CN113406122B - Double-mechanical-arm digital ray detection device and automatic detection method - Google Patents

Abstract

The invention relates to a double-manipulator digital ray detection device and an automatic detection method, which belong to the field of non-destructive ray detection, and solve the problems of complex motion mechanism design, difficult control, inability to realize automatic detection and inability to detect complex curved surface workpieces in the existing workpiece detection system. The problem of realizing vertical transillumination detection. The present application provides a double-manipulator digital radiation detection device and an automatic detection method based on the detection device. The device drives the ray source and the detector to move by setting two mechanical arms on both sides of the workpiece, which reduces the difficulty of controlling the motion mechanism, and at the same time can realize the detection of any position, angle, and magnification of the workpiece; at the same time, based on the device, through The control program of the manipulator is written to realize the automatic detection of the workpiece, and the automatic detection of the vertical transillumination of the complex surface is realized by obtaining the scanning path points based on the three-dimensional model of the workpiece through computer graphics. The device and method can be widely used in the field of non-destructive testing of workpieces, reduce the difficulty of control and improve the automation of testing.

Description

A digital ray detection device with dual robotic arms and an automatic detection method

The invention relates to the field of digital ray nondestructive testing, in particular to a double-manipulator digital ray testing device and an automatic testing method.

Background technique

Non-destructive testing is an indispensable tool in industrial development, which reflects a country's industrial development level to a certain extent. As a conventional non-destructive testing method, X-ray testing technology has been used in the industrial field for nearly a hundred years. In the early days and in some current industrial fields (such as the field of military manufacturing), X-ray inspection usually uses film photography as the main detection method. And other problems, it has not adapted to the development trend of non-destructive testing in the information age. At present, digital ray nondestructive testing technology has been widely used in the industrial field. On the premise of ensuring the quality of product inspection, digital ray nondestructive testing technology has the characteristics of fast detection speed, low detection cost, easy image preservation, and easy remote analysis and diagnosis. It is the development direction of ray inspection. The use of digital ray nondestructive testing technology can improve image contrast and defect identification through digital image processing methods such as gray scale adjustment, enhancement, and sharpening, and further use defect identification algorithms to realize automatic screening, positioning, and classification of defects, thereby realizing intelligent evaluation. films, greatly improving the accuracy of defect identification and film review efficiency.

At present, digital ray inspection schemes usually place the workpiece on the stage, and the stage is located between the X-ray tube and the detector, so as to realize X-ray transillumination imaging of the workpiece. In order to meet the transillumination requirements for different workpiece sizes, different workpiece positions, different transillumination angles, and different magnification ratios, it is necessary to add multiple degrees of freedom of motion to the ray tube, detector, and workpiece stage. Since the imaging field of view of digital ray detection is limited by factors such as the size of the detector plane, the radiation angle of the ray, and the imaging magnification ratio, in order to meet the full coverage detection of large-sized workpieces, the ray tube and detector (or workpiece stage ) increases multiple linear motion degrees of freedom, thereby expanding the detection range. In order to meet the detection of different angles of the workpiece, it is usually realized by using the rotation of the workpiece stage or the rotation of the X-ray tube detector (such as C-arm).

For the above general workpiece detection system, in order to meet the transillumination requirements for different workpiece sizes, different workpiece positions, different transillumination angles, and different magnification ratios, it is necessary to add multiple degrees of freedom to the ray source, detector, and workpiece stage , usually requires about 10 degrees of freedom of motion. For the detection of different angles, especially when it is necessary to perform multi-angle detection on multiple rotation axis directions, or when it is necessary to detect along the normal direction of the workpiece surface, the design of the system mechanical motion mechanism will be very complicated. , making the motion control extremely complicated, and the detection device based on this complex motion mechanism cannot realize automatic detection.

In addition, for workpieces with complex curved surfaces, the existing digital ray inspection methods cannot achieve vertical transillumination on any surface position of the workpiece, while oblique transillumination increases the penetration wall thickness of rays, which also affects imaging sensitivity and imaging quality, and cannot Locate the specific location of the workpiece surface where the defect is located.

