CN113064139B - Laser radar with high measurement accuracy and application method thereof - Google Patents
Laser radar with high measurement accuracy and application method thereof Download PDFInfo
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- CN113064139B CN113064139B CN202110274257.6A CN202110274257A CN113064139B CN 113064139 B CN113064139 B CN 113064139B CN 202110274257 A CN202110274257 A CN 202110274257A CN 113064139 B CN113064139 B CN 113064139B
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- 238000005259 measurement Methods 0.000 title claims abstract description 41
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- 230000003287 optical effect Effects 0.000 claims abstract description 105
- 230000005540 biological transmission Effects 0.000 claims abstract description 84
- 238000012935 Averaging Methods 0.000 claims abstract description 13
- 238000000926 separation method Methods 0.000 claims abstract description 12
- 238000013519 translation Methods 0.000 claims description 55
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- 230000008878 coupling Effects 0.000 claims description 7
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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
- 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
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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
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/46—Indirect determination of position data
- G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
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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
- G01S7/483—Details of pulse systems
- G01S7/484—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
- G01S7/483—Details of pulse systems
- G01S7/486—Receivers
- G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
Abstract
The invention discloses a laser radar with high measurement accuracy and a use method thereof, wherein the laser radar with high measurement accuracy comprises a multi-wavelength emission light source, an emission contact pin, an emission lens, a receiving lens, a wavelength separation element and an array detector; the multi-wavelength transmitting light source is used for providing optical signals with different wavelengths, the transmitting pin is used for transmitting multi-wavelength multiplexing detection optical signals, and the transmitting lens is used for carrying out collimation transmission or focusing transmission; the array detector is used for acquiring the independent transmission time of the optical signals with different wavelengths, summing and averaging the optical signals, and then calculating the distance of the target. The invention improves the light path design of the prior laser radar, couples the light signals with a plurality of wavelengths into the same detection light pulse and simultaneously transmits and detects the light signals to obtain the distance data of each wavelength to the same detection target, sums and averages the distance data corresponding to each wavelength, avoids the influence of random errors and improves the measurement accuracy of the laser radar.
Description
Technical Field
The invention belongs to the technical field of laser detection, and particularly relates to a laser radar with high measurement accuracy and a use method thereof.
Background
The laser radar is used for detecting the distance of the surrounding target environment by emitting detection light signals to the target, can be used for acquiring the information of the distance, angle, relative position and the like of the target, and belongs to target sensing equipment. With the increase of the real-time requirement on target detection, the laser radar develops a multi-line laser radar, and can acquire the target information of the surrounding environment in real time. However, both single-line and multi-line lidars perform distance calculation based on the time of flight of a pulsed light signal, and are mostly based on the measurement principle of single-pulse detection of a single target. The technical method has the defects of larger precision, is difficult to meet the test requirement of high measurement precision, and has further requirements on the measurement precision requirement of the laser radar along with the development of the application of the laser radar industry, especially the development of the field of the high measurement precision industry.
At present, the method for improving the measurement accuracy of the laser radar basically adopts a multi-pulse averaging method, namely, a plurality of pulse signals are emitted in a single target and a single angle direction, and then the distances obtained by calculating the flight time of the pulse signals are summed and averaged to obtain the distance between the target and the laser radar equipment. The technical method can optimize the ranging accuracy of the laser radar, but repeatedly transmits the pulse light signals in a single direction, so that the practical use repetition frequency of the laser radar is reduced, the angle resolution of the laser radar is further reduced, and the overall performance is influenced.
Disclosure of Invention
The technical problems to be solved by the invention are as follows:
most of the existing laser radars adopt a single-wavelength light source, pulse light signals are repeatedly emitted in a single direction, targets are detected, the distance between the targets is obtained, random errors in the technical scheme can influence the ranging accuracy, and the angular resolution of the laser radars can be reduced due to the fact that the single targets are repeatedly detected.
In order to solve the technical problems, the invention adopts the following technical scheme:
in a first aspect, a high measurement accuracy lidar is provided, including a multi-wavelength transmitting light source, a transmitting pin, a transmitting lens, a receiving lens, a wavelength-dividing element and an array detector;
the multi-wavelength emitting light source is used for providing light signals with different wavelengths, and is coupled with the emitting pin; the transmitting contact pin is used as a secondary transmitting light source and used for transmitting multi-wavelength multiplexing detection light signals, and the transmitting lens is used for carrying out collimation transmission or focusing transmission;
the receiving lens is used for receiving the multi-wavelength multiplexed detection light signals reflected by the target to the wavelength division element; the wavelength separation element is used for spatially separating optical signals with different wavelengths in the multi-wavelength multiplexed detection optical signals;
the array detector is used for acquiring the independent transmission time of the optical signals with different wavelengths, summing and averaging the optical signals, and then calculating the distance of the target.
Preferably, the multi-wavelength light source comprises different single-wavelength light sources and an array waveguide grating, wherein the light signals emitted by the different single-wavelength light sources are received by the array waveguide grating, and the array waveguide grating is used for coupling the light signals emitted by the different single-wavelength light sources to obtain multi-wavelength multiplexed detection light signals.
