Optical distance measuring sensor external parameter calibration system

Abstract

The invention discloses an optical distance measuring sensor external parameter calibration system, and the system comprises a calibration device which can be selectively disposed in the field of view of a two-dimensional optical distance measuring sensor; the two-dimensional optical distance measuring sensor is used as a calibrated object to sequentially acquire line scanning data of the calibration device; the three-coordinate measuring device is used for measuring the structural data of the calibration device in sequence by taking an external coordinate system as a coordinate axis; and the data processing device is used for solving conversion parameters of the two-dimensional optical distance measuring sensor and the external coordinate system according to the line scanning and structural data of the calibration device so as to realize joint calibration. The technical problems that an existing calibration system is complex in calibration process and poor in flexibility can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of railway engineering measurement, and in particular to an external parameter calibration system for an optical distance measuring sensor. Background Art

[0002] At present, two-dimensional optical ranging sensors are widely used in the fields of contour detection and spatial distance detection. In addition to internal parameters, two-dimensional optical ranging sensors often need to be converted to the world coordinate system or jointly solved with other sensors during actual use. Therefore, external parameter calibration is required to convert them to a unified coordinate system. There are currently two commonly used calibration methods. One is the joint camera calibration method, in which the camera and the two-dimensional optical ranging sensor respectively collect and process image information and two-dimensional information, and then match the processed camera information with the two-dimensional laser rangefinder information one by one. Finally, the relationship between the calibration tool and the target coordinate system is used to achieve joint calibration. This method has the technical problems of complex calibration process and high tool processing requirements. The other is to use a specific calibration tool to achieve external parameter calibration for a specific working environment and the target coordinate system within the field of view of the two-dimensional optical ranging sensor. This method has the technical problems of fixed usage scenarios and poor flexibility.

[0003] In the prior art, the following documents are mainly related to this application:

[0004] Document 1 is a Chinese invention application filed by Beijing University of Technology on February 19, 2019 and published on June 14, 2019, with publication number CN109883443A. The application discloses a method for calibrating the spatial attitude of a line structured light sensor, which is suitable for measuring rotating shaft parts with line structured light, including cylinders, cones, gears, bearings, etc. The method uses a cylinder as a calibration fixture, and uses the algebraic distance method least squares fitting and the geometric distance method least squares fitting. At the same time, a fixed coordinate system is used, and constraints are added in the fitting process according to the geometric relationship, and the parameter conversion is realized by directly converting the elliptical coordinate system to the rectangular coordinate system, and finally an accurate spatial attitude calibration result is obtained, realizing the measurement of rotating parts by line structured light. However, the method uses a cylinder as a calibration fixture, the optical sensor is fixed on the workstation, the sensor coordinates are converted to a fixed rectangular coordinate system, and the solution is performed by fitting an ellipse, which is mainly used for part detection.

[0005] Document 2 is a Chinese invention application filed by Dalian Maritime University on September 22, 2009 and published on March 3, 2010, with the publication number CN101660903A. The application discloses a method for calculating the external parameters of a robot. First, the robot drives the probe to perform pure translational motion along the three directions of X, Y, and Z, and measures the plane target. The rotation matrix of the external parameters can be calculated from the measurement data and the robot's posture data. Then, the robot end is controlled to perform at least three rotational movements, and the plane target is measured. The translation vector of the external parameters can be calculated from the measurement data and the robot's posture data. The method uses a plane target as a calibration fixture, a random physical coordinate system, and solves the parameter conversion through the test data such as its own displacement and angle. However, the method uses a customized plane target as a calibration fixture, and uses a fixed coordinate system (robot coordinate system), and solves the test data such as its own displacement and angle, and is mainly used for the coordinate system calibration of robot vision. Summary of the invention

[0006] In view of this, the purpose of the present application is to provide an optical ranging sensor external parameter calibration system to solve the technical problems of the existing calibration system having a complex calibration process and poor flexibility.

[0007] In order to achieve the above-mentioned invention object, the present application specifically provides a technical implementation scheme of an optical ranging sensor external parameter calibration system, including:

[0008] a calibration device, optionally placed within the field of view of the two-dimensional optical distance measuring sensor;

[0009] A two-dimensional optical distance measuring sensor, as a calibrated object, sequentially collects line scan data of the calibration device;

[0010] A three-coordinate measuring device, using an external coordinate system as coordinate axes, sequentially measures the structural data of the calibration device;

[0011] The data processing device solves the conversion parameters between the two-dimensional optical ranging sensor and the external coordinate system according to the line scan and structure data of the calibration device to realize joint calibration.

