CN115307571B - A Pose Calibration Part and Calibration Method for a Planar Line Laser Sensor - Google Patents

Abstract

The invention discloses a plane type line laser sensor pose calibration part and a calibration method. Based on the existing gear measurement center, a non-contact three-dimensional gear measurement system is established to realize the design of the line structured light sensor pose calibration part and the confirmation of the calibration method. The pose calibration part of geometric features is a cylindrical central rotating structure, which specifically includes plane I, outer cylindrical surface I, V-shaped groove, outer cylindrical surface II, plane II, lower end surface, upper end surface, plane III, and inner cylindrical surface. Each geometric feature has a certain precision shape error requirement, and a certain precision position error requirement between each geometric feature, which meets the precision machining requirements of geometric features. Combined with the measurement process of the gear measurement center, the calibration operation is simple and easy, and the accurate calibration of the line laser sensor can be realized. The calibration method uses the least squares to fit the straight line with mature technology, high precision, and can truly reflect the relationship between the actual coordinate values.

Description

A Pose Calibration Part and Calibration Method for a Planar Line Laser Sensor

technical field

The invention relates to a line laser sensor pose calibration part and a calibration method thereof, in particular to a line laser sensor space pose calibration part and a calibration method for three-dimensional measurement of gears, and belongs to the technical field of precision measurement.

Background technique

The traditional gear measurement mostly adopts the contact measurement method, which has the following disadvantages: 1. The measurement efficiency is low, and it is difficult to obtain the required tooth surface information in a short time. 2. The overall gear is judged only by specific information such as points and lines on the tooth surface of some gears, and the full information of the tooth surface cannot be obtained, and the evaluation is not comprehensive. 3. There are problems such as wear and radius compensation of the contact probe. In comparison, the non-contact gear laser measurement method has obvious advantages, which greatly improves the measurement efficiency and can quickly obtain full information on the tooth surface of all gear teeth.

As a typical non-contact measurement technology, line laser measurement is widely used in the field of product shape and size measurement, and has the characteristics of fast, high precision, high efficiency, convenient operation, and no loss. The many advantages of the line laser sensor facilitate industrial applications, and its high packaging reduces the technical requirements for operators, making it easier and more convenient to achieve precise measurement of the measured object.

Line laser measurement is a comparative measurement technology. Before precise measurement of object surface information, it is particularly important to accurately calibrate the spatial pose relationship between the line laser sensor and the measured object, and it is also an important prerequisite for accurate 3D information reconstruction. For a rotating structure such as a gear, the calibration of a line laser sensor is generally accomplished by means of a standard mandrel with a simple structure or a special calibration piece with complex geometric features. The calibration method based on the standard mandrel with a simple structure needs to accumulate multiple small sample data for fitting calculations, and the sensor needs to be adjusted multiple times during the calibration process, which inevitably introduces multi-source errors in the process; the calibration method based on the calibration of special complex geometric features brings great challenges to the processing and accuracy requirements of the calibration components.

Based on the above-mentioned status quo and problems, a line laser sensor pose calibration component for gear measurement and its calibration method are proposed. This patent is aimed at gear-type cylindrical rotating structures, and uses specific cylindrical, plane, and groove structures to achieve accurate pose calibration of line laser sensors.

Contents of the invention

The object of the present invention is to provide a line laser sensor pose calibration component and a calibration method for gear measurement, aiming at the problem of the pose calibration of the line laser sensor in the existing gear measurement process.

The line laser sensor pose calibration part involved in the present invention includes a central rotating structure whose upper and lower end surfaces are flat structures; the side of the central rotating structure is provided with a plurality of specific geometrical units, each structural unit includes an outer cylindrical surface I (2), a V-shaped groove (3) and an outer cylindrical surface II (4), and the V-shaped groove (3) is arranged between the outer cylindrical surface I ( 2 ) and the outer cylindrical surface II ( 4 ), and the outer cylindrical surface I ( 2 ) and the outer cylindrical surface II ( 4 ) are symmetrically arranged up and down; A vertical section structure is provided between the structural units, and the vertical section structure is the side vertical structural surface of the central rotating structure; the middle of the central rotating structure is provided with an inner cylindrical surface (9); as shown in Figure 1, the vertical section structure includes plane I (1), plane II (5) and plane III (9); the lower end surface (6) and the upper end surface (7) are the upper and lower end surfaces of the central rotating structure.

