Automatic workpiece three-dimensional size detection system and method based on laser scanning
阅读说明：本技术 一种基于激光扫描的工件三维尺寸自动检测系统及方法 (Automatic workpiece three-dimensional size detection system and method based on laser scanning ) 是由 张瀚文 任伟 陈爱军 马桂红 马德智 沈小燕 侯清锋 卢焕然 赵兰 于 2019-09-02 设计创作，主要内容包括：本发明为一种基于激光扫描的工件三维尺寸自动检测系统及方法,该系统包括三维移动平台、三维移动平台数控模块、激光扫描传感器、激光扫描传感器数控模块、激光扫描传感器转动机构、电源模块、检测软件,属于三维扫描及数字化分析技术领域。本发明中采用数控三维移动平台,实现全程动态测量,取代了手工移动检测,提高了检测效率；采用气浮导轨,提高了移动精度；在Z轴气浮导轨上装配激光扫描传感器转动机构,可实现激光扫描传感器的偏转,对工件进行不同角度的扫描；选用蓝色线扫式激光扫描传感器,抗干扰能力强,测量精度高。(The invention relates to a laser scanning-based workpiece three-dimensional size automatic detection system and a laser scanning-based workpiece three-dimensional size automatic detection method. According to the invention, a numerical control three-dimensional mobile platform is adopted, so that the whole-course dynamic measurement is realized, the manual movement detection is replaced, and the detection efficiency is improved; the air-float guide rail is adopted, so that the moving precision is improved; the laser scanning sensor rotating mechanism is assembled on the Z-axis air-floating guide rail, so that the deflection of the laser scanning sensor can be realized, and the workpiece can be scanned at different angles; the blue line scanning type laser scanning sensor is selected, so that the anti-interference capability is strong, and the measurement precision is high.)
1. The utility model provides a three-dimensional size automatic check out system of work piece based on laser scanning which characterized in that: the system comprises a three-dimensional mobile platform, a three-dimensional mobile platform numerical control module, a laser scanning sensor numerical control module and detection software; wherein:
the three-dimensional moving platform comprises an X-axis air-floating guide rail, a Y-axis air-floating guide rail, a Z-axis air-floating guide rail and a displacement platform, and the workpiece to be measured is horizontally placed on the displacement platform; the X-axis air floatation guide rail drives the displacement platform to move along the X-axis direction of the measurement coordinate system; the tail end of the Z-axis air-floating guide rail is provided with a laser scanning sensor, and the Y-axis air-floating guide rail and the Z-axis air-floating guide rail drive the laser scanning sensor to move relative to the displacement platform along the Y-axis direction and the Z-axis direction of the measurement coordinate system;
the three-dimensional moving platform numerical control module controls the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail to move in the three-dimensional direction according to a preset movement track and speed, acquires the position information of the workpiece to be detected in real time and sends the position information to the detection software, and sends a measuring pulse signal to the laser scanning sensor numerical control module when the workpiece to be detected moves for a certain distance;
the laser scanning sensor numerical control module generates an acquisition driving signal after receiving the measurement pulse signal and sends the acquisition driving signal to the laser scanning sensor;
the laser scanning sensor scans the workpiece to be detected under the control of the acquisition driving signal to obtain the distance information from a scanning point on the workpiece to be detected to the sensing head, and sends the distance information to the detection software;
the detection software is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting initial position information of a measuring head of the laser scanning sensor and generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail; setting angle information of a laser scanning sensor and sending the angle information to a numerical control module of the laser scanning sensor; obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to position information of the measured workpiece and distance information from the scanning points on the measured workpiece to a sensing head, denoising, simplifying and splicing the three-dimensional coordinate point cloud data, selecting point cloud data corresponding to geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data according to a drawing file of the measured workpiece, then generating an image of the geometric features, measuring the size of the geometric features, comparing the measured size of the geometric features with a standard size to obtain form and position errors of the geometric features of the workpiece, judging the qualification of the measured workpiece according to the form and position error result, generating a detection report, and storing and displaying the detection report.
2. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 1, characterized in that: the laser scanning sensor rotating mechanism (3) is also included;
one end of a laser scanning sensor rotating mechanism (3) is connected with the Z-axis air-floating guide rail (2), and the other end of the laser scanning sensor rotating mechanism is connected with the laser scanning sensor and is used for driving the laser scanning sensor to swing in two directions of a Y axis and a Z axis of a measurement coordinate system;
and the laser line scanning sensor numerical control module is used for realizing the motion control of the laser scanning sensor rotating mechanism (3) and setting the deflection angle and speed of the laser scanning sensor.
3. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 2, characterized in that: the laser scanning sensor rotating mechanism (3) comprises an upper upright post (17), a servo motor (18) and a lower upright post (23); the upper upright post (17) is fixedly arranged on an air floatation block of the Z-axis air floatation guide rail (2) along the Z-axis direction, a servo motor (18) main body is arranged on the upper upright post (17), a rotating shaft of the servo motor (18) is parallel to the X-axis direction of a measurement coordinate system, the rotating shaft of the servo motor (18) is in interference fit with the lower upright post, and the shaft is not contacted with the upper upright post (17). The laser line scanning sensor (19) is fixedly connected with the other end of the lower upright post, and the lower upright post rotates by a certain deflection angle under the driving of the servo motor (18), namely, the laser line scanning sensor (19) is driven to deflect together, so as to scan workpieces at different angles.
4. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 1 or 2, characterized in that: the laser scanning sensor is a line scanning sensor.
5. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 4, wherein: the laser scanning sensor is a blue laser line scanning sensor.
6. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 1, characterized in that: grating rulers are respectively installed on the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail, and the three-dimensional moving platform numerical control module and the grating rulers form a closed-loop feedback system: the grating ruler is used for measuring the position information of the measured workpiece in the three-dimensional direction and feeding the position information back to the three-dimensional moving platform numerical control module; the three-dimensional moving platform numerical control module continuously compares the theoretical position of the workpiece to be measured with the actual position of the workpiece fed back by the grating ruler, and adjusts the movement of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail in the three-dimensional direction at any time through the control of PID parameters.
7. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 1, characterized in that: the detection software comprises a data acquisition and processing module, a size measurement and error identification module and a parameter setting module;
the data acquisition and processing module is used for obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and the distance information from the scanning points on the measured workpiece to the sensing head, then carrying out denoising, simplification and splicing processing on the three-dimensional coordinate point cloud data of the scanning points on the measured workpiece, and sending the processed three-dimensional coordinate point cloud data of the scanning points on the measured workpiece to the size measurement and error identification module;
the size measurement and error identification module selects point cloud data corresponding to the geometric features to be measured of the workpiece to be measured according to a drawing file of the workpiece to be measured, then generates an image of the geometric features, measures the sizes of the geometric features, compares the measured sizes of the geometric features with standard sizes to obtain form and position errors of the geometric features of the workpiece, judges the qualification of the workpiece to be measured according to error results, generates a detection report, and stores and displays the detection report.
And the parameter setting module is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting the initial position information of a measuring head of the laser scanning sensor, generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and sending the movement tracks to the numerical control module of the three-dimensional moving platform. And setting angle information of the laser scanning sensor and sending the angle information to the numerical control module of the laser scanning sensor.
8. The automatic detection system for the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 1, characterized in that: the quality tracing module is used for inquiring the historical detection data of the corresponding detection sample according to the user requirement; and carrying out statistical analysis on historical detection data of the detected sample.
9. A method for automatically detecting the three-dimensional size of a workpiece based on laser scanning is characterized by comprising the following steps:
s1, carrying out scanning work on the workpiece to obtain multilayer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected;
s2: after scanning, carrying out denoising, simplification and splicing treatment on the multi-layer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected, and finally synthesizing the data to be detected in the same coordinate system;
s3: and according to the drawing file of the measured workpiece, selecting point cloud data corresponding to the geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data, then generating an image of the geometric features, and measuring the size of the geometric features.
S4: and comparing the measured size of the geometric features with the standard size to obtain the form and position errors of the geometric features of the workpiece, judging the qualification of the workpiece to be detected according to the form and position error result, generating a detection report, and storing and displaying the detection report.
