CN117055061A

CN117055061A - Ranging method, laser radar, robot and storage medium

Info

Publication number: CN117055061A
Application number: CN202311310656.9A
Authority: CN
Inventors: 欧阳家斌; 陈悦
Original assignee: Shenzhen Camsense Technologies Co Ltd
Current assignee: Shenzhen Camsense Technologies Co Ltd
Priority date: 2023-10-11
Filing date: 2023-10-11
Publication date: 2023-11-14
Anticipated expiration: 2043-10-11
Also published as: CN117055061B

Abstract

The embodiment of the invention relates to the technical field of laser radars, and discloses a ranging method, a laser radar, a robot and a storage medium.

Description

Ranging method, laser radar, robot and storage medium

Technical Field

The embodiment of the invention relates to the technical field of laser radars, in particular to a ranging method, a laser radar, a robot and a storage medium.

Background

Before the laser radar works normally, the laser radar needs to be subjected to distance correction, also called distance calibration, and the purpose of the calibration is to enable the radar to obtain good distance correction parameters and obtain accurate measurement distance by utilizing the parameters in actual measurement. However, at present, only one white target with common reflectivity in living environment is adopted for each calibration distance, so that the laser radar has low ranging accuracy due to the fact that different distances are deviated by a high-reflection lattice target for other materials such as a low-reflection white target.

Disclosure of Invention

The invention aims to provide a ranging method, a laser radar, a robot and a storage medium, which can improve the calibration precision and the ranging precision of the laser radar.

In a first aspect, an embodiment of the present invention provides a ranging method, applied to a laser radar, where the method includes:

determining a plurality of theoretical distances between a calibration target with different reflectivity and the laser radar in each calibration section in the range of the laser radar;

acquiring the brightness corresponding to each calibration target under each theoretical distance;

determining calibration parameters corresponding to the calibration targets with different reflectivities in each calibration section according to the theoretical distance and the brightness corresponding to each calibration target under the theoretical distance;

when the laser radar measures the distance of the object to be measured, correcting the measured distance output by the laser radar according to the calibration parameters, the measured distance output by the laser radar and the measured brightness, and obtaining the final measured distance.

In some embodiments, the determining the calibration parameters corresponding to the calibration targets with different reflectivities in each calibration segment according to the theoretical distance and the brightness corresponding to each calibration target under the theoretical distance includes:

Selecting a calibration target with one reflectivity in one calibration section as a first reference calibration target;

acquiring an initial value of a reference correction parameter and first reference brightness at each theoretical distance, wherein the reference correction parameter is a correction parameter corresponding to a selected calibration section of the first reference calibration target, and the first reference brightness is the brightness of the first reference calibration target at each theoretical distance of the selected calibration section;

calculating a first difference value between the brightness corresponding to the calibration targets with residual reflectivity except the first reference calibration target at each theoretical distance and the first reference brightness;

calculating a second difference value between the initial value of the correction parameter of the residual reflectivity calibration target except the first reference calibration target in the calibration section and the initial value of the reference correction parameter;

and determining the calibration parameters corresponding to the selected calibration segments according to each theoretical distance, the first difference value corresponding to each theoretical distance and the second difference value.

In some embodiments, determining the calibration parameter corresponding to the selected calibration segment according to each theoretical distance, the first difference value corresponding to each theoretical distance, and the second difference value includes:

Constructing a first calibration equation according to the first difference value and the second difference value corresponding to each theoretical distance;

solving the first calibration equation to obtain a first mapping parameter between the first difference value and the second difference value under each theoretical distance;

constructing a second calibration equation according to each theoretical distance and the corresponding first mapping parameter;

and solving the second calibration equation to obtain a second mapping parameter between the theoretical distance and the first mapping parameter, wherein the second mapping parameter and the first mapping parameter together form the calibration parameter of the selected calibration section.

In some embodiments, correcting the measured distance output by the laser radar according to the calibration parameter, the measured distance output by the laser radar and the measured brightness to obtain a final measured distance includes:

acquiring a first measurement distance of an object to be measured, which is output by the laser radar;

determining a first target calibration parameter corresponding to the object to be measured according to the first measurement distance;

calculating a third difference between the corresponding luminance at the first measurement distance and the first reference luminance;

Determining a first variation of the target correction parameter according to the first target calibration parameter, the first measurement distance and the third difference value;

determining the target correction parameter according to the first variation and the reference correction parameter;

and correcting the measurement distance output by the laser radar by adopting the target correction parameters to obtain a final measurement distance.

In some embodiments, the determining, according to the first measurement distance, a first target calibration parameter corresponding to the object to be measured includes:

determining the calibration section to which the object to be measured belongs according to the first measurement distance;

and determining the first target calibration parameters corresponding to the calibration sections to which the object to be measured belongs.

In some embodiments, the determining the first variation of the target corrective parameter based on the first target calibration parameter, the first measured distance, and the third difference comprises:

substituting the first measurement distance and the second mapping parameter into the second calibration equation to obtain the first mapping parameter corresponding to the first measurement distance;

substituting the first mapping parameter corresponding to the first measurement distance and the third difference value into the first calibration equation to obtain a first variation of the target correction parameter.

In some embodiments, the correction parameter is a measured distance of the radar output, and determining, according to the theoretical distance and the brightness corresponding to each calibration target under the theoretical distance, the calibration parameter corresponding to each calibration segment of each calibration target with different reflectivity, further includes:

selecting a calibration target with one reflectivity in one calibration section as a second reference calibration target, and determining second reference brightness, wherein the second reference brightness is the brightness of the second reference calibration target at each theoretical distance in the selected calibration section;

calculating a fourth difference value between the brightness corresponding to the theoretical distance of the residual reflectivity calibration targets except the second reference calibration target and the second reference brightness;

calculating a fifth difference value between a measured distance of the radar output corresponding to the calibration targets of the residual reflectivity except the second reference calibration target under the theoretical distance and a first reference distance, wherein the first reference distance is the measured distance of the radar output corresponding to the second reference calibration target under the theoretical distance;

and determining calibration parameters corresponding to the calibration targets with different reflectivities in the selected calibration section according to the fourth difference and the fifth difference.

In some embodiments, the determining the second reference brightness includes:

determining a reference distance brightness curve corresponding to the selected calibration segment, wherein the reference distance brightness curve is a brightness curve of the second reference calibration target along with the change of distance;

and obtaining second reference brightness under the theoretical distance according to the reference distance brightness curve.