The above calibration parts meet the following design requirements:

S1: The inner cylindrical surface (9) is the positioning datum of the calibration part, which has strict requirements on its size and shape tolerance. It has the same aperture size as the gear under test (Fig. 5). In order to achieve the accuracy of radial positioning accuracy, the cylindricity of the inner cylindrical surface is required to be 0.3 μm.

S2: Plane I(1), Plane II(5), and Plane III(8) have the same plane structure, ensuring that the independent flatness is 1 μm, and their distances from the central axis are consistent (Fig. 2, Fig. 5) and are related to the diameter of the root circle of the gear to be tested; Plane I(1), Plane II(5), and Plane III(8) are all 1 μm perpendicular to the lower end face (6); the parallelism between Plane I(1) and Plane III(8) is 1 μm; Plane I(1) and Plane III (8) The symmetry about the center line is 1 μm; the perpendicularity between plane II (5), plane I (1), and plane III (8) is 1 μm.

S3: The outer cylindrical surface I (2) and the outer cylindrical surface II (4) have a consistent cylindricity of 0.3 μm; the overall size is related to the addendum circle of the gear to be tested (Figure 2, Figure 5); the coaxiality with the positioning reference inner circular surface (9) of the calibration piece is 1 μm.

S4: The V-shaped groove (3) divides the outer circular surface into the outer circular surface I (2) and the outer circular surface II (4). The total runout of the tapered surfaces on both sides of the V-shaped groove is 1 μm; the V-shaped groove has a specific width value, which is determined according to the parameters of the gear to be tested.

S5: The lower end surface (6) and the upper end surface (7) are the auxiliary reference planes of the calibration piece, each independently having a flatness of 1 μm; the two planes have a perpendicularity of 1 μm to the inner cylindrical surface (9) of the positioning reference of the calibration piece; the two planes are parallel to each other and the flatness is 1 μm; the dimension between the two planes is related to the tooth width of the measured gear (Figure 4, Figure 5).

Based on the above-mentioned calibration parts, the present invention designs a method for calibrating the space pose of a line laser sensor for gear measurement. The specific steps are as follows:

S1: The coordinate system of the calibration system is established.

Establish the coordinate system of the calibration system as shown in Figure 6, including: calibration piece coordinate system δ _c : O _c -X _c Y _c Z _c and sensor coordinate system δ _s : O _s -X _s Y _s Z _s . Among them, δ _c is the label of the calibration piece coordinate system, O _c is the origin of the calibration piece coordinate system, and X _c , Y _c , Z _c are the three coordinate axes of the calibration piece coordinate system. δ _s is the label of the sensor coordinate system, O _s is the origin of the sensor coordinate system, X _s , Y _s , Z _s are the three coordinate axes of the sensor coordinate system. The sensor is arranged in the circumferential direction of the calibration piece, and the offsets of the origin O _s of the sensor coordinate system relative to the origin O _c of the calibration piece coordinate system in the direction of the three coordinate axes of the calibration piece coordinate system are a, b, and c, respectively. The deflection angles of the three coordinate axes X _s , Y _s , and Z _s of the sensor coordinate system relative to the three coordinate axes X _c , Y _c , and Z _c of the calibration piece coordinate system are α, β, and γ, respectively. Therefore, a, b, c, α, β, and γ constitute the six degrees of freedom parameters of the sensor in the coordinate system of the calibration piece, and the space pose calibration of the sensor is to calibrate these six degrees of freedom parameters.

S2: Calibration data acquisition and coordinate transformation.

According to the coordinate system and coordinate relationship established by S1, the calibration piece is installed on the main shaft of the measuring instrument. The calibration piece can rotate with the given speed of the main shaft. The main shaft rotation signal of the measuring instrument is used as a trigger signal to trigger the sensor to collect data, and the point cloud information {D _s } on the surface of the calibration piece in the sensor coordinate system is obtained. According to the coordinate relationship of S1, the point cloud information {D _c } of the calibration piece in the calibration piece coordinate system is obtained from the formula (1).

D _c = M·D _s (1)

Among them, M is the transformation matrix between the sensor coordinate system and the calibration part coordinate system, which is related to the six degrees of freedom parameters a, b, c, α, β, γ of the sensor space pose.

