CN106154279B - A kind of laser range finder bearing calibration - Google Patents
A kind of laser range finder bearing calibration Download PDFInfo
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- CN106154279B CN106154279B CN201610587015.1A CN201610587015A CN106154279B CN 106154279 B CN106154279 B CN 106154279B CN 201610587015 A CN201610587015 A CN 201610587015A CN 106154279 B CN106154279 B CN 106154279B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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- 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
- G01S7/497—Means for monitoring or calibrating
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Abstract
The present invention provides a kind of laser range finder bearing calibrations, this method comprises: multiple targets are successively set on predetermined position identical apart from laser range finder；Wherein, the corresponding reflectivity of each target is all different；The laser signal of each target reflection is received using laser range finder, and waveform analysis, range value and corresponding measurement distance value after obtaining waveform analysis are carried out to the laser signal of reflection；To the analysis processing that all measurement distance values and all range values are fitted, corresponding fitting function relationship is obtained；Measurement distance value is corrected according to fitting function relationship, obtain correction distance value, the above method reduces the amplitude phase error due to caused by the difference of reflectivity, to improve the accuracy of range measurement by the fitting correction to measurement distance value to greatest extent.
Description
Technical Field
The invention relates to the technical field of measuring instruments, in particular to a laser range finder correction method.
Background
A laser rangefinder is an instrument that accurately measures the distance to a target using a parameter of modulated laser light. Pulsed laser distance measuring devices are known as laser distance measuring devices, which emit a short pulse laser beam or a series of short pulse laser beams to a target during operation, receive the laser beam reflected by the target by a photoelectric element, measure the time from emission to reception of the laser beam by a timer, and calculate the distance from an observer to the target. For purposes of the following description, the transmission time is recorded as T1 and the reception time is recorded as T2.
However, since the reflectance of different targets is not the same, the intensity of the return light signal generated by targets of different materials at a specific distance fluctuates within a specific range, and the signal amplitude of the corresponding electric pulse also changes, and therefore, the determination at time T2 is also disturbed, and the measured value may be distorted. Referring to fig. 1, a general method for determining the time T2 is to determine the intersection point between the detection threshold and the waveform shown by the dotted line for two reflectivity targets at a specific distance, and it can be seen that for the same detection threshold, the large amplitude signal rises faster with a smaller amplitude signal, and the time T2 of the large amplitude signal is earlier than that with a smaller amplitude, and for different reflectivity targets at a specific distance, the corresponding distance measurement values are different due to the amplitude-phase error.
In order to solve the above problems, the prior art provides a zero crossing detection method, in which an electrical pulse signal is subjected to differential transformation, and then the intersection point of the differential waveform and a zero level is taken as the time T2, and the essence of the method is that the peak value of the pulse signal is taken as the time T2.
The inventor finds in research that, in the zero-crossing detection method in the prior art, due to the nonlinear characteristic of the signal amplification link, the peak value of the pulse signal still changes with the magnitude of the signal, that is, amplitude and phase errors still exist, so that the distance measurement is not accurate enough.
Disclosure of Invention
In view of the above, the present invention provides a method for calibrating a laser range finder, which reduces amplitude and phase errors generated by targets with different reflectivities by using a fitting technique, and further improves accuracy of distance measurement.
In a first aspect, an embodiment of the present invention provides a method for calibrating a laser range finder, including a laser range finder and a plurality of targets; the method comprises the following steps:
sequentially arranging a plurality of targets at the same preset positions away from the laser range finder; wherein the reflectivity corresponding to each target is different;
receiving the laser signal reflected by each target by using the laser range finder, and performing waveform analysis on the reflected laser signal to obtain an amplitude value after waveform analysis and a corresponding measured distance value;
performing fitting analysis processing on all the measured distance values and all the amplitude values to obtain corresponding fitting functional relations;
and correcting the measured distance value according to the fitting function relationship to obtain a corrected distance value.