[0012] Furthermore, the calibration device is placed in the field of view of the two-dimensional optical ranging sensor for no less than three times in sequence.

[0013] Furthermore, the calibration device includes a target sphere, and the tangent line of the structured light emitted by the two-dimensional optical ranging sensor is offset from the center of the target sphere.

[0014] Furthermore, the calibration device also includes a base, and the target sphere is fixed in the field of view through the base.

[0015] Furthermore, the external coordinate system is determined by three mutually perpendicular planes.

[0016] Furthermore, the housing of the inertial navigation device is used as the external coordinate system.

[0017] Furthermore, the coordinates of the center of the target ball in the external coordinate system are measured by the three-coordinate measuring device, and then the section circular curve of the target ball is measured by the two-dimensional optical ranging sensor. The data processing device calculates the center of the circular curve, and obtains the coordinates of the center of the target ball in the coordinate system of the two-dimensional optical ranging sensor according to the placement position of the target ball and the coordinate definition of the two-dimensional optical ranging sensor. The position of the target ball is transformed and the measurement is repeated for no less than 3 times. The data processing device solves the conversion parameters between the two-dimensional optical ranging sensor and the external coordinate system according to multiple sets of coordinates of the center of the target ball in the two coordinate systems to achieve joint calibration.

[0018] Furthermore, the data processing device includes a contour extraction unit, a fitting unit, a solving unit and a conversion parameter calculation unit. The data collected by the two-dimensional optical ranging sensor is extracted by the contour extraction unit to extract the target sphere section contour, and then fitted by the fitting unit to obtain the center coordinates and radius of the section circle. The solving unit solves the target sphere center coordinates in the two-dimensional optical ranging sensor coordinate system according to the target sphere center offset direction and the target sphere radius measured by the three-coordinate measuring device through trigonometric relationship. The three-coordinate measuring device obtains the target sphere center coordinates in the external coordinate system through data solving, and the conversion parameter calculation unit solves the target sphere center coordinates in the two-dimensional optical ranging sensor coordinate system and the target sphere center coordinates in the external coordinate system to obtain the proportional coefficient, conversion matrix and translation vector of the conversion relationship from the two-dimensional optical ranging sensor coordinate system to the external coordinate system.

[0019] Furthermore, the coordinate system OXZ of the two-dimensional optical ranging sensor is located in the laser plane, the Z axis is located at the center of the laser plane and points to the light source, and the coordinate system satisfies the right-hand rule. The circular curve coordinates of the target ball measured by the two-dimensional optical ranging sensor are expressed as [X l ,Z l ], the center coordinates of the target ball in the two-dimensional optical ranging sensor coordinate system are expressed as [X l ,Y l ,Z l ].

[0020] Furthermore, the external coordinate system is based on the processing reference plane, with the Z axis pointing vertically upward, in accordance with the right-hand rule. The coordinates of the center of the target ball in the external coordinate system are expressed as [X i ,Y i ,Z i ] T .

[0021] Further, the data processing device calculates the coordinates of the center of the target ball in the two-dimensional optical ranging sensor coordinate system according to the following formula [AY l B]:

[0022]

[0023]

[0024]

[0025] D=(N∑X l,i Z l,i -∑X l,i ∑Z l,i )

[0026]

[0027] Among them, A, Y l , B are the X, Y and Z coordinates of the center of the target ball 11 respectively, R is the radius of the target ball, and the point [X l,i ,Z l,i ] to the center of the section circle is d i , i∈(1,2,3…N), N is the number of sample points.

[0028] Furthermore, the data processing device calculates the conversion parameters between the two-dimensional optical ranging sensor and the external coordinate system according to the following formula:

[0029]

[0030] Among them, λ, R, and t are the scale factor, transformation matrix, and translation vector from the 2D optical ranging sensor coordinate system to the external coordinate system, respectively. i , Y i , Z i is the coordinate of the target ball center in the external coordinate system, X l , Y l , Z l is the coordinate of the center of the target ball measured by the two-dimensional optical ranging sensor, p0 is the real part of the unit quaternion, p1, p2, p3 are the imaginary parts of the unit quaternion, X l , Y l , Z l The coordinates after centration, X i , Y i , Z i The centroided coordinates.