S3: Calibration feature extraction.

According to the point cloud information of the calibration piece obtained in S2 {D _c : x _c , y _c , z _c }, the calibration piece information can be extracted according to the geometric features as cylindrical point cloud information {D _cY : x _cY , y _cY , z _cY }, plane point cloud information {D _cP : x _cP , y _cP , z _cP } and V-shaped groove point cloud information {D _cV : x _cV , y _cV , z _cV } , as shown in Figure 7. Each feature information contains six degrees of freedom parameters a, b, c, α, β, γ of the sensor space pose. Among them, x _c , y _c , z _c are the three-dimensional coordinate values of the point cloud information of the calibration piece in space, x _cY , y _cY , z _cY are the three-dimensional coordinate values of the cylindrical surface point cloud information of the calibration piece in space, x _cP , y _cP , z _cP are the three-dimensional coordinate values of the plane point cloud information of the calibration piece in space, x _cV , y _cV , z _c -V are the three-dimensional coordinate values of the V-shaped groove point cloud information of the calibration piece in space coordinate value.

S4: Calibration of six degrees of freedom parameters.

According to the characteristic information of the calibration piece extracted by S3, the parameters of the six degrees of freedom of the sensor space pose are determined one by one.

First, according to the cylindrical surface point cloud information {D _cY : x _cY , y _cY , z _cY } extracted by S3, the two deflection angles α and β of the sensor space pose are determined by formula (2) using the least squares fitting optimization program.

Among them, r ₀ is the radius of the outer cylinder of the calibration piece.

Then, according to the planar point cloud information {D _cP : x _cP , y _c -P, z _c -P} extracted by S3, two optimizations are performed using the least squares fitting optimization program by formula (3). The result of the first optimization is used as the initial value of the second optimization for optimization correction, and an angle parameter γ and two position parameters a and b of the sensor space pose can be determined.

min{∑|x _cP cosθ ₀ +y _cP sinθ ₀ -r _f |} (3)

Among them, r _f is the parameter related to the plane of the calibration piece and the root circle of the gear under test, and is the radius of the dedendum circle of the gear under test; θ ₀ is the initial position angle of the plane of the calibration piece.

Finally, according to the V-groove point cloud information {D _cV : x _cV , y _cV , z _cV } extracted by S3, the intersection position of the two cone surfaces of the V-groove is determined by formula (4), and then the last position parameter c of the sensor space pose can be determined.

z _cV =z _s +c (4)

So far, the spatial pose relationship of the line laser sensor is confirmed, and the calibration is completed.

The invention provides a line laser sensor space pose calibration component and calibration method for three-dimensional measurement of gears, which has the following characteristics:

1. The overall structure of the calibration piece is simple, and the existing manufacturing technology can well meet the processing requirements of high-precision geometric features.

2. The gear measurement center is combined with the measurement process, the calibration operation is simple and easy, and the precise calibration of the line laser sensor can be realized.

3. The calibration method uses the least squares to fit the straight line with mature technology and high precision, which can truly reflect the relationship between the actual coordinate values.

Description of drawings

Figure 1 The overall structure of the calibration parts

Figure 2 Top view structure diagram of the calibration piece

Figure 3 The YOZ plane cross-sectional structure diagram of the calibration piece

Figure 4 Structural comparison between the calibration piece and the gear product to be tested

Figure 5 Comparison of the YOZ plane section structure between the calibration piece and the gear product to be tested

Figure 6 Schematic diagram of establishing the coordinate system of the calibration system

Figure 7(a) Calibration piece point cloud information

Figure 7(b) Point cloud information of the outer cylindrical surface of the calibration piece

Figure 7(c) Planar point cloud information of the calibration piece

Figure 7(d) V-groove point cloud information of the calibration piece

In the figure: 1, plane I, 2, outer cylindrical surface I, 3, V-shaped groove, 4, outer cylindrical surface II, 5, plane II, 6, lower end surface, 7, upper end surface, 8, plane III, 9, inner cylindrical surface, I, calibration piece, II, comparison gear

Detailed ways

Below in conjunction with accompanying drawing and processing example the present invention is further described.