Preferably, the multi-wavelength light source comprises a broad spectrum light source for providing light signals of different wavelengths.
Preferably, pixels are arranged at different positions of the array detector, and the pixels are independently controlled and used for acquiring independent transmission time of optical signals with different wavelengths.
Preferably, the array detector comprises a processor for summing and averaging transmission times acquired by the pixels and corresponding to different wavelengths, and then calculating the distance of the target.
Preferably, when the emission lens performs focusing emission, the laser radar with high measurement precision further comprises a translation device and a camera;
the translation device is connected with the transmitting pin or the transmitting lens and is used for adjusting the position of the transmitting pin or the transmitting lens so as to adjust the relative distance d1 between the transmitting pin and the transmitting lens;
the camera is used for collecting calibration object images at different detection distances, and further calibrating the relative distance d1 corresponding to the light spot focusing at different detection distances in advance by combining the definition of the calibration object images, and storing the corresponding relation between the detection distances and the relative distance d1.
Preferably, the device further comprises a position sensor, wherein the position sensor is connected with the transmitting pin or the transmitting lens and is used for monitoring the real-time position of the transmitting pin or the transmitting lens so as to further determine the relative distance d1 between the transmitting pin and the transmitting lens.
Preferably, the device further comprises a data register and a translation control device, and the position sensor, the data register, the translation control device and the translation device are sequentially connected, wherein the data register is used for storing the corresponding relation between the detection distance and the relative distance d1 in advance; the translation control device is used for controlling the translation device according to the relative distance d1 read from the data register, and then the multi-wavelength emission light source or the emission lens is moved to a specified position.
In a second aspect, the present invention provides a method for using a high measurement accuracy lidar, where the high measurement accuracy lidar in the first aspect is used, and the method includes:
selecting a plurality of different detection distances, setting corresponding calibration objects at each detection distance, and acquiring corresponding calibration object images through the camera after the emission contact pin emits detection light signals;
continuously adjusting the position of the transmitting contact pin or the transmitting lens through the translation device until the definition of the image of the calibration object reaches the best, and finding out the light spot focusing state;
monitoring the position of the transmitting pin or the transmitting lens through a position sensor, further determining the relative distance d1 between the transmitting pin and the transmitting lens at the moment, and storing the corresponding relation between the detecting distance and the relative distance d1 in a data register;
when a user sets a detection distance to be used, determining a relative distance d1 corresponding to the detection distance according to a pre-stored corresponding relation, and further moving the transmitting contact pin or the transmitting lens to a designated position through the translation device to complete the focusing of the light spots at a certain distance;
coupling optical signals with different wavelengths emitted by a multi-wavelength emission light source to obtain multi-wavelength multiplexing detection optical signals, emitting the multi-wavelength multiplexing detection optical signals from the emission contact pin, and detecting a target after focusing through the emission lens; after the multi-wavelength multiplexing detection optical signals reflected by the target pass through the receiving lens, the wavelength separation element separates optical signals with different wavelengths in the multi-wavelength multiplexing detection optical signals in space, the separated optical signals with different wavelengths are received by the array detector, the independent transmission time of each optical signal with different wavelengths is obtained, the independent transmission time of the optical signals with different wavelengths is processed, the actual transmission time of the multi-wavelength multiplexing detection optical signals is obtained, and the distance of the target is calculated according to the actual transmission time.
Preferably, the processing is performed on the independent transmission time of the optical signals with different wavelengths, specifically:
and summing and averaging the independent transmission time of the optical signals with different wavelengths to obtain a first average value, sequentially comparing the independent transmission time of the optical signals with different wavelengths with the first average value to obtain a difference value between the transmission time with different wavelengths and the first average value, removing the independent transmission time of the optical signals with the wavelengths corresponding to the maximum two difference values, and summing and averaging the rest independent transmission time of the optical signals with different wavelengths again to obtain a new average value which is used as the actual transmission time of the multi-wavelength multiplexing detection optical signals.
In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: the invention improves the light path design of the existing laser radar, couples the light signals with a plurality of wavelengths into the same detection light pulse and simultaneously transmits and detects the light signals to obtain the distance data of each wavelength to the same detection target, sums and averages the distance data corresponding to each wavelength, avoids the influence of random errors and improves the ranging precision and the angle resolution of the laser radar.
Drawings
Fig. 1 is a schematic structural diagram of a laser radar with high measurement accuracy according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a laser radar with high measurement accuracy with a single wavelength light source according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a laser radar with high measurement accuracy with a broad spectrum light source according to an embodiment of the present invention;
FIG. 4 is a flowchart of a method for using a laser radar with high measurement accuracy according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a spot scanning effect of a laser radar with high measurement accuracy according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of laser radar detection when a transmitting pin is positioned in front of a transmitting lens according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of laser radar focusing detection when a transmitting pin is far from the front focal plane of a transmitting lens according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of a connection of structural members of a transmitting pin according to an embodiment of the present invention;
fig. 9 is a flowchart of another method for using a laser radar with high measurement accuracy according to an embodiment of the present invention.