Contents of the invention

In view of the above analysis, in order to solve the problems that the existing workpiece detection system is difficult to control the motion mechanism, cannot realize automatic detection, and cannot realize the vertical transillumination detection of complex curved surface workpieces, the embodiment of the present invention aims to provide a dual-manipulator digital ray A detection device and an automatic detection method based on the device.

On the one hand, an embodiment of the present invention provides a dual-manipulator digital radiation detection device, which includes a radiation source, a detector, a workpiece turntable, a first robot arm, a second robot arm, a control system, and a data acquisition system;

The first mechanical arm and the second mechanical arm are placed on both sides of the workpiece turntable, and the radiation source and detector are respectively installed on the first mechanical arm and the second mechanical arm;

The workpiece to be tested is installed on the workpiece turntable;

The data acquisition system is used to collect the imaging data of the detector;

The control system changes the position and direction of the detector and the ray source by adjusting the movement axes of the first mechanical arm and the second mechanical arm, so as to realize the detection of the workpiece; the central beam of the ray source is always perpendicular to the surface of the detector and passes through the detection during scanning. device center point.

Further, the control system keeps the central beam direction of the radiation source unchanged by adjusting the movement axes of the first mechanical arm and the second mechanical arm, so that the detector and the radiation source perform synchronous translational movement along a certain direction, and realize the control of different positions of the workpiece. detection.

Further, the control system rotates the detector along the horizontal or vertical bisector of the detector by adjusting the movement axes of the first mechanical arm and the second mechanical arm, keeping the position of the detector center point unchanged, and at the same time makes the ray source rotate with the detector The center point is the center of the circle, and the distance from the center point of the detector to the focal point of the ray source is used as the radius to make an arc orbit to detect different angles of the workpiece.

Further, the control system adjusts the movement axes of the first mechanical arm and the second mechanical arm so that the detector and the ray source move along a distance from the center point of the detector to the point to be measured with a certain point in the workpiece as the center of the circle. The distance is the radius, and the ray source takes the distance from the point to be measured to the focus of the ray source as the radius, and the two rotate in an arc orbit in the opposite direction to realize the detection of different angles of the workpiece.

Further, the control system adjusts the movement axes of the first mechanical arm or the second mechanical arm so that the detector or the ray source moves along the line connecting the ray source and the detector, thereby changing the distance between the ray source and the detector, and realizing Detection of workpieces with different magnification ratios.

Further, the detection of different angles in the circumferential direction of the workpiece is realized through the rotation of the workpiece turntable.

On the other hand, an embodiment of the present invention provides an automatic detection method based on a double-manipulator digital radiation detection device, which is characterized in that it includes the following steps:

S1. The control system runs the robotic arm control program;

S2. The control system controls the ray source and the detector to move to the i-th scanning path point, and the initial value of i is 1;

S3. The control system outputs an instruction to start collecting signals to the data acquisition system, then executes the input waiting instruction, and waits for the data acquisition system to complete data acquisition;

S4. After the data acquisition system receives the instruction to start collecting signals, it turns on the ray source and the detector, and collects the data output by the detectors, and outputs a collection completion signal to the control system after the collection is completed;

S5. After the control system receives the collection completion signal, it judges whether the program is finished, if yes, completes the detection, if not, adds 1 to the value of i, and returns to step S2.

Further, the scanning path points are obtained by manual teaching, specifying offsets, or extracting path points through computer graphics based on the three-dimensional model of the workpiece.

Further, the above-mentioned method for extracting path points based on the three-dimensional model of the workpiece through computer graphics includes:

S21. Obtain a three-dimensional model of the workpiece;

S22, dividing the surface of the workpiece to be measured into a plurality of regions to be detected;

S23. Obtain the center point position and normal direction of each area to be detected on the surface of the workpiece based on computer graphics;

S24. Determine the position and normal direction of the center point of the detector according to the position and normal direction of the center point above, wherein the normal direction of the detector is consistent with the normal direction of the area;

S25. Obtain the focus position of the ray source and the direction of the central beam according to the position of the center point of the detector and the normal direction, wherein the direction of the central beam is consistent with the normal direction of the detector;

The center position and normal direction of the detector, the focus position of the ray source and the direction of the center beam corresponding to each of the above regions to be measured are the acquired scanning path points.