10. The method for automatically detecting the three-dimensional size of the workpiece based on the laser scanning as claimed in claim 9, wherein the step S1 comprises the following steps:
s1.1, defining a processing base surface of a workpiece to be detected as the front surface of the workpiece to be detected, taking the processing base surface as an initial surface to be detected, placing the workpiece to be detected on a mobile platform, wherein the surface to be detected is upward, and a laser line scanning sensor is downward vertically;
s1.2, setting the X-axis air-floating guide rail, the Y-axis air-floating guide rail movement speed and movement track of the three-dimensional moving platform, the initial height of the laser line scanning sensor in the Z-axis direction and the angle of the laser line scanning sensor according to the known size of the surface to be measured of the workpiece to be measured, and setting the scanning layer number of the surface to be measured according to the height ranges of the laser line scanning sensor and the surface to be measured of the workpiece to be measured;
s1.3: placing a workpiece to be detected on a displacement platform, wherein the workpiece to be detected alternately performs reciprocating stable uniform motion along an X axis and a Y axis relative to a laser line scanning sensor, and the laser line scanning sensor performs uninterrupted scanning on the surface to be detected of the workpiece to be detected until the first layer of scanning on the surface to be detected of the workpiece to be detected within the range of the scanning sensor is finished, so as to obtain first layer of three-dimensional point cloud data of the surface to be detected of the workpiece to be detected;
s1.4: controlling the scanning sensor to move a certain distance in the Z-axis direction according to the height of the surface to be measured of the measured workpiece and the distance measurement range of the laser line scanning sensor, scanning the second layer according to the scanning method in the step two, and repeating the steps until multilayer three-dimensional point cloud data of the surface to be measured of the measured workpiece are obtained;
s1.5: turning the tested workpiece by 180 degrees, taking the reverse side as the side to be tested to be upward, placing the tested workpiece on a mobile platform, enabling a laser line scanning sensor to be vertical to be downward, repeating the steps S1.2, S1.3 and S1.4, and obtaining multilayer three-dimensional point cloud data of the reverse side of the tested workpiece;
s1.6: and controlling the laser line scanning sensor to deflect by a certain angle, scanning the side surface of the workpiece, and acquiring multilayer three-dimensional point cloud data of the side surface of the workpiece to be detected.
Technical Field
The invention relates to a system and a method for automatically detecting the three-dimensional size of a workpiece based on laser scanning, belonging to the technical field of three-dimensional scanning and digital analysis.
Background
At present, the aerospace system has more types of workpieces, complex structure and small batch. If the shape and position parameters of the workpiece are detected by the conventional universal measuring tools such as a vernier caliper and a micrometer by an inspector, the measured size of the workpiece with medium complexity is about 300-400, the measurement of the sizes such as wall thickness and the like needs a plurality of positions, a skilled operator needs (3-5) hours to complete the measurement, and a plurality of inspectors need to be arranged. At present, the problems of large total amount of workpieces, low testing efficiency, manual judgment of qualification, unretraceable quality, large consumption of manpower and material resources, easy error and the like exist, and the problems become factors restricting the quality and the progress of workpiece products.
The workpiece is made of a high-brightness material, so that the traditional photogrammetry method is not suitable, the acquired original image is not clear enough, the interference is more, and the form and position parameters cannot be accurately measured; due to the restriction of the measurement efficiency, the contact type measurement method of the three-coordinate measuring machine is not suitable; in addition, according to the tolerance of the workpiece, the precision of instruments and equipment used for detecting the workpiece is required to be better than +/-0.03 mm, and the errors of other scanning methods such as articulated arm laser scanning measurement, rotary table scanning measurement method, 3D scanning method and the like are all larger than +/-0.05 mm, so that the requirement is not met.
Disclosure of Invention
The technical problem solved by the invention is as follows: the invention provides a system and a method for automatically detecting the three-dimensional size of a workpiece based on laser scanning, aiming at the problems of low detection efficiency and low automation level of the existing workpiece measuring method, and the detection efficiency and the automation level are improved.
