CN113687387B - Laser radar scanning device and laser radar scanning method - Google Patents
Laser radar scanning device and laser radar scanning method Download PDFInfo
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- CN113687387B CN113687387B CN202111043088.1A CN202111043088A CN113687387B CN 113687387 B CN113687387 B CN 113687387B CN 202111043088 A CN202111043088 A CN 202111043088A CN 113687387 B CN113687387 B CN 113687387B
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- 238000000034 method Methods 0.000 title claims abstract description 33
- 230000008569 process Effects 0.000 claims abstract description 14
- 238000010586 diagram Methods 0.000 description 6
- 230000010355 oscillation Effects 0.000 description 4
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- 230000009286 beneficial effect Effects 0.000 description 1
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Classifications
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- 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
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
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- 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
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
- G01S7/4815—Constructional features, e.g. arrangements of optical elements of transmitters alone using multiple transmitters
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- 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
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4816—Constructional features, e.g. arrangements of optical elements of receivers alone
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- 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
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
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- 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
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- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a laser radar scanning device and a laser radar scanning method, wherein a first laser emitter is controlled to emit first laser and a first vibrating mirror is controlled to rotate so as to scan the first laser along the transverse direction of a target object, a second laser emitter is controlled to emit second laser and a second vibrating mirror is controlled to rotate so as to scan the second laser along the longitudinal direction of the target object, so that the first laser and the second laser respectively scan along different directions of the target object, and the coverage of the target object in the scanning process is improved; the method comprises the steps of determining a first flight time from transmitting first laser to receiving the first laser by the first laser receiving module and a second flight time from transmitting second laser to receiving the second laser by the second laser receiving module, determining a first position of a first laser point and a second position of a second laser point, generating a depth image of a target object, and enriching details of the depth image.
Description
Technical Field
The invention relates to the field of laser radars, in particular to a laser radar scanning device and a laser radar scanning method.
Background
The laser radar is one of the most important sensors in application products such as unmanned vehicles, unmanned aerial vehicles, intelligent robots and the like, the maximum scanning angle and the ranging precision of the laser radar are important parameters for reflecting the safety degree of the application products, and particularly in urban environments, a high-precision laser radar system is important. The laser radar technology is to collect original point cloud data by using laser radar equipment, and reversely establish a model capable of truly reflecting the appearance and the internal structure of a target object, however, the current scanning mode of the laser radar capable of realizing two-dimensional scanning and depth point cloud image construction cannot completely cover the area in a field of view, and effective two-dimensional point cloud information is difficult to extract for some target objects with extreme length and width, so that the details of the restored depth image are not abundant enough and the resolution is low, so that a solution is required to be sought.
Disclosure of Invention
In view of the above, it is an object of the present invention to provide a laser radar scanning device and a laser radar scanning method for improving coverage and resolution.
The technical scheme adopted by the invention is as follows:
a lidar scanning device, comprising:
the first laser radar system comprises a first laser transmitter, a first galvanometer and a first laser receiving module;
the second laser radar system comprises a second laser transmitter, a second galvanometer and a second laser receiving module;
the processing module comprises a control unit and a processing unit;
the control unit is used for controlling the first laser emitter to emit first laser and controlling the first galvanometer to rotate so as to scan the first laser along the transverse direction of the target object, and controlling the second laser emitter to emit second laser and controlling the second galvanometer to rotate so as to scan the second laser along the longitudinal direction of the target object; the first laser emits a plurality of first laser points on the target object, and the second laser emits a plurality of second laser points on the target object;
the processing unit is used for determining a first flight time from transmitting the first laser to the first laser receiving module for receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module for receiving the second laser, determining a first position of the first laser point and a second position of the second laser point according to the first flight time and the second flight time, and generating a depth image of the target object according to the first position and the second position.
Further, the first laser receiving module comprises a first receiving lens and a first photoelectric receiving diode, the first photoelectric receiving diode is electrically connected with the processing module, the first photoelectric receiving diode is arranged behind the first receiving lens, and the first laser is received by the first photoelectric receiving diode through the first receiving lens.
