CN117471431B - Laser radar optical power automatic gain adjustment method, device and system - Google Patents
Laser radar optical power automatic gain adjustment method, device and system Download PDFInfo
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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
- 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
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated 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
- G01S7/486—Receivers
- G01S7/487—Extracting wanted echo signals, e.g. pulse detection
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3084—Automatic control in amplifiers having semiconductor devices in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
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Abstract
The invention relates to a laser radar optical power automatic gain adjustment method, a device and a system, wherein the method comprises the following steps: according to the technical scheme, the high PWM duty ratio signal is transmitted for the first time to obtain the initial measurement distance and echo pulse width intensity information of the measured target, and the second PWM duty ratio signal which is suitable for the measured target is modulated according to the initial measurement distance and the echo pulse width intensity information, so that the distance between the measured target and the laser radar and the optical power which is suitable for the reflectivity of the surface of the measured target are quickly and automatically adjusted, the accurate distance measurement of the measured object is realized, the distance measurement error of the laser radar is reduced, and the distance measurement precision of the laser radar is improved.
Description
Technical Field
The invention relates to the technical field of laser ranging, in particular to a laser radar optical power automatic gain adjustment method, device and system.
Background
In the current laser radar ranging process, fixed optical power is generally adopted to transmit laser for ranging, but when laser irradiates the surface of a measured target, the laser power is too large or too small to have great influence on the laser radar ranging precision: ① The laser power is too high, so that saturation distortion is easy to generate on echo signals reflected by a short-distance measured object; ② The laser power is too small, the amplitude of the echo signal reflected by the long-distance measured object is easy to be small, the jitter is large, and the signal is too weak and does not return to the echo signal. The laser radar adopts an advanced power control technology, and can conveniently and rapidly control the laser power through the duty ratio of PWM (pulse width modulation) signals. However, it is most suitable to irradiate the surface of the measured object with the optical power value, and the ranging research shows that the measured object is in different distance ranges and the reflectivity of the reflecting surface of the measured object is different, and the corresponding suitable PWM duty ratio signal and optical power are different.
Therefore, on the premise that the laser distance accuracy is expected to be improved by adjusting the PWM duty ratio signal to rapidly control the optical power, how to rapidly and automatically adjust the PWM duty ratio signal to perform distance measurement with appropriate optical power so as to improve the laser radar distance accuracy is a technical problem to be solved.
Disclosure of Invention
Based on the above-mentioned current situation, the main objective of the present invention is to provide a method, a device and a system for automatic gain of laser radar optical power, which can control the optical power by adjusting the PWM duty ratio signal so as to improve the laser distance accuracy.
The technical scheme adopted for solving the technical problems is as follows:
In a first aspect, the present invention provides a method for adjusting automatic gain of optical power of a laser radar, which is applied to ranging of the laser radar, wherein the automatic gain of the optical power of the laser radar is automatically adjusted by adjusting a PWM signal, and the method comprises the steps of:
S1, primary distance measurement: transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
S2, PWM duty ratio signal matching: the first detection distance information and the first detection echo pulse width intensity information are matched with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
S3, distance accurate measurement: and transmitting a second PWM duty ratio signal to the measured target with preset light emitting times to accurately measure the distance.
Optionally, the first PWM duty cycle employs a fixed pulse width of a high duty cycle, and the preset first PWM duty cycle is not less than 90%, so that the basic full-range preliminary measurement data is obtained by a larger emitted light power proportional to the high duty cycle.
Optionally, the preset parameter comparison table has row attribute of distance segment data, column attribute of pulse width segment data or row attribute of pulse width segment data, and column attribute of distance segment data, and the data at the intersection of the row and the column is a second PWM dot-space ratio corresponding to the distance segment and the pulse width segment.
Optionally, the distance segmentation data is formed by equally dividing the measurement range of the laser radar into a plurality of distance ranges, and the segmentation rule of equally dividing the measurement range into the plurality of distance ranges is as follows: the maximum measuring range of the laser radar is equally divided into 20-30 equal parts.
Optionally, the pulse width classification data is classified in the following manner: dividing pulse width intensity full-range signal values 0-2 n into five stages according to the reflectivity grading correspondence of the reflecting surface of the measured object, wherein the correspondence relations are respectively: the pulse width intensity range corresponding to the ultra-high reflectivity object is as follows: the pulse width intensity range corresponding to the object with high reflectivity is:/> The pulse width intensity range corresponding to the medium reflectivity object is:/>The pulse width intensity range corresponding to the object with low reflectivity is:/>The pulse width intensity range corresponding to the object with weak reflectivity is:/>Where n is the number of signal channels.
The laser radar optical power automatic gain method comprises the following steps: s4, calculating a precise measurement distance: and acquiring the precise detection distance from the laser radar to the measured target from the precise detection signal echo signal reflected by the measured target.
Optionally, the preset calculation formula of the light emitting number m is:
Wherein m is the number of luminescence, f is the emission frequency of the laser radar, θ is the angular resolution of the laser radar, and r is the scanning frequency of the laser radar;
the calculation method of the precise measurement distance comprises the following steps: and taking distance values of m times of transmitting accurate detection signal ranging to perform median average filtering algorithm processing to obtain accurate measurement distance.
In a second aspect, the present invention provides an automatic gain adjustment device for laser radar optical power, applied to laser ranging, the magnitude of optical power realizes automatic gain adjustment by adjusting PWM duty cycle signal, the automatic gain adjustment device for laser radar optical power comprises:
A distance initial measurement module: the method comprises the steps of transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
the PWM duty ratio signal matching module: the method comprises the steps of matching primary detection distance information and primary detection echo pulse width intensity information with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
Distance accurate measurement module: and the device is used for transmitting a second PWM duty cycle signal to the measured target for accurate ranging with preset lighting times.
Optionally, the laser radar optical power automatic gain adjustment device further includes:
And calculating a precise distance measuring module: the method is used for acquiring the precise detection distance of the laser radar to the measured target from the precise detection signal echo signal reflected by the measured target.
In a third aspect, the present invention provides a laser radar optical power automatic gain adjustment system, applied to laser ranging, where the optical power is automatically gain adjusted by adjusting a PWM duty cycle signal, the laser radar optical power automatic gain adjustment system includes a central processing unit, an automatic gain control unit, a laser emission unit and a laser receiving unit, which are respectively connected to the central processing unit, and a PWM output unit and a high voltage driving unit, which are connected between the central processing unit and the laser emission unit, the PWM output unit is connected to the central processing unit, the high voltage driving unit is connected to the PWM output unit, and the laser emission unit is connected to the PWM output unit;
The central processing unit is used for controlling the laser emission unit to emit a preset first PWM duty cycle signal to a measured target, receiving first PWM duty cycle echo signal information transmitted by the laser receiving unit and reflected by the measured target, extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal information, transmitting the primary detection distance information and the primary detection echo pulse width intensity information to the automatic gain control unit, transmitting second PWM duty cycle signal information output by the automatic gain control unit to the PWM output unit, receiving second PWM duty cycle echo signal information transmitted by the laser receiving unit according to preset luminous times m and reflected by the mh measured target, and respectively extracting distance information from m times of second PWM duty cycle echo signal information to perform median average filtering algorithm processing to obtain a precise measurement distance;
the automatic gain control unit is used for matching second PWM duty ratio signal information according to the primary detection distance information and the primary detection echo pulse width intensity information transmitted by the central processing unit, and transmitting the second PWM duty ratio signal information to the PWM output unit through the central processing unit;
the laser transmitting unit is used for transmitting a first PWM duty cycle signal according to the instruction of the central processing unit and transmitting a second PWM duty cycle signal according to the high voltage output by the high voltage driving unit;
The laser receiving unit is used for receiving the first PWM duty cycle signal echo signal and the second PWM duty cycle echo signal reflected by the measured target and transmitting the first PWM duty cycle signal echo signal information and the second PWM point duty cycle echo signal information to the central processing unit;
The PWM output unit is used for receiving the second PWM duty ratio signal information transmitted by the central processing unit and driving the high-voltage driving unit to output high voltage;
the high voltage driving unit is used for outputting the high voltage which is transmitted by the PWM output unit and is driven according to the second PWM duty ratio signal information to the laser emitting unit.
Advantageous effects
According to the invention, the high PWM duty ratio signal is transmitted for the first time to rapidly acquire the initial measurement distance and echo pulse width intensity information of the measured target, and the second PWM duty ratio signal which is suitable for the measured target is modulated according to the initial measurement distance and echo pulse width intensity information, so that the optical power which is suitable for the distance between the measured target and the laser radar and the reflectivity of the surface of the measured target is rapidly and automatically adjusted, and the accurate ranging of the measured object is realized, the ranging error of the laser radar is reduced, and the ranging accuracy of the laser radar is improved.
Drawings
FIG. 1 is a flowchart of a method for automatically adjusting the gain of the laser radar optical power according to an embodiment of the present invention;
FIG. 2 is a flowchart II of a method for adjusting the automatic gain of the laser radar optical power according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the number of light-emitting times of the distance primary measurement and the distance precise measurement according to the embodiment of the present invention;
Fig. 4 is a schematic diagram of a structure of an automatic gain adjustment device for laser radar optical power according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a second embodiment of an automatic gain adjustment device for laser radar optical power according to the present invention;
Fig. 6 is a schematic diagram of a laser radar optical power automatic gain system according to an embodiment of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
In a first aspect, referring to fig. 1, in order to transmit an optical power signal with a proper size to a measured target for accurate ranging, the invention provides a laser radar optical power automatic gain adjustment method, which is applied to laser radar ranging, wherein the optical power is fast and automatically gained by adjusting the size of a PWM duty ratio signal, and the laser radar optical power automatic gain adjustment method comprises the steps of:
S1, primary distance measurement: transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
S2, PWM duty ratio signal matching: the first detection distance information and the first detection echo pulse width intensity information are matched with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
S3, distance accurate measurement: and transmitting a second PWM duty ratio signal to the measured target with preset light emitting times to accurately measure the distance.
Specifically, in the laser ranging process, under the condition that the distance information of the measured object and the reflectivity information of the reflecting surface are not available, a PWM duty ratio signal with the adaptive optical power cannot be emitted, therefore, the high PWM duty ratio signal is adopted to perform primary detection, initial measured distance information and echo pulse width intensity information of the measured object can be obtained, the initial measured distance information and the echo pulse width intensity information are used as reference data for accurate ranging, namely PWM point duty ratio modulation, the primary detection can be used for rapidly measuring and obtaining the approximate distance between the measured object and the laser radar by emitting a signal once, and the PWM duty ratio signal can be used as reference data for subsequently adjusting the PWM duty ratio signal to be adaptive to the measured object.
After the initial measurement distance information and the echo pulse width intensity information are acquired, the initial measurement distance information and the echo pulse width intensity information can be compared and matched with a parameter information table with the distance segmentation information and the pulse width classification information being row attributes or column attributes respectively, and the matched PWM duty ratio signal value is a second PWM duty ratio signal which is suitable for carrying out multiple times of accurate ranging with follow-up, so that accurate ranging is realized.
It should be noted that, the advanced power control technology is adopted in the laser radar before light, and the system can conveniently and rapidly control the laser power through the duty ratio of the PWM (pulse width modulation) signal, that is, the automatic gain of the light power is realized by adjusting the duty ratio of the PWM.
In order to obtain the test data of the basic full range during the distance fine detection, the first PWM duty cycle adopts a fixed pulse width of a high duty cycle, and the preset first PWM duty cycle is not less than 90 percent, so that the initial test data of the basic full range is obtained through larger emitted light power in direct proportion to the high duty cycle.
Specifically, the higher and better the PWM duty ratio value adopted by the high PWM duty ratio signal is, the test data which is basically measured completely can be obtained, but because of the different performances of the laser radars, the partial laser radars hardly reach the PWM duty ratio of 100 percent, so the scheme adopts the PWM duty ratio of more than 90 percent for setting, and the requirement of autonomous setting of most of the laser radars can be met. It should be noted that, although the first detection is performed by using a high PWM duty cycle, the first detection distance information and the echo pulse width intensity information of the first detection may have an error and the accuracy may not be very high due to problems such as a distance of the measured object or a reflectivity of the reflecting surface of the measured object, but the difference of the error is insufficient to affect the data reference value of the first detection distance, and the first detection distance information and the echo pulse width intensity information are sufficient to make a reference for adjusting the subsequent emission of the second PWM duty cycle signal.
In order to quickly and automatically adjust the light power to be suitable for a measured target, the application adopts a preset parameter comparison table, wherein the row attribute of the parameter comparison table is distance segmentation data, the column attribute of the parameter comparison table is pulse width classification data or the row attribute of the parameter comparison table is pulse width classification data, the column attribute of the parameter comparison table is distance segmentation data, and the data at the intersection of the row and the column is a second PWM point-to-space ratio corresponding to the distance segmentation and the pulse width classification.
Because the range of different lidars is very different, such as an intelligent sweeping robot, a guiding robot of a market and the like, the range of the ranging robot can be in a range of a few meters or a few tens of meters, the range of the ranging radar of a new energy automobile can reach 200-300 meters, the shorter the distance of a distance section is, the more accurate the measurement is, the complexity of the setup production is increased, the calculated data volume is large, if the distance of the distance section is longer, the advantage of easy operability is provided, but the measurement cannot be performed in some severe environments, therefore, the distance section data of the scheme is formed by equally dividing the measuring range of the lidar into a plurality of sections of distance ranges, and the section rule of the distance ranges in a plurality of sections is as follows: the maximum measuring range of the laser radar is equally divided into 20-30 equal parts.
Reflectivity refers to the ratio of the intensity of light reflected from the surface of the object being measured to the intensity of the incident light. Therefore, the reflectivity of the target object is obtained by the first detection of the emitted incident light intensity and the first detection of the echo signal. Further, in the subsequent accurate detection, the light intensity of the object is reversely determined according to the reflectivity of the obtained object. Different objects to be measured have different reflectivities of their reflecting surfaces, such as: high reflectivity scenes, such as snow white, with 98% reflectivity; poor reflectivity is a scene with low reflectivity, such as soot with 2% reflectivity; typically, there are not as many high and low reflectivity objects in a subject, with an average reflectivity of about 12.5%, so 12.5% is "neutral gray". Experimenters know that the reflectivity of the exposed skin of white and yellow people is about 18%, and the classification mode of pulse width classification data according to the reflecting surfaces of most common different objects is as follows: dividing pulse width intensity full-range signal values 0-2 n into five stages according to the reflectivity grading correspondence of the reflecting surface of the measured object, wherein the correspondence relations are respectively: the pulse width intensity range corresponding to the ultra-high reflectivity object with the reflectivity of more than 90 percent is as follows: The pulse width intensity range corresponding to the high-reflectivity object with the reflectivity between 40% and 90% is:/> The pulse width intensity range corresponding to the medium-reflectivity object with the reflectivity between 10% and 40% is:/>The pulse width intensity range corresponding to the low-reflectivity object with the reflectivity between 2% and 10% is:/>The pulse width intensity range corresponding to the object with the low reflectivity below 2% is as follows: Where n is the number of signal channels.
The following is an embodiment of a specific parameter comparison table for ranging by a certain laser radar:
In the table above, s is the full range of the laser radar; n is the number of signal channels of the laser radar, a symbol "(" or ")" adopted by the range indicates a range value which does not contain the symbol next, a symbol "[" or "]" adopted by the range indicates a range value which contains the symbol next, and if the initial measurement distance information and the echo information are matched with the contents PWM1, PWM1,2, … …, PWM30,4 and PWM30,5 which are crossed by the row attribute and the column attribute, the signal information is the second PWM duty ratio signal information.
Referring to fig. 2, after obtaining m ranging information transmitted by the second PWM duty cycle signal, the automatic gain adjustment method for laser radar optical power further includes the steps of: s4, calculating a precise measurement distance: and acquiring the precise detection distance from the laser radar to the measured target from the precise detection signal echo signal reflected by the measured target.
Referring to fig. 3, the laser radars have different light emitting periods, and can emit light for multiple times in the same period, but emitting light for multiple times in the same period to perform ranging can generate larger energy consumption and calculation data, so that in order to simplify calculation and reduce energy consumption, the information of ranging can be obtained by emitting light once in one period, therefore, according to the light emitting frequency, scanning frequency and angular resolution of the laser radars, the light emitting times of the laser radars can be calculated under the condition of emitting light once in the same period, the light emitting times of the laser radars are subtracted, and the preset calculation formula of the light emitting times m is as follows:
Wherein m is the number of luminescence, f is the emission frequency of the laser radar, θ is the angular resolution of the laser radar, and r is the scanning frequency of the laser radar;
In order to simply calculate and well inhibit interference of different period data, a median-level-increase filtering algorithm is adopted to calculate the distance of m times of second PWM point-space ratio signal acquisition, and the specific precise distance calculation method comprises the following steps: and taking distance values of m times of transmitting accurate detection signal ranging to perform median average filtering algorithm processing to obtain accurate measurement distance.
In a second aspect, referring to fig. 4, the present invention provides an automatic gain adjustment device for laser radar optical power, applied to laser radar ranging, for implementing automatic gain adjustment by adjusting PWM duty cycle signals, where the device is used to implement the automatic gain adjustment method for laser radar optical power according to the first aspect, and the automatic gain adjustment device for laser radar optical power includes:
A distance initial measurement module: the method comprises the steps of transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
The PWM duty ratio signal matching module: the method comprises the steps of matching primary detection distance information and primary detection echo pulse width intensity information with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
Distance accurate measurement unit: and the device is used for transmitting a second PWM duty cycle signal to the measured target for accurate ranging with preset lighting times.
Referring to fig. 5, in an alternative embodiment, the laser radar optical power automatic gain adjustment apparatus further includes:
And calculating a precise distance measuring module: the method is used for acquiring the precise detection distance of the laser radar to the measured target from the precise detection signal echo signal reflected by the measured target.
In a third aspect, referring to fig. 6, the present invention provides an automatic gain adjustment system for laser radar optical power, applied to laser ranging, where the magnitude of optical power is adjusted by adjusting a PWM duty ratio signal, the system is used to implement the automatic gain adjustment method for laser radar optical power according to the first aspect, the system for laser radar optical power automatic gain adjustment includes a central processing unit, an automatic gain control unit, a laser transmitting unit and a laser receiving unit respectively connected to the central processing unit, and a PWM output unit and a high voltage driving unit connected between the central processing unit and the laser transmitting unit, where the PWM output unit is connected to the central processing unit, the high voltage driving unit is connected to the PWM output unit, and the laser transmitting unit is connected to the PWM output unit;
The central processing unit is used for controlling the laser emission unit to emit a preset first PWM duty cycle signal to a measured target, receiving first PWM duty cycle echo signal information transmitted by the laser receiving unit and reflected by the measured target, extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal information, transmitting the primary detection distance information and the primary detection echo pulse width intensity information to the automatic gain control unit, transmitting second PWM duty cycle signal information output by the automatic gain control unit to the PWM output unit, receiving second PWM duty cycle echo signal information transmitted by the laser receiving unit according to preset luminous times m and reflected by the mh measured target, and respectively extracting distance information from m times of second PWM duty cycle echo signal information to perform median average filtering algorithm processing to obtain a precise measurement distance;
the automatic gain control unit is used for matching second PWM duty ratio signal information according to the primary detection distance information and the primary detection echo pulse width intensity information transmitted by the central processing unit, and transmitting the second PWM duty ratio signal information to the PWM output unit through the central processing unit;
the laser transmitting unit is used for transmitting a first PWM duty cycle signal according to the instruction of the central processing unit and transmitting a second PWM duty cycle signal according to the high voltage output by the high voltage driving unit;
The laser receiving unit is used for receiving the first PWM duty cycle signal echo signal and the second PWM duty cycle echo signal reflected by the measured target and transmitting the first PWM duty cycle signal echo signal information and the second PWM point duty cycle echo signal information to the central processing unit;
The PWM output unit is used for receiving the second PWM duty ratio signal information transmitted by the central processing unit and driving the high-voltage driving unit to output high voltage;
the high voltage driving unit is used for outputting the high voltage which is transmitted by the PWM output unit and is driven according to the second PWM duty ratio signal information to the laser emitting unit.
