CN117538884A - Laser ranging method and system based on error compensation - Google Patents
Laser ranging method and system based on error compensation Download PDFInfo
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- 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
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Abstract
The invention discloses a laser ranging method and a system based on error compensation, which determine the distance of an initial measurement target based on a ranging scene; performing error compensation on the initial measurement target distance by using a theoretical model to obtain a final ranging result; by reducing the index requirements on the pulse width of the laser and the resolution of the counter, the hardware cost is reduced. Obtaining an initial measurement distance through counting the statistical histogram peak value of the data, calculating an estimation error through the detection probability of the detector, and finally obtaining a target distance to be measured through error compensation calculation; therefore, the problem of limited ranging precision caused by low hardware cost is solved.
Description
Technical Field
The invention belongs to the technical field of laser ranging, and particularly relates to a laser ranging method and system based on error compensation.
Background
The laser ranging technology can realize long-distance ranging in airborne environments with limited equipment volume, mass and the like, has very important application in civil use, scientific research and military use, and has good research value and application prospect. Further, in order to reduce the cost of the ranging system, improve the ranging accuracy and expand the ranging range, the related research of the laser ranging technology is particularly important. The traditional laser ranging method is a Time-dependent single photon counting (Time-Correlated Single Photon Counting, TCSPC) technology, and can achieve high-speed, low-energy consumption and high-precision distance information acquisition on a remote target. The TCSPC technology divides a time axis into discrete time intervals, the size of the time intervals determines the precision of the system, when the detector detects one or more photons, a response output is generated, the occurrence time of the response is recorded, the photon count value in the time interval is added with 1, and after a large number of repeated pulses are detected, a statistical histogram of the photon count corresponding to the response time can be obtained through statistics. After the echo time statistical histogram is obtained, the histogram needs to be subjected to data processing to obtain a distance value of the detection target. The common data processing method is a peak value discrimination method, namely, by finding the peak value of the statistical histogram, the abscissa corresponding to the peak value position is used for representing the photon flight time of the current detection output. The peak value discrimination method has simple algorithm, high accuracy when a narrow pulse width laser is used for ranging, and lower accuracy when a wide pulse width laser is used for ranging. Therefore, the traditional laser ranging method depends on the parameter performance of hardware equipment, and cannot meet the higher requirements of the modern industry.
Aiming at the problem of how to further improve the ranging accuracy, a plurality of detectors are used for simultaneously detecting echo signals, and the method reduces the error response number generated by random distribution noise to a certain extent, so that the error alarm rate is reduced, but also reduces the detection efficiency, has limited help to improve the ranging accuracy, and the plurality of single photon detectors greatly improve the hardware cost and are not suitable for the study of a low-cost ranging system.
Disclosure of Invention
The invention aims to solve the technical problems of providing a laser ranging method and a system based on error compensation aiming at the defects in the prior art, and solves the technical problem of limited ranging precision caused by low hardware cost by the error compensation method, so that the ranging system has good ranging precision on the basis of reducing the hardware cost.
The invention adopts the following technical scheme:
a laser ranging method based on error compensation comprises the following steps:
s1, determining a ranging scene and a theoretical model;
s2, determining an initial measurement target distance based on the ranging scene obtained in the step S1;
and S3, performing error compensation on the initial measurement target distance obtained in the step S2 by utilizing the theoretical model in the step S1, and obtaining a final ranging result.
Specifically, in step S1, the theoretical model includes a laser pulse model, an echo signal model and a detector detection probability model, and the ranging scene considers the ranging scene of a single target in a low signal-to-noise ratio scene, and performs simulation on the target position of [10,100,1000,10000] m under the conditions of laser pulse width of 4ns and signal-to-noise ratio of 20 dB; under the condition of 1km of target position and 20dB of signal-to-noise ratio, the pulse width of [2,4,6,8,10] ns is simulated; and under the condition of 4ns of laser pulse width and 1km of target distance, selecting the signal-to-noise ratio of [10,12,14,16,18,20] dB for distance measurement.