[0031] By implementing the technical solution of the optical ranging sensor external parameter calibration system provided by the present application, the following beneficial effects are achieved:

[0032] (1) The optical ranging sensor external parameter calibration system of the present application realizes the conversion calibration between the two-dimensional optical ranging sensor coordinates and an external arbitrary physical reference coordinate system by converting the two-dimensional optical ranging data into three-dimensional coordinates. The calibration process is relatively simple.

[0033] (2) The optical distance measurement sensor external parameter calibration system of the present application adopts a precision sphere as a calibration tool, which greatly reduces the difficulty of tool processing. It only needs to collect two-dimensional optical distance measurement data and three-dimensional coordinate data, meeting the operability requirements of on-site data collection;

[0034] (3) The optical ranging sensor external parameter calibration system of the present application adopts the least square method to obtain the center of the circular curve, and adopts the unit quaternion method to solve the transformation parameters between the two-dimensional optical ranging sensor and the external coordinate system, thereby realizing the solution of the coordinate transformation parameters, which can well meet the calibration accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a schematic block diagram of the structure of a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0037] Figure 2 It is a structural schematic diagram of a calibration device in a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0038] Figure 3 It is a system structure block diagram of a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0039] Figure 4 It is a schematic diagram of a two-dimensional optical ranging sensor coordinate system in a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0040] Figure 5 It is a schematic diagram of an external coordinate system in a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0041] Figure 6 This is a schematic diagram of the coordinates of the center of a target ball of a calibration device in a specific embodiment of the optical ranging sensor external parameter calibration system of the present application;

[0042] Figure 7 This is a program flow chart of a specific embodiment of the optical distance measuring sensor external parameter calibration method based on the system of the present application;

[0043] In the figure: 1-calibration device, 2-two-dimensional optical ranging sensor, 3-three-coordinate measuring device, 4-external coordinate system, 5-data processing device, 51-contour extraction unit, 52-fitting unit, 53-solving unit, 54-conversion parameter calculation unit, 11-target ball, 12-base. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] As attached Figure 1 To Attachment Figure 7 As shown, a specific embodiment of the optical ranging sensor external parameter calibration system of the present application is given, and the present application is further described below in conjunction with the drawings and specific embodiments.

[0046] Example 1

[0047] As attached Figure 1 As shown, an embodiment of the optical distance measuring sensor external parameter calibration system of the present application specifically includes:

[0048] The calibration device 1 can be selectively placed in the field of view of the two-dimensional optical distance measuring sensor 2; in this embodiment, the two-dimensional optical distance measuring sensor 2 can specifically adopt a laser camera assembly;

[0049] The two-dimensional optical distance measuring sensor 2, as the calibrated object, sequentially collects the line scan data of the calibration device 1;

[0050] The three-coordinate measuring device 3 uses the external coordinate system 4 as the coordinate axis to measure the structural data of the calibration device 1 in sequence (specifically including the center coordinates and diameter of the target sphere 11);

[0051] The data processing device 5 solves the conversion parameters between the two-dimensional optical ranging sensor 2 and the external coordinate system 4 according to the line scan and structure data of the calibration device 1 to achieve joint calibration.

[0052] As a typical specific embodiment of the present application, the calibration device 1 is placed in the field of view of the two-dimensional optical ranging sensor 2 for no less than 3 times in sequence. Figure 1In the embodiment shown, there are four positions, namely A, B, C, and D. Figure 2 As shown, the calibration device 1 further includes a target ball 11, and the tangent line of the structured light emitted by the two-dimensional optical ranging sensor 2 offsets the center of the target ball 11. Among them, the target ball 11 is made of a material with high hardness and low thermal expansion coefficient, and the size of the target ball 11 can be selected according to the resolution of the two-dimensional optical ranging sensor 2. At the same time, the target ball 11 is processed with high precision, and the sphericity is better than 1 / 3 of the accuracy required for calibration. Its surface is matte-finished and has low reflectivity. The calibration device 1 also includes a base 12, and the target ball 11 is fixed in the field of view through the base 12. The base 12 is made of permanent magnetic material, which is used to adsorb and fix the target ball 11 in the field of view during the calibration process. The bottom of the base 12 is flat, and the size can be customized according to needs. The target ball 11 and the base 12 are fixedly connected by materials such as structural adhesive. The external coordinate system 4 is determined by three mutually perpendicular planes. As a preferred specific embodiment of the present application, the outer shell of the inertial navigation device is used as the external coordinate system 4.

