A micro solid-state laser radar and data processing method thereof

Abstract

The present invention relates to a micro solid-state laser radar and a data processing method thereof, wherein the micro solid-state laser radar comprises a laser emitter, an imaging lens, an imaging sensor, and a control and data processing device; the laser emitter is used to emit linear laser; the imaging lens is used to collect the reflected laser light and image it on the imaging sensor; the imaging sensor receives the light focused by the imaging lens and forms an image; the control and data processing device is used to control the operation of the laser emitter, receive the imaging data of the imaging sensor and run the structured light algorithm, and finally obtain the point cloud data in the space environment. The present invention adopts a linear laser for triangulation, and adopts a laser short pulse working mode in combination with a data processing method, which can improve the working distance under the premise of lower average power and human eye safety, avoid the scanning device cost caused by the point laser plus mechanical scanning, and can improve the system stability, extend the service life, and reduce the system volume.

Description

Technical Field

[0001] The present invention relates to the field of distance measuring equipment, and in particular to a miniature solid-state laser radar and a data processing method thereof. Background Art

[0002] Currently, there are many ways to measure distance in the existing technology, among which ultrasonic ranging and laser ranging are the mainstream ranging methods.

[0003] Ultrasonic ranging uses piezoelectric or magnetostrictive deformation phenomena to generate ultrasonic waves for ranging. The ultrasonic ranging system includes an ultrasonic generator and an ultrasonic receiver. The ultrasonic generator emits ultrasonic waves, which will be reflected when encountering obstacles or targets during propagation and are finally received by the ultrasonic receiver. The distance can be calculated based on the ultrasonic propagation speed and the time required for ultrasonic propagation. However, due to the diffuse reflection of ultrasonic waves on curved surfaces, the measurement accuracy is affected. At the same time, the ultrasonic ranging device has low anti-interference ability and is easily affected by wind or other natural factors.

[0004] Laser ranging is another way of measuring distance. Laser ranging can be divided into many ways according to the different physical information used. Some laser ranging uses the phase change of the reflected wave to indirectly measure the laser round-trip time; some use pulses to directly measure the laser round-trip time, and the distance information can be calculated based on the laser round-trip time. Among them, laser triangulation places the laser, target point and laser receiving device at three points. The laser emits laser, which is then reflected by the target point and finally received by the laser receiver. After the laser receiver receives the laser, it calculates the distance according to the principle of laser triangulation.

[0005] The mechanical scanning laser radar in the prior art is based on point laser triangulation ranging, and adds laser rotation scanning transposition to complete 360-degree scanning and ranging of the surrounding environment. However, due to the existence of motion transposition, the mechanical scanning laser radar needs to drive the point laser ranging module to maintain circular motion through motor rotation, which makes it short-lived, large in size, and expensive. Summary of the invention

[0006] The purpose of the present invention is to provide a miniature solid-state laser radar to measure the surrounding environment in view of the defects in the prior art.

[0007] To solve the above technical problems, the technical solution of the present invention is achieved as follows:

[0008] A miniature solid-state laser radar, characterized in that it comprises: a laser transmitter, an imaging lens, an imaging sensor, a control and data processing device;

[0009] The laser emitter is used to emit linear laser;

[0010] The imaging lens is used to collect the reflected laser light and form an image on the imaging sensor;

[0011] The imaging sensor receives the light focused by the imaging lens and forms an image;

[0012] The control and data processing device is used to control the operation of the laser transmitter, receive imaging data from the imaging sensor and run the structured light algorithm, and finally obtain point cloud data in the space environment;

[0013] After the light emitted by the laser emitter irradiates the surface of the object, it is reflected by the surface of the object and received by the imaging lens, and finally an image is formed on the imaging lens; the laser emitter and the imaging sensor are both electrically connected to the control and data processing device.

[0014] Furthermore, the imaging lens is an asymmetric optical lens, and the asymmetric optical lens has an asymmetric focusing characteristic, that is, the equivalent focal length of the imaging lens in the direction of the line connecting the laser emitter and the imaging lens is greater than the equivalent focal length in the vertical direction between the laser emitter and the imaging lens.

