CN115585750A - Automatic rim roundness detection system and method - Google Patents
Automatic rim roundness detection system and method Download PDFInfo
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- CN115585750A CN115585750A CN202211333282.8A CN202211333282A CN115585750A CN 115585750 A CN115585750 A CN 115585750A CN 202211333282 A CN202211333282 A CN 202211333282A CN 115585750 A CN115585750 A CN 115585750A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2408—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures for measuring roundness
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/17—Mechanical parametric or variational design
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
- G06T17/005—Tree description, e.g. octree, quadtree
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/70—Arrangements for image or video recognition or understanding using pattern recognition or machine learning
- G06V10/74—Image or video pattern matching; Proximity measures in feature spaces
- G06V10/761—Proximity, similarity or dissimilarity measures
Abstract
The invention discloses an automatic rim roundness detection system and method. The system is based on the automatic rim roundness detection method, a device of a hub clamping rotary table and a laser lifting sliding table is set up, and external parameter calibration of a measurement system is completed by means of a laser tracker; secondly, the position of the sliding table changing line laser is changed to realize the multi-time measurement of the rim section, and the splicing of multi-time measurement data is realized based on mechanical constraint to obtain a complete rim measurement point cloud model; the conversion process of the measured three-dimensional point cloud data of the rim from a measuring coordinate system to a turntable coordinate system is realized according to an external calibration result; and finally, matching the measurement model with the CAD model based on the k-dtree improved ICP algorithm, and calculating the rim roundness deformation according to the matching result so as to realize the rim roundness detection. The invention can realize the automatic detection of the roundness of the rim and output the machining allowance, and provides guidance for the subsequent roundness correction of the rim.
Description
Technical Field
The invention belongs to the field of automatic detection, and particularly relates to a rim roundness automatic detection system and a rim roundness automatic detection method.
Background
The wheel hub is an important metal part in the tire, and the aluminum alloy wheel hub is increasingly widely applied due to the advantages of light weight, high manufacturing precision, high strength, small inertia resistance, strong heat dissipation capability and the like. Most aluminum alloy hubs are cast by using A356 material at present, but the mechanical property of the material is relatively low. In order to improve the mechanical property of the material, the aluminum alloy hub is generally subjected to heat treatment in the hub manufacturing process, however, in the whole heat treatment process, the yield strength of the material is exceeded due to uneven heating and cooling and the impact action of external forces such as generated internal stress and impact, and finally the heat treatment deformation of the hub can be caused, so that the circular deformation (radial deformation) is generated in a rim area, troubles are brought to the subsequent machining of the hub, and the product yield is reduced. For such problems, the industry generally adopts a shape correction mode to repair. The hub sizing mainly aims at sizing a rim area, and in order to ensure the hub sizing effect, the roundness of a rim needs to be detected, but the current rim detection method is slightly insufficient.
However, in the wheel hub and rim roundness detection scheme in the prior art, the requirements of the wheel hub and rim shape detection method are high, the process is complicated, the shape detection is not intuitive, and the problems of installation errors, uneven ground and the like are not considered, for example, chinese patent CN201310135298.2 discloses a method for detecting wheel hub deformation by using line lasers, wherein two line lasers are simultaneously applied in the method, and the method is matched with a ball screw, a wheel hub rotating device and other devices, and can only detect wheel hub deformation step by step; patent CN207423095U discloses a rim deformation detection device, the measuring element of which is a dial indicator, the deformation of the rim is obtained by the contact of the dial indicator and the rim, the precision is low, sliding friction is generated during measurement, and certain damage is caused to the hub; patent CN114088024A discloses a rim flatness detection method, which does not consider the situations of installation errors and uneven ground, and is applicable to a special scene.