In some embodiments, the determining the reference distance brightness curve corresponding to the selected calibration segment includes:

if the selected calibration section is a first calibration section, fitting the theoretical distance of the second reference calibration target in the first calibration section and the brightness corresponding to the theoretical distance by adopting a curve function to obtain a reference distance brightness curve;

if the selected calibration section is a second calibration section, fitting the theoretical distance of the second reference calibration target in the second calibration section and the brightness corresponding to the theoretical distance by adopting a linear function to obtain a reference distance brightness curve;

and if the selected calibration section is a third calibration section, obtaining the reference distance brightness curve based on the second reference brightness corresponding to the theoretical distance at the first point of the third calibration section and the brightness corresponding to the high-reflectivity calibration target, and the second reference brightness corresponding to the theoretical distance at the last point of the third calibration section.

In some embodiments, the obtaining the reference distance luminance curve based on the second reference luminance at the theoretical distance corresponding to the first point of the third calibration segment, the luminance corresponding to the high-reflectivity calibration target, and the second reference luminance at the theoretical distance corresponding to the last point of the third calibration segment includes:

calculating the average value between the second reference brightness corresponding to the first point of the third calibration section under the theoretical distance and the brightness corresponding to the high-reflectivity calibration target, and taking the average value as the first point brightness of the first point;

taking the second reference brightness under the theoretical distance corresponding to the end point of the third calibration section as the end point brightness;

and fitting the theoretical distance corresponding to the first point, the first point brightness, the theoretical distance corresponding to the last point and the last point brightness by adopting a linear function to obtain the reference distance brightness curve.

In some embodiments, the correcting the measured distance output by the laser radar according to the calibration parameter, the measured distance output by the laser radar and the measured brightness to obtain a final measured distance includes:

Acquiring a second measurement distance of the object to be measured, which is output by the laser radar;

calculating a sixth difference between the corresponding luminance at the second measurement distance and the second reference luminance;

determining the calibration section to which the object to be measured belongs according to the second measurement distance;

selecting a second target calibration parameter corresponding to the reflectivity of the object to be measured from the calibration parameters corresponding to the calibration section;

determining a second variation of the measured distance output by the radar according to the second target calibration parameter and the sixth difference;

and determining the sum of the second variation and the second measurement distance as a final measurement distance.

In some embodiments, the method further comprises:

acquiring a third measurement distance from a transmitting end of the laser radar to a rotation center of the laser radar;

and determining the distance from the object to be measured to the rotation center according to the final measurement distance and the third measurement distance.

In a second aspect, an embodiment of the present invention provides a lidar, including:

at least one processor; the method comprises the steps of,

a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the ranging method as described above.

In a third aspect, embodiments of the present invention provide a robot comprising a lidar as described above.

In a fourth aspect, in an embodiment of the present invention, there is provided a computer-readable storage medium storing computer-executable instructions for causing a computer device to perform the ranging method as described above.

The embodiment of the invention has the beneficial effects that: compared with the prior art, the ranging method provided by the embodiment of the invention is applied to the laser radar, the method is characterized in that firstly, a plurality of theoretical distances between the calibration targets with different reflectivities and the laser radar in each calibration section in the range of the laser radar are determined, then the brightness corresponding to each calibration target under each theoretical distance is obtained, then the calibration parameters of each calibration target with different reflectivities corresponding to each calibration section are determined according to the brightness corresponding to each theoretical distance and each calibration target under the theoretical distance, and finally, when the laser radar ranges an object to be measured, the measurement distance output by the laser radar is corrected according to the calibration parameters, the measurement distance output by the laser radar and the measurement brightness, and the final measurement distance is obtained. According to the ranging method, the brightness corresponding to the calibration targets with different reflectivities at the theoretical distance is added to the determination process of the calibration parameters, and the brightness corresponding to the object to be measured at the measured distance is added to the subsequent correction, so that the calibration targets with different reflectivities are calibrated, the calibration parameters of the calibration targets with different reflectivities are obtained, the distance deviation caused by different reflectivities is compensated, and the ranging accuracy of the laser radar is improved.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.

Fig. 1 is a schematic view of an application environment of one ranging method according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a ranging method according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a distance brightness curve corresponding to each calibration target according to an embodiment of the present invention;

fig. 4 is a schematic flow chart of step S30 in fig. 2;

FIG. 5 is a flowchart illustrating step S40 in FIG. 2;

FIG. 6 is a schematic diagram of the relationship between the center of rotation, the transmitting end and the object to be measured of the lidar;

FIG. 7 is a schematic diagram of another flow chart of step S30 in FIG. 2;

FIG. 8 is a schematic diagram of a reference distance luminance curve of a second reference calibration target according to an embodiment of the present invention;

FIG. 9 is another flow chart of step S40 in FIG. 2;

fig. 10 is a schematic diagram of a ranging apparatus according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a robot according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

It should be noted that, if not in conflict, the features of the embodiments of the present invention may be combined with each other, which is within the protection scope of the present invention. In addition, while functional block division is performed in a device diagram and logical order is shown in a flowchart, in some cases, the steps shown or described may be performed in a different order than the block division in the device, or in the flowchart. Moreover, the words "first," "second," "third," and the like as used herein do not limit the data and order of execution, but merely distinguish between identical or similar items that have substantially the same function and effect.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.

In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

Referring to fig. 1, fig. 1 is a schematic view of an application environment provided in an embodiment of the present invention, as shown in fig. 1, the application environment 100 includes: the laser radar system comprises a laser radar 10 and a plurality of calibration targets 20, wherein each calibration target 20 is arranged at the periphery of the laser radar 10 according to a certain angle or distance step interval.

For example, calibration targets are arranged in a range from a blind area to a range of the laser radar according to a certain distance, and three calibration targets with different reflectivity materials, such as a high-reflectivity target, a white target and a low-reflectivity target, are arranged at each distance, wherein the reflectivity of the high-reflectivity target is higher than the reflectivity of a vast number of objects in a family living environment, such as a lattice target, and the reflectivity of the low-reflectivity target is lower than the reflectivity of a vast number of objects in the family living environment, such as a black target, so that the reflectivity of various objects to be measured is in the range of the three materials as much as possible. The following examples are presented by way of example with reference targets of different reflectivities, including high reflectivity targets, white targets, and low reflectivity targets, and will not be described in further detail.