Further, the control procedure of the manipulator is as follows:

S1. Create a robotic arm control program;

S2. Insert a motion command into the program to make the ray source and detector move to the scanning path point;

S3, inserting the command to start collecting signals in the program, and notifying the data collection system to start collecting data;

S4, inserting the input waiting instruction in the program, waiting for the data acquisition system to collect and complete;

S5. Judging whether the scanning path planning is completed, if not, return to step S2, and if yes, end.

Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

1. The present invention simplifies the motion structure by adopting double mechanical arms to drive the detector and the ray source, and the motion control of the mechanical arms is easy to realize; and the device drives the detector through the control and adjustment of the movement axes of the mechanical arms by the control system. It can move synchronously with the ray source along a certain direction, the detector can keep the center point unchanged for rotational movement, and the detector and ray source can make reverse rotation along the arc track, and finally realize the different positions and angles of the workpiece. , Detection of different magnification ratios.

2. By using three-dimensional modeling of the workpiece, the position and normal direction of the center point of the area to be measured on the surface of the workpiece are obtained by using computer graphics, and the position and normal direction of the center point of the detector corresponding to each detection area are obtained according to the position and normal direction of the center point. direction, the focus position of the ray source, and the direction of the central beam, and make the normal direction of the detector and the direction of the central beam of the ray source consistent with the normal direction of the area to be measured. The scanning path points obtained in this way can realize the vertical penetration of complex curved surfaces. The imaging quality and detection accuracy are improved.

3. By writing the control program of the robotic arm, insert three control instructions corresponding to each path point into the program. According to the instructions, the control system controls the movement of each movement axis of the robotic arm, so that the detector and the ray source reach the point corresponding to the scanning path point. position, and control the acquisition system to complete data acquisition and realize automatic detection.

In the present invention, the above technical solutions can also be combined with each other to realize more preferred combination solutions. Additional features and advantages of the invention will be set forth in the description which follows, and some of the advantages will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the matter particularly pointed out in the written description and appended drawings.

Description of drawings

Fig. 1 is a schematic diagram of a double-manipulator digital radiation detection device;

Fig. 2 is a schematic diagram of the structure of the mechanical arm;

Figure 3 is the definition and reference relationship of the dual-manipulator linkage coordinate system;

Fig. 4 is a schematic diagram of detector scanning position adjustment;

Fig. 5 is a schematic diagram of detector scanning angle adjustment;

Figure 6 is a comparison of imaging results of overlapping defects at different transillumination angles;

Fig. 7 is a schematic diagram of scanning focal length adjustment;

Fig. 8 is a flowchart of an automatic detection method based on a double-manipulator digital radiation detection device;

Fig. 9 is a flow chart of the robotic arm program;

Fig. 10 is a schematic diagram of division of workpiece surface detection areas;

Fig. 11 is a schematic diagram of the world coordinate system in the detection device.

The drawings are for the purpose of illustrating specific embodiments only and are not to be considered as limitations of the invention, and like reference numerals refer to like parts throughout the drawings.

Detailed ways

Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the application and together with the embodiments of the present invention are used to explain the principle of the present invention and are not intended to limit the scope of the present invention.

Example 1

A specific embodiment of the present invention discloses a dual-manipulator digital radiation detection device,

The device includes a ray source, a detector, a workpiece turntable, a first mechanical arm, a second mechanical arm, a control system and a data acquisition system;

The first mechanical arm and the second mechanical arm are placed on opposite sides of the workpiece turntable, and the radiation source and detector are installed on the first mechanical arm and the second mechanical arm respectively; the workpiece to be measured is installed on the workpiece turntable; the data acquisition system is used To collect detector imaging data;

The control system changes the position and direction of the detector and the ray source by adjusting the movement axes of the first mechanical arm and the second mechanical arm, so as to realize the detection of the workpiece; the central beam of the ray source is always perpendicular to the surface of the detector and passes through the detection during scanning. The central point of the detector, specifically, through the linkage of the first mechanical arm and the second mechanical arm, the central beam of the ray source is always perpendicular to the surface of the detector and passes through the central point of the detector.

The device uses double mechanical arms to drive the detector and the ray source to move, which simplifies the motion structure and is easy to realize the motion control of the mechanical arm; The source can move synchronously along a certain direction, the detector can keep the position of the center point unchanged for rotational movement, the detector and the ray source can make reverse rotation along the arc track, and finally realize the different positions, angles and different positions of the workpiece. Detection of magnification ratio.