Disclosure of Invention
The invention aims to provide a rim roundness automatic detection system formed by combining functional modules, and provides a rim roundness automatic detection method according to the system.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
an automatic rim roundness detection system comprises an industrial personal computer control module, a line laser scanning module and a workpiece placing module; the industrial personal computer control module comprises an industrial personal computer and a compactRIO module, wherein the industrial personal computer is a terminal device, the compactRIO module is a product of NI company, and the industrial personal computer can simultaneously control the laser scanning module and a movable device hub clamping turntable and a laser lifting sliding table in the workpiece placing module through the compactRIO module; the linear laser scanning module comprises 2D linear laser and laser installation equipment, the laser installation equipment is a laser lifting sliding table, and the laser can scan the surface depth and height information of a workpiece at the same time; the workpiece placing module comprises a workpiece and workpiece placing equipment, and the hub is placed on the hub clamping rotary table. The industrial control machine control module is matched with other modules, so that a series of complete functions of automatic detection of workpieces, three-dimensional modeling and calculation of the roundness deformation of the rim can be realized, and automatic detection of the roundness of the rim is realized.
An automatic rim roundness detection method is characterized by comprising the following steps:
1) Obtaining the relative position and orientation relation among all devices by means of a Leica tracker, and finishing external reference calibration of the measuring system;
2) Respectively fixing a hub and 2D line laser on a hub clamping rotary table and a laser lifting sliding table, wherein the line laser obtains a group of measurement data after the hub rotates for a circle along with the rotary table;
3) Repeating the steps 2) to 3) according to the measuring position of the sliding table adjusting line laser to obtain a next section of rim measuring point cloud data model;
4) Repeating the step 2) to the step 3) to obtain all the measurement data of the rim, and splicing the data measured for multiple times in a segmented manner based on a splicing method to obtain the measurement point cloud data of the complete surface of the rim;
5) According to the result of external reference calibration, completing the conversion of the measurement data from a measurement coordinate system to a turntable coordinate system, and completing the rotation of the converted data based on a coordinate rotation model to obtain a three-dimensional measurement point cloud data model of the rim;
6) And matching the measurement model with the standard CAD model by using a matching algorithm, and calculating the rim machining area and the roundness deformation based on the matching result.
Further, an automatic rim roundness detection method comprises the following steps:
1) Establishing a kinematic model among all devices by means of a Leica tracker through a vector method; carrying out association matching on the coordinate system and the direction vector by the actual kinematics model so as to obtain the relative pose relationship among the devices and finish the external reference calibration of the measurement system; the calibration result is that if the wheel hub clamping turntable coordinate system is { A } line laser measurement coordinate system is { B }:
2) Fixing a hub to be measured on a hub clamping rotary table, fixing 2D line laser on a laser lifting sliding table, driving the hub to start rotating by the rotary table, and measuring a rim by the line laser; when the encoder sends f pulse signals to the line laser after the rotary table rotates for one circle, the line laser completes f times of measurement so as to
As a trigger interval for line laser rim measurements; the method comprises the steps that a rotary table rotates for a circle, and then a line laser scans a rim to obtain contour information of f pieces of the surface of a rim part in a coordinate system { B };
3) Because the range of the line laser is limited, the position of the line laser needs to be changed for multiple times to carry out multiple scanning measurement. According to the measuring position of the sliding table adjusting line laser, repeating the steps 2) -3) to obtain the next section of rim measuring point cloud data, and recording the rising height of the sliding table each time measured by the line laser;
4) Repeating the step 2) to the step 3) to complete all scanning of the surface of the rim by the line laser, splicing data obtained by multiple scanning based on a mechanical constraint method, and finally obtaining f pieces of contour information of all the surfaces of the rim;
5) Let the coordinate of a measuring point P on the rim in the coordinate system { A } be P (x) A ,y A ,z A ) The coordinate in the coordinate system { B } is P (x) B ,y B ,z B ) According to formula (1) there are:
line point P '(x' A ,y′ A ,z′ A ) The point P is a new coordinate position after the ith triggering of the two-dimensional laser profiler, and the wheel hub clamping rotary table rotates by an angle (i-1) theta at the moment; since the point P and the point P 'are the point P and the point P' are on the plane O A -x A y A The projected point on the coordinate point P 'can calculate the coordinate value of the new coordinate point P' from the coordinate of the point P and the trigger angle θ according to the geometric relationship in the figure, as shown in the following formula.
Wherein
Initially measuring a deviation angle;
after the turntable rotates for a fixed angle theta each time, the coordinate value of the rim profile in the coordinate system { A } acquired by the above formula calculating line laser is utilized, and the three-dimensional point cloud data information of the measured rim can be obtained after one rotation.