When calibrating the calibration targets with different reflectivity materials, the blind area can be partitioned to a plurality of distance points in the range of the measuring range, and the blind area is divided into a plurality of area sections, which are also called as calibration sections, such as a first calibration section, a second calibration section and a third calibration section in the figure, and then the calibration parameters corresponding to the calibration sections of the calibration targets with different reflectivities are obtained for each calibration section.

It should be noted that, the above application environments are only for illustrative purposes, and in practical applications, the ranging method and the related apparatus provided in the following embodiments of the present invention may be further extended to other suitable application environments, and are not limited to the application environments shown in fig. 1. For example, in an actual application scenario, the type of the laser radar may be set according to needs, such as a pulse laser radar, a continuous wave laser radar, etc., the laser radar 10 and the calibration target 20 may be set, such as selection of a range of the laser radar 10, setting angles and numbers of the calibration targets 20, setting of calibration segments, etc., may be set according to actual needs, and the present invention is not limited by the embodiments of the present invention.

In the conventional calibration method or ranging method, white targets are generally used for calibration, and the disadvantage caused by the conventional calibration method or ranging method is that the ranging accuracy of the white targets is within the specification requirement range under each distance, and larger deviation can be generated on the reflectivity materials of other non-white targets, such as lattice of high-reflectivity targets or larger 3M ranging, such as smaller ranging of black targets or gray targets of low-reflectivity targets. Therefore, if the white target is only used for calibration, the calibration parameters of the white target are still used for ranging other materials, and then larger errors are caused.

Based on the above reasons, the embodiment of the invention provides a ranging method, which is applied to a laser radar, and the ranging method calibrates calibration targets with different reflectivities to obtain calibration parameters of the calibration targets with different reflectivities, so as to solve the ranging deviation problem caused by calibrating only a white target and improve the ranging precision of the laser radar.

Referring to fig. 2, fig. 2 is a flowchart of a ranging method according to an embodiment of the invention, and as shown in fig. 2, the ranging method S100 includes:

s10, determining a plurality of theoretical distances between a calibration target with different reflectivities in each calibration section in the range of the laser radar and the laser radar;

setting calibration targets with different reflectivity materials according to a preset theoretical distance in a range from a dead zone to a measuring range, for example: if the range from the blind area to the measuring range of the laser radar is 0.12m to 8m, targets can be placed at the distances of 0.15m,0.3m,0.6m,1m,1.5m,2m,4m,6m and 8m, the theoretical distances from the calibration targets to the laser radar are 0.15m,0.3m,0.6m,1m,1.5m,2m,4m,6m and 8m, and the theoretical distances are preset distances and are the actual distances from the calibration targets to the laser radar.

In the calibration process, the theoretical distances can be segmented to obtain a plurality of calibration segments, for example: 1m,1.5m,2m are set as the same calibration section, the first point of the calibration section is 1m, the last point is 2m, 1m,1.5m,2m,4m can also be set as the same calibration section, the first point of the calibration section is 1m, and the last point is 4m. The specific arrangement of the calibration sections can be set according to the needs, and each calibration section comprises at least two theoretical distance points.

When the calibration is carried out, the plurality of calibration sections are respectively calibrated, one of the calibration sections can be selected for calibration, after the calibration is completed, the rest calibration sections are calibrated in sequence, and finally, the calibration parameters of the calibration targets with different reflectivities corresponding to each calibration section are obtained.

S20, acquiring the brightness corresponding to each calibration target under each theoretical distance;

and each calibration section comprises a plurality of theoretical distances, and under each theoretical distance, calibration targets with different reflectivities are arranged, and the brightness corresponding to the calibration targets with different reflectivities is different.

And acquiring brightness, namely transmitting laser to each calibration target through a laser radar, outputting point cloud data, and acquiring brightness values under each theoretical distance according to the point cloud data. In the follow-up actual measurement, a distance brightness curve can be obtained by fitting the theoretical distance and the corresponding brightness value, and then the brightness value under each distance can be obtained according to the distance brightness curve. For example, taking 1m,1.5m,2m as the same calibration segment as an example, if the calibration targets with different reflectivities are respectively a lattice target, a white target and a black target, the distance brightness curves corresponding to the calibration targets are shown in fig. 3, wherein the abscissa is a distance, the ordinate is a brightness value (this time, a 10bit brightness value is adopted, and thus the value is higher than 255), the "×" number is a coordinate point under the distance, the curve L1 is a curve fitted by the black target under each distance, the curve L2 is a curve fitted by the white target under each distance, and the curve L3 is a curve fitted by the lattice target under each distance, so that, for the purpose of being able to be closer to the brightness curve trend under the material, if the calibration segment is 2-3 theoretical distance ranges, linear fitting can be selected, and quadratic or cubic fitting can be selected over or over 3 theoretical distances.

S30, determining calibration parameters corresponding to the calibration targets with different reflectivities in each calibration section according to the theoretical distance and the brightness corresponding to each calibration target under the theoretical distance;

the specific physical meaning of the correction parameters can be set according to the needs, in some embodiments, the correction parameters can be parameters for representing the mapping relation between the theoretical distance and the central value of the light spot, and then the calibration parameters of the same calibration section are the same, in other embodiments, the correction parameters can be measurement distance parameters output by the laser radar, and then the calibration parameters corresponding to the objects to be measured of the same material in the same calibration section are the same, and the calibration parameters corresponding to the objects to be measured of different materials are different.

Specifically, as shown in fig. 4, if the correction parameter is a parameter for representing a mapping relationship between the theoretical distance and the center value of the light spot, step S30 includes:

s301, selecting a calibration target with reflectivity in one calibration section as a first reference calibration target;

s302, acquiring an initial value of a reference correction parameter and first reference brightness at each theoretical distance, wherein the reference correction parameter is a correction parameter corresponding to a selected calibration section of the first reference calibration target, and the first reference brightness is the brightness of the first reference calibration target at each theoretical distance of the selected calibration section;

One of the calibration targets may be selected as a first reference calibration target, for example, a low-reflectivity target is selected as the first reference calibration target, and then correction parameters of the low-reflectivity target at the calibration section may be obtained later as reference correction parameters, and brightness of the low-reflectivity target at each theoretical distance is obtained as first reference brightness, where the number of the first reference brightness corresponds to the number of the theoretical distances.

In this embodiment, the correction parameters are parameters for characterizing the mapping relationship between the theoretical distance and the spot center value, i.e., n1 and n2. Wherein,d' is the distance and cx is the spot center value.