A laser radar scanning method, comprising:
controlling a first laser emitter to emit first laser and controlling a first vibrating mirror to rotate so as to scan the first laser along the transverse direction of a target object, and controlling a second laser emitter to emit second laser and controlling a second vibrating mirror to rotate so as to scan the second laser along the longitudinal direction of the target object; the first laser emits a plurality of first laser points on the target object, and the second laser emits a plurality of second laser points on the target object;
determining a first flight time for transmitting the first laser to a first laser receiving module for receiving the first laser and a second flight time for transmitting the second laser to a second laser receiving module for receiving the second laser;
determining a first position of the first laser spot and a second position of the second laser spot according to the first flight time and the second flight time;
and generating a depth image of the target object according to the first position and the second position.
Further, the controlling the first laser emitter to emit the first laser light and controlling the first galvanometer to rotate so as to scan the first laser light along the transverse direction of the target object includes:
the first laser transmitter is controlled by a first pulse signal to transmit first laser, and the first galvanometer is controlled by a first triangular wave signal to rotate so as to scan the first laser along the transverse direction of a target object; the frequency of the first triangular wave signal is used for controlling the rotation frequency of the first vibrating mirror, and the amplitude of the first triangular wave signal is used for controlling the rotation amplitude of the first vibrating mirror.
Further, the controlling the first galvanometer to rotate to scan the first laser light along a lateral direction of the target object, and controlling the second galvanometer to rotate to scan the second laser light along a longitudinal direction of the target object includes:
controlling the first galvanometer to rotate so as to scan the first laser along a first path along a first transverse direction of the target object, and controlling the second galvanometer to rotate so as to scan the second laser along a second longitudinal direction of the target object along a second path, so as to complete the first scanning;
controlling the first galvanometer to rotate so as to scan the first laser along a third path in a repeated manner or a non-repeated manner along a first reverse direction of the transverse direction of the target object, and controlling the second galvanometer to rotate so as to scan the second laser along a fourth path in a repeated manner or a non-repeated manner along a second reverse direction of the longitudinal direction of the target object, so as to complete second scanning; the first path and the third path are staggered and form the same angle, the second path and the fourth path are staggered and form the same angle, and the first laser point and the second laser point are formed in the process of the first scanning and the second scanning.
Further, the first galvanometer includes first cross axle and first vertical axis, the second galvanometer includes second cross axle and second vertical axis, control first galvanometer rotates and control second galvanometer rotates, include:
controlling the first transverse axis to rotate at a first frequency and the first longitudinal axis to rotate at a second frequency, and controlling the second transverse axis to rotate at the second frequency and the second longitudinal axis to rotate at the first frequency; the first frequency is greater than the second frequency.
Further, the determining a first time of flight for transmitting the first laser light to a first laser light receiving module for receiving the first laser light and a second time of flight for transmitting the second laser light to a second laser light receiving module for receiving the second laser light includes:
and calculating a first flight time from transmitting the first laser to the first laser receiving module and receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module and receiving the second laser through a time-to-digital converter unit.
Further, the determining the first position of the first laser point and the second position of the second laser point according to the first flight time and the second flight time includes:
acquiring azimuth angles and elevation angles of each first laser spot and each second laser spot;
calculating first distance information of each first laser point according to each first flight time and light speed, and calculating three-dimensional coordinates of each first laser point to serve as the first position according to the first distance information, the azimuth angle and the elevation angle of the first laser point;
and calculating second distance information of each second laser point according to each second flight time and the light speed, and calculating three-dimensional coordinates of each second laser point as the second position according to the second distance information, the azimuth angle and the elevation angle of the second laser point.