6) Let CAD model point cloud data set Q = { Q = i I =1,2,3. When performing registration, first, at a CAD model point set Q = { Q = i I =1,2,3.. N } and the measured set of points P = { P = { P } i Finding a corresponding point pair q with the minimum Euclidean distance between I =1,2,3 i And p i Disclosure of the inventionAnd (3) increasing the searching speed of the corresponding point pair by establishing a k-dtree structure and setting an objective function as follows:
and solving a space transformation parameter rotation matrix R and a translation matrix t which enable the value of the objective function f (R, t) to be minimum through singular value decomposition calculation.
Finding the corresponding point cloud data set Q = { Q } of the collected actually-measured rim point cloud data set P in the CAD model point cloud data set based on the k-dtree structure of the formula i I =1,2,3.., n }, wherein q is i The point closest to the space distance of the actually measured rim point cloud data set on the model is designed. The roundness deformation of the rim measurement data is as follows
Δr i ＝Rp i +t-q i (5)
Final output (x) i ,y i ,z i |Δr i ) Wherein (x) i ,y i ,z i ) For deformation region coordinate position information,. DELTA.r i Is the corresponding deformation amount.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention provides a method for completing external reference calibration of a measuring system by means of a Leica tracker, which reduces the influence of installation errors and ground level errors on measuring precision.
2) The invention only uses a high-precision non-contact line laser to scan and measure the wheel hub and the wheel rim, if the size of the wheel rim exceeds the range of the line laser, complete workpiece data can be obtained by sectional measurement and data splicing.
3) The invention provides a method for completing model matching based on k-dtree improved ICP algorithm and applying the method to the calculation output (x) of the roundness deformation of a rim i ,y i ,z i |Δr i ) The machining allowance of the form provides guidance for subsequent roundness correction of the rim.
4) The hub detection program is developed based on the open programming environment, a series of complete functions such as automatic workpiece detection, three-dimensional modeling and rim roundness deformation calculation can be realized, and the automatic detection of the rim roundness is realized.
Drawings
FIG. 1 is a schematic diagram of the system components of the present invention;
FIG. 2 is a schematic flow chart of rim roundness detection;
FIG. 3 is a schematic view of a measurement system;
FIG. 4 is a schematic diagram of system calibration;
FIG. 5 is a diagram illustrating the transformation relationship between coordinate systems;
fig. 6 is a schematic view of a coordinate rotation model.
Detailed Description
The invention will be more fully understood from the following detailed description when read together with the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed embodiment.
As shown in FIG. 1, the system function module mainly comprises an industrial personal computer control module, a line laser scanning module, a workpiece placing module and the like. The industrial personal computer control module mainly comprises an industrial personal computer and a Compact RIO module, wherein the industrial personal computer is a terminal device, the Compact RIO control module is a product of NI company, and the industrial personal computer can simultaneously control movable devices in the laser scanning module and the workpiece placing module, such as a hub clamping table and a laser lifting sliding table, through the Compact RIO module; the line laser scanning module mainly includes 2D line laser and laser erection equipment, and the laser erection equipment is laser lift slip table, and the surface depth and the height information of work piece can be scanned out simultaneously to this laser, and the work piece is placed the module and is mainly settled equipment by work piece and constitute, and wheel hub places on wheel hub clamping platform. The industrial control machine control module is matched with other modules, so that a series of complete functions of automatic detection of workpieces, three-dimensional modeling, calculation of circular degree deformation of the rim and the like can be realized, and automatic detection of circular degree of the rim is realized.
Fig. 2 is a detection flowchart, which includes the following steps:
the principle of the measurement system is schematically shown in FIG. 3, where the coordinate system { A } is a turntable coordinate system, where the origin O is A Is the central point of the lower surface of the circumference of the turntable, axis z A Heavy with the turntable axis of rotation. Coordinate system { B } is the measured coordinate system of the 2D line laser, where plane O B -z B y B Is planar to the light emitted by the 2D line laser.
