar ranging method and lidar system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111141316.9A CN115877396A (en) | 2021-09-28 | 2021-09-28 | Laser radar ranging method and laser radar system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115877396A true CN115877396A (en) | 2023-03-31 |
Family
ID=85763314
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111141316.9A Pending CN115877396A (en) | 2021-09-28 | 2021-09-28 | Laser radar ranging method and laser radar system |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN115877396A (en) |
| WO (1) | WO2023051482A1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102012006347A1 (en) * | 2012-03-28 | 2013-10-02 | Brose Fahrzeugteile Gmbh & Co. Kg, Hallstadt | Method for determining distance between object e.g. person and motor vehicle e.g. car, involves receiving light reflected by object using light receiver at predetermined angle of incidence |
| CN108414999A (en) * | 2017-12-01 | 2018-08-17 | 深圳市速腾聚创科技有限公司 | Laser radar and laser radar control method |
| CN110940990A (en) * | 2018-09-21 | 2020-03-31 | 宁波舜宇车载光学技术有限公司 | Laser radar system and detection method and application thereof |
| CN112654879B (en) * | 2020-12-11 | 2022-04-15 | 华为技术有限公司 | Anti-interference method, device and system based on vehicle-mounted millimeter wave radar and vehicle |
-
2021
- 2021-09-28 CN CN202111141316.9A patent/CN115877396A/en active Pending
-
2022
- 2022-09-27 WO PCT/CN2022/121526 patent/WO2023051482A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO2023051482A1 (en) | 2023-04-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110988846B (en) | Noise point identification method for laser radar and laser radar system | |
| WO2020215369A1 (en) | Noise point recognition method applicable to lidar and lidar system | |
| CN110749898B (en) | Laser radar ranging system and ranging method thereof | |
| EP2475957B1 (en) | Optical distance measuring device | |
| US20210278540A1 (en) | Noise Filtering System and Method for Solid-State LiDAR | |
| CN107037432A (en) | Radar installations and its determination mesh calibration method for vehicle | |
| WO2012135874A1 (en) | Method for measuring distance | |
| US10725155B2 (en) | Method for measuring a distance | |
| CN101408618A (en) | Wide light beam illumination three-dimensional gating imaging system of airborne laser radar | |
| JP2015219120A (en) | Distance measuring apparatus | |
| WO2020006924A1 (en) | Tof module-based depth information measurement method and device | |
| CN110850426A (en) | TOF depth camera | |
| JP5025359B2 (en) | Radar equipment | |
| CN108303702B (en) | Phase type laser ranging system and method | |
| CN107505628B (en) | Optical phased array variable resolution imaging system and method | |
| WO2022105273A1 (en) | Control method for lidar, and lidar | |
| CN112578390A (en) | Laser radar and method for generating laser point cloud data | |
| WO2022134525A1 (en) | Lidar control method and lidar | |
| CN115877396A (en) | Laser radar ranging method and laser radar system | |
| CN116106928B (en) | Underwater self-adaptive full-gating imaging method | |
| US11921238B2 (en) | Convolved augmented range LIDAR nominal area | |
| WO2022227607A1 (en) | Control method for laser radar, and laser radar | |
| WO2023133122A3 (en) | Lidar system with detector array | |
| CN113050119B (en) | Judgment method suitable for optical flash three-dimensional imaging radar interference | |
| AT411402B (en) | METHOD FOR DISTANCE MEASUREMENT WITH AN OPTO-ELECTRONIC DISTANCE METER |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |