CN115656966A - Laser radar ranging method based on zoom Samm imaging principle - Google Patents
Laser radar ranging method based on zoom Samm imaging principle Download PDFInfo
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Abstract
The invention discloses a laser radar ranging method based on a zoom Samm imaging principle. The laser emitted by the laser device forms an approximate straight beam with a low divergence angle through the collimation system to irradiate on a target object, light scattered by the target object is collected through the focusing lens group with a short focal length, and then the light is imaged on the image detector to obtain low-resolution distance information of the target object. And adjusting the focal length in the focusing lens group to focus the ranging view field near the target object, adjusting the position of the image detector, and uploading the acquired image information to the computer by the image detector again, thereby completing one-time distance measurement on the target object. The invention can make the pixels of the image detector correspond to the range of the measured target object one by one as much as possible, effectively improves the pixel utilization rate of the image detector, and further can well improve the defect that the resolution ratio of the triangular distance measuring system is reduced at a distance.
Description
Technical Field
The invention relates to the technical field of laser detection, in particular to a laser radar ranging method based on a zoom Samm imaging principle.
Background
Laser ranging is a non-contact detection technology with high precision and high speed, and is widely applied to various industries such as unmanned vehicles, robots, industrial detection and the like. In the existing laser ranging schemes, most of the schemes adopt a pulse type laser ranging mode, and the pulse type laser ranging principle is that a beam of laser is emitted towards a target direction and is shot on the target, then the time of the laser reflected by the target is calculated, and finally the target distance is obtained by utilizing the relationship between displacement, time and speed. Although pulsed laser ranging can maintain a stable high resolution over the measurement range, pulsed laser ranging systems are far more costly than triangular laser ranging systems, due primarily to the need for a highly sensitive detector, such as a photomultiplier tube, and a high speed signal sampling system. The triangular laser ranging method mainly calculates the target distance by calculating the position of light reflected back by a target through the triangular relation among a laser, the target and a detector. The triangular laser ranging system has the characteristics of low cost, high resolution at a short distance and gradually reduced resolution at a far distance.
The samm imaging principle means that when the imaging optical system is not parallel to the object plane, as long as the object plane, the imaging optical system and the image plane intersect in a straight line under the condition of satisfying the gaussian equation, a clear image can still be formed on the object plane. The distance measurement system adopting the Samm imaging principle can overcome the defect of small depth of field of a large-caliber imaging system, the resolution ratio is greatly improved compared with the conventional triangular laser distance measurement, but the laser distance measurement based on the Samm imaging principle still belongs to the triangular laser distance measurement, and therefore the defect that the resolution ratio at a far distance is nonlinearly reduced is still kept.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a laser radar ranging method based on a zoom Samm imaging principle.
The technical scheme of the invention is as follows:
step (1): laser emitted by the laser forms an approximate straight-line beam with a low divergence angle through the collimation system to irradiate on a target object, and light scattered back by the target object is collected through the focusing lens group with a short focal length and then imaged on the image detector.
It should be noted that, by using the short focal length, a wide range of field of view can be obtained first, so as to achieve ranging within a wide range of distance, and low-resolution distance information of the target object can be obtained. The focusing lens group is internally provided with a narrow-band filter, and the central wavelength of the narrow-band filter is consistent with that of the laser, so that the system can filter the interference of other ambient light.
And the image detector uploads the obtained image information to a computer, and the computer calculates the low-resolution distance information of the target object through a Simm imaging principle related algorithm.
Step (2): after the low-resolution distance information of the target object is obtained, the computer sends a command to the system control board, and the system control board adjusts the focal length in the focusing lens group, so that the ranging field of view is focused near the target object, the field of view range is narrowed, and the resolution of the system near the target object is improved.
In order to enable the object plane, the image plane and the imaging optical system of the system to meet the Simm imaging law, the system control panel controls the two-dimensional translation platform to adjust the position of the image detector, finally the image detector uploads the acquired image information to the computer, and the computer calculates the high-resolution distance information of the target object through an algorithm, so that one-time distance measurement of the target object is completed.
The computer is connected with a system control board, the system control board is connected with a three-dimensional rotating platform, and devices such as a laser light source, a collimation and beam expansion system, a focusing lens group, a two-dimensional translation platform for placing an image detector and the like are all fixed on the three-dimensional rotating platform. The three-dimensional rotating platform is a mature product and can rotate 360 degrees in the horizontal direction and 360 degrees in the vertical direction. The computer controls the three-dimensional rotating platform to scan within a horizontal alpha degree range and a vertical beta degree range by the system control board, and the first step and the second step are repeated simultaneously, so that 3D distance information within the horizontal alpha degree range and the vertical beta degree range around the system is obtained.
The invention has the beneficial effects that: the invention can make the pixel of the image detector correspond to the range of the measured target object one by one as much as possible, effectively improves the pixel utilization rate of the image detector and further can well improve the resolution ratio of the distance measuring system at a distance.
Drawings
FIG. 1 is a schematic diagram of one embodiment of lidar ranging based on the zoom-Scheimer imaging principle.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, the apparatus according to the present invention includes a laser light source 1, a collimated beam expanding system 2, a target 3, a focusing lens group 4, an image detector 5, an image detector 6 with a changed position, a two-dimensional translation platform 7, a three-dimensional rotation platform 8, a computer 9, and a system control board 10.
In order to protect the safety of human eyes, the laser source 1 adopts an infrared 808nm semiconductor laser, laser beams emitted by the laser source 1 pass through the collimation and beam expansion system 2, the collimation and beam expansion system 2 is utilized to expand point-shaped 808nm laser beams into approximate straight-line beams with a low divergence angle, the beams are irradiated on a target object 3, light scattered back by the target object is converged on the image detector 5 through the focusing lens group 4 with the focal length set to be 500mm, the focusing lens group 4 contains a narrow-band filter, the central wavelength of the narrow-band filter is 808nm, the bandwidth of the narrow-band filter is 5nm, then the image detector 5 uploads image data to the computer 9, the computer 9 preliminarily calculates the position of the target object through a Samm imaging related algorithm, and then a modulation command is sent to the system control panel 10.