[0015] Furthermore, a narrow-band band-pass filter lens is provided at the front end of the imaging sensor, and the central wavelength of the narrow-band band-pass filter lens is the same as the wavelength of the laser emitted by the laser transmitter.

[0016] Furthermore, the laser emitter includes a laser driving circuit, a laser diode, and a laser projection lens.

[0017] Furthermore, it is characterized in that the control and data processing device is electrically connected to the laser emitter and the imaging sensor; the control and data processing device is composed of a timing control interface, a data communication interface and a central processing unit, the timing control interface is electrically connected to the laser emitter and the imaging sensor, and the data communication interface is electrically connected to the imaging sensor.

[0018] Furthermore, the control and data processing device is connected to four laser emitters and four imaging sensors at the same time, the data communication interface is connected to the imaging sensor through an electronic switch, the imaging lens is arranged in front of the imaging sensor to focus light on the imaging sensor, the horizontal angle of the imaging lens is greater than or equal to 90 degrees, the diffusion angle of the laser line emitted by the laser emitter is greater than or equal to 90 degrees, and the field of view of the imaging lens coincides with the laser line area emitted by the laser emitter.

[0019] A data processing method for a micro solid-state laser radar, characterized in that the micro solid-state laser radar includes a laser transmitter, an imaging lens, an imaging sensor, and a control and data processing device, wherein the control and data processing device is composed of a timing control interface, a data communication interface, and a central processing unit, and comprises the following steps:

[0020] Step 1, the laser emitter is controlled by a timing control interface to select and emit linear laser;

[0021] Step 2: The imaging lens collects the reflected laser light and forms an image on the imaging sensor;

[0022] Step 3: The imaging sensor starts exposure under the control of the timing control interface, receives the light focused by the imaging lens and sends imaging data to the central processor through the data communication interface;

[0023] Step 4: The central processing unit receives the imaging data and runs the structured light algorithm to finally obtain point cloud data in the spatial environment.

[0024] Furthermore, in step three, the central processing unit alternately controls the operation of the laser emitter through the timing control interface on the basis of periodically controlling the exposure of the imaging sensor: in the first time period, the timing control circuit controls the laser emitter to emit laser, and the imaging sensor starts to expose synchronously; after the Ton time interval, the laser emitter is turned off, and the imaging sensor stops exposing; in the second time period, the central processing unit controls the laser emitter not to emit laser through the timing control interface, and the imaging sensor starts to expose; after the Ton time interval, the imaging sensor stops exposing, and the first and second time periods run repeatedly.

[0025] Furthermore, the timing control interface controls the laser emitter and the imaging sensor to work in time-sharing mode, and splices the final multiple groups of point cloud data results to obtain spliced ​​point cloud data with a large angle range.

[0026] Furthermore, the structured light algorithm includes two parts: laser line extraction and triangulation solution. The laser line extraction is specifically to extract the laser line by background modeling, that is, to compare the imaging data of two adjacent frames of the imaging sensor. When the difference between the collected pixel data of the two frames is greater than a given threshold, it is determined that the pixel is located in the laser line candidate area; the triangulation solution is specifically for each sub-pixel point belonging to the laser line on the imaging sensor, and its three-dimensional coordinates in space are calculated by the triangulation principle.

[0027] The present invention can bring the following beneficial effects:

[0028] The technical effects of the present invention are mainly reflected in the following aspects:

[0029] 1. The present invention innovatively adopts line laser for triangulation measurement. By integrating the laser emitter, imaging lens, imaging sensor, control and data processing device, combined with electronic switching technology, solid-state ranging modeling of the surrounding environment is performed. This can avoid the scanning device cost caused by point laser plus mechanical scanning, and can also improve the stability of the system, extend the service life, and reduce the system size.

[0030] 2. The present invention uses an asymmetric optical lens as an imaging lens, which can greatly reduce the baseline distance between the laser emitter and the imaging lens and the imaging chip, thereby miniaturizing the system.

[0031] 3. The data processing method of the present invention adopts a laser short pulse working mode, which can provide sufficiently high peak power under the premise of lower average power and human eye safety, compensate for the energy attenuation problem caused by linear laser, and improve the working distance.