[0053] The coordinates of the center of the target ball 11 in the external coordinate system 4 are measured by the three-coordinate measuring device 3, and then the section circular curve of the target ball 11 is measured by the two-dimensional optical ranging sensor 2. The data processing device 5 calculates the center of the circular curve, and obtains the coordinates of the center of the target ball 11 in the coordinate system of the two-dimensional optical ranging sensor 2 according to the placement position of the target ball 11 and the coordinate definition of the two-dimensional optical ranging sensor 2. The position of the target ball 11 is transformed and the measurement is repeated for no less than 3 times. The data processing device 5 solves the conversion parameters between the two-dimensional optical ranging sensor 2 and the external coordinate system 4 according to multiple groups of coordinates of the center of the target ball 11 in two coordinate systems (i.e., the external coordinate system 4 and the coordinate system of the two-dimensional optical ranging sensor 2), and realizes joint calibration.

[0054] As attached Figure 3 As shown, the data processing device 5 further includes a contour extraction unit 51, a fitting unit 52, a solution unit 53 and a conversion parameter calculation unit 54. The data collected by the two-dimensional optical ranging sensor 2 is extracted by the contour extraction unit 51 to extract the target sphere section contour, and then fitted by the fitting unit 52 to obtain the center coordinates and radius of the section circle. The solution unit 53 obtains the center coordinates of the target sphere 11 in the coordinate system of the two-dimensional optical ranging sensor 2 by trigonometric relationship according to the center offset direction of the target sphere 11 and the radius of the target sphere 11 measured by the three-coordinate measuring device 3. The three-coordinate measuring device 3 obtains the center coordinates of the target sphere 11 in the external coordinate system by data solution, and the conversion parameter calculation unit 54 obtains the proportional coefficient, conversion matrix and translation vector of the conversion relationship from the coordinate system of the two-dimensional optical ranging sensor 2 to the external coordinate system 4 according to the center coordinates of the target sphere 11 in the coordinate system of the two-dimensional optical ranging sensor 2 and the center coordinates of the target sphere 11 in the external coordinate system.

[0055] The coordinate system OXZ of the two-dimensional optical distance measuring sensor 2 is located in the laser plane, the Z axis is located at the center of the laser plane and points to the light source, and the coordinate system satisfies the right-hand rule. The circular curve coordinates of the target ball 11 measured by the two-dimensional optical distance measuring sensor 2 are expressed as [X l ,Z l ], the coordinates of the center of the target ball 11 in the coordinate system of the two-dimensional optical distance measuring sensor 2 are expressed as [X l ,Y l ,Z l ], as attached Figure 4 The external coordinate system 4 is based on the machining reference plane, with the Z axis vertically upward, which conforms to the right-hand rule. The coordinates of the center of the target ball 11 in the external coordinate system 4 are expressed as [X i ,Y i ,Z i ] T , as attached Figure 5 shown.

[0056] The target ball 11 is placed within the field of view of the two-dimensional optical distance sensor 2. The coordinates of the center of the ball 11 in the external coordinate system 4 can be directly measured by the three-coordinate measuring device 3. The coordinates of the center of the ball 11 in the coordinate system of the two-dimensional optical distance sensor 2 need to first obtain the partial coordinates of the laser line section circle. The data processing device 5 further solves the radius r and the center of the section circle by the least square method, and finally obtains h, that is, the Y coordinate value of the center of the target ball 11. A is the X coordinate value of the center, and B is the Z coordinate value of the center. As shown in the attached figure Figure 6 As shown, O is the center of the section circle, O′ is the center of the target ball 11, E is the section circle, F is the case where the center of the target ball 11 is at the rear, and G is the case where the center of the target ball 11 is at the front.