The space pose calibration part of the line laser sensor involved in the present invention comprises a central rotating structure, the upper and lower end surfaces of the central rotating structure are flat structures; the side of the central rotating structure is provided with a plurality of specific geometric units, each structural unit includes an outer cylindrical surface I (2), a V-shaped groove (3) and an outer cylindrical surface II (4), and the V-shaped groove (3) is arranged between the outer cylindrical surface I ( 2 ) and the outer cylindrical surface II ( 4 ), and the outer cylindrical surface I ( 2 ) and the outer cylindrical surface II ( 4 ) are symmetrically arranged up and down; Each structural unit is provided with a vertical section structure, and the vertical section structure is the side vertical structural surface of the central rotating structure; the middle of the central rotating structure is provided with an inner cylindrical surface (9); as shown in Figure 1, the vertical section structure includes plane I (1), plane II (5) and plane III (9); the lower end surface (6) and the upper end surface (7) are the upper and lower end surfaces of the central rotating structure.

The inner cylindrical surface (9) of the calibration piece involved in the present invention is the positioning reference of the calibration piece, and has strict requirements on its size and shape and position tolerance. It has the same aperture size as the gear to be tested (Fig. 5). To achieve the accuracy of the radial positioning accuracy, the cylindricity of the inner circular surface is required to be 0.3 μm.

The plane I (1), plane II (5), and plane III (8) of the calibration piece involved in the present invention have the same plane structure, ensuring that the independent flatness is 1 μm, and their distances with respect to the central axis are consistent (Figure 2, Figure 5) and are related to the diameter of the dedendum circle of the gear to be measured; the plane I (1), plane II (5), and plane III (8) are all 1 μm perpendicular to the lower end face (6); the parallelism between plane I (1) and plane III (8) is 1 μm; plane I ( 1) The symmetry with plane III(8) about the center line is 1 μm; the mutual perpendicularity between plane II(5) and plane I(1) and plane III(8) is 1 μm.

The outer cylindrical surface I (2) and outer cylindrical surface II (4) of the calibration piece involved in the present invention have a consistent cylindricity of 0.3 μm; the overall size is associated with the addendum circle of the gear to be tested (Figure 2, Figure 5); the coaxiality with the positioning reference inner cylindrical surface (9) of the calibration piece is 1 μm.

The V-shaped groove (3) of the calibration piece involved in the present invention is processed and formed on the outer cylindrical surface of the calibration piece, and the outer cylindrical surface is divided into the outer cylindrical surface I (2) and the outer cylindrical surface II (4). The full run-out of the tapered surfaces on both sides of the V-shaped groove is 1 μm; the V-shaped groove has a specific width value, which is determined according to the gear parameters.

The lower end surface (6) and the upper end surface (7) of the calibration piece involved in the present invention are the auxiliary reference planes of the calibration piece, respectively independently having a flatness of 1 μm; the two planes and the positioning reference inner circular surface (9) of the calibration piece have a perpendicularity of 1 μm; the two planes are parallel to each other, and have a flatness of 1 μm; the size between the two planes is correlated with the tooth width of the measured gear (Fig. 4, Fig. 5).

The above is the specific implementation manner of the calibration piece of the present invention.

The present invention also relates to a specific calibration method about the calibration piece, and the specific steps of the method are as follows:

S1. Establish the position model of the line laser sensor and the calibration piece:

Establish the coordinate system of the calibration system as shown in Figure 6, including: calibration piece coordinate system δ _c : O _c -X _c Y _c Z _c and sensor coordinate system δ _s : O _s -X _s Y _s Z _s . Among them, δ _c is the label of the calibration piece coordinate system, O _c is the origin of the calibration piece coordinate system, and X _c , Y _c , Z _c are the three coordinate axes of the calibration piece coordinate system. δ _s is the label of the sensor coordinate system, O _s is the origin of the sensor coordinate system, X _s , Y _s , Z _s are the three coordinate axes of the sensor coordinate system. The sensor is arranged in the circumferential direction of the calibration piece, and the offsets of the origin O _s of the sensor coordinate system relative to the origin O _c of the calibration piece coordinate system in the direction of the three coordinate axes of the calibration piece coordinate system are a, b, and c, respectively. The deflection angles of the three coordinate axes X _s , Y _s , and Z _s of the sensor coordinate system relative to the three coordinate axes X _c , Y _c , and Z _c of the calibration piece coordinate system are α, β, and γ, respectively. Therefore, a, b, c, α, β, and γ constitute the six degrees of freedom parameters of the sensor in the coordinate system of the calibration piece, and the space pose calibration of the sensor is to calibrate these six degrees of freedom parameters.