With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where the receiving, by the laser range finder, the laser signal reflected by each target, and performing waveform analysis on the reflected laser signal to obtain a waveform-analyzed amplitude value and a corresponding measured distance value includes:
the laser range finder emits laser signals to the target and receives the laser signals reflected by the target;
carrying out waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and corresponding receiving time;
and calculating to obtain a measurement distance value corresponding to the amplitude value according to the time difference between the transmitting time corresponding to the laser signal and the receiving time corresponding to the reflected laser signal.
With reference to the first possible implementation manner of the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, where the performing waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and a corresponding receiving time includes:
obtaining the receiving time corresponding to the reflected laser signal according to the crossing position of a preset first detection threshold and the received reflected laser signal;
and obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
With reference to the first possible implementation manner of the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where the performing waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and a corresponding receiving time includes:
carrying out differential conversion processing on the received reflected laser signal to obtain a laser signal subjected to differential conversion processing;
obtaining the receiving time corresponding to the reflected laser signal according to the preset second detection threshold and the intersection position of the laser signal after differential conversion processing;
and obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
With reference to the first possible implementation manner of the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, where the performing waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and a corresponding receiving time includes:
carrying out photoelectric conversion processing on the reflected laser signal to obtain a corresponding analog electric signal;
performing analog-to-digital conversion processing on the analog electric signal to obtain a corresponding digital electric signal;
and carrying out waveform analysis on the digital electric signal to obtain an amplitude value of the digital electric signal and corresponding receiving time.
With reference to the fourth possible implementation manner of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the performing waveform analysis on the digital electrical signal to obtain an amplitude value of the digital electrical signal and a corresponding receiving time includes:
obtaining the receiving time corresponding to the digital electric signal according to the crossing position of a preset third detection threshold and the digital electric signal;
obtaining an amplitude value of the digital electric signal by taking the cross position as a reference position;
or,
carrying out differential transformation processing on the digital electric signal to obtain a digital electric signal after differential transformation processing;
obtaining the corresponding receiving time of the digital electric signal according to the preset second detection threshold and the intersection position of the digital electric signal after differential conversion processing;
and obtaining the amplitude value of the digital electric signal by taking the cross position as a reference position.
With reference to the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, where the analyzing and fitting all the measured distance values and all the amplitude values to obtain corresponding fitting functional relationships includes:
performing difference analysis on each measured distance value according to the real distance value corresponding to the preset position to obtain a plurality of corresponding ranging deviation values;
and performing fitting analysis processing on the plurality of ranging deviation values and the plurality of corresponding amplitude values to obtain corresponding fitting functional relations.
With reference to the sixth possible implementation manner of the first aspect, an embodiment of the present invention provides the seventh possible implementation manner of the first aspect, where the analyzing and processing the fitting of the plurality of ranging deviation values and the corresponding plurality of amplitude values to obtain corresponding fitting functional relationships includes:
forming a discrete function point set by the plurality of ranging deviation values and the corresponding plurality of amplitude values; the range finding deviation value is a dependent variable, and the amplitude value is an independent variable;
fitting analysis processing is carried out on the function point set according to a polynomial method to obtain a corresponding fitting function relation; wherein the fitted functional relationship is closest to the set of function points.
With reference to the seventh possible implementation manner of the first aspect, an embodiment of the present invention provides an eighth possible implementation manner of the first aspect, where the method further includes:
finding a part of fitting functional relation exceeding a preset slope change rate from the fitting functional relation;
obtaining a reflectivity interval corresponding to a part of fitting function relation according to the matching relation between the reflectivity of the prestored target and the corresponding amplitude value;
and adding a target corresponding to the new reflectivity in the reflectivity interval.
With reference to the first aspect, an embodiment of the present invention provides a ninth possible implementation manner of the first aspect, where the laser range finder is a pulsed laser range finder.