The technical scheme of the invention is as follows: a workpiece three-dimensional size automatic detection system based on laser scanning comprises a three-dimensional moving platform, a three-dimensional moving platform numerical control module, a laser scanning sensor numerical control module and detection software; wherein:
the three-dimensional moving platform comprises an X-axis air-floating guide rail, a Y-axis air-floating guide rail, a Z-axis air-floating guide rail and a displacement platform, and the workpiece to be measured is horizontally placed on the displacement platform; the X-axis air floatation guide rail drives the displacement platform to move along the X-axis direction of the measurement coordinate system; the tail end of the Z-axis air-floating guide rail is provided with a laser scanning sensor, and the Y-axis air-floating guide rail and the Z-axis air-floating guide rail drive the laser scanning sensor to move relative to the displacement platform along the Y-axis direction and the Z-axis direction of the measurement coordinate system;
the three-dimensional moving platform numerical control module controls the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail to move in the three-dimensional direction according to a preset movement track and speed, acquires the position information of the workpiece to be detected in real time and sends the position information to the detection software, and sends a measuring pulse signal to the laser scanning sensor numerical control module when the workpiece to be detected moves for a certain distance;
the laser scanning sensor numerical control module generates an acquisition driving signal after receiving the measurement pulse signal and sends the acquisition driving signal to the laser scanning sensor;
the laser scanning sensor scans the workpiece to be detected under the control of the acquisition driving signal to obtain the distance information from a scanning point on the workpiece to be detected to the sensing head, and sends the distance information to the detection software;
the detection software is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting initial position information of a measuring head of the laser scanning sensor and generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail; setting angle information of a laser scanning sensor and sending the angle information to a numerical control module of the laser scanning sensor; obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to position information of the measured workpiece and distance information from the scanning points on the measured workpiece to a sensing head, denoising, simplifying and splicing the three-dimensional coordinate point cloud data, selecting point cloud data corresponding to geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data according to a drawing file of the measured workpiece, then generating an image of the geometric features, measuring the size of the geometric features, comparing the measured size of the geometric features with a standard size to obtain form and position errors of the geometric features of the workpiece, judging the qualification of the measured workpiece according to the form and position error result, generating a detection report, and storing and displaying the detection report.
The automatic detection system for the three-dimensional size of the workpiece further comprises a laser scanning sensor rotating mechanism;
one end of the laser scanning sensor rotating mechanism is connected with the Z-axis air floatation guide rail, and the other end of the laser scanning sensor rotating mechanism is connected with the laser scanning sensor and used for driving the laser scanning sensor to swing in two directions of a Y axis and a Z axis of a measurement coordinate system;
and the laser line scanning sensor numerical control module is used for realizing the motion control of the rotating mechanism of the laser scanning sensor and setting the deflection angle and speed of the laser scanning sensor.
The laser scanning sensor rotating mechanism comprises an upper upright post, a servo motor and a lower upright post; the upper upright post is fixedly arranged on an air floating block of the Z-axis air floating guide rail along the Z-axis direction, the servo motor main body is arranged on the upper upright post, a rotating shaft of the servo motor is parallel to the X-axis direction of a measurement coordinate system, the rotating shaft of the servo motor is in interference fit with the lower upright post, and the shaft is not in contact with the upper upright post. The laser line scanning sensor is fixedly connected with the other end of the lower upright post, and the lower upright post is driven by the servo motor to rotate by a certain deflection angle, so that the laser line scanning sensor is driven to deflect together, and the workpiece is scanned at different angles.
The laser scanning sensor is a line scanning sensor.
The laser scanning sensor is a blue laser line scanning sensor.
Grating rulers are respectively installed on the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail, and the three-dimensional moving platform numerical control module and the grating rulers form a closed-loop feedback system: the grating ruler is used for measuring the position information of the measured workpiece in the three-dimensional direction and feeding the position information back to the three-dimensional moving platform numerical control module; the three-dimensional moving platform numerical control module continuously compares the theoretical position of the workpiece to be measured with the actual position of the workpiece fed back by the grating ruler, and adjusts the movement of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail in the three-dimensional direction at any time through the control of PID parameters.
The detection software comprises a data acquisition and processing module, a size measurement and error identification module and a parameter setting module;
the data acquisition and processing module is used for obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and the distance information from the scanning points on the measured workpiece to the sensing head, then carrying out denoising, simplification and splicing processing on the three-dimensional coordinate point cloud data of the scanning points on the measured workpiece, and sending the processed three-dimensional coordinate point cloud data of the scanning points on the measured workpiece to the size measurement and error identification module;
the size measurement and error identification module selects point cloud data corresponding to the geometric features to be measured of the workpiece to be measured according to a drawing file of the workpiece to be measured, then generates an image of the geometric features, measures the sizes of the geometric features, compares the measured sizes of the geometric features with standard sizes to obtain form and position errors of the geometric features of the workpiece, judges the qualification of the workpiece to be measured according to error results, generates a detection report, and stores and displays the detection report.