S100, first, a come absolute tracker is used to measure 3 points P1, P2, P3 on the surface of the line laser support plate on the slide table and establish a coordinate system { P } based on these three points, as shown in fig. 4. Wherein
Is a unit vector in the principal direction of the coordinate system P. They are defined as the following formula (1)
Projecting the unit vectors of each axis of the coordinate system { P } to each coordinate axis of the coordinate system { L } of the come card to obtain a rotation matrix, as shown in the following formula (2)
Wherein
A unit basis vector representing a coordinate system { L }. Therefore, the number of the first and second electrodes is increased,
wherein d = L P 1 . As shown in FIG. 4, the relative pose from coordinate system { P } to coordinate system { B } is known B PT, thus giving a transformation from the coordinate system { B } to the coordinate system { L }
In order to establish a coordinate system { A } of the hub clamping rotary table, the circle center of the rotary table needs to be solved. Measuring n points on the surface circumference of the turntable by using a Leica tracker, fitting the n points based on least square method to obtain a plane equation ax + by + cz-1=0 and a circumference center coordinate O of the lower circumference of a Leica coordinate system { L }, and calculating a center coordinate of the circumference A (x 0 ,y 0 ,z 0 ). The equation of the rotation axis of the turntable is shown as formula (4)
Taking a point Q on the axis as shown in FIG. 5 2 And a point Q on the plane 1 Based on O A ,Q 1 ,Q 2 The three points establish a turntable coordinate system { A }, wherein
Is a unit vector in the principal direction of the coordinate system P. Then there is
FIG. 5 shows the conversion relationships of the turntable coordinate system { A }, the measurement coordinate system { B }, the coordinate system { P } and the come card coordinate system { L }, which are obtained by the above solutions
And
we can get the relation between the measured coordinate system { B } and the turntable coordinate system { A }
I.e. external parameters of the system as follows
Based on equation (7) solve to obtain
The external reference calibration of the measuring system is completed;
s200, fixing a hub to be measured on a hub clamping rotary table, fixing 2D line laser on a laser lifting sliding table, driving the hub to start rotating by the rotary table, and measuring the rim by the line laser. When the encoder sends f pulse signals to the line laser after the rotary table rotates for one circle, the line laser completes f times of measurement so as to
As the trigger interval for line laser rim measurements. The laser scanning wheel rim is linearly rotated after the rotary table rotates one circle to obtain the contour information of f pieces of the wheel rim part surface in a coordinate system B,
s300, because the range of the line laser is limited, the position of the line laser needs to be changed for multiple times to carry out multiple scanning measurement. And (5) repeating the steps S200-S300 according to the measuring position of the sliding table adjusting line laser to obtain the point cloud data of the next section of the rim, and recording the height of the sliding table which is measured by the line laser to rise every time.
S400, repeating the steps S200-S300 to complete all scanning of the surface of the rim by the line laser, splicing information obtained by multiple scanning based on a mechanical constraint method, and finally obtaining f pieces of contour information of all the surfaces of the rim.
S500, FIG. 6 shows a coordinate rotation model with the coordinate of a measurement point P on the rim in the coordinate system { A } as P (x) A ,y A ,z A ) The coordinate in the coordinate system { B } is P (x) B ,y B ,z B ) According to formula (7) then have
Line point P '(x' A ,y′ A ,z′ A ) And the point P is a new coordinate position after the ith triggering of the two-dimensional laser profiler, and the hub clamping turntable rotates by an angle of (i-1) theta at the moment. Since the point P and the point P 'are the point P and the point P' are on the plane O A -x A y A The projected point on the graph can calculate the coordinate value of a new coordinate point P' from the coordinate of point P and the trigger angle θ according to the geometric relationship in the graph, as shown in the following formula.
Wherein
For initially measuring deviation angle
After the turntable rotates for a fixed angle theta each time, the coordinate value of the rim profile in the coordinate system { A } acquired by the line laser is calculated by the formula, and the three-dimensional point cloud data model of the measured rim in the coordinate system { A } can be obtained after the turntable rotates for a circle.