Further, the laser pulse model:
where τ is the laser pulse width, n=1;
echo signal model:
wherein E is T For laser pulse energy, η is the detector detection efficiency, D is the target distance, ρ is the reflectivity of the smooth diffuse reflection target, h is the Planckian constant, λ is the laser wavelength, c is the speed of light, FOV is the angle of view of the receiving system, θ T For emitting laser light, angle of divergence, θ target Is the included angle between the laser beam and the normal direction of the target surface, A R For the size of the receiving aperture of the receiving system, eta T For efficiency of the transmitting system η R For receiving efficiency of receiving system, eta A Is the transmission rate of the atmosphere;
detector detection probability model P D (i) The method comprises the following steps:
where R (k) is the number of photons per interval when the echo signal does not arrive, and R (i) is the number of photons in the i time interval.
Specifically, step S2 specifically includes:
for single laser pulse, carrying out detector response judgment on each time interval in sequence according to a time axis: the Poisson distribution generator which takes the echo photoelectron number in the time interval as a parameter generates a random number, and if the generated random number is larger than 0, the detector responds in the corresponding time interval; and for each pulse, sequentially carrying out simulation from the first time interval until the detector responds, and determining the initial measurement target distance according to the corresponding moment of the peak value interval of the statistical graph.
Further, the initial target distance is:
wherein T is s And c is the light speed at the corresponding time of the peak interval of the statistical graph.
Specifically, the step S3 specifically includes:
will initially test result D s Obtaining the average photon number S returned by single pulse as reference distance p The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the echo photon number R' (i) of each interval; determining the detection probability P ' of each time interval according to the echo photon number R ' (i) ' D (i) The method comprises the steps of carrying out a first treatment on the surface of the Peak error err obtained by error compensation s Final compensated ranging result D c Error err c 。
Further, the compensated ranging result D c Error err c The method comprises the following steps:
D c ＝D 0 +err s -err e
err c ＝err s -err e
wherein D is 0 For the true distance of the target err s Obtaining peak error for error compensation, err e Is the error between the corresponding distance and the reference distance.
Further, the detection probability P 'of each time interval' D (i)：
Where R '(k) is the number of photons per section when the echo signal does not arrive, and R' (i) is the number of photons per section.
Further, the average photon number S of single pulse return p ：
Wherein E is T The laser pulse energy is lambda is laser wavelength, h is Planck constant, c is light speed, FOV is field angle of receiving system, theta T For the divergence angle of the outgoing laser, ρ is the reflectivity of the smooth diffuse reflection target, θ target Is the included angle between the laser beam and the normal direction of the target surface, A R For the size of the receiving aperture of the receiving system, eta T For the effect of the transmitting system, eta R For receiving efficiency of receiving system, eta A Is the transmission rate of the atmosphere.
In a second aspect, an embodiment of the present invention provides a laser ranging system based on error compensation, including:
the condition module is used for determining a ranging scene and a theoretical model;
the initial measurement module is used for determining the initial measurement target distance based on the ranging scene obtained by the condition module;
and the output module is used for performing error compensation on the initial measurement target distance obtained by the initial measurement module by utilizing the theoretical model of the condition module, so as to obtain a final ranging result.
Compared with the prior art, the invention has at least the following beneficial effects:
the laser ranging method based on error compensation has low requirement on device performance index, and can reduce cost by selecting laser with larger pulse width (nanosecond level), but the system error performance is poor, and the method of selecting laser with high pulse energy and narrow pulse width or circuit shaping can generally improve the measurement accuracy, but the cost of a hardware system can be improved. Through detection probability model analysis and experimental verification, the larger the detection probability of the detector is in any detection interval, the easier the detector responds, so after repeated pulse transmission, the response times of the detector in each interval are accumulated to obtain a photon accumulation statistical histogram, the statistical curve is a restored echo signal, and the maximum response times of the detector in the time interval with the maximum detection probability are the peak position of the photon accumulation statistical histogram is similar to the detection probability peak position of the detector. After the ranging scene and the theoretical model are determined, simulation is carried out to obtain a primary measurement result, the primary measurement result is substituted into the position of the detection probability peak value of the detection probability model, and the peak value corresponding error is similar to the photon cumulative histogram peak value error, so that the error compensation is carried out on the primary measurement result by utilizing the detector peak value error, and a more accurate ranging result is obtained.