[0057] Among them, the section circle is obtained by the least square method, and the circular curve equation is as follows:

[0058] r 2 =(XA) 2 +(ZB) 2 Formula 1)

[0059] make:

[0060] a=-2A

[0061] b=-2B

[0062] c=A 2 +B 2 -r 2

[0063] Another form of the circular curve equation can be obtained:

[0064] X 2 +Z 2 +aX+bZ+c=0 Formula 2)

[0065] Assume that the center of the target ball 11 is at a point [X l,i ,Z l,i ]i∈(1,2,3…N) The distance from the center of the section circle is d i , then:

[0066]

[0067] Combined with formula 2), the square difference between it and the radius is δ i ,have:

[0068]

[0069] Assume Δ(a,b,c) is δ i The sum of squares is:

[0070]

[0071] Solve for the parameters a, b, and c to minimize Δ(a,b,c). Because Δ(a,b,c)≥0, it has a minimum value greater than or equal to 0, and a maximum value of infinity. Take the partial derivative of Δ(a,b,c), set the partial derivative equal to 0, and find the extreme value. Compare the function values ​​of all extreme values ​​to get the minimum value. Find the partial derivative:

[0072]

[0073] Solve the system of equations, let:

[0074]

[0075] D=(N∑X l,i Z l,i -∑X l,i ∑Z l,i )

[0076]

[0077] It can be solved as follows:

[0078]

[0079] Get the estimated values ​​of A, B, and r:

[0080]

[0081] If the radius of the target sphere 11 is R, the Y coordinate value of the center of the sphere can be calculated by the following formula:

[0082]

[0083] Yl The sign of is determined by the position of the center of the target ball 11 during measurement. In this way, the coordinates of the center of the target ball 11 under the two-dimensional optical distance measuring sensor 2 can be obtained as [AY l B].

[0084] The data processing device 5 calculates the conversion parameters between the two-dimensional optical ranging sensor 2 and the external coordinate system 4 by using the unit quaternion method. The conversion from the coordinate system of the two-dimensional optical ranging sensor 2 to the external coordinate system 4 requires a scale factor λ, a conversion matrix R, and a translation vector t = [ΔXΔYΔZ] T , the conversion relationship can be expressed as:

[0085]

[0086] Assuming that the position measurement of the target ball 11 is performed M times, the two-dimensional optical distance measuring sensor 2 and the external coordinates can be expressed as follows after centration:

[0087]

[0088]

[0089] List the error equation and use the least squares principle to solve the proportional coefficient:

[0090]

[0091] The unit quaternion P consists of a real number and three complex numbers and can be expressed as:

[0092] P=p0+p1i+p2j+p3k Formula 9)

[0093] Its relationship with the transformation matrix R can be expressed as:

[0094]

[0095] Solving the unit quaternion P is to solve the optimal unit quaternion within the unit quaternion range. Suppose there are N (N ≥ 3) measuring points i = 1, 2 ... N, so that the residual: Δ = ∑ ‖ q i,i -θpq l,i p * ‖Minimum.

[0096] Among them, q i,i is the representation of the i-th measuring point in the external coordinate system 4, q l,i is the representation of the i-th measuring point in the coordinate system of the two-dimensional optical distance measuring sensor 2, p * is the conjugate transposed matrix of p, where p is the matrix form of the unit quaternion P, i.e. p = [p0, p1, p2, p3]. Expanding the above formula, when Δ is the smallest, the component D needs to be maximized:

[0097] D=∑(pq l,i p * )·q i,i

[0098] It can also be written as:

[0099] D=p T ·M·R·p

[0100] Where:

[0101]

[0102] Then the eigenvector corresponding to the maximum eigenvalue of the matrix M is the vector form of the unit quaternion P.

[0103] in, And so on. is the difference between the X value of the i-th point in the external coordinate system 4 and the average X value of all points, and so on.

[0104] The translation vector can be obtained by the following formula 7).

[0105]

[0106] In this embodiment, the material of the target ball 11 can be selected from cemented carbide, polymer materials, etc. The two-dimensional optical ranging sensor 2 can adopt sensors based on the principles of line scanning structured light, two-dimensional laser radar, laser triangulation, etc. The three-coordinate measurement equipment can adopt three-coordinate measurement equipment such as laser three-dimensional scanners and three-coordinate mechanical arms. This embodiment innovatively uses a calibration device 1, a two-dimensional optical ranging sensor 2 and a three-coordinate measurement device 3 to form a calibration system, thereby realizing the external parameter calibration of the two-dimensional optical ranging sensor. The system has the characteristics of simple operation process, flexibility and reliability, high calibration accuracy, etc., and can be used for the association of the two-dimensional optical ranging sensor 2 with the external (reference) coordinate system 4, or a detection system combined with other space detection sensors.