The beneficial effects of the invention are as follows: the first laser emitter is controlled to emit first laser and the first vibrating mirror is controlled to rotate so as to scan the first laser along the transverse direction of the target object, the second laser emitter is controlled to emit second laser and the second vibrating mirror is controlled to rotate so as to scan the second laser along the longitudinal direction of the target object, and the first laser and the second laser are respectively scanned along the target object in different directions by controlling the rotation of different first vibrating mirrors and second vibrating mirrors, so that the first laser points and the second laser points have a certain quantity and density, and the coverage of the target object in the scanning process is improved; determining a first flight time from transmitting the first laser to the first laser receiving module for receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module for receiving the second laser; according to the first flight time and the second flight time, the first position of the first laser point and the second position of the second laser point are determined, the depth image of the target object is generated, details of the finally generated depth image are enriched, and resolution is improved.
Drawings
FIG. 1 is a schematic perspective view of a laser radar scanning apparatus according to an embodiment of the present invention;
FIG. 2 is a top view of FIG. 1;
FIG. 3 is a schematic flow chart of steps of a laser radar scanning method according to the present invention;
fig. 4 (a) is a schematic diagram of a repeated scanning mode according to an embodiment of the present invention, fig. 4 (b) is a schematic diagram of a non-repeated scanning mode according to an embodiment of the present invention, fig. 4 (c) is a schematic diagram of a first scanning mode according to an embodiment of the present invention, and fig. 4 (d) is a schematic diagram of a second scanning mode according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating the operation of a lidar system according to an embodiment of the present invention;
fig. 6 is a schematic diagram showing the positions of laser points according to an embodiment of the present invention.
Detailed Description
In order to make the present application solution better understood by those skilled in the art, the following description will be made in detail and with reference to the accompanying drawings in the embodiments of the present application, it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
The terms "first," "second," "third," and "fourth" and the like in the description and in the claims of this application and in the drawings, are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
As shown in fig. 1 and 2, an embodiment of the present invention provides a laser radar scanning apparatus, which includes a first laser radar system 100, a second laser radar system 200, and a processing module (not shown).
As shown in fig. 1 and 2, the first lidar system 100 optionally includes a first laser transmitter 11, a first galvanometer 12, and a first laser receiving module. In the embodiment of the invention, the first laser receiving module includes a first receiving lens 13 and a first photodiode 14, the first photodiode 14 is electrically connected with the processing module, the first photodiode 14 is disposed behind the first receiving lens 13, and the first laser is received by the first photodiode 14 through the first receiving lens 13. Optionally, the first galvanometer 12 includes a first transverse axis X1 and a first longitudinal axis Y1, where the first transverse axis X1 and the first longitudinal axis Y1 have corresponding control mirrors, and the processing module performs rotation control on the first transverse axis X1 and the first longitudinal axis Y1 so as to enable rotation of the first galvanometer 12.
As shown in fig. 1 and 2, the second lidar system 200 optionally includes a second laser transmitter 21, a second galvanometer 22, and a second laser receiving module. In the embodiment of the invention, the second laser receiving module includes a second receiving lens 23 and a second photodiode 24, the second photodiode 24 is electrically connected with the processing module, the second photodiode 24 is disposed behind the second receiving lens 23, and the second laser is received by the second photodiode 24 through the second receiving lens 23. Optionally, the second galvanometer 22 includes a second transverse axis X2 and a second longitudinal axis Y2, where the second transverse axis X2 and the second longitudinal axis Y2 have corresponding control mirrors, and the processing module performs rotation control on the second transverse axis X2 and the second longitudinal axis Y2 so as to enable rotation of the second galvanometer 22. The first galvanometer 12 and the second galvanometer 22 include, but are not limited to, galvanometer galvanometers or MEMS galvanometers.
As shown in fig. 1 and 2, it should be noted that the first galvanometer 12 and the second galvanometer 22 are used to control the path of the laser scanning; the first laser transmitter 11 and the second laser transmitter 21 comprise laser transmitter driving functions, and are provided with collimating lenses, which can make the light spot smaller than the lens. The first laser receiving module and the second laser receiving module can comprise echo amplifying circuits; the first receiving lens 13 and the second receiving lens 23 are large-area optical dedicated convex lenses for focusing the echo signals, that is, focusing the laser light reflected from the target object, so that the laser light strikes the first photodiode 14 or the second photodiode 24 to be absorbed.