Further, the accuracy of the range error depends on whether the position of the photon accumulation peak is correctly obtained, and the correct peak position depends on whether the echo signal can be correctly recovered, that is, whether the probe responds in the interval with the echo signal, and does not respond as much as possible in the interval without the echo signal. In the environment with high signal-to-noise ratio, the detector can more easily detect echo photons and respond in the interval with echo signals. If the target distance is far, the number of photons contained in the echo signal reaching the receiving end is small, the signal-to-noise ratio is reduced, the signal-to-noise ratio of the ranging environment is poor, the echo photons are easy to annihilate in the noise photons, whether the echo photons or the noise photons are detected by the detector cannot be ensured, the echo signal recovery difficulty is higher, and the index requirement of the ranging error is difficult to ensure. Therefore, in order to detect the signal-to-noise ratio range and the range which can be satisfied, consider the range of different distance targets under different signal-to-noise ratio scenes, and analyze the condition of the range performance change.
Further, in laser detection, the number of primary electrons reaching the detector satisfies a negative exponential distribution, which can be approximately replaced by a poisson distribution when the number of received photons is much smaller than the spot photon distribution. Therefore, the poisson distribution random number is generated by taking the echo photon number of each section of the receiving end as a parameter, and if the generated random number is larger than 0, the original electrons are considered to be generated in the time section. And then accumulating the response times of the detector in each interval according to repeated experiments to obtain a time interval index of the peak area, a corresponding time offset value and photon flight time, thereby determining the initial measurement position of the target. And performing error compensation according to the initial measurement result to obtain a more accurate ranging result.
Further, D is s Substituting the reference distance into the average photon number model to obtain the average photon number S returned by single pulse p And then the calculated S P Substituting the echo photon number model to obtain echo photoelectron number R '(i) in each time interval, and substituting R' (i) into the detection probability model to obtain detection probability P in each time interval D '(i)，P D Maximum value P of' (i) (i.ltoreq.M) Dmax The corresponding time of the interval is marked as T d Corresponding distance D p ＝T d C/2, the error between the corresponding distance and the reference distance is recorded as an estimated error err e ＝D p -D s ＝T d ·c/2-D s . Due to D p ≈D s ，err e ≈err s The peak error err can be obtained through error compensation s Error compensation method for ranging error from err s Reduced to err s -err e The ranging result is more accurate.
It will be appreciated that the advantages of the second aspect may be found in the relevant description of the first aspect, and will not be described in detail herein.
In summary, the method of the invention reduces the hardware cost by reducing the index requirements on the pulse width of the laser and the resolution of the counter.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a diagram showing the comparison of ranging accuracy based on an error compensation method at different target distances;
FIG. 2 is a graph of the comparison of ranging accuracy based on error compensation under different laser pulse widths;
FIG. 3 is a graph of ranging accuracy versus error compensation based at different signal-to-noise ratios;
FIG. 4 is a schematic diagram of a laser ranging hardware system;
FIG. 5 is a schematic diagram of a laser ranging process based on error compensation;
FIG. 6 is a schematic diagram of a computer device according to an embodiment of the present invention;
fig. 7 is a block diagram of a chip according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it will be understood that the terms "comprises" and "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification 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.
It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In the present invention, the character "/" generally indicates that the front and rear related objects are an or relationship.
It should be understood that although the terms first, second, third, etc. may be used to describe the preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish one preset range from another. For example, a first preset range may also be referred to as a second preset range, and similarly, a second preset range may also be referred to as a first preset range without departing from the scope of embodiments of the present invention.
Depending on the context, the word "if" as used herein may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to detection". Similarly, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event)" or "in response to detection (stated condition or event), depending on the context.
Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and their relative sizes, positional relationships shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.
The invention provides a laser ranging method based on error compensation, which reduces hardware cost by reducing index requirements on pulse width of a laser and resolution of a counter. Obtaining an initial measurement distance through counting statistical histogram peak values of data:probability of detection P by detector D (i) Calculating an estimation error->Finally, calculating the distance of the target to be measured through error compensation: />Therefore, the problem of limited ranging precision caused by low hardware cost is solved.
Referring to fig. 4, the hardware unit used in the present invention includes:
the controller unit is used for controlling the laser emitting module and the receiving module and driving the pulse laser to emit signals and the counter to start working; configuring a related register of the TDC chip to finish measurement of time intervals; processing experimental data results;
the laser emission unit is used for sending Gaussian laser pulses;
the laser receiving unit is used for receiving the echo signals reflected by the target and converting received light into received signals through photoelectric conversion;
a counting unit for recording the laser emission time T s And the arrival time T of the received signal e 。
Referring to fig. 5, the laser ranging method based on error compensation of the present invention includes the following steps:
s1, firstly, determining a ranging scene and a theoretical model;
ranging scene
Consider the ranging scene of a single target under the high signal-to-noise ratio scene, and research on the ranging results after error compensation under the conditions of different distances, laser pulse widths and signal-to-noise ratios.