S600, the three-dimensional point cloud data model of the rim in the turntable coordinate system { A } can be obtained through the steps, but in order to complete roundness detection, roundness deformation corresponding to the point cloud data needs to be calculated. Let CAD model point cloud data set Q = { Q = i I =1,2,3. When registration is performed, first, in a CAD model point set Q = { Q = i I =1,2,3.. N } and the measured set of points P = { P = | i Finding a corresponding point pair q with the minimum Euclidean distance between I =1,2,3 i And p i The speed of searching the corresponding point pair is improved by establishing a k-dtree structure, and an objective function as the formula is set:
and solving the space transformation parameter rotation matrix R and the translation matrix t which enable the f (R, t) value of the objective function to be minimum through singular value decomposition calculation. The concrete solving steps are as follows:
1) Setting an initial rotation matrix R as an identity matrix, a translation matrix t as a zero vector, and the maximum iteration times k =0 max ；
2) Establishing k-dtree topological structure of CAD model point set, and measuring obtained rim point set p i Quickly and accurately finding the nearest point q on the corresponding CAD model through the kd-tree topological structure i ；
3) Solving for f based on singular value decomposition method k Spatial transformation parameter R with minimum (R, t) value k And t k .
4) With R k And t k For the measured rim point set p i Carry out the update p i ＝R k p i +t k Simultaneously update R = R k R,t＝R k t+t k 。
5) Determining whether an iteration end condition f is satisfied k (R,t)-f k+1 (R, t) < ε or k = k max And if epsilon is a given threshold, stopping iteration, otherwise, enabling k = k +1, and repeating the steps 2 to 4.
Finding the corresponding point cloud data set Q = { Q } of the collected actually-measured rim point cloud data set P in the CAD model point cloud data set based on the k-dtree structure of the formula i I =1,2,3.., n }, wherein q is i And (4) the point on the CAD model closest to the space distance of the actually measured rim point cloud data set. The roundness deformation of the rim measurement data is as shown in formula (11)
Δr i ＝Rp i +t-q i (11)
Final output (x) i ,y i ,z i |Δr i ) A process allowance of the form wherein (x) i ,y i ,z i ) As coordinate position information of the rim deformation region, Δ r i And providing guidance for subsequent roundness correction for the corresponding deformation.
The aspects, embodiments, features and examples of the present invention should be considered illustrative in all respects and not restrictive, the scope of the invention being defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.
Although the present invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (4)
1. An automatic rim roundness detection system is characterized by comprising an industrial personal computer control module, a line laser scanning module and a workpiece placing module;
the industrial personal computer control module comprises an industrial personal computer and a Compact RIO module, and the industrial personal computer simultaneously controls a laser lifting sliding table of the laser scanning module and a hub clamping rotary table in the workpiece placing module through the Compact RIO module;
the linear laser scanning module comprises 2D linear laser and laser installation equipment, and can scan the surface depth and height information of a workpiece at the same time, and the laser installation equipment is a laser lifting sliding table;
the workpiece placing module comprises a workpiece and workpiece placing equipment, the workpiece is placed on the hub clamping rotary table, and the industrial control machine control module is matched with other modules, so that a series of complete functions of automatic workpiece detection, three-dimensional modeling and calculation of the roundness deformation of the rim are realized, and the automatic detection of the roundness of the rim is realized.
2. An automatic rim roundness detection method is characterized by comprising the following steps:
1) Obtaining the relative position and orientation relation among all devices by means of a Leica tracker, and completing external reference calibration of the measuring system;
2) Respectively fixing a hub and 2D line laser on a hub clamping rotary table and a laser lifting sliding table, and after the hub rotates for a circle along with the rotary table, obtaining a group of measurement data by the line laser;
3) Repeating the steps 2) -3) according to the measuring position of the sliding table adjusting line laser to obtain a rim measuring point cloud data model of the next section;
4) Repeating the step 2) to the step 3) to obtain all the measurement data of the rim, and splicing the data measured for multiple times in a segmented manner based on a splicing method to obtain the measurement point cloud data of the complete surface of the rim;
5) According to the result of external parameter calibration, completing the conversion of the measurement data from a measurement coordinate system to a turntable coordinate system, and completing the rotation of the converted data based on a coordinate rotation model to obtain a three-dimensional measurement point cloud data model of the rim;
6) And matching the measurement model with the standard CAD model by using a matching algorithm, and calculating the rim machining area and the roundness deformation based on the matching result.