Optionally, in an embodiment of the present invention, the processing module includes a control unit and a processing unit.
Specifically, the control unit is configured to control the first laser emitter 11 to emit first laser light and control the first galvanometer 12 to rotate so that the first laser light scans along the lateral direction of the target object, and control the second laser emitter 21 to emit second laser light and control the second galvanometer 22 to rotate so that the second laser light scans along the longitudinal direction of the target object. In the scanning process, the first laser emits a plurality of first laser points on the target object, and the second laser emits a plurality of second laser points on the target object.
Specifically, the processing unit is configured to determine a first flight time from transmitting the first laser to the first laser receiving module receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module receiving the second laser, determine a first position of the first laser point and a second position of the second laser point according to the first flight time and the second flight time, and generate a depth image of the target object according to the first position and the second position.
The first laser radar system and the second laser radar system in the embodiment of the present invention are not limited to the left-right distribution structure, and may be an up-down distribution structure, etc. It should be noted that, the processing module in the embodiment of the present invention includes, but is not limited to, an FPGA main controller, and controls the first laser transmitter 11 and the second laser transmitter 21 to transmit laser through the generated pulse signals; generating a triangular wave signal to drive the first vibrating mirror 12 and the second vibrating mirror 22 to rotate; the first time of flight and the second time of flight are determined by a time-to-digital converter unit (TDC) in the processing unit, and then the first location and the second location are determined. It should be noted that, generating the depth image of the target object according to the first location and the second location may be transmitting the point cloud data including the first location and the second location to the upper computer to generate the depth image of the target object, that is, the processing module includes the FPGA main controller and a part of the upper computer. Optionally, the time-to-digital converter unit is a dual-channel time-to-digital converter, which may be built in the FPGA master controller or may be a TDC-GP2X timing chip, which is not limited specifically, and may be used to implement the timing of the high-precision time-of-flight techniques TOF (Time of Flight) of the first lidar system 100 and the second lidar system 200, and store the timing result in a digital register of the 8-bit FPGA master controller, where the TDC implemented based on the FPGA has the functions of a basic coarse-fine time counter, delay calibration, temperature compensation, and the like.
As shown in fig. 3, an embodiment of the present invention provides a laser radar scanning method, which can be applied to the laser radar scanning device, including steps S100-S400:
s100, controlling the first laser emitter to emit first laser and controlling the first galvanometer to rotate so as to scan the first laser along the transverse direction of the target object, and controlling the second laser emitter to emit second laser and controlling the second galvanometer to rotate so as to scan the second laser along the longitudinal direction of the target object.
In the embodiment of the invention, in the scanning process, a plurality of first laser points are emitted on a target object by the first laser, and a plurality of second laser points are emitted on the target object by the second laser.
It should be noted that the frequency of laser emission and the frequency of oscillation of the oscillating mirror affect the point cloud data contained in each image, and the amplitude of oscillation of the oscillating mirror affects the maximum scanning angle, so that the internal program of the FPGA can be adjusted according to the actual situation, and the frequency of laser emission and the frequency and amplitude of rotation (oscillation) of the oscillating mirror can be adjusted to obtain the point cloud data meeting the actual requirements.