Theoretical model
Laser pulse model:
where τ is the laser pulse width, and n=1 is taken for a common Q-switched laser.
Normalizing the laser waveform:
echo signal model:
wherein E is T ＝P T ×τ width For laser pulse energy, P T For emitting laser power τ width For the laser pulse width, η is the detection efficiency of the detector, D is the target distance, ρ is the reflectivity of the smooth diffuse reflection target, h is the Planckian constant, λ is the laser wavelength, c is the speed of light, FOV is the angle of view of the receiving system, θ T For emitting laser light, angle of divergence, θ target Is the included angle between the laser beam and the normal direction of the target surface, A R For the size of the receiving aperture of the receiving system, eta T For efficiency of the transmitting system η R ＝η T X eta is the receiving efficiency of the receiving system, eta A Is the transmission rate of the atmosphere.
Probability model for detector detection
The typical planar diffuse reflection target approximately describes an effective pulse echo model by using a Gaussian function and characteristic parameters thereof, and the number of echo laser photons in a time interval i is as follows:
in the whole detection process, the echo photoelectron number in the i time interval is as follows:
wherein M is the total average excitation noise frequency; j is the time interval index corresponding to the target position, η is the quantum efficiency of the detector, and integration is started from the i=j+1 interval.
The maximum detection range of the detector is the Nth interval, the detector responds to the first original electron which arrives in the single laser pulse, if the detector generates excitation response in the ith time interval, the maximum detection range of the detector means that the detector does not respond in the previous i-1 time interval, and at least one original electron is generated in the ith time interval; when i<j, the response probability is only equal to the noise photon number n b Related to the following.
The detection probability model of the detector is as follows:
where R (k) is the number of photons per interval when the echo signal does not arrive, and R (i) is the number of photons in the i time interval.
1. Target distance:
and under the condition of 4ns of laser pulse width and 20dB of signal-to-noise ratio, the target position of [10,100,1000,10000] m is simulated.
2. Laser pulse width:
and (3) carrying out simulation on pulse width of [2,4,6,8,10] ns under the condition of 1km of target position and 20dB of signal-to-noise ratio.
3. Signal-to-noise ratio SNR:
the signal-to-noise ratio of the receiving end is generally greater than or equal to 10dB, otherwise, the receiving signal is easy to submerge in noise, and the error compensation method is not good for carrying out the ranging research, so that the higher signal-to-noise ratio of [10,12,14,16,18,20] dB is selected for carrying out the ranging research under the condition that the laser pulse width is 4ns and the target distance is 1 km.
S2, determining the initial measurement target distance
And carrying out detector response judgment on each time interval on single laser pulse according to the time axis sequence: and generating random numbers by using the Poisson distribution generator with the echo photoelectron number in the time interval as a parameter, and considering the detector response in the time interval if the generated random numbers are larger than 0. Each pulse is simulated in turn from the first time interval until the detector responds. 2000 repeated pulses are sent to the target, a receiving end obtains a statistical distribution histogram of the response times of the detector, and the corresponding moment of the peak interval of the statistical graph is marked as T s Thereby calculating the initial distance:
the invention aims to solve the key problem that the error compensation is carried out on the initial measurement result, so that higher ranging precision is obtained under a ranging system with low hardware cost.
And S3, performing error compensation on the initial measurement result obtained in the step S2 by utilizing the theoretical model in the step S1 to obtain a final ranging result.
Will initially test result D s Obtaining the average photon number S returned by single pulse as reference distance p ：
Further, the echo photon number R' (i) per section is obtained:
further, the detection probability P of each time interval is obtained D ' D (i)：
Wherein P is D Maximum value P of' (i) (i.ltoreq.M) Dmax The corresponding time of the interval is marked as T d Corresponding distance D p ＝T d C/2, the error between the corresponding distance and the reference distance is recorded as an estimated error err e ＝D p -D s ＝T d ·c/2-D s 。
Due to D p ≈D s ，err e ≈err s Peak error err is obtained by error compensation s Compensated distance measurement result D c Error err c The method comprises the following steps:
wherein D is 0 For the true distance of the target err s Obtaining peak error for error compensation, err e Is the error between the corresponding distance and the reference distance.