Compared with the zero-crossing detection method in the prior art, which has amplitude-phase errors due to the nonlinear characteristics of a signal amplification link and causes inaccurate distance measurement, the method provided by the embodiment of the invention has the advantages that firstly, the multiple targets are sequentially arranged at the same preset position of the laser range finder, namely, different reflectivity targets at the same position are used as implementation conditions, then, the laser range finder is used for carrying out waveform analysis on laser signals reflected by each target to obtain amplitude values after the waveform analysis and corresponding measured distance values, then, all the amplitude values and the measured distance values are subjected to fitting analysis, and the measured distance values are corrected by using the fitting function relationship obtained by the fitting analysis to obtain corrected distance values, and the method carries out fitting correction on the measured distance values, the amplitude and phase errors caused by different reflectivity are reduced to the maximum extent, so that the accuracy of distance measurement is improved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 shows a schematic diagram of a fixed threshold detection method in the prior art;
FIG. 2 is a flow chart illustrating a method for calibrating a laser range finder according to an embodiment of the present invention;
FIG. 3 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 4 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 5 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 6 is a flow chart illustrating another laser rangefinder calibration method provided by embodiments of the present invention;
FIG. 7 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 8 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 9 is a flow chart illustrating another laser rangefinder calibration method provided by an embodiment of the present invention;
FIG. 10 is a flow chart illustrating another method of calibrating a laser rangefinder provided by an embodiment of the present invention;
fig. 11 is a flowchart illustrating another laser range finder calibration method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of 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 present invention, 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 derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
In consideration of the zero-crossing detection method in the prior art, due to the nonlinear characteristic of the signal amplification link, the peak value of the pulse signal still changes with the magnitude of the signal, that is, amplitude and phase errors still exist, so that the distance measurement is not accurate enough. Based on this, the embodiment of the invention provides a laser range finder correction method, which adopts a fitting technical means to reduce amplitude and phase errors generated by measured targets with different reflectivities and further improve the accuracy of distance measurement.
Referring to fig. 2, a flowchart of a method for calibrating a laser range finder according to an embodiment of the present invention is shown, where the method specifically includes the following steps:
s101, sequentially arranging a plurality of targets at the same preset positions away from a laser range finder; wherein the reflectivity corresponding to each target is different;
specifically, the implementation condition of the laser range finder correction method provided in the embodiment of the present invention is that all targets are arranged at the same preset position from the laser range finder, and the reflectivities of the targets are different, and at this time, only different reflectivities of the targets are used as the variation.
S102, receiving the laser signals reflected by each target by using a laser range finder, and carrying out waveform analysis on the reflected laser signals to obtain amplitude values after the waveform analysis and corresponding measured distance values;
specifically, for each of the plurality of targets set at the fixed positions, the laser signal reflected by the target is received by using the matched laser ranging distance and the reflected laser signal can be subjected to waveform analysis, so that not only is a measured distance value obtained by calculation, but also a corresponding amplitude value can be acquired, and the targets with different reflectivities and the corresponding amplitude values thereof are correspondingly stored.
The waveform analysis not only comprises a waveform analysis mode corresponding to a fixed threshold detection method, and a waveform analysis mode corresponding to a differential zero-crossing detection method, but also comprises a digital waveform analysis mode of the two methods, so as to meet different requirements of different users.
S103, performing fitting analysis processing on all the measured distance values and all the amplitude values to obtain corresponding fitting functional relations;
specifically, for the amplitude value and the measured distance value obtained by the laser range finder, fitting analysis is performed on a discrete function point set corresponding to the amplitude value and the measured distance value according to a plurality of coefficients to be determined, so that the difference between the obtained fitting function relation and the function point set is minimum, that is, the least square method is met.
And S104, correcting the measured distance value according to the fitting function relationship to obtain a corrected distance value.
Specifically, for the obtained fitting function relationship, in the subsequent measurement, the amplitude value is substituted into the fitting function relationship to realize the correction of the measured distance value, so as to obtain the final corrected distance value.
Compared with the zero-crossing detection method in the prior art, in the correction method for the laser range finder provided by the embodiment of the invention, the inaccurate distance measurement is caused by the amplitude-phase error due to the nonlinear characteristic of the signal amplification link, the method comprises the steps of firstly sequentially arranging a plurality of targets at the same preset position of the laser range finder, namely using different reflectivity targets at the same position as implementation conditions, then carrying out waveform analysis on laser signals reflected by each target by using the laser range finder to obtain amplitude values after the waveform analysis and corresponding measured distance values, then carrying out fitting analysis on all the amplitude values and the measured distance values, correcting the measured distance values by using the fitting function relationship obtained by the fitting analysis to obtain corrected distance values, and reducing the amplitude-phase error caused by the different reflectivity to the maximum extent by the fitting correction of the measured distance values by the method, thereby improving the accuracy of the distance measurement.