The device will be specifically described below with reference to FIGS. 1-7. As shown in FIG. 1, the device includes: a radiation source, a detector, a first mechanical arm, a second mechanical arm, a workpiece turntable, a data acquisition system and a control system. A Cartesian coordinate system is established at the center of the workpiece turntable, and the Z axis is vertically upward. The end effector of the second mechanical arm is a detector, the end effector of the first mechanical arm is a radiation source, and the workpiece to be detected is placed on the workpiece turntable. The control system controls the movement axes of the first mechanical arm and the second mechanical arm to translate the detector and the ray source along the Y-axis or the Z-axis to realize the scanning detection of different transillumination positions in the same transillumination direction; make the detector and the ray source Translate along the X axis to realize the adjustment of the focal length, object distance, image distance and magnification ratio of the imaging system. By controlling the movement axes of the second mechanical arm and the first mechanical arm, the detector and the ray source rotate along the Y axis and move oppositely along the Z axis, so as to realize multi-angle detection of the detected workpiece along the rotation direction of the Y axis. By controlling the movement axes of the second mechanical arm and the first mechanical arm, the detector and the ray source rotate along the Z axis and move oppositely along the Y axis to realize multi-angle detection of the detected workpiece along the Z axis rotation direction. Considering the limitation of the movement range of the manipulator, the multi-angle detection of the detected workpiece along the Z-axis rotation direction is realized by the rotation of the workpiece turntable.

The control system completes the scanning detection of any position, any transmission angle, and any focal length magnification ratio of the detected workpiece through the coordinated control of the first mechanical arm, the second mechanical arm, the workpiece turntable, the ray source switch and the detector acquisition.

Specifically, the first robotic arm and the second robotic arm are six-degree-of-freedom robotic arms, including a base, a shoulder joint assembly, a large arm structural member, an elbow joint assembly, a forearm structural member, and a wrist joint assembly connected in sequence, as shown in the figure 2.

The workpiece to be tested can be any material and any shape that can be penetrated by rays. Specifically, it can be castings, weldments, composite materials, etc.; the workpiece turret is capable of supporting the weight of the workpiece and can rotate clockwise or counterclockwise. mechanical mechanism. Specifically, the rotary part of the turntable adopts a precision ring guide rail, and the upper part is supported by a ring product, with teeth on the outside, driven by a servo motor with a driving gear.

In the scanning inspection process of different positions and angles of the workpiece, it is necessary to keep the ray source facing the detector plane all the time, that is, the central beam of the ray source always passes through the center of the detector and is perpendicular to the detector surface. Therefore, when adjusting the position or angle of the detector, the ray source needs to be controlled in linkage. Here, the second robotic arm corresponding to the detector is the main controlling robotic arm, and the first robotic arm corresponding to the radiation source is the linkage robotic arm for description.

The definition and reference relationship of the linkage coordinate system of the double manipulator is shown in Figure 3. The base coordinate system is the reference point for the position of the manipulator. According to the geometric dimensions of each joint of the manipulator and the rotation angle of each axis, the positional relationship of the flange coordinate system to the reference base coordinate system can be calculated through the forward solution algorithm of the manipulator kinematics.

和

为第二机械臂和第一机械臂的法兰坐标系相对于基坐标系的位置变换矩阵(机械臂运动学正解算法)，

为第二机械臂各轴位置，

为第一机械臂各轴位置。Among them, P _FA and P _FB are the positions of the flange coordinate system of the second manipulator and the first manipulator, P _BA and P _BB are the positions of the base coordinate system of the second manipulator and the first manipulator,

and

is the position transformation matrix of the flange coordinate system of the second mechanical arm and the first mechanical arm relative to the base coordinate system (forward solution algorithm of mechanical arm kinematics),

is the position of each axis of the second mechanical arm,

is the position of each axis of the first mechanical arm.

Through the calibration method of the base coordinate system, the positional relationship between the base coordinate system B and the base coordinate system A can be calibrated.

为基坐标系B相对于基坐标系A的位置变换矩阵。in,

is the position transformation matrix of the base coordinate system B relative to the base coordinate system A.