In the embodiment of the invention, the processing module controls the first laser emitter to emit first laser through the first pulse signal and controls the first galvanometer to rotate through the first triangular wave signal so as to scan the first laser along the transverse direction of the target object, controls the second laser emitter to emit second laser through the second pulse signal and controls the second galvanometer to rotate through the second triangular wave signal so as to scan the second laser along the longitudinal direction of the target object. Alternatively, the first pulse signal and the second pulse signal are 24khz, 50ns narrow trigger pulse signals. The first triangular wave signal includes two triangular wave signals, which drive the first horizontal axis X1 and the first vertical axis Y1, respectively, and the second triangular wave signal also includes two triangular wave signals, which drive the second horizontal axis X2 and the second vertical axis Y2, respectively. The frequency of the first triangular wave signal is used for controlling the rotation frequency of the first vibrating mirror, specifically the rotation frequency of the first transverse axis X1 and the first vertical axis Y1, and the frequency of the second triangular wave signal is used for controlling the rotation frequency of the second vibrating mirror, specifically the rotation frequency of the second transverse axis X2 and the second vertical axis Y2; the amplitude of the first triangular wave signal is used for controlling the rotation amplitude of the first vibrating mirror, specifically the rotation amplitude of the first transverse axis X1 and the first longitudinal axis Y1, and the amplitude of the second triangular wave signal is used for controlling the rotation amplitude of the second vibrating mirror, specifically the rotation amplitude of the second transverse axis X2 and the second longitudinal axis Y2. It should be noted that, when a higher imaging speed is required, the rotation frequency of the galvanometer may be adjusted in real time, for example, the adjustment procedure may cause the frequency of the driving triangular wave signal to be increased, while, for a target object with a larger width, the rotation amplitude of the transverse axis of the galvanometer may be adjusted in real time, for example, the adjustment procedure may cause the driving triangular wave signal to have a larger amplitude.
In the embodiment of the invention, the driving signal of the triangular wave is used, and the angle of the triangular wave is linearly changed to achieve the consistency of the front and back scanning angles, so that the scanning angle of the second scanning is consistent with the first scanning angle when the first scanning and the second scanning are carried out subsequently, the scanning paths are not overlapped but staggered, and the number and the density of the acquired laser points are increased. In addition, if square waves are used, the oscillation change of the oscillating mirror is uneven, and if saw-tooth waves are used, the front-back scanning angle is not uniform.
Optionally, in the embodiment of the present invention, the first transverse axis is controlled to rotate at a first frequency and the first longitudinal axis is controlled to rotate at a second frequency, and the second transverse axis is controlled to rotate at the second frequency and the second longitudinal axis is controlled to rotate at the first frequency; the first frequency is (far) greater than the second frequency. It is understood that the first frequency and the second frequency are frequencies of a triangular wave signal. For example, in the case where the frame rate is 10fps and each frame is scanned in a single pass, the frequency of rotation of the first horizontal axis is 340Hz and the frequency of rotation of the first vertical axis is 10Hz, and accordingly, the frequency of rotation of the second horizontal axis is 10Hz and the frequency of rotation of the second vertical axis is 340Hz.
In the embodiment of the present invention, in step S100, the first galvanometer is controlled to rotate so as to scan the first laser along the transverse direction of the target object, and the second galvanometer is controlled to rotate so as to scan the second laser along the longitudinal direction of the target object, which includes steps S110-S120:
s110, controlling the first galvanometer to rotate so that the first laser scans along a first path along a first positive direction of the target object in the transverse direction, and controlling the second galvanometer to rotate so that the second laser scans along a second path along a second positive direction of the target object in the longitudinal direction, so that the first scanning is completed.
S120, controlling the first galvanometer to rotate so that the first laser scans along a third path in a repeated mode or a non-repeated mode along a first reverse direction of the transverse direction of the target object, and controlling the second galvanometer to rotate so that the second laser scans along a fourth path in a repeated mode or a non-repeated mode along a second reverse direction of the longitudinal direction of the target object, so as to finish second scanning; the first path and the third path are staggered and form the same angle, the second path and the fourth path are staggered and form the same angle, and the first laser spot and the second laser spot are formed in the process of first scanning and second scanning.