In order to better acquire the fitting-related amplitude value and the measured distance value, the analysis process of S102 is specifically implemented by the following steps, referring to the flowchart illustrated in fig. 3, and the method further includes:
s201, a laser range finder emits laser signals to a target and receives the laser signals reflected by the target;
specifically, after the fixed position distance setting is performed on each target, the laser range finder in the embodiment of the present invention uses the pulse laser generator included in the laser range finder to transmit a laser signal to the target, the target receives the laser signal and returns the signal, and the laser range finder may receive the laser signal reflected by the target according to the receiving system of the laser range finder.
The laser range finder in the embodiment of the invention preferably adopts a pulse type laser range finder.
S202, performing waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and corresponding receiving time;
specifically, for the distance measurement of the photometric distance meter, after the receiving time of the reflected laser signal is determined, the corresponding measured distance value can be calculated by using the receiving time, and thus, the determination of the receiving time is a key point. For the laser range finder correction method provided by the embodiment of the present invention, the corresponding receiving time may be determined by a fixed threshold detection method and a differential zero-crossing detection method. Similarly, for the received reflected laser signal, amplitude values corresponding to different detection methods can be obtained.
S203, calculating to obtain a measurement distance value corresponding to the amplitude value according to the time difference between the transmitting time corresponding to the laser signal and the receiving time corresponding to the reflected laser signal.
Specifically, when the pulse type laser range finder works, the pulse laser generator is triggered to generate a laser signal. The laser signal has a small amount of energy sent directly from the reference signal sampler to the receiving system as a starting point for timing. Most of the light pulse energy is directed to the target and the light pulse energy reflected by the target back to the rangefinder is received by the receiving system, which is the echo signal (reflected laser signal). The reference signal and the echo signal are converted into electric pulses by the photoelectric detector, amplified and shaped. The shaped reference signal can enable the trigger to turn over, and the counter is controlled to start counting clock pulses sent by the crystal lattice oscillator.
And calculating to obtain a measurement distance value corresponding to each target according to the time difference between the receiving time of the echo signal and the transmitting time corresponding to the transmitted laser signal and the light speed. The measured distance values are in one-to-one correspondence with their amplitude values.
In consideration of the fact that the laser range finder correction method provided by the embodiment of the present invention can not only suppress amplitude-phase errors generated in the fixed threshold detection method, but also further suppress nonlinear amplitude-phase errors of the circuit in the differential zero-crossing detection method, that is, the method in the embodiment is suitable for amplitude-phase errors generated in the fixed threshold detection method and the differential zero-crossing detection method, wherein the fixed threshold detection method and the differential zero-crossing detection method have different waveform analysis methods, and the receiving time of the laser range finder receiving the reflected laser signal is also different. For the fitting data sources generated by the two methods, referring to fig. 4, the specific process of waveform analysis S202 in the calibration method for a laser range finder provided by the embodiment of the present invention can be implemented by the following steps:
s301, obtaining receiving time corresponding to the reflected laser signal according to the crossing position of a preset first detection threshold and the received reflected laser signal;
and S302, obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
Specifically, for fixed threshold detection, a preset first detection threshold and a waveform rising section crossing position of an analog electrical signal obtained by photoelectrically converting a reflected laser signal by a photoelectric detector are taken as receiving time, and the crossing position is taken as a reference position to determine an amplitude value of the reflected laser signal through a waveform peak value.
In addition, referring to fig. 5, the waveform analysis of S202 may be further implemented by the following steps:
s401, carrying out differential transformation processing on the received reflected laser signal to obtain a laser signal subjected to differential transformation processing;
s402, obtaining the corresponding receiving time of the reflected laser signal according to the preset second detection threshold and the intersection position of the laser signal after differential conversion processing;
and S403, obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
Specifically, for differential zero-crossing detection, the crossing position of a differential waveform after analog electrical signal differential change processing and a preset second detection threshold (i.e., zero level) is taken as the receiving time, and the amplitude value of the reflected laser signal is determined by the waveform peak value with the crossing position as the reference position. The waveform peak comprises a positive peak, a negative peak, a peak of the original pulse, or a combination thereof of the differentiated waveform.