And the parameter setting module is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting the initial position information of a measuring head of the laser scanning sensor, generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and sending the movement tracks to the numerical control module of the three-dimensional moving platform. And setting angle information of the laser scanning sensor and sending the angle information to the numerical control module of the laser scanning sensor.
The automatic workpiece three-dimensional size detection system based on laser scanning also comprises a quality tracing module, and historical detection data of corresponding detection samples are inquired according to the requirements of users; and carrying out statistical analysis on historical detection data of the detected sample.
The other technical solution of the invention is as follows: a method for automatically detecting the three-dimensional size of a workpiece based on laser scanning is characterized by comprising the following steps:
s1, carrying out scanning work on the workpiece to obtain multilayer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected;
s2: after scanning, carrying out denoising, simplification and splicing treatment on the multi-layer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected, and finally synthesizing the data to be detected in the same coordinate system;
s3: and according to the drawing file of the measured workpiece, selecting point cloud data corresponding to the geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data, then generating an image of the geometric features, and measuring the size of the geometric features.
S4: and comparing the measured size of the geometric features with the standard size to obtain the form and position errors of the geometric features of the workpiece, judging the qualification of the workpiece to be detected according to the form and position error result, generating a detection report, and storing and displaying the detection report.
The specific steps of step S1 are:
s1.1, defining a processing base surface of a workpiece to be detected as the front surface of the workpiece to be detected, taking the processing base surface as an initial surface to be detected, placing the workpiece to be detected on a mobile platform, wherein the surface to be detected is upward, and a laser line scanning sensor is downward vertically;
s1.2, setting the X-axis air-floating guide rail, the Y-axis air-floating guide rail movement speed and movement track of the three-dimensional moving platform, the initial height of the laser line scanning sensor in the Z-axis direction and the angle of the laser line scanning sensor according to the known size of the surface to be measured of the workpiece to be measured, and setting the scanning layer number of the surface to be measured according to the height ranges of the laser line scanning sensor and the surface to be measured of the workpiece to be measured;
s1.3: placing a workpiece to be detected on a displacement platform, wherein the workpiece to be detected alternately performs reciprocating stable uniform motion along an X axis and a Y axis relative to a laser line scanning sensor, and the laser line scanning sensor performs uninterrupted scanning on the surface to be detected of the workpiece to be detected until the first layer of scanning on the surface to be detected of the workpiece to be detected within the range of the scanning sensor is finished, so as to obtain first layer of three-dimensional point cloud data of the surface to be detected of the workpiece to be detected;
s1.4: controlling the scanning sensor to move a certain distance in the Z-axis direction according to the height of the surface to be measured of the measured workpiece and the distance measurement range of the laser line scanning sensor, scanning the second layer according to the scanning method in the step two, and repeating the steps until multilayer three-dimensional point cloud data of the surface to be measured of the measured workpiece are obtained;
s1.5: turning the tested workpiece by 180 degrees, taking the reverse side as the side to be tested to be upward, placing the tested workpiece on a mobile platform, enabling a laser line scanning sensor to be vertical to be downward, repeating the steps S1.2, S1.3 and S1.4, and obtaining multilayer three-dimensional point cloud data of the reverse side of the tested workpiece;
s1.6: and controlling the laser line scanning sensor to deflect by a certain angle, scanning the side surface of the workpiece, and acquiring multilayer three-dimensional point cloud data of the side surface of the workpiece to be detected.
Compared with the prior art, the invention has the advantages that:
(1) according to the invention, the numerical control three-dimensional moving platform is adopted, so that the movement of the workpiece to be detected relative to the laser sensor in the X-axis direction and the movement of the laser line scanning sensor in the Y-axis and Z-axis directions are realized, the whole-course dynamic measurement is realized, the manual movement detection is replaced, and the detection efficiency is improved.
(2) The three-dimensional moving platform provided by the invention realizes three-dimensional movement by adopting the air-floating guide rail, realizes translational sliding, has the advantages of no friction and no vibration, achieves the effect of high moving precision, and can control the measurement error within +/-5 mu m.
(3) The laser scanning sensor rotating mechanism is assembled on the Z-axis air-floating guide rail, so that the deflection of the laser scanning sensor can be realized, and the workpiece can be scanned at different angles.