Detailed Description
The multi-wavelength emitting light source provides light signals with different wavelengths, and different wavelengths lambda are assumed 1 、λ 2 、λ 3 、……、λ n The transmission time from the laser radar with high measurement accuracy to the target is respectively In theory, the transmission time from the target to the laser radar equipment is delta t, each test data of the laser radar is affected by random errors and other factors, a certain random deviation exists between the transmission time of the optical signal and the theoretical value, and the transmission time deviation of each wavelength is assumed to be> The transmission time per wavelength is then:
……
because of random errors, the flight time of each wavelength optical signal has different fluctuation, and compared with a theoretical value, the random errors are possibly increased or decreased, and the flight time of all the wavelengths is summed and averaged to obtain the actual transmission time deltat' of each target:
according to the theoretical knowledge of random errors, as the number of test samples increases, the average value of the fluctuation of random errors of a plurality of measured values approaches zero, namely:
thus, the more test values, the more accurate the result of summing the averages.
Based on the above principle, the present invention will be further described in detail with reference to the drawings and the embodiments, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In the embodiments of the present invention, the symbol "/" means that there are two functions at the same time, and the symbol "a and/or B" means that the combination between the front and rear objects connected by the symbol includes three cases "a", "B", "a and B". In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other. The invention will be described in detail below with reference to the drawings and examples.
Example 1
In order to solve the technical problem that the ranging accuracy and the angular resolution of the traditional laser radar are lower due to the fact that the traditional laser radar detects a single target based on single pulse, the embodiment of the invention improves the optical path design of the traditional laser radar, optical signals with multiple wavelengths are coupled into the same detection optical pulse, emission detection is carried out at the same time, distance data of each wavelength on the same detection target are obtained, summation and average are carried out on the distance data corresponding to each wavelength, and high-accuracy detection of the laser radar with high measurement accuracy is achieved.
With reference to fig. 1, the laser radar with high measurement accuracy provided by the embodiment of the invention includes a multi-wavelength emission light source, an emission pin, an emission lens, a receiving lens, a wavelength separation element and an array detector;
the multi-wavelength emitting light source is used for providing light signals with different wavelengths, and is coupled with the emitting pin; the transmitting contact pin is used as a secondary transmitting light source and used for transmitting multi-wavelength multiplexing detection light signals, and the transmitting lens is used for carrying out collimation transmission or focusing transmission; the multi-wavelength transmitting light source can be connected with the transmitting pin through an optical fiber or an optical waveguide and is used for coupling optical signals with different wavelengths emitted by the multi-wavelength transmitting light source into multi-wavelength multiplexing detection optical signals; when the emission lens performs focusing emission, the distance between the emission contact pin and the emission lens can be adjusted, so that the size of a target light spot can be adjusted, and high-resolution measurement can be realized.
The receiving lens is used for receiving the multi-wavelength multiplexed detection light signals reflected by the target to the wavelength division element; the wavelength separation element is used for spatially separating optical signals with different wavelengths in the multi-wavelength multiplexing detection optical signals, and the optical signals are respectively received by different positions of the array detector.
The array detector is used for acquiring independent transmission time of optical signals with different wavelengths, summing and averaging, and then calculating the distance of a target; specifically, the individual transmission times of the optical signals with different wavelengths are summed and averaged to obtain a first average value, the individual transmission times of the optical signals with different wavelengths are sequentially compared with the first average value to obtain a difference value between the transmission times with different wavelengths and the first average value, the individual transmission time of the optical signals with the wavelengths corresponding to the maximum two difference values is removed, and the remaining individual transmission times of the optical signals with different wavelengths are summed and averaged again to obtain a new average value which is used as the actual transmission time of the multi-wavelength multiplexing detection optical signal.
The wavelength division element is used for dividing optical signals with different wavelengths in the multi-wavelength multiplexing detection optical signals in space, the optical signals are respectively received by different positions of the array detector, and specifically, the array detector comprises pixels and a processor, each pixel is independently controlled, the pixels are used for acquiring independent transmission time of the optical signals with different wavelengths, the independent transmission time refers to the transmission time of each optical signal with different wavelengths from the high-measurement-precision laser radar to a target, and the processor is used for summing and averaging the transmission time corresponding to the different wavelengths acquired by the pixels, and then calculating the distance of the target, so that the high-precision detection of the high-measurement-precision laser radar is realized.
As shown in fig. 2, in the embodiment of the present invention, the multi-wavelength light source includes different single-wavelength light sources and an arrayed waveguide grating, where the optical signals emitted by the different single-wavelength light sources are received by the arrayed waveguide grating, and the arrayed waveguide grating is used to couple the optical signals emitted by the different single-wavelength light sources to obtain multi-wavelength multiplexed detection optical signals.