In order to perform digitized analysis processing on the reflected laser signal, the laser range finder correction method provided by the embodiment of the invention can also realize the range finding function by a digital means, and can correspondingly store the extracted amplitude value and the measured distance value. Then, the waveform analysis process of S202 is specifically implemented by the following steps, referring to the flowchart shown in fig. 6, and the method further includes:
s501, performing photoelectric conversion processing on the reflected laser signal to obtain a corresponding analog electric signal;
s502, carrying out analog-to-digital conversion processing on the analog electric signal to obtain a corresponding digital electric signal;
specifically, for analog signal analysis corresponding to fixed threshold detection and differential zero-crossing detection, the corresponding amplitude value is further converted, so that the laser range finder correction method provided by the embodiment of the invention can also directly perform digital processing on the originally reflected laser signal to obtain a corresponding digital electric signal.
S503, carrying out waveform analysis on the digital electric signal to obtain an amplitude value of the digital electric signal and corresponding receiving time.
Considering that the waveform analysis process of the digital electrical signal is similar to the waveform analysis process of the reflected laser signal, the analysis process of the digital electrical signal corresponding to S503, referring to fig. 7, can be specifically implemented by the following steps:
s601, obtaining the receiving time corresponding to the digital electric signal according to the crossing position of the preset third detection threshold and the digital electric signal;
s602, obtaining an amplitude value of the digital electric signal by taking the cross position as a reference position;
specifically, for the digital fixed threshold detection, the crossing position of the preset third detection threshold and the waveform rising segment of the digital electric signal is taken as the receiving time, and then the amplitude value of the digital electric signal corresponding to the reflected laser signal is determined through the waveform peak value by taking the crossing position as the reference position.
In addition, corresponding to the differential zero-crossing detection method, the analysis process of the digital electrical signal corresponding to S503 above, referring to fig. 8, can be specifically implemented by the following steps:
s701, carrying out differential transformation processing on the digital electric signal to obtain a digital electric signal after the differential transformation processing;
s702, obtaining the corresponding receiving time of the digital electric signal according to the preset second detection threshold and the crossing position of the digital electric signal after differential conversion processing;
and S703, obtaining the amplitude value of the digital electric signal by taking the cross position as a reference position.
Specifically, for digitized differential zero-crossing detection, the crossing position of a differential waveform after differential change processing and a preset second detection threshold (i.e., zero level) is taken as the receiving time, and the amplitude value of the digital electric signal corresponding to the reflected laser signal is determined by the waveform peak value with the crossing position as the reference position. The waveform peak comprises a positive peak, a negative peak, a peak of the original pulse, or a combination thereof of the differentiated waveform.
In order to better perform the fitting analysis on the obtained measured distance value and amplitude value, the fitting analysis process of S103, referring to fig. 9, is specifically implemented by the following steps:
s801, performing difference analysis on each measured distance value according to the real distance value corresponding to the preset position to obtain a plurality of corresponding ranging deviation values;
s802, performing fitting analysis processing on the plurality of ranging deviation values and the plurality of corresponding amplitude values to obtain corresponding fitting functional relations.
Specifically, for the measured distance values corresponding to the targets with different reflectivities, the calibration method for the laser range finder provided in the embodiment of the present invention first performs difference analysis on the measured distance values according to the real distance values corresponding to the preset positions to obtain a plurality of distance measurement deviation values corresponding to each target, then establishes a corresponding fitting functional relationship according to the plurality of distance measurement deviation values and the corresponding plurality of amplitude values, and finally calibrates any measured distance value of the laser range finder according to the fitting functional relationship.