For each reflectivity calibration target in the calibration section, selecting a point cloud with a preset angle value (the position of the preset angle value is provided with a proper length of the reflectivity calibration target) within a preset range (such as a + -1 DEG range), for example, selecting a point cloud with a range of + -1 DEG of 270 DEG of the target, averaging the distance of the point cloud within the range, averaging the center of a light spot generating each point cloud, obtaining the initial value of n1 and the initial value of n2 of the reflectivity calibration target corresponding to the calibration section through the average value of the distance of the point cloud and the average value of the center value of the light spot, namely obtaining the initial value of n1 and the initial value of n2 of the high reflectivity target, the initial value of n1 and the initial value of n2 of the low reflectivity target, and the initial value of n1 and the initial value of n2 of the white target corresponding to the calibration section, and taking the initial value of n1 and the initial value of n2 of the first reference calibration target corresponding to the calibration section as reference correction parameters.

S303, calculating a first difference value between the brightness corresponding to each theoretical distance of the residual reflectivity calibration targets except the first reference calibration target and the first reference brightness;

s304, calculating a second difference value between an initial value of the correction parameter of the calibration target of the residual reflectivity except the first reference calibration target in the calibration section and an initial value of the reference correction parameter;

the first difference value delta pi of the calibration targets with different reflectivities is different under each theoretical distance, wherein i is the ith calibration target in the calibration targets with residual reflectivities, and the number of delta pi corresponds to the number of the theoretical distances.

And a second difference delta nj, wherein j is the j-th parameter in the correction parameters, and delta nj of the same material in the same calibration section is the same.

If the low reflectivity target is used as the first reference calibration target, the initial value of the corresponding reference correction parameter is (73.4145, 590.0229), wherein 73.4145 is the initial value of the correction parameter n1, 590.0229 is the initial value of the correction parameter n2, and the initial values of the correction parameters of the white targets are (74.0655, 590.6901) and the initial values of the correction parameters of the high reflectivity targets are (74.1161, 591.4590),

The variation of the first difference from the second difference for each theoretical distance is shown in table 1:

TABLE 1 variation of first and second differences for each theoretical distance

In the above table, the first four columns represent the relationship between the theoretical distance and the luminance difference, the luminance of the low-reflectivity target at each theoretical distance is taken as the first reference luminance, Δp1 represents the first difference between the white target luminance and the first reference luminance at each theoretical distance, Δp2 represents the first difference between the high-reflectivity target luminance and the first reference luminance at each theoretical distance, the second two columns represent the difference between the initial values of the corresponding correction parameters, for example, (0.6510, 0.6672) is the second difference between the initial values of n1 and n2 corresponding to the white target and the initial value of the reference correction parameter, and (0.7016,1.4361) is the second difference between the initial values of n1 and n2 corresponding to the high-reflectivity target and the initial value of the reference correction parameter.

S305, determining calibration parameters corresponding to the selected calibration segments according to each theoretical distance, the first difference value corresponding to each theoretical distance and the second difference value.

Corresponding calibration equations can be constructed through the mapping relation between the first difference value and the second difference value, corresponding first mapping parameters are obtained, the first mapping parameters reflect the change of the second difference value along with the change of the first difference value, namely the change amount along with the change of brightness, corresponding second mapping parameters are obtained through the mapping relation between the theoretical distance and the first mapping parameters, the second mapping parameters reflect the change amount of the first mapping parameters along with the change of the theoretical distance, and finally, the first mapping parameters and the second mapping parameters jointly form calibration parameters corresponding to the calibration section. The first and second mapping parameters reflect the change in the second difference value, i.e. the change in the correction parameters deltan 1 and deltan 2, with the change in luminance and theoretical distance.

When determining the calibration parameters corresponding to the calibration segments, firstly constructing a first calibration equation according to the first difference value and the second difference value corresponding to each theoretical distance, then solving the first calibration equation to obtain first mapping parameters between the first difference value and the second difference value under each theoretical distance, then constructing a second calibration equation according to each theoretical distance and the first mapping parameters corresponding to each theoretical distance, and finally solving the second calibration equation to obtain second mapping parameters between the theoretical distance and the first mapping parameters, wherein the second mapping parameters and the first mapping parameters jointly form the calibration parameters of the calibration segments.

The specific forms of the first calibration equation and the second calibration equation can be set according to the needs, and the specific forms are based on the fact that hardware can be realized, the calculated amount is small, and the corresponding mapping relation can be reflected more accurately.

Taking the data of table 1 as an example, a first calibration equation between the first difference Δp and the second difference Δn is first constructed, that is, a functional relationship is established between the rows of table 1:

(1-1)

wherein,i is a first difference value corresponding to an ith calibration target in the calibration targets of the residual reflectivity, the number of Δpi corresponds to the number of theoretical distances, and Δnj is a second difference value corresponding to the initial value of the jth correction parameter.

In an embodiment of the present invention, in the present invention,i is taken as->1 and->2, Δnj is taken as Δn1 and Δn2.

Thus, for 1mAnd->The first calibration equation between:

(1-2)

for 1mAnd->The first calibration equation between:

(1-3)

by calculating the above equation set, a first mapping parameter can be obtained at 1 m:

and->(1-4)

Similarly, at 1.5m, can be obtained respectivelyAnd->And->And->The corresponding first calibration equation yields a first mapping parameter at 1.5 m:

and->(1-5)

Similarly, at 2m, can be respectively obtainedAnd->And->And->And obtaining a first mapping parameter at the position of 2m according to a corresponding first calibration equation:

and->(1-6)

In summary, the first mapping parameters (k, b) corresponding to each theoretical distance may be obtained by constructing and solving a first calibration equation.

And then constructing and solving a second calibration equation according to the first mapping parameters and the theoretical distance, namely, establishing the second calibration equation by taking the distance change as an independent variable and the change of the first mapping parameters (k and b) as the dependent variable for the distance direction (column of a table):

(1-7)

the change in k in correction parameter n1 for 1m,1.5m,2m distances is as follows:

(1-8)

the change in b in correction parameter n1 is:

(1-9)

the solution coefficients are as follows:

(1-10)

it can be understood thatCoefficients of the first mapping parameters k and b as a function of theoretical distance:

(1-11)

That is, the second mapping parameter corresponding to the correction parameter n1 isThe second mapping parameter corresponding to the correction parameter n2 is +.>。

In actual measurement, no matter whether the reflectivity of the object to be measured is high or low, the first mapping parameter and the second mapping parameter jointly form the calibration parameter of the calibration section, and the calibration parameter is adopted for calibration as long as the calibration section to which the distance of the object to be measured belongs is the calibration section from 1m to 2 m.

