CN111551911A - Laser radar echo signal processing method based on spatial domain weighting - Google Patents
Laser radar echo signal processing method based on spatial domain weighting Download PDFInfo
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- CN111551911A CN111551911A CN202010452587.5A CN202010452587A CN111551911A CN 111551911 A CN111551911 A CN 111551911A CN 202010452587 A CN202010452587 A CN 202010452587A CN 111551911 A CN111551911 A CN 111551911A
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- 238000001514 detection method Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 19
- 238000012545 processing Methods 0.000 claims description 18
- 239000013598 vector Substances 0.000 claims description 16
- 238000010606 normalization Methods 0.000 claims description 6
- 230000010287 polarization Effects 0.000 claims description 6
- 238000002310 reflectometry Methods 0.000 claims description 6
- 239000004973 liquid crystal related substance Substances 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 7
- 238000009825 accumulation Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000002592 echocardiography Methods 0.000 description 1
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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
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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
- G01S17/08—Systems determining position data of a target for measuring distance only
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Abstract
The invention provides a laser radar echo signal processing method based on spatial domain weighting. The laser radar echo signal processing method based on the spatial domain weighting comprises the following steps: s1: the light source forms an emission module and emits a detection light signal; s2: the detection light signal is converted into collimated parallel light after passing through a collimating mirror; s3: the parallel light rays are deflected through the optical light splitting device; s4: the parallel light rays passing through the optical light splitting device enter a light beam deflection system to control the light emitting direction to carry out space scanning. The laser radar echo signal processing method based on airspace weighting has the advantages of ensuring that the angular resolution index of the laser radar is ensured and the quality of a point cloud image is improved while a certain radar signal-to-noise ratio is improved.
Description
Technical Field
The invention relates to the technical field of engineering surveying and mapping, in particular to a laser radar echo signal processing method based on spatial weighting.
Background
Lidar employing time-of-flight ranging (TOF) techniques are currently common measurement methods. The principle is to calculate the distance of the target by calculating the round trip time of the light propagating in the space between the transceiver components. In a receiving part of the laser radar, an optical signal is converted into an electric signal through a photoelectric sensor, then the electric signal is converted into a digital signal through an analog-to-digital converter (ADC), and the real distance of a target is obtained after the digital signal is processed. In the actual working process, the echo received by the laser radar is not ideal, and the echo signal to be detected is accompanied by ambient light interference, dark current of a photoelectric conversion device, thermal noise of a hardware circuit and the like. This results in a lower signal-to-noise ratio of the echo signal during the radar operation, which reduces the detection capability of the radar. In order to improve the performance of the radar, a digital signal processing method is often adopted, and signals overlapped by a plurality of light spots are directly accumulated. The conventional accumulation method is mainly determined by the overlapping area of multiple laser spots, and the principle is as follows:
the laser emitting light spot has a certain divergence angle and gradually becomes larger along with the increase of the propagation distance, as shown in the specification and figure 1;
in order to improve the signal-to-noise ratio of the echo signal, it is generally ensured in space that laser spots emitted for multiple times have a certain overlapping area in the scanning process, so that multiple times of superposition can be performed through a rear-end digital signal processing part, and the quality of the echo signal is improved, as shown in the attached figure 2 of the specification; by taking three times of emission as an example and a schematic diagram of superposition of three light spots, we can find that the first emitted laser light spot comprises areas a, b and c, the second emitted laser light spot comprises areas b, c and d, and the third emitted laser light spot comprises areas c, d and e. In the three regions, only the c region is the intersection of the light spots 1,2 and 3, and in order to improve the signal-to-noise ratio of the echo signals, the echo signals of the light spots 1,2 and 3 are directly added to improve the signal-to-noise ratio of the c region.
The conventional overlapping mode is shown in the attached figure 3 in the specification; although the signal-to-noise ratio of echo signals is directly improved by the direct superposition of the three light spots, actually, the equivalent light spots are the union set of the light spots 1,2 and 3, the horizontal width side length of the light spots is long, and the angular resolution of the laser radar is sacrificed under the condition.