[0107] Example 2

[0108] As attached Figure 7 As shown, an embodiment of an optical ranging sensor extrinsic parameter calibration method based on the system described in Example 1 specifically includes the following steps:

[0109] S1) measuring the coordinates of the center of the target sphere 11 of the calibration device 1 in the external coordinate system 4 by means of a three-coordinate measuring device 3;

[0110] S2) measuring the circular curve of the section of the target sphere 11 by the two-dimensional optical distance measuring sensor 2;

[0111] S3) calculating the center of the circular curve, and obtaining the coordinates of the center of the target ball 11 in the coordinate system of the two-dimensional optical ranging sensor 2 according to the placement position of the target ball 11 and the coordinate definition of the two-dimensional optical ranging sensor 2;

[0112] S4) transform the position of the target sphere 11 for no less than 3 times, repeat steps S1) to S3), obtain multiple sets of coordinates of the center of the target sphere 11 in two coordinate systems, and solve the conversion parameters between the two-dimensional optical ranging sensor 2 and the external coordinate system 4 by the unit quaternion method to achieve joint calibration.

[0113] The calibration device 1 is placed in the field of view of the two-dimensional optical ranging sensor 2 for no less than three times.

[0114] The calibration device 1 further comprises a base 12, through which the target sphere 11 is fixed in the field of view. The tangent line of the structured light emitted by the two-dimensional optical distance measuring sensor 2 deviates from the center of the target sphere 11.

[0115] The external coordinate system 4 is defined by three mutually perpendicular planes. As a typical specific embodiment of the present application, the housing of the inertial navigation device is used as the external coordinate system 4 .

[0116] The data collected by the two-dimensional optical ranging sensor 2 is extracted from the target sphere section profile, and then the least square method is used to fit the center coordinates and radius of the section circle. The center offset direction of the target sphere 11 and the radius of the target sphere 11 measured by the three-coordinate measuring device 3 are solved by trigonometric relationship to obtain the center coordinates of the target sphere 11 in the coordinate system of the two-dimensional optical ranging sensor 2. The three-coordinate measuring device 3 obtains the center coordinates of the target sphere 11 in the external coordinate system by data solution. According to the center coordinates of the target sphere 11 in the coordinate system of the two-dimensional optical ranging sensor 2 and the center coordinates of the target sphere 11 in the external coordinate system, the unit quaternion method is used to solve the proportional coefficient, conversion matrix and translation vector of the conversion relationship from the coordinate system of the two-dimensional optical ranging sensor 2 to the external coordinate system 4.

[0117] The coordinate system OXZ of the two-dimensional optical distance measuring sensor 2 is located in the laser plane, the Z axis is located at the center of the laser plane and points to the light source, and the coordinate system satisfies the right-hand rule. The circular curve coordinates of the target ball 11 measured by the two-dimensional optical distance measuring sensor 2 are expressed as [X l ,Z l ], the coordinates of the center of the target ball 11 in the coordinate system of the two-dimensional optical distance measuring sensor 2 are expressed as [X l ,X l ,Z l The external coordinate system 4 takes the machining reference plane as reference, with the Z axis vertically upward, in accordance with the right-hand rule. The coordinates of the center of the target sphere 11 in the external coordinate system 4 are expressed as [X i ,Y i ,Z i ] T.

[0118] As a typical specific embodiment of the present application, the coordinates of the center of the target ball 11 in the coordinate system of the two-dimensional optical distance measuring sensor 2 are further calculated according to the following formula: l B]:

[0119]

[0120]

[0121]

[0122] D=(N∑X l,i Z l,i -∑X l,i ∑Z l,i )

[0123]

[0124] Among them, A, Y l , B are the X, Y and Z coordinates of the center of the target sphere 11, R is the radius of the target sphere 11, and the point [X l,i ,Z l,i ] to the center of the section circle is d i , i∈(1,2,3…N), N is the number of sample points.