S2: Calibration data acquisition and coordinate transformation.

According to the coordinate system and coordinate relationship established by S1, the calibration piece is installed on the main shaft of the measuring instrument. The calibration piece can rotate with the given speed of the main shaft. The rotation signal of the main shaft of the measuring instrument is used as a trigger signal to trigger the sensor to collect data, and the point cloud information {D _s } on the surface of the calibration piece in the sensor coordinate system is obtained. According to the coordinate relationship of S1, the point cloud information {D _c } of the calibration piece in the calibration piece coordinate system is obtained from the formula (1).

D _c = M·D _s (1)

Among them, M is the transformation matrix between the sensor coordinate system and the calibration part coordinate system, which is related to the six degrees of freedom parameters a, b, c, α, β, γ of the sensor space pose.

S3: Calibration feature extraction.

According to the point cloud information of the calibration piece obtained in S2 {D _c : x _c , y _c , z _c }, the calibration piece information can be extracted according to the geometric features as cylindrical point cloud information {D _cY : x _cY , y _cY , z _cY }, plane point cloud information {D _cP : x _cP , y _cP , z _cP } and V-shaped groove point cloud information {D _cV : x _cV , y _cV , z _cV } , as shown in Figure 7. Each feature information contains six degrees of freedom parameters a, b, c, α, β, γ of the sensor space pose. Among them, x _c , y _c , z _c are the three-dimensional coordinates of the point cloud information of the calibration piece in space, x _cY , y _cY , z _cY are the three-dimensional coordinates of the cylindrical point cloud information of the calibration piece in space, x _cP , y _cP , z _cP are the three-dimensional coordinates of the plane point cloud information of the calibration piece in space, x _cV , y _cV , z _cV are the three-dimensional coordinates of the V-shaped groove point cloud information of the calibration piece in space value.

S4: Calibration of six degrees of freedom parameters.

According to the characteristic information of the calibration piece extracted by S3, the parameters of the six degrees of freedom of the sensor space pose are determined one by one.

First, according to the cylindrical surface point cloud information {D _cY : x _cY , y _cY , z _cY } extracted by S3, the two deflection angles α and β of the sensor space pose can be determined by using the least squares fitting optimization program from formula (2).

Among them, r ₀ is the radius of the outer cylinder of the calibration piece.

Then, according to the planar point cloud information {D _cP : x _cP , y _cP , z _cP } extracted by S3, two optimizations are performed using the least squares fitting optimization program by formula (3), and the result of the first optimization is used as the initial value of the second optimization for optimization correction, which can uniquely determine an angle parameter γ and two position parameters a and b of the sensor space pose.

min{∑|x _cP cosθ ₀ +y _cP sinθ ₀ -r _f |} (3)

Among them, r _f is the parameter related to the plane of the calibration piece and the root circle of the gear under test, and is the radius of the dedendum circle of the gear under test; θ ₀ is the initial position angle of the plane of the calibration piece.

Finally, according to the V-groove point cloud information {D _cV : x _cV , y _cV , z _cV } extracted by S3, the intersection position of the two cone surfaces of the V-groove is determined by formula (4), and then the last position parameter c of the sensor space pose can be uniquely determined.

z _cV =z _s +c (4)

So far, the spatial pose relationship of the line laser sensor is confirmed, and the calibration is completed.

The invention provides a line laser sensor space pose calibration component and a calibration method for three-dimensional measurement of gears. The overall structure of the calibration piece is simple, and the existing manufacturing technology can well meet the processing requirements of high-precision geometric features; the combination of gear measurement center measurement technology, the calibration operation is simple and easy, and the accurate calibration of the line laser sensor can be realized; the calibration method uses the least square to fit the straight line with mature technology, high precision, and can truly reflect the relationship between the actual coordinate values.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. The planar linear laser sensor pose calibration piece for realizing the calibration method comprises a central rotating structure body, wherein the upper end face and the lower end face of the central rotating structure body are of a flat structure; the side face of the central rotating structure body is provided with a plurality of structural units with specific geometric shapes, each structural unit comprises an outer cylindrical surface I (2), a V-shaped groove (3) and an outer cylindrical surface II (4), the V-shaped groove (3) is arranged between the outer cylindrical surface I (2) and the outer cylindrical surface II (4), and the outer cylindrical surface I (2) and the outer cylindrical surface II (4) are arranged symmetrically up and down; a vertical section structure is arranged between each structural unit, and the vertical section structure is a side vertical structural surface of the central rotating structural body; an inner cylindrical surface (9) is arranged in the middle of the central rotary structure body; the vertical section structure comprises a plane I (1), a plane II (5) and a plane III (9); the lower end face (6) and the upper end face (7) are the upper end face and the lower end face of the central rotating structure;