Therefore, there is a need to provide a new method for processing laser radar echo signals based on spatial weighting to solve the above technical problems.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a laser radar echo signal processing method based on airspace weighting, which ensures that the angular resolution index of a laser radar is ensured and the quality of a point cloud image is improved while ensuring that a certain radar signal-to-noise ratio is improved.
In order to solve the technical problem, the laser radar echo signal processing method based on spatial domain weighting provided by the invention comprises the following steps:
s1: the light source forms an emission module and emits a detection light signal;
s2: the detection light signal is converted into collimated parallel light after passing through a collimating mirror;
s3: the parallel light rays are deflected through the optical light splitting device;
s4: parallel light rays passing through the optical light splitting device enter a light beam deflection system to control the light emitting direction to carry out space scanning;
s5: when laser irradiates a space target, scattered light returns through an original path, the optical light-splitting device guides the returned optical signal to a receiving part, and the receiving part converges the optical signal to a receiving module through a focusing lens;
s6: the receiving module converts the optical signal into an electric signal and transmits the electric signal to the control and signal processing system;
s7: and the control and signal processing system performs distance estimation and reflectivity estimation of echo signals on the electric signals.
Preferably, the optical splitting device comprises a perforated mirror, a beam splitter, a liquid crystal polarization grating and a polarization splitting cube.
Preferably, the receiving module is a photoelectric conversion device and is responsible for converting an optical signal into an electrical signal.
Preferably, the control and signal processing system includes a control section, a distance information calculation section, and a reflectivity information calculation section.
Preferably, the control and signal processing system is connected with a beam deflection system control part, and the beam deflection system control part is connected with the beam deflection system.
Preferably, the beam deflection system control part, the receiving module and the transmitting module are all connected with the control part.
Preferably, the distance information calculation part collects and superposes the electric signals transmitted by the receiving module for multiple times, a weight coefficient W is added during superposition to multiply the echo signals, which is equivalent to sharpening the laser beams emitted by the space, and the sharpening form is determined by the weight coefficient W.
Preferably, in the process of superposing the electric signals transmitted by the receiving module by the distance information calculating part, the number of superposed light spots is determined by the intersection of the light spots, and the intersection of the light spots is not an empty set under the condition of ensuring that the number of the light spots is large as much as possible; after multiple overlapping, the output waveform is represented as:
in the formula, xiIs the ith echo signal, wiFor weighting vector, performing multiple average accumulation on m-times signals to obtain output signal of
The weight vector normalization ∑ w is satisfied during the superposition process i1 is ═ 1; with W ═ W1,w2,w3,...,wnThe windowed weight vector is represented, and the value of the weight vector W can be flexibly adjusted under the condition of meeting the normalization.
Compared with the related technology, the laser radar echo signal processing method based on the space domain weighting has the following beneficial effects:
the invention provides a laser radar echo signal processing method based on spatial weighting, which adopts a window function weighting mode to carry out superposition processing on echo signals, and improves the adaptability of a laser radar to different scenes. The method has the advantages that the angular resolution of the original radar point cloud image is kept while a certain signal-to-noise ratio is improved.
Drawings
FIG. 1 is a schematic view of laser spot diffusion;
FIG. 2 is a schematic view of triple emission laser spot superposition;
FIG. 3 is a schematic diagram of multiple superposition of echo signals;
FIG. 4 is a schematic block diagram of a laser radar echo signal processing method based on spatial domain weighting according to the present invention;
FIG. 5 is a schematic diagram of a multiple superposition of the spatially weighted echo signals shown in FIG. 1;
FIG. 6 is a graph of triple echo signal data;
figure 7 is a graph of echo signal data for weighted overlap-add using normalized kelmer weight vectors.
Detailed Description
The invention is further described with reference to the following figures and embodiments.