As shown in fig. 3, in the embodiment of the present invention, in order to further simplify the structure of the laser radar, a plurality of different single-wavelength light sources and the arrayed waveguide grating may be replaced by a broad-spectrum light source integrally, that is, the broad-spectrum light source provides optical signals with different wavelengths, and the broad-spectrum light source may be connected to an optical fiber, so as to couple the optical signals with different wavelengths emitted by the broad-spectrum light source into the same optical fiber.
In the embodiment of the invention, pixels are arranged at different positions of the array detector, and are independently controlled and used for acquiring independent transmission time of optical signals with different wavelengths.
In an embodiment of the present invention, the array detector includes a processor, where the processor is configured to sum and average transmission times acquired by the pixels and corresponding to different wavelengths, and then calculate a distance of a target.
In the embodiment of the invention, when the transmitting lens performs focusing transmission, the laser radar with high measurement precision further comprises a translation device and a camera;
the translation device is connected with the transmitting pin or the transmitting lens and is used for adjusting the position of the transmitting pin or the transmitting lens so as to adjust the relative distance d1 between the transmitting pin and the transmitting lens;
the camera is used for collecting calibration object images at different detection distances, and further calibrating the relative distance d1 corresponding to the light spot focusing at different detection distances in advance by combining the definition of the calibration object images, and storing the corresponding relation between the detection distances and the relative distance d1.
In the embodiment of the invention, the device further comprises a position sensor, wherein the position sensor is connected with the transmitting contact pin or the transmitting lens and is used for monitoring the real-time position of the transmitting contact pin or the transmitting lens so as to further determine the relative distance d1 between the transmitting contact pin and the transmitting lens.
In the embodiment of the invention, the device further comprises a data register and a translation control device, and the position sensor, the data register, the translation control device and the translation device are sequentially connected, wherein the data register is used for storing the corresponding relation between the detection distance and the relative distance d1 in advance; the translation control device is used for controlling the translation device according to the relative distance d1 read from the data register, and then the multi-wavelength emission light source or the emission lens is moved to a specified position.
Example 2
On the basis of the above embodiment 1, the embodiment of the present invention provides a method for using a laser radar with high measurement accuracy, where in the embodiment of the present invention, a multi-wavelength multiplexed probe optical signal is collimated and transmitted by the transmitting lens, as shown in fig. 4, the method mainly includes:
step 101, connecting the optical fiber with the multi-wavelength emitting light source, coupling the optical signals with different wavelengths emitted by the multi-wavelength emitting light source into the same optical fiber to obtain the multi-wavelength multiplexing detection optical signal, and emitting the detection optical signal from the emitting contact pin.
102, detecting a target after the light path of the multi-wavelength multiplexing detection light signal is collimated by the emission lens; the optical path of the multi-wavelength multiplexing detection optical signal reflected by the target passes through the receiving lens and then reaches the wavelength division element.
And 103, separating optical signals with different wavelengths in the multi-wavelength multiplexed detection optical signals in space by the wavelength separation element, wherein the separated optical signals with different wavelengths are respectively received by pixels at different positions of the array detector.
Step 104, obtaining the independent transmission time of each optical signal with different wavelengths through the pixel, processing the transmission time corresponding to the different wavelengths obtained by the pixel through the processor, thereby obtaining the actual transmission time deltat 'of the multi-wavelength multiplexing detection optical signal, and calculating the distance of the target according to the actual transmission time deltat'.
In the embodiment of the invention, the transmission time acquired by the pixel and corresponding to different wavelengths is processed by a processor, specifically:
the processor of the array detector sums and averages the transmission time acquired by the pixel and corresponding to different wavelengths, specifically, the processor firstly sums and averages the transmission time acquired by the pixel and corresponding to different wavelengths for the first time to obtain a first average delta t' 1 The method comprises the steps of carrying out a first treatment on the surface of the Sequentially combining the transmission times corresponding to different wavelengths with a first average value Deltat' 1 Comparing the transmission time corresponding to different wavelengths with the first average value Deltat' 1 The transmission time of the wavelength corresponding to the maximum two differences is removed, and the transmission time of the rest different wavelengths is summed again to obtain an average value delta t' 2 As the actual transmission time Δt' of the multi-wavelength multiplexed probe optical signal.
Based on the method, the value with larger deviation can be firstly screened out and filtered out, which is helpful for improving the measurement accuracy of the laser radar.
Example 3
In order to further solve the technical problem of poor spatial resolution in the conventional collimating optical path design, in the embodiment of the invention, the transmitting lens is used for focusing and transmitting, the laser radar in the embodiment 1 is designed into a focusing mode, and the light spot imaging of the laser radar is focused on different detection distances by changing the relative distance between the transmitting pin and the transmitting lens, so that the size of the light spot at the fixed distance can be reduced, the spatial resolution of the detection target at the fixed distance can be improved, and the high-resolution detection can be realized.