[0032] 4. The data processing method of the present invention adopts a method based on narrow-band filters and background modeling, which can effectively extract laser lines and suppress noise interference, so that the system can operate under daylight.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 This is a schematic diagram of the solid-state laser radar structure;

[0036] Figure 2 is the asymmetric characteristic of the imaging lens in the present invention;

[0037] Figure 3 is a diagram showing the positional relationship between the laser beam, the imaging lens, and the imaging sensor;

[0038] Figure 4 It is a principle diagram of measuring the distance between a target point and a device in the present invention;

[0039] Figure 5A timing diagram for controlling the laser emitter and imaging sensor for the timing control interface;

[0040] Figure 6 This is a flow chart of the data processing method of the solid-state laser radar of the present invention;

[0041] Figure 7 Schematic diagram of laser line extraction and structured light algorithm of the present invention

[0042] 1Laser emitter 2Imaging lens 3Imaging sensor 4Control and data processing device

[0043] 5-line laser ranging system 6-line laser ranging system working angle

[0044] 7 Asymmetric field of view 8 Solid-state laser radar 9 Line laser plane 10 Obstacle

[0045] 11 Image of the first clock cycle 12 Image of the second clock cycle

[0046] 13 Laser line area 14 Extracted laser line 15 Point cloud data DETAILED DESCRIPTION

[0047] In order to further illustrate the technical means, creative features, objectives and effects achieved by the present invention and make them easier to understand, the following, in combination with the accompanying drawings and preferred embodiments, a specific implementation method, structure, characteristics, data processing method and effects of a micro solid-state laser radar provided according to the present invention are described in detail as follows.

[0048] like Figure 1 As shown, a micro solid-state laser radar includes: a laser emitter 1, an imaging lens 2, an imaging sensor 3, and a control and data processing device 4; the laser emitter 1 is used to emit linear laser; the imaging lens 2 is used to collect the reflected laser light and form an image on the imaging sensor; the imaging sensor 3 receives the light focused by the imaging lens and forms an image; the control and data processing device 4 is used to control the operation of the laser emitter, receive the imaging data of the imaging sensor 3 and run the structured light algorithm, and finally obtain the point cloud data in the space environment.

[0049] Among them, a laser transmitter 1, an imaging lens 2 and an imaging sensor 3 constitute a group of line laser ranging systems 5. Four groups of line laser ranging systems 5 are arranged in a circle in space and are respectively connected to the control and data processing device 4, thereby forming a solid-state laser radar with a large-angle working range. A narrow-band bandpass filter lens is arranged at the front end of the imaging sensor 3. The central wavelength of the narrow-band bandpass filter lens is the same as the wavelength of the laser emitted by the laser transmitter.

[0050] like Figure 2As shown, the equivalent focal length of the imaging lens 2 in the horizontal direction is short, and the equivalent focal length in the vertical direction is long, and the field of view 7 presents an asymmetric structure. The application of an asymmetric imaging lens can greatly reduce the baseline distance between the laser emitter and the imaging lens and the imaging chip, thereby allowing the system to be miniaturized.

[0051] like Figure 3 As shown, the control and data processing device 4 in the solid-state laser radar 8 controls the laser emitter 1 to emit a line laser 9. The line laser 9 is reflected after encountering the measured object 10 during the space propagation process, and is converged by the imaging lens 2 and imaged on the imaging sensor 3 (virtual imaging plane position). After the imaging data is analyzed and processed by the control and data processing device 4, the final laser ranging point cloud data is obtained.

[0052] like Figure 4 As shown, in the present invention, the principle of triangulation is: the angle between the laser beam and the optical axis of the camera is θ, and the intersection point is O. The laser beam is projected onto the obstacle to form point P. P' is the mirror image of point P. The vertical distance from point O to the optical center plane is h, and the vertical distance from point P to point O is Δh. v is the distance from point P' to the u axis of the imaging plane, and z is the vertical distance from point P to the optical center plane. The focal length of the camera is f. So:

[0053]

[0054] The following provides a set of application and data processing examples of the micro solid-state laser radar of the above embodiment:

[0055] Step 1: The laser emitter is controlled by the timing control interface to emit a linear laser;