The scanning principle of the repetition mode is as shown in fig. 4 (a), the repetition mode refers to that the scanning path of the laser radar system is repeated, and one image is obtained after one frame is reached, while the scanning principle of the non-repetition mode refers to that the laser radar system is scanned for two or more frames and the scanning path is not repeated as one image, the arrow indicates the direction of the scanning path, the X indicates the transverse direction, and the Y indicates the longitudinal direction, as shown in fig. 4 (b). In the embodiment of the present invention, a non-repeating manner is taken as an example, that is, the path of the second scan and the path of the first scan are not repeated, that is, the first path and the third path are staggered, and the second path and the fourth path are staggered. It will be appreciated that when scanned in a repetitive manner, the third path overlaps (or is identical) at least a portion of the first path and the fourth path overlaps (or is identical) at least a portion of the second path.
Specifically, as shown in fig. 4 (c), during the first scanning, the first path extends in the first transverse direction (scans in the left-right direction and ends in the longitudinal direction from bottom to top), starting with the path L11 and ending with the path L12, and the second path extends in the second longitudinal direction (scans in the longitudinal direction and ends in the transverse direction from left to right), starting with the path L21 and ending with the path L22. As shown in fig. 4 (d), the second scanning is performed on the basis of the first scanning, and in the process of the second scanning, the third path extends in a first transverse direction (the first reverse direction is opposite to the first forward direction, specifically, the first reverse direction is scanned in a left-right direction and is scanned from top to bottom in a longitudinal direction), the path L31 is used as a start and the path L32 is used as an end, the fourth path extends in a second longitudinal direction (the second reverse direction is opposite to the second forward direction, is scanned in the longitudinal direction and is scanned from right to left in the transverse direction) and the path L41 is used as a start and the path L42 is used as an end, so that the scanning of the target object M is realized, the integrity of the scanning of the target object M is ensured, and the coverage of the scanning process is improved. The first laser spot exists in the first path and the third path, the second laser spot exists in the second path and the fourth path, and it can be seen that the first path is staggered, parallel and at the same angle with respect to the third path, that is, the angle between the sub-paths included in the first path is the same as the angle between the sub-paths of the third path, and the second path is staggered, parallel and at the same angle with respect to the fourth path, that is, the angle between the sub-paths included in the second path is the same as the angle between the sub-paths of the fourth path.
As shown in fig. 5, in the embodiment of the present invention, during the first scanning and the second scanning, the first (group) of laser radar systems starts to operate, the second (group) of laser radar systems is in a stationary state, when the first laser radar system emits single photon (first laser) and is received by the first laser receiving module, the first (group) of laser radar systems is turned into the stationary state, the second (group) of laser radar systems is turned into the operating state, and similarly, the second (group) of laser radar systems completes the transceiving of single photon (second laser)), and the first (group) of laser radar systems is turned into the operating state, so that the process of the first scanning and the second scanning can be completed.
S200, determining a first flight time from transmitting the first laser to the first laser receiving module for receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module for receiving the second laser.
In the embodiment of the invention, the first flight time refers to the time that the first laser transmitter transmits the first laser to reach the target object and reflect the first laser to the first laser receiving module for receiving (specifically, the first photodiode for receiving); the second time of flight refers to the time that the second laser transmitter transmits the second laser light to reach the target object and reflect the second laser light to the second laser light receiving module for receiving (specifically, the second photodiode for receiving). Specifically, the first time of flight and the second time of flight are calculated by a time-to-digital converter unit (TDC).
S300, determining a first position of the first laser point and a second position of the second laser point according to the first flight time and the second flight time.
Specifically, step S300 includes steps S310 to S330:
s310, acquiring azimuth angles and elevation angles of each first laser spot and each second laser spot.
S320, calculating first distance information of each first laser point according to each first flight time and the light speed, and calculating three-dimensional coordinates of each first laser point to serve as a first position according to the first distance information, the azimuth angle and the elevation angle of the first laser point.
S330, calculating second distance information of each second laser point according to each second flight time and the light speed, and calculating to obtain a three-dimensional coordinate of each second laser point as a second position according to the second distance information, the azimuth angle and the elevation angle of the second laser point.