Please refer to fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6, and fig. 7 in combination, wherein fig. 1 is a schematic view of laser spot diffusion; FIG. 2 is a schematic view of triple emission laser spot superposition; FIG. 3 is a schematic diagram of multiple superposition of echo signals; FIG. 4 is a schematic block diagram of a laser radar echo signal processing method based on spatial domain weighting according to the present invention; FIG. 5 is a schematic diagram of a multiple superposition of the spatially weighted echo signals shown in FIG. 1; FIG. 6 is a graph of triple echo signal data; figure 7 is a graph of echo signal data for weighted overlap-add using normalized kelmer weight vectors. The laser radar echo signal processing method based on the space domain weighting comprises the following steps:
s1: the light source forms an emission module and emits a detection light signal;
s2: the detection light signal is converted into collimated parallel light after passing through a collimating mirror;
s3: the parallel light rays are deflected through the optical light splitting device;
s4: parallel light rays passing through the optical light splitting device enter a light beam deflection system to control the light emitting direction to carry out space scanning;
s5: when laser irradiates a space target, scattered light returns through an original path, the optical light-splitting device guides the returned optical signal to a receiving part, and the receiving part converges the optical signal to a receiving module through a focusing lens;
s6: the receiving module converts the optical signal into an electric signal and transmits the electric signal to the control and signal processing system;
s7: and the control and signal processing system performs distance estimation and reflectivity estimation of echo signals on the electric signals.
The optical light splitting device comprises a perforated reflector, a beam splitter, a liquid crystal polarization grating and a polarization light splitting cube, and is mainly responsible for deflecting two coaxial beams in different directions, namely two coaxial beams in different directions, wherein the light path is reversible, and the two coaxial beams in different propagation directions are deflected.
The receiving module is a photoelectric conversion device and is responsible for converting optical signals into electric signals.
The control and signal processing system includes a control section, a distance information calculation section, and a reflectivity information calculation section.
The control and signal processing system is connected with a light beam deflection system control part, and the light beam deflection system control part is connected with the light beam deflection system.
The control part of the light beam deflection system, the receiving module and the transmitting module are all connected with the control part, and the control part can synchronously control the transmitting module, the receiving module and the deflection of the light beam, so that the accuracy of parameter estimation of the signal processing part is ensured.
The distance information calculation part collects and superposes electric signals transmitted by the receiving module for multiple times, a weight coefficient W is added during superposition to multiply echo signals, the method is equivalent to sharpening laser beams emitted by a space, the sharpening form is determined by the weight coefficient W, and the angular resolution of the laser radar is improved by adjusting the proportion of each echo signal in a superposition interval.
In the process of superposing the electric signals transmitted by the receiving module by the distance information calculating part, the number of superposed light spots is determined by the intersection of the light spots, and the intersection of the light spots is not an empty set under the condition of ensuring that the number of the light spots is large as much as possible; after multiple overlapping, the output waveform is represented as:
in the formula, xiIs the ith echo signal, wiFor weighting vector, performing multiple average accumulation on m-times signals to obtain output signal of
The weight vector normalization ∑ w is satisfied during the superposition process i1 is ═ 1; with W ═ W1,w2,w3,...,wnThe windowing weight vector is represented, the value of the weight vector W can be flexibly adjusted under the condition of meeting the normalization condition, for example, a Gaussian window, a Chebyshev window, a Hamming window, a Taylor window and the like are adopted, the adaptability of the laser radar to different scenes is greatly improved, the number of superposed signals is not less than 3 times, and the superposed signals can be repeated.
Taking triple superposition as an example, performing spatial domain weighting on echo signals, wherein triple echoes are shown in fig. 6;
weighting and superposing the normalized Kernel weight vectors, wherein the weight vector W is [0.3260.3470.326], weighting and summing the three echo signals, and obtaining the echo signals as shown in FIG. 7; as can be seen from fig. 7, the waveform noise after the superimposition is reduced compared to that before the superimposition, and the signal-to-noise ratio of the echo signal is improved.