The following is a specific embodiment, which specifically describes the method, device and system for adjusting the optical power automatic gain of the laser radar in the three aspects to realize laser radar ranging, taking a laser radar with a specific performance as an example, and assuming that the laser radar has a light emitting frequency of 500kHz, a rotating speed of 20kHz and an angular resolution of 0.36 °; the number of times light can be emitted for one turn is 360 °/0.36 ° =1000 times; and a light emission period within 0.36 °:500kHz/20 Hz/1000=25. Each period is set to emit light once, the first luminescence is the initial detection, and the subsequent 24 luminescence is the accurate detection. The optical power automatic gain light-emitting control flow is as follows:
① The first luminescence needs to control the luminescence power at a proper value, the pwm output with the duty ratio of 90% is selected, the first luminescence is primary detection, and the larger luminescence power is selected as much as possible, so that the data to be analyzed in the full range can be basically obtained;
② After the first luminescence is controlled, the distance L from the laser radar to the target is obtained;
③ Simultaneously obtaining the pulse width intensity PW of the signal reflected by the laser to the target;
④ According to the distance L and the pulse width PW, carrying out automatic gain adjustment to obtain proper luminous power w, and controlling the luminous power to emit light according to w for 24 subsequent times;
⑤ Performing median average filtering algorithm processing on the distance values obtained after 24 times of light emission, and finally outputting a distance;
⑥ Outputting a point according to the angular resolution, namely outputting a point at intervals of 0.36 degrees;
the scheme is also suitable for the laser radars with different luminous frequencies and different rotating speeds.
The laser radar optical power automatic gain adjustment content comprises:
The automatic gain adjustment comprises distance segmentation control and pulse width grading control, and is set according to the self ranging capability and the optical power of the radar.
The distance interval for the distance segmentation control is as follows: 0-1 m, 1-2 m, 2-3 m, 23-24 m, 24-25 m.
Control of pulse width classification: the 8-bit signal intensity value is taken to represent the pulse width intensity (intensity value is from 0 to 255) and is divided into an ultra-high reflection surface (100-255), a high reflection surface (60-100), a medium reflection surface (40-60), a low reflection surface (20-40) and a weak reflection surface (0-20).
The corresponding PWM, n is obtained by performing a lookup table according to the distance L and the pulse width PW obtained from the first point, so that the following points are all subjected to light emission control according to the PWM, n, and the optimal echo signal can be obtained.
PWM, n is the best duty ratio obtained according to the actual test, and can be the laser radar emits the laser of suitable optical power to the measured object under the distance to be measured to make the echo signal that returns promptly unsaturated distortion, also be unlikely too little and shake big, be that laser ranging accuracy is higher more stable.
The distance segment control and the pulse width step setting are not limited to the setting scheme of the present scheme.
In a fourth aspect, the present invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method steps of the first aspect as described above when executing the program.
In a fifth aspect, the present invention also provides a computer-readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, carries out the method steps as described in the first aspect above.
It will be apparent to those skilled in the art from this disclosure that various other changes and modifications can be made which are within the scope of the invention as defined in the appended claims.