(4) The invention adopts the laser scanning sensor, the measuring mode is non-contact measuring, and compared with the traditional contact measuring method, the invention can greatly shorten the detection time and improve the detection efficiency.
(5) The invention selects the blue line scanning type laser scanning sensor, so that the anti-interference capability is strong, and the measurement precision is high;
(6) after the detection of the detected sample is finished, the detection result of the detected sample can be stored in the database server, the database is established, the product quality process tracing and data analysis can be realized, and meanwhile, a corresponding detected sample detection report can be automatically generated.
(7) The invention does not need to reprogram different products, has no workload of repeated programming, is suitable for detecting workpiece products with less batch, and improves the detection efficiency.
Drawings
FIG. 1 is a system block diagram of an embodiment of the invention.
FIG. 2 is a block diagram of the detection software modules of the embodiment of the present invention.
Fig. 3 is a three-dimensional effect diagram of the automatic detection system according to the embodiment of the invention.
FIG. 4 is a three-dimensional effect diagram of the air rail portion of the embodiment of the invention.
Fig. 5 is a three-dimensional effect diagram of a rotating column according to an embodiment of the present invention.
FIG. 6 is a flow chart of a data stitching algorithm according to an embodiment of the present invention.
FIG. 7 is a flow chart of detection according to an embodiment of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific examples.
As shown in fig. 1, the present invention provides a three-dimensional automatic workpiece dimension detection system based on laser scanning. The system comprises a three-dimensional mobile platform, a three-dimensional mobile platform numerical control module, a laser scanning sensor numerical control module, a laser scanning
the three-dimensional moving platform comprises an X-axis air-floating guide rail, a Y-axis air-floating guide rail, a Z-axis air-floating guide rail and a displacement platform, and the workpiece to be measured is horizontally placed on the displacement platform; the X-axis air floatation guide rail drives the displacement platform to move along the X-axis direction of the measurement coordinate system; and the tail end of the Z-axis air-floating guide rail is provided with a laser scanning sensor, and the Y-axis air-floating guide rail and the Z-axis air-floating guide rail drive the laser scanning sensor to move relative to the displacement platform along the Y-axis direction and the Z-axis direction of the measurement coordinate system.
And the three-dimensional moving platform numerical control module controls the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail to move in the three-dimensional direction according to a preset movement track and speed, acquires the position information of the workpiece to be detected in real time and sends the position information to the detection software, and sends a measuring pulse signal to the laser scanning sensor numerical control module when the workpiece to be detected moves for a certain distance.
The laser scanning sensor numerical control module generates an acquisition driving signal after receiving the measurement pulse signal and sends the acquisition driving signal to the laser scanning sensor; the motion control of the
And the laser scanning sensor is a blue laser line scanning sensor, scans the workpiece to be detected under the control of the acquisition driving signal, obtains the distance information from the scanning point on the workpiece to be detected to the sensing head, and sends the distance information to the detection software.
One end of a laser scanning sensor
the detection software is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting initial position information of a measuring head of the laser scanning sensor and generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail; setting angle information of a laser scanning sensor and sending the angle information to a numerical control module of the laser scanning sensor; obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to position information of the measured workpiece and distance information from the scanning points on the measured workpiece to a sensing head, denoising, simplifying and splicing the three-dimensional coordinate point cloud data, selecting point cloud data corresponding to geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data according to a drawing file of the measured workpiece, then generating an image of the geometric features, measuring the dimensions of the geometric features, comparing the measured dimensions of the geometric features with standard dimensions (drawing dimensions) to obtain form and position errors of the geometric features of the workpiece, judging the qualification of the measured workpiece according to the form and position error result, generating a detection report, and storing and displaying the detection report.
The power supply module supplies power for the three-dimensional moving platform, the three-dimensional moving platform numerical control module, the laser scanning sensor and the laser scanning sensor numerical control module.
The power supply module comprises a switching power supply, a power supply filter and a power supply conversion circuit. The switching power supply generates power supply voltage and outputs the power supply voltage to the power supply filter; the power filter filters interference generated when the switching power supply is started or shut down, so that the switching power supply can work normally and stably; the power supply conversion circuit converts the power supply voltage after the interference is filtered into the working voltage required by the three-dimensional mobile platform, the three-dimensional mobile platform numerical control module, the laser scanning sensor numerical control module and the like.