The calibration of the other calibration sections is similar to the calibration process of the calibration sections of 1m to 2m, and will not be described again here. Through the calibration process, the calibration parameters of each calibration section are calibrated one by one, so that the measurement distance output by the laser radar can be corrected by adopting the calibration parameters in the follow-up actual measurement.

And S40, correcting the measuring distance output by the laser radar and obtaining the final measuring distance according to the calibration parameters, the measuring distance output by the laser radar and the measuring brightness when the laser radar measures the distance of the object to be measured.

In actual measurement, when the object to be measured is measured, firstly, the variation of the correction parameter is obtained, then the corrected correction parameter is obtained, and the corrected correction parameter is adopted to correct the measurement distance output by the laser radar and obtain the final measurement distance. Specifically, as shown in fig. 5, step S40 includes:

S401, acquiring a first measurement distance of an object to be measured output by the laser radar;

the first measured distance is an initial distance d _{Initially, the method comprises} The distance between the object to be measured and the laser radar measured by the laser radar before uncorrected.

S402, determining a first target calibration parameter corresponding to the object to be measured according to the first measurement distance;

the calibration parameters corresponding to the different calibration sections are different, so that the calibration section to which the object to be measured belongs is determined according to the first measurement distance, and then the first target calibration parameter corresponding to the calibration section to which the object to be measured belongs is determined. For example, if the first measurement distance is in the calibration segment of 1m to 2m in the above embodiment, the first mapping parameter and the second mapping parameter corresponding to the calibration segment are used.

S403, calculating a third difference value between the corresponding brightness under the first measurement distance and the first reference brightness;

the corresponding brightness p3 at the first measurement distance can be obtained through the point cloud data, and then the first reference brightness p 'is obtained, and the third difference value Δp3=p3-p'. The corresponding brightness at the first measurement distance is the measurement brightness.

S404, determining a first variation of a target correction parameter according to the first target calibration parameter, the first measurement distance and the third difference value;

And obtaining a first variation of the target correction parameter according to the second calibration equation and the first calibration equation. Specifically, the first measurement distance and the second mapping parameter are substituted into the second calibration equation to obtain the first mapping parameter corresponding to the first measurement distance, and then the first mapping parameter corresponding to the first measurement distance and the third difference value are substituted into the first calibration equation to obtain the variation of the target correction parameter.

For example, if the first measurement distance is in the calibration segment of 1m to 2m in the above embodiment, the second mapping parameter corresponding to the correction parameter n1 isThe second mapping parameter corresponding to the correction parameter n2 is +.>First, the second mapping parameter is separated from the first measurement distance d _{Initially, the method comprises} Substituting the second calibration equation. For correction parameter n1, the second calibration equation is equation (1-7).

First measured distance d _{Initially, the method comprises} After substitution, the equation is obtained:

(1-12)

and solving the equation to obtain first mapping parameters k and b corresponding to the correction parameter n 1.

Similarly, for correction parameter n2, the second calibration equation is:

(1-13)

then the first measurement distance d _{Initially, the method comprises} After substitution, the equation is obtained:

(1-14)/>

and solving the equation to obtain first mapping parameters k and b corresponding to the correction parameter n 2.

And substituting the first mapping parameter (k, b) and the third difference value delta p3 into a first calibration equation, and solving the variation of the correction parameter.

Specifically, for correction parameter n1, after substitution, the equation is derived:

(1-15)

solving the equation to obtain the variation of the correction parameter n1。

Similarly, for correction parameter n2, after substitution, the equation is obtained:

(1-16)

solving the equation to obtain the variation of the correction parameter n2。

In summary, whether the reflectivity of the object to be measured is high or low, the sameThe calibration parameters of the calibration sections are the same, and the first mapping parameters and the second mapping parameters of the calibration sections are used for calibrating the correction parameters to obtain the variation of the correction parametersAnd->I.e. the first amount of variation.

S405, determining the target correction parameter according to the first variation and the reference correction parameter;

and determining the sum of the variation of the target correction parameter and the reference correction parameter as the target correction parameter. Namely:

(1-17)

wherein,and->For baseline correction parameters, +>And->For the target correction parameters->And->2 is the first variation.

S406, correcting the measured distance output by the laser radar by adopting the target correction parameters, and obtaining the final measured distance.

Substituting the target correction parameter into a mapping relation equation of the distance and the light spot central value, namely substituting

(1-18)

Solving the equation to obtain the corrected final measured distance d _{Terminal (A)} 。

In some embodiments, the final measured distance d _{Terminal (A)} The distance from the transmitting end to the object to be measured is the same as the distance, the acquired target angle is the angle position of the object relative to the transmitting end, for some machines comprising the laser radar, such as a sweeper, the radar rotation center is used as the polar coordinate origin, so that the subsequent measurement and calculation of the sweeper are more convenient, and therefore, the distance and the position of the object to be measured are correspondingly and secondarily corrected at the radar sensor end, the third measurement distance from the transmitting end of the laser radar to the rotation center of the laser radar is firstly acquired, and then the distance from the object to be measured to the rotation center is determined according to the final measurement distance and the third measurement distance.

Specifically, as shown in fig. 6, the distance between the transmitting end and the object is d, the angle formed by the transmitting end and the vertical line in front is yaw, the rotation center is o, the size from the transmitting end to the rotation center is b1, the straight line formed from the rotation center to the transmitting end is perpendicular to the straight line formed from the target object to the transmitting end, the distance between the rotation center and the target object is d, the angle formed by the rotation center and the vertical line in front is AC, and the included angle between the line segment from the rotation center to the transmitting end and the horizontal line is equal to yaw.

The distance after the secondary correction is calculated by the following formula:

(1-19)

wherein,for the distance of the centre of rotation to the object to be measured, +.>Is the distance from the transmitting end to the rotation center, and the rotation center is from the object to be measuredThe angle formed by the direction and the vertical line right in front +.>。

Therefore, the ranging method can be added into a calibration process and a subsequent ranging process in brightness so as to correct the measured distance output by the laser radar, compensate the deviation of different reflectivities on the ranging precision, and improve the ranging precision.