It should be noted that: the embodiments described above are only some, but not all, embodiments of the invention. As used in the examples and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Claims (4)
1. An automatic gain adjustment method for laser radar optical power is applied to laser radar ranging, and the magnitude of the optical power is adjusted by adjusting PWM duty ratio signals, and is characterized by comprising the following steps:
S1, primary distance measurement: transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
The preset first PWM duty cycle adopts a high duty cycle fixed pulse width which is not less than 90% and can obtain basic full-range test data;
S2, PWM duty ratio signal matching: the first detection distance information and the first detection echo pulse width intensity information are matched with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
The preset parameter comparison table has row attribute of distance segmentation data, column attribute of pulse width classification data or row attribute of pulse width classification data, column attribute of distance segmentation data, and the data at the intersection of the row and the column is a second PWM point-to-space ratio corresponding to the distance segmentation and the pulse width classification;
The distance segmentation data are formed by equally dividing the measuring range of the laser radar into a plurality of distance ranges, and the segmentation rule of the distance ranges in the equally divided sections is as follows: dividing the maximum measuring range of the laser radar into 20-30 equal parts;
s3, distance accurate measurement: transmitting a second PWM duty ratio signal to a measured target for accurate ranging according to preset luminous times;
the preset calculation formula of the luminous times m is as follows: Wherein m is the number of luminescence, f is the frequency of laser radar emission, θ is the angular resolution of the laser radar, and r is the scanning frequency of the laser radar;
s4, calculating a precise measurement distance: acquiring the precise detection distance from the laser radar to the measured target from the precise detection signal echo signal reflected by the measured target;
The calculation method of the precise measurement distance comprises the following steps: and taking distance values of m times of transmitting accurate detection signal ranging to perform median average filtering algorithm processing to obtain accurate measurement distance.
2. The automatic gain adjustment method of laser radar optical power according to claim 1, wherein the pulse width classification data is classified in the following manner: dividing pulse width intensity full-range signal values 0-2 n into five stages according to the reflectivity grading correspondence of the measured target reflecting surface, wherein the correspondence relations are as follows: the pulse width intensity range corresponding to the ultra-high reflectivity measured target is as follows: The pulse width intensity range corresponding to the high-reflectivity measured target is:/> The pulse width intensity range corresponding to the measured medium reflectivity is:/>The pulse width intensity range corresponding to the measured target with low reflectivity is:/>The pulse width intensity range corresponding to the weak reflectivity measured object is as follows: Where n is the number of signal channels.
3. An automatic gain adjustment device for laser radar optical power, which is applied to laser radar ranging, wherein the magnitude of the optical power realizes automatic gain adjustment by adjusting PWM duty ratio signals, and the device is characterized by comprising:
A distance initial measurement module: the method comprises the steps of transmitting a first PWM duty cycle signal preset once to a detected target, receiving a first PWM duty cycle echo signal reflected by the detected target, and extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal;
The preset first PWM duty cycle adopts a high duty cycle fixed pulse width which is not less than 90% and can obtain basic full-range test data;
The PWM duty ratio signal matching module: the method comprises the steps of matching primary detection distance information and primary detection echo pulse width intensity information with a preset parameter comparison table to obtain second PWM duty ratio signal information, wherein the preset parameter comparison table consists of distance segmentation information, pulse width intensity classification information and corresponding PWM duty ratio information;
The preset parameter comparison table has row attribute of distance segmentation data, column attribute of pulse width classification data or row attribute of pulse width classification data, column attribute of distance segmentation data, and the data at the intersection of the row and the column is a second PWM point-to-space ratio corresponding to the distance segmentation and the pulse width classification;
The distance segmentation data are formed by equally dividing the measuring range of the laser radar into a plurality of distance ranges, and the segmentation rule of the distance ranges in the equally divided sections is as follows: dividing the maximum measuring range of the laser radar into 20-30 equal parts;
distance accurate measurement unit: the device is used for transmitting a second PWM duty ratio signal to a measured target for accurate ranging according to preset lighting times;
and calculating a precise distance measuring module: the precise detection distance from the laser radar to the measured target is obtained from the precise detection signal echo signal reflected by the measured target;
the preset calculation formula of the luminous times m is as follows: Wherein m is the number of luminescence, f is the frequency of laser radar emission, θ is the angular resolution of the laser radar, and r is the scanning frequency of the laser radar;
The calculation method of the precise measurement distance comprises the following steps: and taking distance values of m times of transmitting accurate detection signal ranging to perform median average filtering algorithm processing to obtain accurate measurement distance.