The X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail have the same structure. As shown in fig. 4, the air-floating guide rail includes an
Air is injected into the
The X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail are respectively provided with a grating ruler, a controller and a motor, and the three-dimensional moving platform numerical control module and the grating ruler form a closed-loop feedback system: the grating ruler is used for measuring the position information of the measured workpiece in the three-dimensional direction and feeding the position information back to the three-dimensional moving platform numerical control module; the three-dimensional moving platform numerical control module continuously compares the theoretical position of the workpiece to be measured with the actual position of the workpiece fed back by the grating ruler, and adjusts the movement of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail in the three-dimensional direction by controlling the three guide rail servo motors at any time through the control of PID parameters, so that the actual position of the movement is consistent with the theoretical position required by a computer as much as possible, and the control precision is improved.
The laser line scanning sensor
As shown in fig. 5, the laser scanning sensor
As shown in fig. 2, the detection software includes a data acquisition and processing module, a dimension measurement and error identification module, a parameter setting module, a gauge calibration module, and a quality tracing module.
The data acquisition and processing module is used for obtaining three-dimensional coordinate point cloud data of scanning points on a measured workpiece according to the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and the distance information from the scanning points on the measured workpiece to the sensing head, then carrying out denoising, simplification and splicing processing on the three-dimensional coordinate point cloud data of the scanning points on the measured workpiece, and sending the processed three-dimensional coordinate point cloud data of the scanning points on the measured workpiece to the size measurement and error identification module;
the size measurement and error identification module selects point cloud data corresponding to geometric features (such as circles, steps, straight line segments, holes and the like on a workpiece) to be measured of the workpiece according to a drawing file of the workpiece to be measured, then generates images (such as circles and straight lines) of the geometric features by a least square method or a Hough transformation method, measures the sizes (such as the length, the width and the height of the workpiece, the diameter of a circle on the workpiece, the height of the steps, the hole spacing and the like) of the geometric features, compares the measured sizes of the geometric features with standard sizes (drawing sizes) to obtain form and position errors of the geometric features of the workpiece, judges the qualification of the workpiece to be measured according to error results, generates a detection report, and stores and displays the detection report.
And the parameter setting module is used for setting the movement speeds of an X-axis air-floating guide rail, a Y-axis air-floating guide rail and a Z-axis air-floating guide rail of the three-dimensional moving platform, setting the initial position information of a measuring head of the laser scanning sensor by combining the surface topography height characteristics of the workpiece and the effective range of the scanning height of the measuring head, generating the movement tracks of the X-axis air-floating guide rail, the Y-axis air-floating guide rail and the Z-axis air-floating guide rail and sending the movement tracks to the numerical. And setting angle information of the laser scanning sensor and sending the angle information to the numerical control module of the laser scanning sensor.
And the quality tracing module is used for storing all the measurement data and establishing a database according to the user requirements. The historical detection data of the corresponding detection sample can be inquired; and carrying out statistical analysis on historical detection data of the detected sample.
The measuring tool calibration module obtains the measuring dimensions (including length, width, height, aperture, pitch, straightness, verticality and the like) of the X, Y, Z axis three-axis direction of the standard part by scanning the three-dimensional standard part, compares the measuring dimensions with the standard dimensions (drawing dimensions) to obtain a compensation coefficient, and compensates the dimension parameters according to the compensation coefficient. The standard parts are flat plate standard parts and step standard parts.