In other embodiments, as shown in fig. 7, if the correction parameter is the measured distance of the radar output, step S30 further includes:

s306, selecting a calibration target with one reflectivity in one calibration section as a second reference calibration target, and determining second reference brightness, wherein the second reference brightness is the brightness of the second reference calibration target in each theoretical distance in the selected calibration section;

since the reflectivity of the white target can show the reflection condition of most objects in the application scene, the white target is preferably used as a second reference calibration target, and the white target is also used as the second reference calibration target for illustration in the invention.

When determining the second reference brightness, firstly determining a reference distance brightness curve corresponding to the selected calibration section, wherein the reference distance brightness curve is a brightness curve of the second reference calibration target along with the change of the distance, and then obtaining the second reference brightness under the theoretical distance according to the reference distance brightness curve.

When the reference distance brightness curve corresponding to the calibration section is determined, different calibration sections can be adopted to fit curves by adopting different function equations.

Specifically, if the selected calibration segment is a first calibration segment, fitting each theoretical distance of the second reference calibration target in the first calibration segment and corresponding brightness under the theoretical distance by adopting a curve function to obtain a reference distance brightness curve;

and if the calibration section is a third calibration section, obtaining the reference distance brightness curve based on the second reference brightness corresponding to the theoretical distance at the first point of the third calibration section, the brightness corresponding to the high-reflectivity calibration target, and the second reference brightness corresponding to the theoretical distance at the last point of the third calibration section. For example: calculating the average value between the second reference brightness corresponding to the first point of the third calibration section under the theoretical distance and the brightness corresponding to the high-reflectivity calibration target, and taking the average value as the first point brightness of the first point;

For example, the reference distance luminance curve of the second reference calibration target is shown in fig. 8, in which the abscissa is distance, the unit is mm, the ordinate is luminance, and here, the two-byte luminance is adopted, the "×" sign is the coordinate point corresponding to the distance, and as can be seen from fig. 8, the luminance decreases with increasing distance, the luminance drops greatly at a short distance, and after increasing distance and reaching a certain degree, the luminance tends to stabilize, thereby forming a similar horizontal line.

According to the curve distribution of white target brightness and considering the factors such as the implementation cost of hardware, parameters and calculated quantity can be reduced while the ranging precision is ensured to be satisfied, the curve is segmented, for example, the curve is divided into three calibration sections, and each calibration section is respectively: 0.15-1.5 m, 1.5-3 m, 3-8 m.

Because the first calibration section comprises a close range of 0.15 m-0.3 m and 0.3 m-1.5 m outside the blind area, the brightness decay is very fast, the precision requirement is very high, and the involved range is slightly wider, in order to better approximate the real white target brightness curve, the fitting is performed by adopting a quadratic function, namely, the brightness fitting function of the first calibration section is as follows:

(1-20)

Substituting each target placement distance within the range of 0.15 m-1.5 m and the corresponding brightness obtained on the target into the formula to carry out least square solution, so as to obtain the parameters a1, b1 and c1, and further obtain the corresponding reference distance brightness curve.

In the range of 1.5 m-3 m, the error requirement is general, and the requirement can be met by adopting linear function fitting according to the trend of a brightness curve, and the brightness fitting function can be expressed as:

(1-21)

substituting the corresponding distance and brightness data in the section, then fitting to obtain parameters a2 and b2, and further obtaining a reference distance brightness curve corresponding to the second calibration section.

In the range of 3 m-8 m, as the brightness of the white target is also not changed much and tends to be horizontal, the difference between the brightness of the lattice target and the brightness of the white target gradually decreases along with the increase of the distance, however, in the actual process, the deviation of the lattice target can be found to become larger along with the increase of the distance, obviously, if the processing method in 3m cannot meet the requirement of large distance increase compensation, the processing process is as follows:

taking the brightness values of the high-reflectivity target and the white target at the position of the first point 3M of the third calibration section as the average value to obtain M points, wherein the coordinates of the M points are Wherein->For a white target at a brightness of 3m +.>Brightness at 3m for high reflectivity target；

Taking the point of the white target at the position of 8m of the last point of the third calibration section as N points, wherein the coordinates of the N points areWhereinBrightness of white target at 8 m;

and connecting the points M and N, obtaining the slope and the intercept in the segment MN, obtaining a linear equation in the segment, and obtaining a fitted linear which is a virtual brightness line of the white target of 3-8M, thereby obtaining a reference distance brightness curve corresponding to the third calibration segment.

S307, calculating a fourth difference value between the brightness corresponding to the theoretical distance of the residual reflectivity calibration targets except the second reference calibration target and the second reference brightness;

the brightness of the target corresponding to the residual reflectivity under the theoretical distance can be obtained through the point cloud data, for example: the brightness of the high reflectivity target at 1m, the brightness of the low reflectivity target at 1m, or the brightness of the high reflectivity target at 1.5m, the brightness of the low reflectivity target at 1.5 m.

The second reference luminance is obtained by the above-mentioned reference distance luminance curve, such as: the brightness of the white target at 1m is obtained through a reference distance brightness curve corresponding to the first calibration segment, or the brightness of the white target at 6m is obtained through a reference distance brightness curve corresponding to the third calibration segment.

At a theoretical distance of 1m, the brightness corresponding to the high-reflectivity target is differenced with the second reference brightness to obtain a fourth difference valueThe brightness corresponding to the low reflectivity target is differenced with the second reference brightness to obtain a fourth difference +.>For subsequent use.

S308, calculating a fifth difference value between a measured distance of the radar output corresponding to the calibration targets with residual reflectivity except the second reference calibration target under the theoretical distance and a first reference distance, wherein the first reference distance is the measured distance of the radar output corresponding to the second reference calibration target under the theoretical distance;

obtaining a measured distance of the radar output of each calibration target at the theoretical distance, for example: the high-reflectivity target or the low-reflectivity target is arranged at a theoretical distance of 1m, the laser radar ranges the high-reflectivity target or the low-reflectivity target, and a corresponding measuring distance is output, wherein the measuring distance is the actual distance calculated or output by the laser radar.

The measured distance of the radar output corresponding to the high-reflectivity target or the low-reflectivity target at 1m is differed from the measured distance of the radar output corresponding to the white target at 1m, and a fifth difference value is obtainedOr->。

Similarly, a plurality of theoretical distances in the calibration section can be obtained 、/>、/>And +.>。

S309, determining calibration parameters corresponding to the calibration targets with different reflectivities in the selected calibration section according to the fourth difference and the fifth difference.