The fitting process of S802 is specifically implemented by the following steps, referring to the flowchart shown in fig. 10, where the method further includes:
s8021, forming a discrete function point set by the plurality of ranging deviation values and the plurality of corresponding amplitude values; the ranging deviation value is a dependent variable, and the amplitude value is an independent variable;
s8022, performing fitting analysis processing on the function point set according to a polynomial method to obtain a corresponding fitting function relation; wherein the fitting functional relationship is closest to the set of function points.
Specifically, the principle of the fitting is that a plurality of discrete function values { f1, f2, …, fn } of a certain function are known, and a plurality of coefficients f (λ 1, λ 2, …, λ n) to be determined in the function are adjusted, so that the difference (least square meaning) between the function and a known point set is minimum. In the embodiment of the invention, the corresponding function point set is formed according to the plurality of ranging deviation values and the corresponding plurality of amplitude values, and the ranging deviation values are used as dependent variables and the amplitude values are used as independent variables. Then, fitting analysis processing is carried out on the function point set by utilizing a polynomial method to obtain a corresponding fitting function relation; the fitting functional relationship is closest to the function point set, that is, the difference between the fitting functional relationship and the function point set is the minimum.
The laser range finder correction method provided by the embodiment of the present invention can further refine the fitting function relationship to increase the number of sampling points of the fitting function relationship, and further increase the accuracy of subsequent correction, referring to fig. 11, the method further includes:
s901, finding out a part of fitting function relation exceeding a preset slope change rate from the fitting function relation;
s902, obtaining a reflectivity interval corresponding to a partial fitting function relation according to a matching relation between the reflectivity of a prestored target and a corresponding amplitude value;
and S903, adding a target corresponding to the new reflectivity in the reflectivity interval.
Specifically, for the fitting functional relationship obtained by fitting the ranging deviation value and the amplitude value, firstly, a partial fitting functional relationship exceeding a preset slope change rate (namely, the curve slope change rate is rich) is searched, then, according to a matching relationship between a prestored reflectivity according to a prestored target and a corresponding amplitude value, a reflectivity interval corresponding to the partial fitting functional relationship is obtained, the reflectivity is appropriately refined in the corresponding reflectivity interval, the corresponding target is increased, then, the increased target is subjected to preset position setting and waveform analysis of a corresponding reflected laser signal, and a function point set is refined through the amplitude value after waveform analysis and a measured distance value, so that the accuracy of subsequent correction of the fitting functional relationship is further improved.
Compared with the zero-crossing detection method in the prior art, in the correction method for the laser range finder provided by the embodiment of the invention, the inaccurate distance measurement is caused by the amplitude-phase error due to the nonlinear characteristic of the signal amplification link, the method comprises the steps of firstly sequentially arranging a plurality of targets at the same preset position of the laser range finder, namely using different reflectivity targets at the same position as implementation conditions, then carrying out waveform analysis on laser signals reflected by each target by using the laser range finder to obtain amplitude values after the waveform analysis and corresponding measured distance values, then carrying out fitting analysis on all the amplitude values and the measured distance values, correcting the measured distance values by using the fitting function relationship obtained by the fitting analysis to obtain corrected distance values, and reducing the amplitude-phase error caused by the different reflectivity to the maximum extent by the fitting correction of the measured distance values by the method, thereby improving the accuracy of the distance measurement.
The computer program product for performing the laser range finder calibration method provided in the embodiment of the present invention includes a computer readable storage medium storing a program code, where instructions included in the program code may be used to execute the method described in the foregoing method embodiment, and specific implementation may refer to the method embodiment, which is not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions when actually implemented, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed 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 can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments provided by the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus once an item is defined in one figure, it need not be further defined and explained in subsequent figures, and moreover, the terms "first", "second", "third", etc. are used merely to distinguish one description from another and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the present invention in its spirit and scope. Are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A laser range finder calibration method is characterized by comprising a laser range finder and a plurality of targets; the method comprises the following steps:
sequentially arranging a plurality of targets at the same preset positions away from the laser range finder; wherein the reflectivity corresponding to each target is different;
receiving the laser signal reflected by each target by using the laser range finder, and performing waveform analysis on the reflected laser signal to obtain an amplitude value after waveform analysis and a corresponding measured distance value;
performing fitting analysis processing on all the measured distance values and all the amplitude values to obtain corresponding fitting functional relations;
and correcting the measured distance value according to the fitting function relationship to obtain a corrected distance value.