In still another embodiment of the present invention, an error compensation-based laser ranging system is provided, which can be used to implement the error compensation-based laser ranging method described above, and specifically, the error compensation-based laser ranging system includes a condition module, a primary measurement module, and an output module.
The condition module is used for determining a ranging scene and a theoretical model;
the initial measurement module is used for determining the initial measurement target distance based on the ranging scene obtained by the condition module;
and the output module is used for performing error compensation on the initial measurement target distance obtained by the initial measurement module by utilizing the theoretical model of the condition module, so as to obtain a final ranging result.
In yet another embodiment of the present invention, a terminal device is provided, the terminal device including a processor and a memory, the memory for storing a computer program, the computer program including program instructions, the processor for executing the program instructions stored by the computer storage medium. The processor may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processor, digital signal processor (Digital Signal Processor, DSP), application specific integrated circuit (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc., which are the computational core and control core of the terminal adapted to implement one or more instructions, in particular to load and execute one or more instructions to implement the corresponding method flow or corresponding functions; the processor according to the embodiment of the invention can be used for the operation of the laser ranging method based on error compensation, and comprises the following steps:
determining a ranging scene and a theoretical model; determining an initial measurement target distance based on the ranging scene; and carrying out error compensation on the initial measurement target distance by utilizing the theoretical model to obtain a final ranging result.
Referring to fig. 6, the terminal device is a computer device, and the computer device 60 of this embodiment includes: a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61, the computer program 63 when executed by the processor 61 implements the reservoir inversion wellbore fluid composition calculation method of the embodiment, and is not described in detail herein to avoid repetition. Alternatively, the computer program 63, when executed by the processor 61, performs the functions of each model/unit in the error compensation-based laser ranging system, and is not described herein in detail to avoid repetition.
The computer device 60 may be a desktop computer, a notebook computer, a palm top computer, a cloud server, or the like. Computer device 60 may include, but is not limited to, a processor 61, a memory 62. It will be appreciated by those skilled in the art that fig. 6 is merely an example of a computer device 60 and is not intended to be limiting of the computer device 60, and may include more or fewer components than shown, or may combine certain components, or different components, e.g., a computer device may also include an input-output device, a network access device, a bus, etc.
The processor 61 may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 62 may be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 may also be an external storage device of the computer device 60, such as a plug-in hard disk provided on the computer device 60, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), or the like.
Further, the memory 62 may also include both internal storage units and external storage devices of the computer device 60. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 may also be used to temporarily store data that has been output or is to be output.
Referring to fig. 7, the terminal device is a chip, and the chip 600 of this embodiment includes a processor 622, which may be one or more in number, and a memory 632 for storing a computer program executable by the processor 622. The computer program stored in memory 632 may include one or more modules each corresponding to a set of instructions. Further, the processor 622 may be configured to execute the computer program to perform the error compensation-based laser ranging method described above.
In addition, chip 600 may further include a power supply component 626 and a communication component 650, where power supply component 626 may be configured to perform power management of chip 600, and communication component 650 may be configured to enable communication of chip 600, e.g., wired or wireless communication. In addition, the chip 600 may also include an input/output (I/O) interface 658. Chip 600 may operate based on an operating system stored in memory 632.
In a further embodiment of the present invention, the present invention also provides a storage medium, in particular, a computer readable storage medium (Memory), which is a Memory device in a terminal device, for storing programs and data. It will be appreciated that the computer readable storage medium herein may include both a built-in storage medium in the terminal device and an extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space storing an operating system of the terminal. Also stored in the memory space are one or more instructions, which may be one or more computer programs (including program code), adapted to be loaded and executed by the processor. The computer readable storage medium may be a high-speed RAM Memory or a Non-Volatile Memory (Non-Volatile Memory), such as at least one magnetic disk Memory.
One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the respective steps of the above-described embodiments with respect to error compensation-based laser ranging methods; one or more instructions in a computer-readable storage medium are loaded by a processor and perform the steps of:
determining a ranging scene and a theoretical model; determining an initial measurement target distance based on the ranging scene; and carrying out error compensation on the initial measurement target distance by utilizing the theoretical model to obtain a final ranging result.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Changing the target position and comparing to obtain a simulation result 1.