3. An automatic rim roundness detection method according to claim 2, characterized by comprising the following steps:
1) Establishing a kinematic model among all devices by means of a Leica tracker through a vector method; carrying out association matching on the coordinate system and the direction vector by the actual kinematics model so as to obtain the relative pose relationship among the devices and finish the external reference calibration of the measurement system; the calibration result is that if the wheel hub clamping turntable coordinate system is { A } line laser measurement coordinate system is { B }:
r is a parameter of the rotation matrix, and t is a parameter of the translation matrix;
2) Fixing a hub to be measured on a hub clamping rotary table, fixing 2D line laser on a laser lifting sliding table, driving the hub to start rotating by the rotary table, and measuring a rim by the line laser; when rotatingThe encoder sends f pulse signals to the line laser after the table rotates for one circle, and the line laser completes f times of measurement so as to
As a trigger interval for line laser rim measurements; the method comprises the steps that a rotary table rotates for a circle, and then a line laser scans a rim to obtain contour information of f pieces of the surface of a rim part in a coordinate system { B };
3) Because the range of the line laser is limited, the position of the line laser needs to be changed for multiple times to carry out multiple scanning measurement; according to the measuring position of the sliding table adjusting line laser, repeating the steps 2) -3) to obtain the next section of rim measuring point cloud data, and recording the rising height of the sliding table each time measured by the line laser;
4) Repeating the step 2) to the step 3) to complete all scanning of the surface of the rim by the line laser, splicing data obtained by multiple times of scanning based on a mechanical constraint method, and finally obtaining f pieces of contour information of all the surfaces of the rim;
5) Let the coordinate of a measuring point P on the rim in the coordinate system { A } be P (x) A ,y A ,z A ) The coordinate in the coordinate system { B } is P (x) B ,y B ,z B ) According to formula (1) there are:
line point P '(x' A ,y′ A ,z′ A ) The point P is a new coordinate position after the ith triggering of the two-dimensional laser profiler, and the hub clamping rotary table rotates by an angle (i-1) theta at the moment; since the point P and the point P 'are the point P and the point P' are on the plane O A -x A y A The coordinate value of the new coordinate point P' is calculated from the coordinate of point P and the trigger angle θ according to the geometric relationship in the diagram, as shown in the following formula:
wherein
Measuring the deviation angle for the initial measurement;
after the turntable rotates for a fixed angle theta each time, the coordinate value of the rim profile in the coordinate system { A } acquired by the above formula calculating line laser is utilized, and three-dimensional point cloud data information of the detected rim can be obtained after the turntable rotates for a circle;
6) Let CAD model point cloud data set Q = { Q = i I =1,2,3.., n }; when performing registration, first, at a CAD model point set Q = { Q = i I =1,2,3.. N } and the measured set of points P = { P = { P } i Finding a corresponding point pair q with the minimum Euclidean distance between | i =1,2,3 i And p i And increasing the searching speed of the corresponding point pair by establishing a k-d tree structure and setting an objective function as follows:
solving a space transformation parameter rotation matrix R and a translation matrix t which enable the value of the objective function f (R, t) to be minimum through singular value decomposition calculation;
finding the corresponding point cloud data set Q = { Q } of the collected actually-measured rim point cloud data set P in the CAD model point cloud data set based on the k-d tree structure of the formula i I =1,2,3.., n }, wherein q is i The point closest to the space distance of the actually measured rim point cloud data set on the model is designed. The roundness deformation of the rim measurement data is as follows:
Δr i ＝Rp i +t-q i (5)
final output of the machining allowance (x) of the rim i ,y i ,z i |Δr i ) Wherein (x) i ,y i ,z i ) For the deformation region coordinate position information, Δ r i Is the corresponding deformation amount.
4. An automatic rim detection method according to claim 2, wherein in the step 2), the line laser is based on the encoder trigger principle to acquire rim point cloud data at equal angles.
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| CN116228831A (en) * | 2023-05-10 | 2023-06-06 | 深圳市深视智能科技有限公司 | Method and system for measuring section difference at joint of earphone, correction method and controller |
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| CN116228831A (en) * | 2023-05-10 | 2023-06-06 | 深圳市深视智能科技有限公司 | Method and system for measuring section difference at joint of earphone, correction method and controller |
| CN116228831B (en) * | 2023-05-10 | 2023-08-22 | 深圳市深视智能科技有限公司 | Method and system for measuring section difference at joint of earphone, correction method and controller |
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