[0125] As a typical specific embodiment of the present application, the conversion parameters between the two-dimensional optical ranging sensor 2 and the external coordinate system 4 are further calculated according to the following formula:

[0126]

[0127] Wherein, λ, R, t are respectively the scale factor, transformation matrix and translation vector from the coordinate system of the two-dimensional optical ranging sensor 2 to the external coordinate system 4, X i , Y i , Z i is the coordinate of the center of the target ball 11 in the external coordinate system 4, X l , Y l , Z l is the coordinate of the center of the target sphere 11 measured by the two-dimensional optical ranging sensor 2, p0 is the real part of the unit quaternion, p1, p2, p3 are the imaginary parts of the unit quaternion, X l , Y l , Z l The centroided coordinates, X i , Y i , Zi The centroided coordinates.

[0128] In the description of this application, it should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly disposed on the other element or indirectly disposed on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0129] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0130] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" and "several" mean two or more, unless otherwise clearly and specifically defined.

[0131] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0132] By implementing the technical solution of the optical ranging sensor external parameter calibration system described in the specific embodiments of this application, the following technical effects can be achieved:

[0133] (1) The optical ranging sensor external parameter calibration system described in the specific embodiment of the present application realizes the conversion calibration between the two-dimensional optical ranging sensor coordinates and an external arbitrary physical reference coordinate system by converting the two-dimensional optical ranging data into three-dimensional coordinates. The calibration process is relatively simple.

[0134] (2) The optical distance measurement sensor external parameter calibration system described in the specific embodiment of the present application uses a precision sphere as a calibration tool, which greatly reduces the difficulty of tool processing. It only needs to collect two-dimensional optical distance measurement data and three-dimensional coordinate data, meeting the operability requirements of on-site data collection;

[0135] (3) The optical ranging sensor external parameter calibration system described in the specific embodiment of the present application adopts the least squares method to obtain the center of the circular curve, and adopts the unit quaternion method to solve the transformation parameters between the two-dimensional optical ranging sensor and the external coordinate system, thereby realizing the solution of the coordinate transformation parameters, which can well meet the calibration accuracy requirements.

[0136] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0137] The above is only a preferred embodiment of the present application, and does not constitute any formal limitation to the present application. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes, without departing from the spirit and technical solution of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the content of the technical solution of the present application, still falls within the scope of protection of the technical solution of the present application.

Claims

1. An optical distance measuring sensor external parameter calibration system, characterized in that: include: A calibration device (1) can be selectively placed in the field of view of a two-dimensional optical distance measuring sensor (2); A two-dimensional optical distance measuring sensor (2), as a calibrated object, sequentially collects line scanning data of the calibration device (1); A three-coordinate measuring device (3) uses an external coordinate system (4) as coordinate axes to sequentially measure the structural data of the calibration device (1); The data processing device (5) solves the conversion parameters between the two-dimensional optical distance measuring sensor (2) and the external coordinate system (4) according to the line scan and structure data of the calibration device (1) to achieve joint calibration.

2. The optical distance measuring sensor external parameter calibration system according to claim 1, characterized in that: The calibration device (1) is placed in the field of view of the two-dimensional optical distance measuring sensor (2) in sequence for no less than three times.

3. The optical distance measuring sensor external parameter calibration system according to claim 1 or 2, characterized in that: The calibration device (1) comprises a target sphere (11), and the tangent line of the structured light emitted by the two-dimensional optical distance measuring sensor (2) is offset from the center of the target sphere (11).

4. The optical distance measuring sensor external parameter calibration system according to claim 3, characterized in that: The calibration device (1) further comprises a base (12), and the target sphere (11) is fixed in the field of view via the base (12).

5. The optical distance measuring sensor external parameter calibration system according to claim 1, 2 or 4, characterized in that: The external coordinate system (4) is defined by three mutually perpendicular planes.

6. The optical distance measuring sensor external parameter calibration system according to claim 5, characterized in that: The housing of the inertial navigation device is used as the external coordinate system (4).