When the detection distance is a certain fixed distance, the spot scanning effect of the laser radar is shown in fig. 5, wherein Δd is the center-to-center distance of the adjacent spots, and represents the minimum scanning distance of the scanning device at the fixed distance; d is the outer diameter dimension of the spot, representing the spot size of the probe spot at that fixed distance. The formulas for Δd and D are shown below, respectively:
Δd＝dtan(Δθ) (7)
wherein d is the distance between the target and the lidar, i.e. the detection distance; delta theta is the rotation angle resolution of the laser radar scanning device, phi is the emergent light spot size of the laser radar,is the divergence angle of the laser radar emergent beam. For a lidar device, the minimum target size Φ that can be effectively resolved at distance d is:
Φ＝D+Δd (9)
as can be seen from equation (9), two techniques can be used to optimize the minimum target size Φ that can be effectively resolved by the lidar: 1) Reducing the minimum angular resolution of the scanning device, i.e. by Δθ; 2) The laser spot size at the target is reduced, i.e. phi is reduced. Among them, technique 1) is determined by a scanning device, and technique 2) is determined by a laser radar.
As shown in fig. 6 and 7, the transmitting pin emits a probe light signal, which is emitted after passing through the transmitting lens; the firing pin may be mounted on a translation device to effect positional movement thereof. When the transmitting pin is positioned on the front focal plane of the transmitting lens, the detection signal is just collimated and output, as shown in fig. 7; when the emitter pins are far from the front focal plane of the emitter lens, the emitter pins may be imaged at a specific distance away. The size of the collimated light spot at the distance d is shown in formula (8), and the imaging light spot size ω' of the transmitting pin at the distance d is:
wherein ω is the exit aperture of the emitter pin and f is the focal length of the emitter lens. In various application fields of the laser radar, a large-range scanning of the whole distance is not needed, and only a specific distance is needed to be subjected to targeted monitoring scanning, so that light spots at the specific distance can be optimized, and the scanning light spot size at the specific distance is reduced; the best effect of the optimization is to focus the laser radar spot image on the specific distance.
With reference to fig. 7, the laser radar with high measurement accuracy provided by the embodiment of the invention mainly includes a multi-wavelength emitting light source, an optical fiber, an emitting pin, a translation device, a camera, an emitting lens, a receiving lens, a wavelength separation element and an array detector. Wherein:
the multi-wavelength emitting light source is used for providing light signals with different wavelengths, the multi-wavelength emitting light source is connected with one end of an optical fiber, the light signals with different wavelengths are coupled into the same optical fiber, and the other end of the optical fiber is connected with the emitting contact pin; the transmitting contact pin is used as a secondary transmitting light source and used for transmitting the multi-wavelength multiplexing detection light signals and focusing and imaging after passing through the transmitting lens.
The receiving lens is used for receiving the multi-wavelength multiplexed detection light signals reflected by the target to the wavelength division element; the wavelength separation element is used for spatially separating optical signals with different wavelengths in the multi-wavelength multiplexing detection optical signals, and the optical signals are respectively received by different positions of the array detector.
The array detector comprises pixels and a processor, each pixel is independently controlled, the pixels are used for acquiring independent transmission time of optical signals with different wavelengths, and the processor is used for summing and averaging the transmission time acquired by the pixels and corresponding to the different wavelengths, and then calculating the distance of a target, so that high-precision detection of the laser radar with high measurement precision is realized.
The translation device is connected with the transmitting pin or the transmitting lens, and is used for adjusting the position of the transmitting pin or the transmitting lens, so as to adjust the relative distance d1 between the transmitting pin and the transmitting lens, wherein the translation device is connected with the transmitting light source, and the transmitting light source is installed on the translation device, as shown in fig. 7, then the translation device mainly adjusts the relative distance d1 between the transmitting pin and the transmitting lens by adjusting the position of the transmitting pin. Of course, in an alternative embodiment, two translation devices may be provided, respectively connected to the emitter pin and the emitter lens, the two translation devices acting together to adjust the relative distance d1.
The camera is used for collecting calibration object images at different detection distances, and further calibrating the relative distance d1 corresponding to the light spot focusing at different detection distances in advance by combining the definition of the calibration object images, and storing the corresponding relation between the detection distances and the relative distance d1. When the method is specifically applied, a plurality of detection distances can be selected in advance, and corresponding calibration objects are arranged at each detection distance; and acquiring corresponding calibration object images by using the cameras under each detection distance, searching for a focusing state according to the definition of the calibration object images, and continuously adjusting the positions of the transmitting pins or the transmitting lenses by using the translation device until the definition of the calibration object images is optimal, considering the light spots to focus at the moment, and recording the relative distance between the transmitting pins and the transmitting lenses at the moment, namely the relative distance d1 corresponding to the light spots to focus under the detection distance.
The optical axis of the camera and the optical axis of the laser radar need to be kept coaxial, for example, the installation setting of the camera can be performed as shown in fig. 7, specifically, a beam splitter can be arranged between the transmitting pin and the transmitting lens, and the beam splitting ratio of the beam splitter can be set according to actual requirements; after the returned light signal reaches the light splitting sheet, light is split according to the set light splitting ratio, wherein part of light reaches the camera, so that the camera can acquire images.