Referring to fig. 1, in order to change the influence of the target position distribution on the error compensation effect, two curves respectively represent the ranging error curves under the peak value method and the error compensation method, and in this step, the influence of two ranging methods on the ranging accuracy is discussed.
Changing the laser pulse width, and comparing to obtain a simulation result 2.
Referring to fig. 2, in order to change the influence of the laser pulse width on the error compensation effect, two curves respectively represent the ranging error curves under the peak value method and the error compensation method, and in this step, the influence of two ranging methods on the ranging accuracy is discussed.
And changing the signal-to-noise ratio of the ranging scene, and comparing to obtain a simulation result 3.
The signal to noise ratio is defined as:
wherein: s is the number of echo photons and N is the number of noise photons.
Referring to fig. 3, to change the influence of the laser pulse width on the error compensation effect, the signal-to-noise ratio of the ranging scene is set to be [10,12,14,16,18,20] db, and ranging is performed on different signal-to-noise ratios, wherein two curves respectively represent the ranging error curves under the peak value method and the error compensation method, so as to obtain a simulation result 3.
The method is compared with other methods in the range finding precision, the method is far better than the traditional peak value range finding method in the range finding precision, and the hardware cost of the system is greatly reduced, so that the method can play a key role in a laser range finding task as the range finding method with the largest comprehensive advantage, namely, the pursued low hardware cost can realize high-precision range finding.
Referring to fig. 1, under the condition of 4ns laser pulse width and 20dB signal-to-noise ratio, simulation is performed on targets at different distances, wherein the target position is [10,100,1000,10000] m, the ordinate of the curve is the average ranging error (m), and the abscissa is the change of the target distance (m). The result of the graph shows that in the range that the target distance is larger than hundred meters, the effect of improving the ranging precision of the system by using an error compensation method is more obvious, and the compensation error is within 0.4 m. The error compensation method has good ranging precision for long-distance laser ranging.
Referring to fig. 2, under the condition of 1km at the target position and 20dB signal-to-noise ratio, the target is simulated by using different laser pulse widths, wherein the pulse width is [2,4,6,8,10] ns, the ordinate of the curve is the average error (m) of the ranging, and the abscissa is the variation of the laser pulse width (ns). The result of the graph shows that the ranging accuracy of the error compensation method is better under different laser pulse widths, the error is within 0.1m, and the effect of error compensation is more obvious when the pulse width is wider.
Referring to fig. 3, under the condition that the laser pulse width is 4ns and the target distance is 1km, simulation is performed on targets under different signal-to-noise ratios, wherein the signal-to-noise ratios are [10,12,14,16,18,20] dB, the ordinate of the curve is the average error (m) of the ranging, and the abscissa is the change of the signal-to-noise ratio (dB). The result of the graph shows that the higher the signal-to-noise ratio is, the better the error performance is, the more obvious the compensation effect of the scheme is, the error is smaller than 0.1m, and the ranging result is more stable.
In summary, according to the laser ranging method and system based on error compensation, the problem that the ranging accuracy is limited due to low hardware cost is solved by the error compensation method through simulation, and the ranging system has better ranging accuracy on the basis of reducing the hardware cost; the method has feasibility, and the simulation effect is far better than that of the traditional laser ranging method.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other manners. For example, the apparatus/terminal embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a usb disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a Random-Access Memory (RAM), an electrical carrier wave signal, a telecommunications signal, a software distribution medium, etc., it should be noted that the content of the computer readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in jurisdictions, such as in some jurisdictions, according to the legislation and patent practice, the computer readable medium does not include electrical carrier wave signals and telecommunications signals.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above is only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. The laser ranging method based on error compensation is characterized by comprising the following steps of:
s1, determining a ranging scene and a theoretical model;
s2, determining an initial measurement target distance based on the ranging scene obtained in the step S1;
and S3, performing error compensation on the initial measurement target distance obtained in the step S2 by utilizing the theoretical model in the step S1, and obtaining a final ranging result.