2. The method for calibrating a laser range finder according to claim 1, wherein the receiving, by the laser range finder, the laser signal reflected by each target, and performing waveform analysis on the reflected laser signal to obtain a waveform-analyzed amplitude value and a corresponding measured distance value comprises:
the laser range finder emits laser signals to the target and receives the laser signals reflected by the target;
carrying out waveform analysis on the reflected laser signal to obtain an amplitude value of the laser signal and corresponding receiving time;
and calculating to obtain a measurement distance value corresponding to the amplitude value according to the time difference between the transmitting time corresponding to the laser signal and the receiving time corresponding to the reflected laser signal.
3. The method for calibrating a laser range finder according to claim 2, wherein said waveform analyzing said reflected laser signal to obtain an amplitude value and a corresponding receiving time of said laser signal comprises:
obtaining the receiving time corresponding to the reflected laser signal according to the crossing position of a preset first detection threshold and the received reflected laser signal;
and obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
4. The method for calibrating a laser range finder according to claim 2, wherein said waveform analyzing said reflected laser signal to obtain an amplitude value and a corresponding receiving time of said laser signal comprises:
carrying out differential conversion processing on the received reflected laser signal to obtain a laser signal subjected to differential conversion processing;
obtaining the receiving time corresponding to the reflected laser signal according to the preset second detection threshold and the intersection position of the laser signal after differential conversion processing;
and obtaining the amplitude value of the reflected laser signal by taking the cross position as a reference position.
5. The method for calibrating a laser range finder according to claim 2, wherein said waveform analyzing said reflected laser signal to obtain an amplitude value and a corresponding receiving time of said laser signal comprises:
carrying out photoelectric conversion processing on the reflected laser signal to obtain a corresponding analog electric signal;
performing analog-to-digital conversion processing on the analog electric signal to obtain a corresponding digital electric signal;
and carrying out waveform analysis on the digital electric signal to obtain an amplitude value of the digital electric signal and corresponding receiving time.
6. The method for calibrating a laser range finder according to claim 5, wherein said waveform analyzing said digital electrical signal to obtain an amplitude value and a corresponding receiving time of said digital electrical signal comprises:
obtaining the receiving time corresponding to the digital electric signal according to the crossing position of a preset third detection threshold and the digital electric signal;
obtaining an amplitude value of the digital electric signal by taking the cross position as a reference position;
or,
carrying out differential transformation processing on the digital electric signal to obtain a digital electric signal after differential transformation processing;
obtaining the corresponding receiving time of the digital electric signal according to the preset second detection threshold and the intersection position of the digital electric signal after differential conversion processing;
and obtaining the amplitude value of the digital electric signal by taking the cross position as a reference position.
7. The method for calibrating a laser range finder according to claim 1, wherein said analyzing and fitting all said measured distance values and all said amplitude values to obtain corresponding fitting functional relationships comprises:
performing difference analysis on each measured distance value according to the real distance value corresponding to the preset position to obtain a plurality of corresponding ranging deviation values;
and performing fitting analysis processing on the plurality of ranging deviation values and the plurality of corresponding amplitude values to obtain corresponding fitting functional relations.
8. The method for calibrating a laser range finder of claim 7, wherein said analyzing and fitting a plurality of said range finder deviation values and a corresponding plurality of said amplitude values to obtain a corresponding fitting functional relationship comprises:
forming a discrete function point set by the plurality of ranging deviation values and the corresponding plurality of amplitude values; the range finding deviation value is a dependent variable, and the amplitude value is an independent variable;
fitting analysis processing is carried out on the function point set according to a polynomial method to obtain a corresponding fitting function relation; wherein the fitted functional relationship is closest to the set of function points.
9. The laser range finder calibration method of claim 8, further comprising:
finding a part of fitting functional relation exceeding a preset slope change rate from the fitting functional relation;
obtaining a reflectivity interval corresponding to a part of fitting function relation according to the matching relation between the reflectivity of the prestored target and the corresponding amplitude value;
and adding a target corresponding to the new reflectivity in the reflectivity interval.