Based on the laser radar structure, when a user sets a detection distance to be used through upper computer software and the like, the relative distance d1 corresponding to the detection distance can be directly determined according to a pre-stored corresponding relation, and then the transmitting contact pin or the transmitting lens is moved to a designated position through the translation device, so that the light spot focusing at a fixed distance is completed.
With further reference to fig. 8, the laser radar provided by the embodiment of the invention further includes a position sensor, a data register and a translation control device, where the position sensor, the data register, the translation control device and the translation device are sequentially connected. Wherein:
the position sensor is connected with the transmitting pin or the transmitting lens and is used for monitoring the real-time position of the transmitting pin or the transmitting lens so as to further determine the relative distance d1 between the transmitting pin and the transmitting lens. In fig. 7, the translation device is connected to the emitter pin, and the position sensor is correspondingly connected to the emitter light source, so as to monitor the real-time position of the emitter pin, as shown in fig. 8.
The data register is used for storing the corresponding relation between the detection distance and the relative distance d1 in advance.
The translation control device is used for controlling the translation device according to the relative distance d1 read from the data register, and then the emission pin or the emission lens is moved to a designated position.
In order to ensure high positioning accuracy, the position sensor can preferably adopt a capacitive position sensor, so that the positioning accuracy can reach the micrometer level. The capacitive position sensor acquires the real-time position of the transmitting pin or the transmitting lens through a capacitive detector, and further determines the relative distance d1 between the transmitting pin and the transmitting lens. Taking fig. 8 as an example, the capacitive position sensor is connected with the transmitting pin, and the real-time position of the transmitting pin is obtained through the capacitive detector, specifically, the position is represented through the capacitance value.
Continuing to combine with figure 8, in actual use, firstly, combining the camera and the translation device to pre-calibrate the relative distance d1 corresponding to the focusing of the light spot under different detection distances, and then pre-storing the corresponding relation between the detection distance and the relative distance d1 and the corresponding relation between the relative distance d1 and the capacitance value in the data register according to the calibration result; when a user sets a detection distance to be used through upper computer software and the like, the relative distance d1 corresponding to the detection distance can be directly determined according to a pre-stored corresponding relation, the capacitance value corresponding to the relative distance d1 is further determined, then the corresponding capacitance value is sent to the translation control device, the translation control device controls the translation device to move the transmitting contact pin to a designated position, namely to a position corresponding to the capacitance value, and the fixed-distance light spot focusing is completed.
The embodiment of the invention improves the light path design of the prior laser radar equipment, designs a focusing mode of the laser radar, focuses the light spot imaging of the laser radar on different detection distances by changing the relative distance between the transmitting contact pin and the transmitting lens, not only can realize the detection of the laser radar with adjustable focal distance, but also can effectively reduce the light spot size at a fixed distance and improve the spatial resolution of a detection target at the fixed distance, thereby realizing higher-level high-precision detection.
Example 4
On the basis of the above embodiment 3, the embodiment of the present invention further provides a method for using a laser radar with high measurement accuracy, which can be implemented by using the laser radar described in embodiment 3. As shown in fig. 9, the ranging method mainly includes:
and 201, calibrating the relative distance d1 between the transmitting contact pin and the transmitting lens corresponding to the light spot focusing under different detection distances in advance by using a camera and a translation device, and storing the corresponding relation between the detection distance and the relative distance d1 in advance.
Firstly, selecting a plurality of different detection distances according to actual requirements, setting corresponding calibration objects at each detection distance, and acquiring corresponding calibration object images through the camera after the emission light source emits detection light signals.
Then, the focusing state is found according to the definition of the image of the calibration object, and the position of the transmitting contact pin or the transmitting lens can be continuously adjusted through the translation device until the definition of the image of the calibration object reaches the best, and then the focusing state of the light spot can be considered to be found.
And finally, monitoring the position of the transmitting pin or the transmitting lens through the position sensor, further determining the relative distance d1 between the transmitting pin and the transmitting lens at the moment, and storing the corresponding relation between the detection distance and the relative distance d1 in the data register in advance.
When the detection distance is selected, a large number of different detection distances can be selected directly according to the requirements, and the corresponding relative distance d1 when the light spot is focused is respectively determined under each detection distance, so that a large number of corresponding relations are stored; for example, 100 detection distances can be selected from the range of 50-500 distances at equal intervals, and the corresponding relation of 100 groups can be obtained after the detection distances are respectively calibrated in advance.