And constructing a corresponding calibration equation through the fourth difference value and the fifth difference value, and obtaining a corresponding mapping parameter through solving the calibration equation so as to obtain a corresponding calibration parameter. Specifically, a third calibration equation is constructed according to the fourth difference value and the fifth difference value, and then the third calibration equation is solved to obtain a third mapping parameter, wherein the third mapping parameter is a calibration parameter corresponding to each calibration target in the calibration section.

For example, for a high reflectivity target, in the first calibration segment, a third calibration equation is constructed:

(1-22)

and obtaining third mapping parameters u1 and v1 through fitting and solving through the brightness difference value and the distance difference value in the distance range.

Similarly, in the second calibration section, the third mapping parameters u2, v2 may be obtained, and in the third calibration section, the third mapping parameters u3, v3 may be obtained.

For a low reflectivity target, in the first calibration segment, a third calibration equation is constructed as follows:

(1-23)

and obtaining third mapping parameters s1 and t1 through fitting and solving through the brightness difference value and the distance difference value in the distance range.

Similarly, in the second calibration section, the third mapping parameters s2, t2 may be obtained, and in the third calibration section, the third mapping parameters s3, t3 may be obtained.

In some embodiments, for low-reflectivity materials, the brightness is not sensitive at a long distance, so that the deviation value of the reflected distance by the difference value of the brightness is weak, and in addition, in the application scene, the distance compensation of the low-reflectivity target is more important than the distance compensation at a short distance, such as in the first calibration section and the second calibration section, so that only the third mapping parameters corresponding to the first calibration section and the second calibration section can be obtained without calculating the third mapping parameters corresponding to the third calibration section.

In summary, by constructing and solving the third calibration equation, a third mapping parameter may be obtained, which characterizes a mapping relationship between the fourth difference and the fifth difference, and the third mapping parameter is used as a calibration parameter corresponding to each calibration target in the calibration segment, so as to perform distance compensation for subsequent actual measurement.

In the embodiment of the invention, the correction parameter is the measurement distance output by the laser radar, so that the distance deviation is obtained according to the third mapping parameter, the measurement distance output by the laser radar and the brightness corresponding to the object to be measured under the measurement distance in actual measurement, and the corrected measurement distance is obtained according to the distance deviation and the measurement distance, so that the subsequent compensation and correction of the measurement distance are realized.

Specifically, as shown in fig. 9, step S40 further includes:

s407, acquiring a second measurement distance of the object to be measured output by the laser radar;

the second measured distance is the initial distance of the laser radar output, and the actual distance before correction.

S408, calculating a sixth difference value between the corresponding brightness at the second measurement distance and the second reference brightness;

acquiring the brightness of the object to be measured at the second measurement distance according to the point cloud data, and acquiring the second reference brightness according to the reference distance brightness curve to obtain a sixth difference value*。

S409, determining the calibration section to which the object to be measured belongs according to the second measurement distance;

s410, selecting a second target calibration parameter corresponding to the reflectivity of the object to be measured from the calibration parameters corresponding to the calibration section;

if the second measurement distance belongs to the first calibration section, determining the reflectivity of the object to be measured from the calibration parameters corresponding to the calibration targets corresponding to the first calibration section, if the reflectivity of the object to be measured is higher than that of the white target, selecting the calibration parameters of the high-reflectivity target in the first calibration section as the second target calibration parameters corresponding to the object to be measured at the second measurement distance, and if the reflectivity of the object to be measured is lower than that of the white target, selecting the calibration parameters of the low-reflectivity target in the first calibration section as the second target calibration parameters corresponding to the object to be measured at the second measurement distance.

S411, determining a second variation of the measured distance of the radar output according to the second target calibration parameter and the sixth difference;

substituting the second target calibration parameter and the sixth difference value into the third calibration equation to obtain a second variation of the measured distance output by the radar.

For example: if the reflectivity of the object to be measured is higher than that of the white target and the second measurement distance belongs to the first calibration section, the second target calibration parameter is u1, v1, and the second target calibration parameter is compared with the sixth difference value* Substituted into->Obtaining a second variation。

S412, determining the sum of the second variation and the second measurement distance as a final measurement distance.

Second variation amountCompensating the second measured distance to obtain a second variation +.>And taking the sum value of the second measurement distance as the final measurement distance.

In some embodiments, the final measured distance may be corrected secondarily, and the method of correcting secondarily is similar to that of the above embodiment, and will not be described herein.

In summary, the ranging method adds the brightness corresponding to the calibration targets with different reflectivities at the theoretical distance into the determination process of the calibration parameters, and adds the brightness corresponding to the object to be measured at the measured distance into the subsequent correction so as to calibrate the calibration targets with different reflectivities, thereby obtaining the calibration parameters of the calibration targets with different reflectivities, compensating the distance deviation caused by different reflectivities, and improving the ranging accuracy of the laser radar.

Referring to fig. 10, fig. 10 is a schematic structural diagram of a ranging apparatus according to an embodiment of the invention. Wherein the ranging device is applied to a laser radar, in particular to one or more processors of the laser radar.

As shown in fig. 10, the distance measuring device 200 includes: a first determination module 201, an acquisition module 202, a second determination module 203, and a correction module 204.

The first determining module 201 is configured to determine a plurality of theoretical distances between the calibration targets with different reflectivities in each calibration segment within the range of the laser radar and the laser radar, the obtaining module 202 is configured to obtain brightness corresponding to each calibration target under each theoretical distance, the second determining module 203 is configured to determine calibration parameters corresponding to each calibration segment for each calibration target with different reflectivities according to brightness corresponding to each calibration target under the theoretical distance, and the correcting module 204 is configured to correct the measurement distance output by the laser radar and obtain a final measurement distance according to the calibration parameters, the measurement distance output by the laser radar, and the measurement brightness when the laser radar measures the distance of the object to be measured.

In the embodiment of the present invention, the ranging device may also be built by hardware devices, for example, the ranging device may be built by one or more than two chips, and each chip may work in coordination with each other to complete the ranging method described in each embodiment above. As another example, the ranging apparatus may also be built from various types of logic devices, such as general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs), single-chip computers, ARM (Acorn RISC Machine) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combinations of these components.

The ranging device in the embodiment of the invention can be a device with an operating system. The operating system may be an Android operating system, an ios operating system, or other possible operating systems, and the embodiment of the present invention is not limited specifically.