Through the calibration method of the tool coordinate system, the positional relationship between the tool coordinate system B and the flange coordinate system B can be calibrated, and the positional relationship between the workpiece coordinate system B and the flange coordinate system A can be calibrated.

为工具坐标系B相对于法兰坐标系B的位置变换矩阵，

为的工件坐标系B相对于法兰坐标系A的位置变换矩阵。Among them, P _TB is the position of tool coordinate system B, P _WB is the position of workpiece coordinate system B,

is the position transformation matrix of tool coordinate system B relative to flange coordinate system B,

is the position transformation matrix of the workpiece coordinate system B relative to the flange coordinate system A.

The motion planning of the first robotic arm can be expressed as moving the tool coordinate system B to a certain coordinate system position Q of the workpiece coordinate system B, and Q can be understood as the position transformation matrix of the tool coordinate system B relative to the workpiece coordinate system B.

P _TB =P _WB ·Q (6)

From formulas (1) to (6), the position transformation relationship of flange coordinate system B relative to base coordinate system B is:

时，计算得到第一机械臂的各轴位置

使得Q保持不变。公式(7)中，

通过标定方法得到为常数，为了达到联动效果，Q也为常数，因此当第二机械臂的各轴移动到某位置

时，可计算出

的值，再根据第一机械臂的运动学逆解算法得到机械臂B的各轴位置

The linkage of the first manipulator can be described as when the position of each axis of the second manipulator is given

, calculate the position of each axis of the first mechanical arm

so that Q remains constant. In formula (7),

It is obtained as a constant through the calibration method. In order to achieve the linkage effect, Q is also a constant. Therefore, when the axes of the second mechanical arm move to a certain position

, it can be calculated

value, and then according to the kinematics inverse solution algorithm of the first mechanical arm to obtain the position of each axis of the mechanical arm B

In the following, how to adjust the scanning position, how to adjust the scanning angle and how to adjust the scanning magnification will be described through several specific examples.

(1) Adjust the scanning position

The adjustment of the scanning position here is to realize the full-coverage detection of the workpiece by synchronously translating the radiation source and the detector under the condition that the scanning angle (the angular relationship between the central beam of the radiation source and the workpiece) remains unchanged. Since the detector and the ray source are always in direct contact with each other, for the adjustment of the scanning position in this section, only the adjustment of the detector position needs to be considered. The manual motion control of the manipulator is divided into two types, axis space motion control and Cartesian space motion control. Axis space motion control can be described as controlling one joint axis individually at a time, and making the detector reach the target position through multiple control adjustments. Using this method to adjust the position of the detector is relatively complicated, and multiple joint axes need to be adjusted in sequence, and the accuracy cannot be guaranteed. Cartesian space motion control is controlled by trajectory planning. First, the reference coordinate system is selected, and then the linear trajectory is planned according to the XYZ axes of the reference coordinate system for motion control. Cartesian spatial motion control is usually used to adjust the detector position. Figure 4 shows several commonly used detector scanning position adjustment methods. Figure (a) is the vertical trajectory of the horizontal incident angle, which is suitable for vertically placed workpieces, and the surface of the workpiece is normally horizontal or approximately horizontal; Figure (b) is the vertical trajectory of the oblique incident angle, for the presence of In the case of horizontal ribs, using method (a) the ray cannot penetrate the thicker ribs, and the detection of the inner ribs of the workpiece is realized by oblique incident angle; Figure (c) is the oblique motion trajectory of the oblique incident angle, for the workpiece For the workpiece whose surface normal direction is inclined, in order to achieve the best imaging effect, the detector needs to face the workpiece surface, and the detector plane is approximately perpendicular to the workpiece surface normal direction by tilting the incident angle, and the motion detection along the inclined direction is used to achieve the best imaging Effect.

In addition to the above two manual motion control methods, more complex motion trajectories can also be planned through multi-point teaching or offline programming. Arc trajectory, spline trajectory, etc. can be planned through multi-point teaching; through offline programming based on the three-dimensional model of the workpiece, the trajectory that the detector plane is always perpendicular to the normal direction of the workpiece surface and the distance from the workpiece surface remains constant can be planned.