The system control board 10 sends a control signal to the focusing lens group 4 to readjust the proper focal length to focus the range finder field near the target object. Meanwhile, the system control board 10 needs to send a control signal to the two-dimensional translation platform 7, the two-dimensional translation platform 7 adopts a high-precision electric linear two-dimensional sliding table, the sliding table is connected with the image detector 5, the sliding table is controlled to move the image detector 5, so that an object plane, an image plane and an optical imaging system of the system meet the Schlemm imaging law, and the position of the image detector 5 after moving is changed into the position of the image detector 6 after changing the position. The image detector 6 after changing the position acquires the image information again and uploads the image information to the computer 9, the computer 9 extracts the coordinates of the imaging point according to the image data, and the distance of the target object is accurately calculated through a related algorithm to finish one measurement.
Wherein the computer 9 is connected with a system control panel 10, the system control panel 10 is connected with a three-dimensional rotating platform 8, and the laser light source 1, the collimation and beam expansion system 2, the focusing lens group 4, the two-dimensional translation platform 7 for placing the image detector 5 and other devices are all fixed on the three-dimensional rotating platform 8. The computer 9 controls the three-dimensional rotating platform 8 to scan within 360 degrees horizontally and 60 degrees vertically by controlling the system control board 10, and repeats the above steps, thereby obtaining 3D distance information within 360 degrees horizontally and 60 degrees vertically around the system.
Now, under the condition that the model parameters of the used component devices are all the same as proved by data, the resolution of the triangular laser ranging at the far end can be effectively improved by adopting the method, and the specific parameter setting and the result are as follows:
| F/mm | theta/degree | L/mm | Resolution/m at 600m | Resolution/m at 800m | Resolution/m at 1000m | |
| ① | 500 | 45 | 500 | 5.623 | 10.11 | 15.88 |
| ② | 866 | 60 | 500 | 2.308 | 4.105 | 6.415 |
The data (1) is an unused method, the data (2) is obtained by using the method of the invention, the parameter F is the focal length of the focusing lens group 4, theta is an included angle between the focusing lens group 4 and the image detector 5, L is a distance from the focusing lens group 4 to a system object plane, an image plane and an imaging optical system in order to meet the intersection straight line of the Schlemm's law of imaging, the parameter of the image detector 5 adopted in the example is 2048 x 2048, and the size of each pixel is 5.5um. As can be seen from the data comparison, the resolution at 600m is improved by 2.43 times; the resolution at 800m is improved by 2.46 times; the resolution at 1000m is improved by 2.47 times. Therefore, the method adopted by the invention can effectively improve the resolution of the triangular laser ranging.
In summary, the invention provides a laser radar ranging method based on the Samm imaging principle, which adopts a mode of adjusting the focal length of an imaging optical system according to the distance of a target object, controls the measurement range of the system, and utilizes the pixel points of a high-resolution image detector as much as possible, thereby effectively improving the resolution of the laser radar ranging method based on the Samm imaging principle at a distance.
Claims (5)
1. A laser radar ranging method based on a zoom Samm imaging principle is characterized by comprising the following steps:
laser emitted by a laser forms an approximate straight beam with a low divergence angle through a collimation system to irradiate on a target object, and light scattered back by the target object is collected through a focusing lens group with a short focal length and then imaged on an image detector;
the image detector uploads the obtained image information to a computer, and the computer calculates the low-resolution distance information of the target object through a Samm imaging algorithm;
after obtaining the low-resolution distance information of the target object, the computer sends a command to a system control board, and the system control board adjusts the focal length in the focusing lens group to enable the ranging view field to be focused near the target object; in order to enable the object plane, the image plane and the imaging optical system of the system to meet the Schlemm imaging law, the system control board also controls the two-dimensional translation platform to adjust the position of the image detector;
and finally, the image detector uploads the acquired image information to a computer, and the computer calculates the high-resolution distance information of the target object through a Samm imaging algorithm, so that one-time distance measurement of the target object is completed.
2. The lidar ranging method based on zoom-based Samm imaging principle according to claim 1, wherein: the focusing lens group is internally provided with a narrow-band filter, and the central wavelength of the narrow-band filter is consistent with that of the laser, so that the system can filter the interference of other ambient light.
3. The lidar ranging method based on zoom-Samm imaging principle of claim 1, wherein: the system control board is connected with the three-dimensional rotating platform, and the laser light source, the collimation and beam expansion system, the focusing lens group and the two-dimensional translation platform for placing the image detector are all fixed on the three-dimensional rotating platform.
4. The lidar ranging method based on zoom-based Samm imaging principle of claim 3, wherein: the three-dimensional rotating platform can rotate 360 degrees in the horizontal direction and 360 degrees in the vertical direction.
5. The lidar ranging method based on zoom-Samm imaging principle of claim 4, wherein: the computer controls the three-dimensional rotating platform to scan within a horizontal alpha degree range and a vertical beta degree range through the system control board, so that 3D distance information within the horizontal alpha degree range and the vertical beta degree range around the system is obtained.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115856835A (en) * | 2023-03-01 | 2023-03-28 | 常州星宇车灯股份有限公司 | Laser radar control system for realizing zoom scanning imaging and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115856835A (en) * | 2023-03-01 | 2023-03-28 | 常州星宇车灯股份有限公司 | Laser radar control system for realizing zoom scanning imaging and control method thereof |
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