10. The method of calibrating a laser rangefinder of claim 1, wherein the laser rangefinder is a pulsed laser rangefinder.
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| CN108226907B (en) * | 2017-12-11 | 2020-05-19 | 武汉万集信息技术有限公司 | Ranging calibration method and device for laser ranging equipment |
| US11155364B2 (en) * | 2018-01-31 | 2021-10-26 | The Boeing Company | Optical systems and methods for aircraft flight control rigging |
| CN108415003B (en) * | 2018-06-08 | 2019-12-27 | 深圳煜炜光学科技有限公司 | Laser ranging calibration device and calibration method thereof |
| CN109116341B (en) * | 2018-07-31 | 2021-02-09 | 北京小米移动软件有限公司 | Distance measurement function establishing method, distance detection method and device and electronic equipment |
| US20200133270A1 (en) * | 2018-10-31 | 2020-04-30 | Baidu Usa Llc | Lidar device with cylindrical lens for autonomous driving vehicles |
| US11320520B2 (en) * | 2018-11-07 | 2022-05-03 | Baidu Usa Llc | Lidar peak detection using time-to-digital converter and multi-pixel photon counter for autonomous driving vehicles |
| CN109597054B (en) * | 2018-12-21 | 2023-06-02 | 宁波傲视智绘光电科技有限公司 | Laser radar calibration method |
| CN109917355A (en) * | 2019-03-04 | 2019-06-21 | 合肥嘉东光学股份有限公司 | Laser radar range error compensation system |
| CN111902730B (en) * | 2019-03-05 | 2021-10-29 | 深圳市大疆创新科技有限公司 | Calibration plate, depth parameter calibration method, detection device and calibration system |
| CN111722205A (en) * | 2019-03-22 | 2020-09-29 | 深圳市速腾聚创科技有限公司 | Calibration method, system, device, equipment and storage medium for laser ranging |
| EP3936893B1 (en) * | 2019-04-04 | 2024-03-13 | Huawei Technologies Co., Ltd. | Method and apparatus for processing echo signals |
| CN112534301A (en) * | 2019-04-09 | 2021-03-19 | 华为技术有限公司 | Distance measurement method, device and equipment |
| CN116973892A (en) * | 2019-04-29 | 2023-10-31 | 深圳市速腾聚创科技有限公司 | Laser radar calibration device |
| WO2021077253A1 (en) * | 2019-10-21 | 2021-04-29 | 深圳市大疆创新科技有限公司 | Measurement method and apparatus, mobile platform and computer-readable medium |
| CN113179653A (en) * | 2019-11-25 | 2021-07-27 | 深圳市大疆创新科技有限公司 | Method and device for measuring reflectivity, movable platform and computer readable medium |
| CN111337907B (en) * | 2020-02-26 | 2022-03-25 | 歌尔光学科技有限公司 | Near object sensor calibration method, device, equipment and computer medium |
| CN111661111A (en) * | 2020-06-03 | 2020-09-15 | 深圳市视晶无线技术有限公司 | Rail transit obstacle detection method and device |
| WO2022141100A1 (en) * | 2020-12-29 | 2022-07-07 | 迅达（中国）电梯有限公司 | Segmented laser ranging method and system |
| CN112711005B (en) * | 2020-12-29 | 2024-05-17 | 深圳市利拓光电有限公司 | Distance measuring device based on laser and control method |
| CN112596066B (en) * | 2021-02-24 | 2021-09-28 | 锐驰智光(北京)科技有限公司 | Laser radar ranging method, ranging device and storage medium |
| CN113376644B (en) * | 2021-08-16 | 2021-11-30 | 深圳煜炜光学科技有限公司 | Method and device for improving laser ranging precision |
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| CN103018749B (en) * | 2012-12-31 | 2015-06-10 | 保定市天河电子技术有限公司 | Device and method for pulse laser ranging |
| CN105549027B (en) * | 2015-12-28 | 2018-04-13 | 北京握奇数据系统有限公司 | A kind of distance measuring method and system based on laser pulse shape leading edge detection |
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