the calibration method is characterized by comprising the following specific steps:

establishing a coordinate system of a calibration system;

obtaining calibration data and transforming coordinates;

extracting calibration characteristics;

calibrating six degrees of freedom parameters;

confirming the space pose relation of the line laser sensor, and finishing calibration;

s1: establishing a coordinate system of a calibration system;

establishing a calibration system coordinate system, comprising: calibration part coordinate system delta _c :O _c -X _c Y _c Z _c And a sensor coordinate system delta _s :O _s -X _s Y _s Z _s The method comprises the steps of carrying out a first treatment on the surface of the Wherein delta _c For marking the coordinate system of the piece, O _c X is the origin of the coordinate system of the calibration piece _c 、Y _c 、Z _c Three coordinate axes of a coordinate system of the calibration piece; delta _s Is the label of the sensor coordinate system, O _s X is the origin of the sensor coordinate system _s 、Y _s 、Z _s Three coordinate axes of a sensor coordinate system; the sensor is arranged in the circumferential direction of the calibration piece, and the origin Os of the coordinate system of the sensor is relative to the origin O of the coordinate system of the calibration piece _c The offset in the three coordinate axis directions of the coordinate system of the calibration piece is a, b and c respectively; three coordinate axes X of sensor coordinate system _s 、Y _s 、Z _s Three coordinate axes X relative to the coordinate system of the calibration piece _c 、Y _c 、Z _c The deflection angles of the (a) are alpha, beta and gamma respectively; therefore, a, b, c, alpha, beta and gamma form six degree of freedom parameters of the sensor in a coordinate system of the calibration piece, and the spatial pose of the sensor is calibrated, namely the six degree of freedom parameters are calibrated; wherein x is _c ,y _x ,z _c Respectively calibrating three-dimensional coordinate values, x of the point cloud information of the piece in space _c-Y ,y _c-Y ,z _c-Y Three-dimensional coordinate values, x, of cylindrical surface point cloud information of the calibration piece in space _c-P ,y _c-P ,z _c-P Three-dimensional coordinate values, x, of plane point cloud information of the calibration piece in space _c-V ,y _c-V ,z _c-V Respectively the three-dimensional coordinate values of the V-shaped groove point cloud information of the calibration piece in space;

s2: obtaining calibration data and transforming coordinates;

according to the coordinate system and the coordinate relation established in the S1, a calibration piece is arranged on a main shaft of a measuring instrument, the calibration piece can do rotary motion along with the given speed of the main shaft, a main shaft rotary signal of the measuring instrument is used as a trigger signal to trigger a sensor to conduct data acquisition, and point cloud information { D (D) of the surface of the calibration piece under the coordinate system of the sensor is obtained _s -a }; according to the coordinate relation of S1, obtaining the point cloud information { D ] of the calibration piece under the coordinate system of the calibration piece by the formula (1) _c }；

D _c ＝M·D _s (1)

M is a transformation matrix between a sensor coordinate system and a calibration piece coordinate system, and is related to six degrees of freedom parameters a, b, c, alpha, beta and gamma of the sensor space pose;

s3: extracting calibration characteristics;

according to the point cloud information { D of the calibration piece obtained in S2 _c :x _c ,y _c ,z _c Extracting the calibration piece information as cylindrical point cloud information { D } according to the geometric features _c-Y :x _c-Y ,y _c-Y ,z _c-Y Planar point cloud information { D } _c-P :x _c-P ,y _c-P ,z _c-P Sum V-groove point cloud information { D } _c-V :x _c-V ,y _c-V ,z _c-V -a }; each piece of calibration piece information comprises six degrees of freedom parameters a, b, c, alpha, beta and gamma of the sensor space pose; wherein x is _c ,y _c ,z _c Respectively calibrating three-dimensional coordinate values, x of the point cloud information of the piece in space _c-Y ,y _c-Y ,z _c-Y Three-dimensional coordinate values, x, of cylindrical surface point cloud information of the calibration piece in space _c-P ,y _c-P ,z _c-P Respectively is calibrated toThree-dimensional coordinate value, x, of plane point cloud information of piece in space _c-V ,y _c-V ,z _c-V Respectively the three-dimensional coordinate values of the V-shaped groove point cloud information of the calibration piece in space;