The ranging device provided by the embodiment of the invention can realize each process which can be realized by the ranging method, and in order to avoid repetition, the description is omitted.

It should be noted that, the ranging device can execute the ranging method provided by the embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method. Technical details not described in detail in the ranging apparatus embodiments may be referred to the ranging method provided by the embodiments of the present invention.

The embodiment of the invention also provides a robot, please refer to fig. 11, and fig. 11 is a schematic hardware structure of the robot according to the embodiment of the invention.

As shown in fig. 11, the robot 300 includes at least one processor 301, a memory 302, and a lidar 303 (bus connection, one processor is exemplified in fig. 11) communicatively connected.

The processor 301 is configured to provide computing and control capabilities to control the robot 300 to perform corresponding tasks, for example, control the robot 300 to perform the ranging method in any of the above method embodiments, where the method includes determining a plurality of theoretical distances between the calibration targets with different reflectivities in each calibration segment within the range of the laser radar and the laser radar, obtaining brightness corresponding to each calibration target under each theoretical distance, determining calibration parameters corresponding to each calibration segment for each calibration target with different reflectivities according to the brightness corresponding to each theoretical distance and each calibration target under the theoretical distance, and correcting the measurement distance output by the laser radar and obtaining a final measurement distance according to the calibration parameters, the measurement distance output by the laser radar and the measurement brightness when the laser radar measures the distance of the object to be measured.

In this embodiment, the robot adds the brightness corresponding to the calibration targets with different reflectivities at the theoretical distance to the determination process of the calibration parameters, and adds the brightness corresponding to the object to be measured at the measured distance to the subsequent correction to calibrate the calibration targets with different reflectivities, thereby obtaining the calibration parameters of the calibration targets with different reflectivities, compensating the distance deviation caused by different reflectivities, and improving the ranging accuracy of the laser radar.

The processor 301 may be a general purpose processor including a central processing unit (CentralProcessingUnit, CPU), a network processor (NetworkProcessor, NP), a hardware chip, or any combination thereof; it may also be a digital signal processor (DigitalSignalProcessing, DSP), an application specific integrated circuit (ApplicationSpecificIntegratedCircuit, ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. The PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field-programmable gate array (field-programmable gate array, FPGA), general-purpose array logic (generic array logic, GAL), or any combination thereof.

The memory 302 serves as a non-transitory computer readable storage medium, and may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the ranging method in the embodiments of the present invention. The processor 301 may implement the ranging method in any of the above method embodiments by running non-transitory software programs, instructions and modules stored in the memory 302, and will not be described herein again to avoid repetition.

In particular, the memory 302 may include Volatile Memory (VM), such as random access memory (random access memory, RAM); the memory 302 may also include a non-volatile memory (NVM), such as read-only memory (ROM), flash memory (flash memory), hard disk (HDD) or Solid State Drive (SSD), or other non-transitory solid state storage devices; memory 302 may also include a combination of the types of memory described above.

In an embodiment of the invention, the memory 302 may also include memory located remotely from the processor, which may be connected to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

In some embodiments, lidar 303 comprises a pulsed lidar, a continuous wave lidar, or the like.

In the embodiment of the present invention, the robot 300 may further have a wired or wireless network interface, a keyboard, an input/output interface, and other components for implementing the functions of the device, which are not described herein.

The present invention also provides a computer-readable storage medium, such as a memory, including program code executable by a processor to perform the ranging method of the above embodiments. For example, the computer readable storage medium may be Read-Only Memory (ROM), random-access Memory (Random Access Memory, RAM), compact disc Read-Only Memory (CDROM), magnetic tape, floppy disk, optical data storage device, etc.

Embodiments of the present invention also provide a computer program product comprising one or more program codes stored in a computer-readable storage medium. The program code is read from the computer readable storage medium by a processor of the electronic device, which is executed by the processor to perform the method steps of the ranging method provided in the above-described embodiments.

It should be noted that the above-described apparatus embodiments are merely illustrative, and 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 over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

From the above description of embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus a general purpose hardware platform, or may be implemented by hardware. Those skilled in the art will appreciate that all or part of the processes implementing the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a computer readable storage medium, and where the program may include processes implementing the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), or the like.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the invention, the steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A ranging method, characterized by being applied to a lidar, the method comprising:

2. The method according to claim 1, wherein determining the calibration parameters corresponding to the calibration targets with different reflectivities in each calibration segment according to the theoretical distance and the brightness corresponding to each calibration target at the theoretical distance comprises:

3. The method according to claim 2, wherein said determining the calibration parameter corresponding to the selected calibration segment based on each of the theoretical distances, the first difference value corresponding to each of the theoretical distances, and the second difference value comprises:

4. A method according to claim 3, wherein correcting the measured distance of the lidar output and obtaining a final measured distance based on the calibration parameter, the measured distance of the lidar output, and the measured brightness comprises:

determining a first variation of a target correction parameter according to the first target calibration parameter, the first measurement distance and the third difference value;

5. The method according to claim 4, wherein determining the first target calibration parameter corresponding to the object to be measured according to the first measured distance includes:

6. The method of claim 4, wherein said determining a first variation of a target correction parameter based on said first target calibration parameter, said first measured distance, and said third difference comprises:

7. The method according to claim 1, wherein the correction parameter is a measured distance of the radar output, and the determining the calibration parameter corresponding to each calibration segment for each calibration target with different reflectivity according to the theoretical distance and the brightness corresponding to each calibration target under the theoretical distance further includes:

8. The method of claim 7, wherein determining the second reference brightness comprises:

9. The method of claim 8, wherein determining the reference distance luminance profile corresponding to the selected calibration segment comprises:

10. The method of claim 9, wherein the deriving the reference distance luminance profile based on the second reference luminance at the theoretical distance corresponding to the first point of the third calibration segment, the luminance corresponding to the high reflectivity calibration target, and the second reference luminance at the theoretical distance corresponding to the last point of the third calibration segment comprises:

11. The method of claim 7, wherein correcting the measured distance of the lidar output and obtaining a final measured distance based on the calibration parameter, the measured distance of the lidar output, and the measured brightness, comprises:

12. The method according to any one of claims 1-11, further comprising:

13. A lidar, comprising:

at least one processor; the method comprises the steps of,

a memory communicatively coupled to the at least one processor; wherein,

The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-12.

14. A robot, comprising: the lidar of claim 13.

15. A computer readable storage medium storing computer executable instructions for causing a computer device to perform the ranging method of any of claims 1-12.