Specifically, as shown in fig. 6, it is assumed that the target object has a laser point P, P with an azimuth angle α and an elevation angle β, X from the origin of coordinates 1 、Y 1 、Z 1 Respectively representing three coordinate axes, and the calculation formula is as follows:
X 2 ＝d sinαcosβ
Y 2 ＝d sinαsinβ
Z 2 ＝d cosα
wherein d is distance information, v is light velocity, t is flight time, X 2 、Y 2 、Z 2 Respectively, the abscissa, the ordinate and the ordinate in the three-dimensional coordinates. It can be understood that when the laser point P is the first laser point, the time of flight is the first time of flight, the origin of coordinates is the position of the first laser transmitter, and the distance information calculated by using the above formula is the first distance information and the first position of the first laser point; when the laser point P is the second laser point, the flight time is the second flight time, the origin of coordinates is the position of the second laser transmitter, and the distance information calculated by using the above formula is the second distance information and the second position of the second laser point.
It should be noted that the above calculation process may be completed by an FPGA, where the azimuth angle α and the elevation angle β may be determined according to the rotation frequencies of the horizontal axis and the vertical axis, and a CORDIC algorithm is adopted in the FPGA to implement operation of a trigonometric function, or MATLAB generates sine values and cosine values corresponding to the azimuth angle α and the elevation angle β of each laser spot, and stores the sine values and the cosine values in two mif files respectively, and stores the two mif files in a ROM of the FPGA, and then sets a specific step size according to the rotation frequencies of the horizontal axis and the vertical axis to extract an effective value therefrom.
S400, generating a depth image of the target object according to the first position and the second position.
In the embodiment of the invention, each first position and each second position represent a depth point, form a part of point cloud, store the first position and the second position in an upper computer, store the first position and the second position by the upper computer, and synthesize all the depth points represented by the first position and the second position to obtain a high-resolution depth image of a target object.
The laser radar scanning method and the laser radar scanning device of the embodiment of the invention adopt a scanning mode that the first vibrating mirror and the second vibrating mirror are used for two groups of vibrating mirrors, can scan the target object of a scanning view field from different directions and angles, enlarge the scanning view field, realize a double-channel high-precision time-digital converter through an FPGA, realize the high-precision high-concentration point cloud information extraction of a laser radar system based on the vibrating mirror scanning, thereby extracting the depth image of the surface of the target object with richer details, improving the coverage of the target object in the scanning process, improving the working efficiency of the laser radar system, enriching the details of the finally generated depth image, improving the resolution, and realizing the high-precision ranging and timing by adopting the double-channel high-precision time-digital converter
It should be understood that in this application, "at least one" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of elements is merely a logical functional division, and there may be additional divisions of actual implementation, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form. The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (2)
1. A laser radar scanning method, wherein the laser radar scanning method employs a laser radar scanning apparatus, the apparatus comprising:
the first laser radar system comprises a first laser transmitter, a first galvanometer and a first laser receiving module;
the second laser radar system comprises a second laser transmitter, a second galvanometer and a second laser receiving module;
the processing module comprises a control unit and a processing unit;
the control unit is used for controlling the first laser emitter to emit first laser and controlling the first galvanometer to rotate so as to scan the first laser along the transverse direction of the target object, and controlling the second laser emitter to emit second laser and controlling the second galvanometer to rotate so as to scan the second laser along the longitudinal direction of the target object; the first laser emits a plurality of first laser points on the target object, and the second laser emits a plurality of second laser points on the target object;
the processing unit is used for determining a first flight time from transmitting the first laser to the first laser receiving module for receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module for receiving the second laser, determining a first position of the first laser point and a second position of the second laser point according to the first flight time and the second flight time, and generating a depth image of the target object according to the first position and the second position;
the first laser receiving module comprises a first receiving lens and a first photoelectric receiving diode, the first photoelectric receiving diode is electrically connected with the processing module, the first photoelectric receiving diode is arranged behind the first receiving lens, and the first laser is received by the first photoelectric receiving diode through the first receiving lens;