7. The optical distance measuring sensor external parameter calibration system according to claim 1, 2, 4 or 6, characterized in that: The coordinates of the center of the target ball (11) in the external coordinate system (4) are measured by the three-coordinate measuring device (3), and the circular curve of the section of the target ball (11) is measured by the two-dimensional optical distance measuring sensor (2); the data processing device (5) calculates the center of the circular curve, and obtains the coordinates of the center of the target ball (11) in the coordinate system of the two-dimensional optical distance measuring sensor (2) according to the placement position of the target ball (11) and the coordinate definition of the two-dimensional optical distance measuring sensor (2); the position of the target ball (11) is transformed and the measurement is repeated for no less than 3 times, and the data processing device (5) solves the conversion parameters between the two-dimensional optical distance measuring sensor (2) and the external coordinate system (4) according to multiple groups of coordinates of the center of the target ball (11) in the two coordinate systems to achieve joint calibration.

8. The optical distance measuring sensor external parameter calibration system according to claim 7, characterized in that: The data processing device (5) comprises a contour extraction unit (51), a fitting unit (52), a solution unit (53) and a conversion parameter calculation unit (54); the data collected by the two-dimensional optical distance measuring sensor (2) is subjected to the contour extraction unit (51) to extract the contour of the target sphere section, and then the contour is fitted by the fitting unit (52) to obtain the center coordinates and radius of the section circle; the solution unit (53) calculates the target sphere (11) according to the center deviation direction of the target sphere (11) and the radius of the target sphere (11) measured by the three-coordinate measuring device (3) through a trigonometric relationship. The coordinates of the center of the target ball (11) in the coordinate system of the two-dimensional optical ranging sensor (2) are obtained by calculation; the three-coordinate measuring device (3) obtains the coordinates of the center of the target ball (11) in the external coordinate system through data calculation; and the conversion parameter calculation unit (54) obtains the proportional coefficient, conversion matrix and translation vector of the conversion relationship between the coordinate system of the two-dimensional optical ranging sensor (2) and the external coordinate system according to the coordinates of the center of the target ball (11) in the coordinate system of the two-dimensional optical ranging sensor (2) and the coordinates of the center of the target ball (11) in the external coordinate system.

9. The optical distance measuring sensor external parameter calibration system according to claim 8, characterized in that: The coordinate system OXZ of the two-dimensional optical distance measuring sensor (2) is located in the laser plane, the Z axis is located at the center of the laser plane and points to the light source, and the coordinate system satisfies the right-hand rule; the circular curve coordinates of the target ball (11) measured by the two-dimensional optical distance measuring sensor (2) are expressed as [X l ,Z l ], the spherical center coordinates of the target sphere (11) in the coordinate system of the two-dimensional optical distance measuring sensor (2) are expressed as [X l ,Y l ,Z l ].

10. The optical distance measuring sensor external parameter calibration system according to claim 9, characterized in that: The external coordinate system (4) is based on the processing reference plane, with the Z axis pointing vertically upward, in accordance with the right-hand rule. The coordinates of the center of the target ball (11) in the external coordinate system (4) are expressed as [X i ,Y i ,Z i ] T .

11. The optical distance measuring sensor external parameter calibration system according to claim 10, characterized in that: The data processing device (5) calculates the coordinates of the center of the target ball (11) in the coordinate system of the two-dimensional optical distance measuring sensor (2) according to the following formula: l B]: Y l 2 =R 2 -r 2 D=(N∑X l,i Z l,i -∑X l,i ∑Z l,i ) Among them, A, Y l , B are respectively the X, Y and Z coordinates of the center of the target sphere (11), R is the radius of the target sphere (11), and the point [X l,i ,Z l,i ] to the center of the section circle is d i , i∈(1,2,3…N), N is the number of sample points.

12. The optical distance measuring sensor external parameter calibration system according to claim 11, characterized in that: The data processing device (5) calculates the conversion parameters between the two-dimensional optical distance measuring sensor (2) and the external coordinate system (4) according to the following formula: Where λ, R, and t are the scale factor, transformation matrix, and translation vector from the coordinate system of the two-dimensional optical ranging sensor (2) to the external coordinate system (4), respectively. i , Y i , Z i is the coordinate of the center of the target sphere (11) in the external coordinate system (4), X l , Y l , Z l are the coordinates of the center of the target sphere (11) measured by the two-dimensional optical distance measuring sensor (2), p0 is the real part of the unit quaternion, p1, p2, p3 are the imaginary parts of the unit quaternion, X l , Y l , Z l The coordinates after centration, X i , Y i , Z i The centroided coordinates.

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