s4: calibrating six degrees of freedom parameters:

determining six degrees of freedom parameters of the sensor space pose one by one according to the characteristic information of the calibration piece extracted in the step S3; first, according to the cylindrical point cloud information { D ] extracted in S3 _c-Y :x _c-Y ,y _c-Y ,z _c-Y Using a least squares fitting optimization procedure from equation (2), determining two deflection angles α, β of the sensor spatial pose;

wherein r is ₀ The radius of the outer cylinder of the calibration piece is the radius;

then, according to the plane point cloud information { D ] extracted in S3 _c-P :x _c-P ,y _c-P ,z _c-P Performing optimization twice by using a least square fitting optimization program according to a formula (3), performing optimization correction by taking the result of the first optimization as an initial value of the second optimization, and determining an angle parameter gamma and two position parameters a and b of the sensor space pose;

min{∑|x _c-P cosθ ₀ +y _c-P sinθ ₀ -r _f |}(3)

wherein r is _f The parameter related to the measured gear tooth root circle is the calibration piece plane and is the radius of the measured gear tooth root circle; θ ₀ An initial position angle of a plane of the calibration piece;

finally, according to the V-shaped groove point cloud information { D ] extracted in the step S3 _c-V :x _c-V ,y _c-V ,z _c-V Determining the intersection line position of two conical surfaces of the V-shaped groove according to the formula (4), and further determining the last position parameter c of the sensor space pose;

z _c-V ＝z _s +c (4)

and confirming the space pose relation of the line laser sensor so as to finish calibration.

2. The line laser sensor space position calibration method for gear measurement according to claim 1, wherein: the inner cylindrical surface is a positioning reference of the calibration piece, has the same aperture size as the gear to be measured, and the cylindricity of the inner cylindrical surface is required to be 0.3 mu m for realizing the accuracy of radial positioning precision.

3. The line laser sensor space position calibration method for gear measurement according to claim 1, wherein: the plane I, the plane II and the plane III of the calibration piece have the same plane structure, ensure that the independent flatness is 1 mu m, have the consistency of the distance relative to the central shaft and are related to the diameter size of the root circle of the gear to be measured; the perpendicularity of the lower end face of each of the plane I, the plane II and the plane III is 1 mu m; the parallelism of the plane I and the plane III is 1 mu m; the symmetry of the plane I and the plane III about the central line is 1 mu m; the mutual perpendicularity of the plane II, the plane I and the plane III is 1 μm.

4. The line laser sensor space position calibration method for gear measurement according to claim 1, wherein: the outer cylindrical surface I and the outer cylindrical surface II of the calibration piece have consistent cylindricity of 0.3 mu m; the overall sizes of the outer cylindrical surface I and the outer cylindrical surface II of the calibration piece are related to the tooth top circle of the gear to be measured; the coaxiality of the outer cylindrical surface I and the outer cylindrical surface II of the calibration piece and the positioning reference inner circular surface of the calibration piece is 1 mu m.

5. The line laser sensor space position calibration method for gear measurement according to claim 1, wherein: the outer circular surface of the calibration piece is divided into an outer circular surface I and an outer circular surface II by the V-shaped groove, and the total runout of conical surfaces at two sides of the V-shaped groove is 1 mu m; the width value of the V-shaped groove is determined according to the parameters of the gear to be measured.

6. The line laser sensor space position calibration method for gear measurement according to claim 1, wherein: the lower end face and the upper end face are auxiliary reference faces of the calibration piece and are respectively and independently provided with a flatness of 1 mu m; the perpendicularity between the two planes and the positioning reference inner cylindrical surface of the calibration piece is 1 mu m; the two planes are parallel to each other and have a flatness of 1 μm; the dimension between the two planes correlates with the tooth width of the gear under test.