4. The automatic gain adjustment system for the laser radar optical power is applied to laser ranging, and the optical power is automatically gain adjusted by adjusting PWM duty ratio signals, and is characterized by comprising a central processing unit, an automatic gain control unit, a laser emission unit, a laser receiving unit, a PWM output unit and a high-voltage driving unit, wherein the automatic gain control unit, the laser emission unit and the laser receiving unit are respectively connected with the central processing unit, the PWM output unit and the high-voltage driving unit are connected between the central processing unit and the laser emission unit, the PWM output unit is connected with the central processing unit, the high-voltage driving unit is connected with the PWM output unit, and the laser emission unit is connected with the PWM output unit;
The central processing unit is used for controlling the laser emission unit to emit a preset first PWM duty cycle signal to a measured target, receiving first PWM duty cycle echo signal information transmitted by the laser receiving unit and reflected by the measured target, extracting primary detection distance information and primary detection echo pulse width intensity information from the first PWM duty cycle echo signal information, transmitting the primary detection distance information and the primary detection echo pulse width intensity information to the automatic gain control unit, transmitting second PWM duty cycle signal information output by the automatic gain control unit to the PWM output unit, receiving second PWM duty cycle echo signal information transmitted by the laser receiving unit according to preset luminous times m and reflected by m measured targets, extracting distance information from m second PWM duty cycle echo signal information respectively, and carrying out average filtering algorithm processing to obtain a median value measured distance;
the second PWM duty cycle signal information is obtained by: matching the primary detection distance information and the primary detection echo pulse width intensity information with a preset parameter comparison table to obtain second PWM duty ratio signal information;
The preset parameter comparison table has row attribute of distance segmentation data, column attribute of pulse width classification data or row attribute of pulse width classification data, column attribute of distance segmentation data, and the data at the intersection of the row and the column is a second PWM point-to-space ratio corresponding to the distance segmentation and the pulse width classification;
The distance segmentation data are formed by equally dividing the measuring range of the laser radar into a plurality of distance ranges, and the segmentation rule of the distance ranges in the equally divided sections is as follows: dividing the maximum measuring range of the laser radar into 20-30 equal parts;
The preset first PWM duty cycle adopts a high duty cycle fixed pulse width which is not less than 90% and can obtain basic full-range test data;
the preset calculation formula of the luminous times m is as follows: Wherein m is the number of luminescence, f is the frequency of laser radar emission, θ is the angular resolution of the laser radar, and r is the scanning frequency of the laser radar;
the calculation method of the precise measurement distance comprises the following steps: the distance value of m times of transmitting accurate detection signal ranging is taken to carry out median average filtering algorithm processing to obtain accurate measurement distance;
The automatic gain control unit is used for matching second PWM duty ratio signal information according to the primary detection distance information and the primary detection echo pulse width intensity information transmitted by the central processing unit, and transmitting the second PWM duty ratio signal information to the PWM output unit through the central processing unit;
The laser transmitting unit is used for transmitting a first PWM duty cycle signal according to the instruction of the central processing unit and transmitting a second PWM duty cycle signal according to the high voltage output by the high voltage driving unit;
the laser receiving unit is used for receiving the first PWM duty cycle signal echo signal and the second PWM duty cycle echo signal reflected by the measured target and transmitting the first PWM duty cycle signal echo signal information and the two PWM point duty cycle echo signal information to the central processing unit;
The PWM output unit is used for receiving the second PWM duty ratio signal information transmitted by the central processing unit and driving the high-voltage driving unit to output high voltage;
the high voltage driving unit is used for outputting the high voltage which is transmitted by the PWM output unit and is driven according to the second PWM duty ratio signal information to the laser emitting unit.
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