Compared with the related technology, the laser radar echo signal processing method based on the space domain weighting has the following beneficial effects:
the invention provides a laser radar echo signal processing method based on spatial weighting, which adopts a window function weighting mode to carry out superposition processing on echo signals, and improves the adaptability of a laser radar to different scenes. The method has the advantages that the angular resolution of the original radar point cloud image is kept while a certain signal-to-noise ratio is improved.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (8)
1. A laser radar echo signal processing method based on spatial domain weighting is characterized by comprising the following steps:
s1: the light source forms an emission module and emits a detection light signal;
s2: the detection light signal is converted into collimated parallel light after passing through a collimating mirror;
s3: the parallel light rays are deflected through the optical light splitting device;
s4: parallel light rays passing through the optical light splitting device enter a light beam deflection system to control the light emitting direction to carry out space scanning;
s5: when laser irradiates a space target, scattered light returns through an original path, the optical light-splitting device guides the returned optical signal to a receiving part, and the receiving part converges the optical signal to a receiving module through a focusing lens;
s6: the receiving module converts the optical signal into an electric signal and transmits the electric signal to the control and signal processing system;
s7: and the control and signal processing system performs distance estimation and reflectivity estimation of echo signals on the electric signals.
2. The method of claim 1, wherein the optical splitter comprises a perforated mirror, a beam splitter, a liquid crystal polarization grating, and a polarization splitting cube.
3. The method as claimed in claim 1, wherein the receiving module is a photoelectric converter and is responsible for converting optical signals into electrical signals.
4. The spatial weighting-based lidar return signal processing method of claim 1, wherein the control and signal processing system comprises a control section, a distance information calculation section, and a reflectivity information calculation section.
5. The spatial-domain-weighting-based lidar echo signal processing method of claim 1, wherein the control and signal processing system is connected to a beam deflection system control portion, and the beam deflection system control portion is connected to the beam deflection system.
6. The spatial-domain-weighting-based lidar echo signal processing method of claim 4, wherein the beam deflection system control portion, the receiving module, and the transmitting module are all connected to the control portion.
7. The method as claimed in claim 4, wherein the distance information calculating part collects and superimposes the electrical signals transmitted by the receiving module for a plurality of times, and adds a weight coefficient W to multiply the echo signals during the superimposing, which is equivalent to sharpening the laser beam emitted from the space, and the sharpening form is determined by the weight coefficient W.
8. The method for processing the laser radar return signals based on the spatial domain weighting according to claim 7, wherein in the process of superposing the electric signals transmitted by the receiving module by the distance information calculating part, the number of superposed light spots is determined by light spot intersection, and in the case of ensuring the number of light spots to be as large as possible, the light spot intersection is not an empty set; after multiple overlapping, the output waveform is represented as:
in the formula, xiIs the ith echo signal, wiFor weighting vectors, for m times of signalsThe signals are averaged and accumulated for a plurality of times to obtain an output signal of
Weight vector normalization ∑ w is satisfied during the superposition processi1 is ═ 1; with W ═ W1,w2,w3,...,wnThe windowed weight vector is represented, and the value of the weight vector W can be flexibly adjusted under the condition of meeting the normalization.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN208421228U (en) * | 2018-06-29 | 2019-01-22 | 上海禾赛光电科技有限公司 | laser radar system |
| CN110333499A (en) * | 2018-10-12 | 2019-10-15 | 深圳市速腾聚创科技有限公司 | Laser radar and laser radar control method |
| CN110749893A (en) * | 2019-09-21 | 2020-02-04 | 深圳奥锐达科技有限公司 | Two-dimensional scanning laser radar device and electronic equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN208421228U (en) * | 2018-06-29 | 2019-01-22 | 上海禾赛光电科技有限公司 | laser radar system |
| CN110333499A (en) * | 2018-10-12 | 2019-10-15 | 深圳市速腾聚创科技有限公司 | Laser radar and laser radar control method |
| CN110749893A (en) * | 2019-09-21 | 2020-02-04 | 深圳奥锐达科技有限公司 | Two-dimensional scanning laser radar device and electronic equipment |
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Application publication date: 20200818 |