[0056] Step 2: The imaging lens collects the reflected laser light and forms an image on the imaging sensor;

[0057] Step three, the imaging sensor starts exposure under the control of the timing control interface, receives the light focused by the imaging lens and sends imaging data to the central processor through the data communication interface; specifically, in the first time period, the timing control circuit controls the laser emitter to emit laser, and the imaging sensor starts exposure synchronously, and after a 1ms time interval, the laser emitter is turned off, and the imaging sensor stops exposing; in the second time period, the timing control circuit controls the laser emitter not to emit laser, the imaging sensor starts exposure, and after a 1ms time interval, the imaging sensor stops exposing; then the first and second time periods are cyclically run, the exposure time of the imaging sensor is between 100us and 10ms, and the exposure time of the imaging sensor in the first and second time periods is equal.

[0058] In step 4, the central processing unit receives the imaging data and runs the structured light algorithm, including laser line extraction and triangulation solution. The laser line extraction is specifically to extract the laser line by background modeling, that is, to compare the imaging data of two adjacent frames of the imaging sensor. When the difference in the collected pixel data between the two frames is greater than a given threshold, it is determined that the pixel is located in the laser line candidate area.

[0059] The triangulation solution specifically calculates the three-dimensional coordinates in space for each sub-pixel point belonging to the laser line on the imaging sensor through the triangulation principle, and finally splices the multiple sets of point cloud data results to obtain the spliced ​​point cloud data with a large angle range, and finally obtains the point cloud data in the spatial environment.

[0060] like Figure 7 By comparing the first clock cycle imaging image 11 and the second clock cycle imaging image 12, the laser line area 13 can be extracted using the background difference method, and the laser line area 13 is subjected to sub-pixel analysis processing to obtain the extracted laser line 14. The structured light algorithm is performed on each pixel point on the extracted laser line 14 to obtain the point cloud data 15.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A miniature solid-state laser radar, It is characterized in that include: Laser emitters, imaging lenses, imaging sensors, control and data processing devices; The laser emitter is used to emit linear laser; The imaging lens is used to collect the reflected laser light and form an image on the imaging sensor; the imaging sensor receives the light focused by the imaging lens and forms an image; The control and data processing device is used to control the operation of the laser transmitter, receive imaging data from the imaging sensor, run the structured light algorithm, and finally obtain point cloud data in the space environment; The light emitted by the laser emitter is irradiated onto the surface of the object, and then reflected by the surface of the object and received by the imaging lens, and finally imaged on the imaging lens; the laser emitter and the imaging sensor are both electrically connected to the control and data processing device; The imaging lens is an asymmetric optical lens having an asymmetric focusing characteristic. The asymmetric focusing characteristic is specifically that the equivalent focal length of the imaging lens in the direction of the line connecting the laser emitter and the imaging lens is greater than the equivalent focal length in the vertical direction between the laser emitter and the imaging lens.

2. A micro solid-state laser radar according to claim 1, It is characterized in that A narrow-band band-pass filter lens is arranged at the front end of the imaging sensor, and the central wavelength of the narrow-band band-pass filter lens is the same as the wavelength of the laser emitted by the laser emitter.

3. A micro solid-state laser radar according to claim 1, It is characterized in that The laser transmitter comprises a laser driving circuit, a laser diode and a laser projection lens.

4. A micro solid-state laser radar according to claim 1, 2 or 3, It is characterized in that The control and data processing device is electrically connected to the laser emitter and the imaging sensor; the control and data processing device consists of a timing control interface, a data communication interface and a central processing unit, the timing control interface is electrically connected to the laser emitter and the imaging sensor, and the data communication interface is electrically connected to the imaging sensor.

5. A micro solid-state laser radar according to claim 4, It is characterized in that The control and data processing device is connected to four laser emitters and four imaging sensors at the same time. The data communication interface is connected to the imaging sensor through an electronic switch. The imaging lens is arranged in front of the imaging sensor to focus light on the imaging sensor. The horizontal angle of the imaging lens is greater than or equal to 90 degrees. The diffusion angle of the laser line emitted by the laser emitter is greater than or equal to 90 degrees. The field of view of the imaging lens coincides with the area of ​​the laser line emitted by the laser emitter.

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