In the preferred scheme, a small amount of typical detection distances can be selected, and the corresponding relative distance d1 when the light spot is focused is respectively determined under each typical detection distance to obtain a small amount of corresponding relations; and then fitting according to the corresponding relations to obtain a relation curve between the detection distance and the relative distance d1, and further obtaining a large number of corresponding relations according to the relation curve and storing. For example, four detection distances of 50, 100, 150 and 200 can be selected first, and 4 groups of corresponding relations are obtained after calibration in advance respectively; fitting according to the 4 groups of corresponding relations to obtain a relation curve between the detection distance and the relative distance d1; and selecting 100 detection distances, and obtaining 100 corresponding groups of corresponding relations according to the relation curve. Compared with the first scheme, the second scheme can save the time of pre-calibration of a large amount of detection distances in the early stage and improve the pre-calibration efficiency.
Step 202, when a user sets a detection distance to be used, determining a relative distance d1 corresponding to the detection distance according to a pre-stored corresponding relation, and further moving the transmitting contact pin or the transmitting lens to a designated position through the translation device, so as to complete the focusing of the light spots at a fixed distance.
Based on the correspondence stored in the data register in step 201, when the user sets the detection distance to be used through the upper computer software, the relative distance d1 corresponding to the detection distance can be directly read from the data register according to the correspondence and sent to the translation control device; and then under the monitoring of the position sensor, the translation control device controls the translation device to move the transmitting contact pin or the transmitting lens to a designated position, so that the fixed-distance light spot focusing is completed.
Further taking fig. 8 as an example, when a capacitive position sensor is used and is connected to the transmitting pin, the capacitive position sensor obtains the real-time position of the transmitting light source through a capacitive detector, that is, characterizes the position through a capacitance value. In this case:
in step 201, after the camera and the translation device perform pre-calibration on the relative distance d1 corresponding to the focusing of the light spot at different detection distances, the corresponding relationship between the detection distance and the relative distance d1 and the corresponding relationship between the relative distance d1 and the capacitance value need to be pre-stored in the data register according to the pre-calibration result.
In step 202, when a user sets a detection distance to be used, firstly reading a relative distance d1 corresponding to the detection distance from the data register according to a corresponding relation, further determining a capacitance value corresponding to the relative distance d1, and sending the capacitance value to the translation control device; and then under the monitoring of the position sensor, the translation control device controls the translation device to enable the transmitting contact pin to move to the position corresponding to the capacitance value, so that the focusing of the facula at a certain distance is finished, and further the high spatial resolution detection of the target at the certain distance is finished.
After the positions of the transmitting pins or the transmitting lenses are adjusted to complete the focusing of the light spots with fixed distance, the optical signals with multiple wavelengths are coupled into the same detection optical pulse, and the transmitting detection is performed at the same time, so that distance data of each wavelength to the same detection target is obtained, and the distance data corresponding to each wavelength are summed and averaged to realize the high-precision detection of the laser radar with high measurement precision, as shown in fig. 9, the specific steps are as follows:
step 203, connecting the optical fiber with the multi-wavelength emitting light source, coupling the optical signals with different wavelengths emitted by the multi-wavelength emitting light source into the same optical fiber, obtaining the multi-wavelength multiplexed detection optical signal, and emitting from the emitting contact pin.
Step 204, detecting the target after the optical path of the multi-wavelength multiplexed detection light signal sent by the transmitting pin is focused by the transmitting lens; the optical path of the multi-wavelength multiplexed probe optical signal reflected back by the target passes through the receiving lens and reaches the wavelength division element.
In step 205, the wavelength separation element spatially separates the optical signals of different wavelengths in the multi-wavelength multiplexed detection optical signal, and the separated optical signals of different wavelengths are respectively received by the pixels at different positions of the array detector.
Step 206, obtaining the independent transmission time of each optical signal with different wavelength through the pixel, processing the transmission time corresponding to different wavelength obtained by the pixel through the processor, thereby obtaining the actual transmission time deltat 'of the multi-wavelength multiplexing detection optical signal, and calculating the distance of the target according to the actual transmission time deltat', thereby realizing high-precision detection.
In the embodiment of the present invention, the processing, by the processor, the transmission time acquired by the pixel and corresponding to different wavelengths is specifically:
the processor sums and averages the transmission time corresponding to different wavelengths acquired by the pixel, specifically, first sums and averages the transmission time corresponding to different wavelengths acquired by the pixel to obtain a first average value deltat' 1 The method comprises the steps of carrying out a first treatment on the surface of the Sequentially combining the transmission times corresponding to different wavelengths with a first average value Deltat' 1 Comparing the transmission time corresponding to different wavelengths with the first average value Deltat' 1 The transmission time of the wavelength corresponding to the maximum two differences is removed, and the transmission time of the rest different wavelengths is summed again to obtain an average value delta t' 2 As the actual transmission time Δt' of the multi-wavelength multiplexed probe optical signal.