2. The error compensation-based laser ranging method according to claim 1, wherein in step S1, the theoretical model includes a laser pulse model, an echo signal model and a detector detection probability model, the ranging scene considers the ranging scene of a single target in a low signal-to-noise ratio scene, and the target position of [10,100,1000,10000] m is simulated under the conditions of laser pulse width 4ns and signal-to-noise ratio 20 dB; under the condition of 1km of target position and 20dB of signal-to-noise ratio, the pulse width of [2,4,6,8,10] ns is simulated; and under the condition of 4ns of laser pulse width and 1km of target distance, selecting the signal-to-noise ratio of [10,12,14,16,18,20] dB for distance measurement.
3. The error compensation-based laser ranging method as claimed in claim 2, wherein the laser pulse model:
where τ is the laser pulse width, n=1;
echo signal model:
wherein E is T In the event of a laser pulse energy,η is the detection efficiency of the detector, D is the target distance, ρ is the reflectivity of the smooth diffuse reflection target, h is the Planck constant, λ is the laser wavelength, c is the speed of light, FOV is the angle of view of the receiving system, θ T For emitting laser light, angle of divergence, θ target Is the included angle between the laser beam and the normal direction of the target surface, A R For the size of the receiving aperture of the receiving system, eta T For efficiency of the transmitting system η R For receiving efficiency of receiving system, eta A Is the transmission rate of the atmosphere;
detector detection probability model P D (i) The method comprises the following steps:
where R (k) is the number of photons per interval when the echo signal does not arrive, and R (i) is the number of photons in the i time interval.
4. The error compensation-based laser ranging method according to claim 1, wherein step S2 is specifically:
for single laser pulse, carrying out detector response judgment on each time interval in sequence according to a time axis: the Poisson distribution generator which takes the echo photoelectron number in the time interval as a parameter generates a random number, and if the generated random number is larger than 0, the detector responds in the corresponding time interval; and for each pulse, sequentially carrying out simulation from the first time interval until the detector responds, and determining the initial measurement target distance according to the corresponding moment of the peak value interval of the statistical graph.
5. The error compensation-based laser ranging method of claim 4, wherein the initial target distance is:
wherein T is s Peak as statistical graphAnd c is the speed of light at the moment corresponding to the value interval.
6. The error compensation-based laser ranging method according to claim 1, wherein step S3 is specifically:
will initially test result D s Obtaining the average photon number S returned by single pulse as reference distance p The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the echo photon number R' (i) of each interval; determining the detection probability P ' of each time interval according to the echo photon number R ' (i) ' D (i) The method comprises the steps of carrying out a first treatment on the surface of the Peak error err obtained by error compensation s Final compensated ranging result D c Error err c 。
7. The error compensation-based laser ranging method as claimed in claim 6, wherein the compensated ranging result D c Error err c The method comprises the following steps:
D c ＝D 0 +err s -err e
err c ＝err s -err e
wherein D is 0 For the true distance of the target err s Obtaining peak error for error compensation, err e Is the error between the corresponding distance and the reference distance.
8. The error compensation-based laser ranging method as claimed in claim 6, wherein the detection probability P 'of each time interval' D (i)：
Where R '(k) is the number of photons per section when the echo signal does not arrive, and R' (i) is the number of photons per section.
9. The error compensation-based laser ranging method as claimed in claim 6, wherein the average number of photons S returned by a single pulse p ：
Wherein E is T The laser pulse energy is lambda is laser wavelength, h is Planck constant, c is light speed, FOV is field angle of receiving system, theta T For the divergence angle of the outgoing laser, ρ is the reflectivity of the smooth diffuse reflection target, θ target Is the included angle between the laser beam and the normal direction of the target surface, A R For the size of the receiving aperture of the receiving system, eta T For the effect of the transmitting system, eta R For receiving efficiency of receiving system, eta A Is the transmission rate of the atmosphere.
10. A laser ranging system based on error compensation, comprising:
the condition module is used for determining a ranging scene and a theoretical model;
the initial measurement module is used for determining the initial measurement target distance based on the ranging scene obtained by the condition module;
and the output module is used for performing error compensation on the initial measurement target distance obtained by the initial measurement module by utilizing the theoretical model of the condition module, so as to obtain a final ranging result.
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| CN117991276B (en) * | 2024-04-03 | 2024-06-07 | 深圳光谦传感科技有限公司 | Laser ranging dynamic adjustment method and system based on environment self-adaption |
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