the method comprises the following steps:
controlling a first laser emitter to emit first laser and controlling a first vibrating mirror to rotate so as to scan the first laser along the transverse direction of a target object, and controlling a second laser emitter to emit second laser and controlling a second vibrating mirror to rotate so as to scan the second laser along the longitudinal direction of the target object; the first laser emits a plurality of first laser points on the target object, and the second laser emits a plurality of second laser points on the target object;
determining a first flight time for transmitting the first laser to a first laser receiving module for receiving the first laser and a second flight time for transmitting the second laser to a second laser receiving module for receiving the second laser;
determining a first position of the first laser spot and a second position of the second laser spot according to the first flight time and the second flight time;
generating a depth image of the target object according to the first position and the second position;
wherein, control first laser emitter and control first galvanometer rotation in order to make first laser scan along the transversal of target object, include:
the first laser transmitter is controlled by a first pulse signal to transmit first laser, and the first galvanometer is controlled by a first triangular wave signal to rotate so as to scan the first laser along the transverse direction of a target object; the frequency of the first triangular wave signal is used for controlling the rotation frequency of the first vibrating mirror, and the amplitude of the first triangular wave signal is used for controlling the rotation amplitude of the first vibrating mirror;
the controlling the first galvanometer to rotate so as to scan the first laser along the transverse direction of the target object, and controlling the second galvanometer to rotate so as to scan the second laser along the longitudinal direction of the target object includes:
controlling the first galvanometer to rotate so as to scan the first laser along a first path along a first transverse direction of the target object, and controlling the second galvanometer to rotate so as to scan the second laser along a second longitudinal direction of the target object along a second path, so as to complete the first scanning;
controlling the first galvanometer to rotate so as to scan the first laser along a third path in a repeated manner or a non-repeated manner along a first reverse direction of the transverse direction of the target object, and controlling the second galvanometer to rotate so as to scan the second laser along a fourth path in a repeated manner or a non-repeated manner along a second reverse direction of the longitudinal direction of the target object, so as to complete second scanning; the first path and the third path are staggered and form the same angle, the second path and the fourth path are staggered and form the same angle, and the first laser point and the second laser point are formed in the process of the first scanning and the second scanning;
the first galvanometer comprises a first transverse shaft and a first longitudinal shaft, the second galvanometer comprises a second transverse shaft and a second longitudinal shaft, the first galvanometer is controlled to rotate and the second galvanometer is controlled to rotate, and the first galvanometer comprises:
controlling the first transverse axis to rotate at a first frequency and the first longitudinal axis to rotate at a second frequency, and controlling the second transverse axis to rotate at the second frequency and the second longitudinal axis to rotate at the first frequency; the first frequency is greater than the second frequency;
the determining the first position of the first laser point and the second position of the second laser point according to the first flight time and the second flight time includes:
acquiring azimuth angles and elevation angles of each first laser spot and each second laser spot;
calculating first distance information of each first laser point according to each first flight time and light speed, and calculating three-dimensional coordinates of each first laser point to serve as the first position according to the first distance information, the azimuth angle and the elevation angle of the first laser point;
and calculating second distance information of each second laser point according to each second flight time and the light speed, and calculating three-dimensional coordinates of each second laser point as the second position according to the second distance information, the azimuth angle and the elevation angle of the second laser point.
2. The lidar scanning method according to claim 1, wherein: the determining a first time of flight for transmitting the first laser light to a first laser light receiving module for receiving the first laser light and a second time of flight for transmitting the second laser light to a second laser light receiving module for receiving the second laser light includes:
and calculating a first flight time from transmitting the first laser to the first laser receiving module and receiving the first laser and a second flight time from transmitting the second laser to the second laser receiving module and receiving the second laser through a time-to-digital converter unit.
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