Based on the system, the invention also provides a method for automatically detecting the three-dimensional size of the workpiece based on laser scanning, as shown in fig. 7, the method comprises the following steps:
fig. 7 shows a detection process of the apparatus of the present invention, which comprises the following steps:
s1: equipment initialization: before the detection work is started, initialization preparation is carried out, the device is powered on, and then the three-dimensional mobile platform, the laser line scanning sensor and the detection software are started successively. And the detection software carries out system self-detection to complete initialization work. After the initialization preparation work is finished, the scanning work of the workpiece is started, and as shown in fig. 3, the multi-layer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected are obtained:
s1.1, defining a processing base surface of a workpiece to be detected as the front surface of the workpiece to be detected, taking the processing base surface as an initial surface to be detected, placing the workpiece to be detected on a mobile platform, wherein the surface to be detected is upward, and a laser line scanning sensor is downward vertically;
s1.2, setting the X-axis air-floating guide rail, the Y-axis air-floating guide rail movement speed and movement track of the three-dimensional moving platform, the initial height of the laser line scanning sensor in the Z-axis direction and the angle of the laser line scanning sensor according to the known size of the surface to be measured of the workpiece to be measured, and setting the scanning layer number of the surface to be measured according to the height ranges of the laser line scanning sensor and the surface to be measured of the workpiece to be measured;
s1.3: placing a workpiece to be detected on a displacement platform, wherein the workpiece to be detected alternately performs reciprocating stable uniform motion along an X axis and a Y axis relative to a laser line scanning sensor, and the laser line scanning sensor performs uninterrupted scanning on the surface to be detected of the workpiece to be detected until the first layer of scanning on the surface to be detected of the workpiece to be detected within the range of the scanning sensor is finished, so as to obtain first layer of three-dimensional point cloud data of the surface to be detected of the workpiece to be detected;
s1.4: controlling the scanning sensor to move a certain distance in the Z-axis direction according to the height of the surface to be measured of the measured workpiece and the distance measurement range of the laser line scanning sensor, scanning the second layer according to the scanning method in the step two, and repeating the steps until multilayer three-dimensional point cloud data of the surface to be measured of the measured workpiece are obtained;
s1.5: turning the tested workpiece by 180 degrees, taking the reverse side as the side to be tested to be upward, placing the tested workpiece on a mobile platform, enabling a laser line scanning sensor to be vertical to be downward, repeating the steps S1.2, S1.3 and S1.4, and obtaining multilayer three-dimensional point cloud data of the reverse side of the tested workpiece;
s1.6: controlling a laser line scanning sensor to deflect a certain angle, scanning the side face of a workpiece, and acquiring multi-layer three-dimensional point cloud data of the side face of the workpiece to be detected;
s2: and after scanning, carrying out denoising, simplification and splicing on the multi-layer three-dimensional coordinate point cloud data of the front surface, the back surface and the side surface of the workpiece to be detected, and finally synthesizing the data to the same coordinate system. As shown in fig. 6, the S2 performs data splicing as follows. It is assumed that the laser
The spatial coordinate transformation of the point set may be expressed as the following transformation:
μ(k+1)’＝Rμk+1+T (1)
wherein, R is a rotation matrix, and T is a translation vector.
The same portion of the environment represented in the two sets of laser data points is referred to as the common portion. The basis of stitching is to find a set of data points mu(k+1)°And mu(k+1)With (R, T) such that the common part between the two sets of data points coincides. Expressed by the formula:
com(|μk-μ(k+1)'|)＝0 (2)
wherein com (-) represents an operator taking the common part of two sets of point sets, and | is the Euclidean distance operator. In general, only part of the two sets of laser data point sets collected by the laser scanning probe at different viewing angles can be overlapped, and then the following form can be written in formula 2:
min(|μk-μ(k+1)'|)＝0 (3)
where min (.) is the minimum operator.
Let { aiIs from muk＝{μkSelect out point set, { b }iIs from muk＝{μk+1And (5) selecting a point set from the points, wherein i is 0,1, … m. Using { aiAnd { b }andiForm a corresponding point set { a }i,biI |, 1,2, … m }. Combining equations (1) and (3), and considering all points in the set of points, one can obtain:
the registration and splicing problem of the laser data point sets under multiple viewing angles can be described as follows: the variation parameters R and T are solved so that the objective evaluation function g (R, T) shown in formula (4) reaches the minimum value. When the rotation matrix R and the translation vector T are obtained by solving, the data point sets under different viewing angles can be registered to the same space coordinate system to complete the splicing of the workpiece three-dimensional model space point cloud data.
S3: and according to the drawing file of the measured workpiece, selecting point cloud data corresponding to the geometric features of the measured workpiece from the processed three-dimensional coordinate point cloud data, then generating an image of the geometric features, and measuring the size of the geometric features.
S4: and comparing the measured size of the geometric features with the standard size (drawing size) to obtain the form and position errors of the geometric features of the workpiece, judging the qualification of the workpiece to be detected according to the form and position error result, generating a detection report, and storing and displaying the detection report.
The device of the invention greatly shortens the detection time of a single workpiece, can automatically generate a test result report, and can establish a workpiece size, shape and position parameter database, thereby solving the problem of workpiece test automation, improving the test efficiency and reliability, forming a workpiece product quality tracing system and improving and analyzing process parameters
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