Based on the method, the value with larger deviation can be firstly screened out and filtered out, which is helpful for further improving the measurement accuracy of the laser radar.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. The laser radar with high measurement accuracy is characterized by comprising a multi-wavelength emission light source, an emission pin, an emission lens, a receiving lens, a wavelength separation element and an array detector;
the multi-wavelength emitting light source is used for providing light signals with different wavelengths, and is coupled with the emitting pin; the transmitting contact pin is used as a secondary transmitting light source and used for transmitting multi-wavelength multiplexing detection light signals, and the transmitting lens is used for carrying out collimation transmission or focusing transmission;
the receiving lens is used for receiving the multi-wavelength multiplexed detection light signals reflected by the target to the wavelength division element; the wavelength separation element is used for spatially separating optical signals with different wavelengths in the multi-wavelength multiplexed detection optical signals;
the array detector is used for acquiring independent transmission time of optical signals with different wavelengths, summing and averaging, and then calculating the distance of a target;
when the transmitting lens performs focusing transmission, the laser radar with high measurement precision further comprises a translation device and a camera;
the translation device is connected with the transmitting pin or the transmitting lens and is used for adjusting the position of the transmitting pin or the transmitting lens so as to adjust the relative distance d1 between the transmitting pin and the transmitting lens;
the camera is used for collecting calibration object images at different detection distances, and further calibrating the relative distance d1 corresponding to the light spot focusing at different detection distances in advance by combining the definition of the calibration object images, and storing the corresponding relation between the detection distances and the relative distance d1.
2. The high measurement accuracy lidar of claim 1, wherein the multi-wavelength light source comprises different single-wavelength light sources and an array waveguide grating, wherein the different single-wavelength light sources emit light signals that are received by the array waveguide grating, and the array waveguide grating is used for coupling the light signals emitted by the different single-wavelength light sources to obtain the multi-wavelength multiplexed detection light signals.
3. The high measurement accuracy lidar of claim 1, wherein the multi-wavelength light-emitting source comprises a broad spectrum light source for providing light signals of different wavelengths.
4. The high measurement accuracy lidar of claim 1 or claim 1, wherein pixels are arranged at different positions of the array detector, and the pixels are independently controlled and are used for acquiring independent transmission time of optical signals with different wavelengths.
5. The high measurement accuracy lidar of claim 4, wherein the array detector comprises a processor for summing and averaging transmission times acquired by the pixels corresponding to different wavelengths, and further calculating a distance of the target.
6. The high measurement accuracy lidar of claim 1, further comprising a position sensor coupled to the emitter pin or the emitter lens for monitoring a real-time position of the emitter pin or the emitter lens to determine a relative distance d1 between the emitter pin and the emitter lens.
7. The high-measurement-accuracy lidar according to claim 6, further comprising a data register and a translation control device, wherein the position sensor, the data register, the translation control device and the translation device are sequentially connected, and wherein the data register is used for storing in advance a correspondence between a detection distance and a relative distance d1; the translation control device is used for controlling the translation device according to the relative distance d1 read from the data register, and then the multi-wavelength emission light source or the emission lens is moved to a specified position.
8. A method for using the high-measurement-precision laser radar according to any one of claims 1 to 7, comprising:
selecting a plurality of different detection distances, setting corresponding calibration objects at each detection distance, and acquiring corresponding calibration object images through the camera after the emission contact pin emits detection light signals;
continuously adjusting the position of the transmitting contact pin or the transmitting lens through the translation device until the definition of the image of the calibration object reaches the best, and finding out the light spot focusing state;
monitoring the position of the transmitting pin or the transmitting lens through a position sensor, further determining the relative distance d1 between the transmitting pin and the transmitting lens at the moment, and storing the corresponding relation between the detecting distance and the relative distance d1 in a data register;
when a user sets a detection distance to be used, determining a relative distance d1 corresponding to the detection distance according to a pre-stored corresponding relation, and further moving the transmitting contact pin or the transmitting lens to a designated position through the translation device to complete the focusing of the light spots at a certain distance;
coupling optical signals with different wavelengths emitted by a multi-wavelength emission light source to obtain multi-wavelength multiplexing detection optical signals, emitting the multi-wavelength multiplexing detection optical signals from the emission contact pin, and detecting a target after focusing through the emission lens; after the multi-wavelength multiplexing detection optical signals reflected by the target pass through the receiving lens, the wavelength separation element separates optical signals with different wavelengths in the multi-wavelength multiplexing detection optical signals in space, the separated optical signals with different wavelengths are received by the array detector, the independent transmission time of each optical signal with different wavelengths is obtained, the independent transmission time of the optical signals with different wavelengths is processed, the actual transmission time of the multi-wavelength multiplexing detection optical signals is obtained, and the distance of the target is calculated according to the actual transmission time.
9. The method for using a high measurement accuracy laser radar according to claim 8, wherein the processing of the individual transmission times of the optical signals with different wavelengths is specifically:
and summing and averaging the independent transmission time of the optical signals with different wavelengths to obtain a first average value, sequentially comparing the independent transmission time of the optical signals with different wavelengths with the first average value to obtain a difference value between the transmission time with different wavelengths and the first average value, removing the independent transmission time of the optical signals with the wavelengths corresponding to the maximum two difference values, and summing and averaging the rest independent transmission time of the optical signals with different wavelengths again to obtain a new average value which is used as the actual transmission time of the multi-wavelength multiplexing detection optical signals.
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