(2) Adjust the scanning angle

Similar to adjusting the scanning position, only the adjustment of the detector scanning angle needs to be considered. The adjustment of the scanning angle is also realized through the space motion control of the manipulator axis and the Cartesian space motion control. Axis space motion control is not intuitive and precision cannot be controlled. Cartesian space motion control can plan the movement trajectory along the X-axis, Y-axis or Z-axis according to the selected reference coordinate system, so as to achieve the effect of changing the posture at a fixed point. Figure 5 shows the effects of two fixed-point attitude changes.

Figure 5(a) changes the posture at a fixed point along the center point of the detector, that is, keeps the position of the center point of the detector unchanged, and makes the detector rotate along the X-axis or Y-axis. In this way, the scanning angle can be changed, combined with (1) 4(b) and 4(c) scanning methods can be realized; Fig. 5(b) is a fixed-point attitude change along a certain point of the workpiece, that is, with a certain point in the workpiece as the center, the detector and The ray source takes the center as the center of the circle, the distance between the detector center and the center is the radius, the ray source takes the distance from the center to the focus of the ray source as the radius, and the two move along the arc in opposite directions. Orbital rotation; in this way, different angles of the point can be detected, and the influence of image overlap on the detection result can be eliminated. As shown in Figure 6, there are two horizontal defects, one large and one small, inside the workpiece. When using horizontal angle transillumination, the imaging result only has large defects, and small defects cannot be seen; by changing the transillumination angle, the imaging results can be simultaneously See big flaws and small flaws.

In general, adjust the scanning angle of the X-axis rotation in Figure 5 by changing the posture at a fixed point, and adjust the scanning angle of the Y-axis rotation in a small range, and adjust the scanning angle of the Y-axis rotation in a large range through the rotation of the workpiece turntable. There is no need to adjust the scan angle for Z-axis rotation.

(3) Adjust the scanning magnification ratio

Define the distance from the focal point of the ray source to the surface of the detector as the focal length, the distance from the workpiece to the surface of the detector as the image distance, and the distance from the workpiece to the focal point of the ray source as the object distance. As shown in Figure 7, control the second mechanical arm to move the detector along the Z-axis of the tool coordinate system A to adjust the image distance. Since the ray source is linked with the detector, the object distance also changes and the focal length remains unchanged; When the linkage control is cancelled, the image distance and focal length can be changed without changing the object distance. The first mechanical arm is controlled to move the ray source along the Z axis of the tool coordinate system B to realize the adjustment of the object distance and focal length.

By executing the method flow of Embodiment 2, any optional implementation manner of this embodiment is used to perform automatic workpiece detection.

Compared with the prior art, the dual-manipulator digital ray detection device provided in this embodiment sets two manipulators on both sides of the workpiece, and drives the detector and the ray source to move through the manipulators, so that different positions, different angles, and For the detection of different amplification ratios, the use of two mechanical arms simplifies the complexity of the motion mechanism, and makes the motion control process simple and easy to implement.

Example 2

Another embodiment of the present invention provides an automatic detection method based on a double-manipulator digital radiation detection device, including the following steps:

S1. The control system runs the robotic arm control program;

S2. The control system controls the ray source and the detector to move to the i-th scanning path point, and the initial value of i is 1;

S3. The control system outputs an instruction to start collecting signals to the data acquisition system, then executes the input waiting instruction, and waits for the data acquisition system to complete data acquisition;

S4. After the data acquisition system receives the instruction to start collecting signals, it turns on the ray source and the detector, and collects the data output by the detectors, and outputs a collection completion signal to the control system after the collection is completed;

S5. After the control system receives the collection completion signal, it judges whether the program is finished, if yes, completes the detection, if not, adds 1 to the value of i, and returns to step S2.

The automatic detection method will be described in detail below with reference to FIGS. 8-11 .

The method controls the movement positions of the detector, the ray source and the workpiece by writing and running the control program of the manipulator, and combines with the data acquisition system to realize the automatic scanning process. The detection method includes the following steps, see FIG. 8 .

S1. The control system runs the robotic arm control program;

The flow chart of the robotic arm control program is shown in Figure 9. For each automated scanning process, a robotic arm control program needs to be created. Insert instruction blocks for each scanning path point in sequence in the robot control program, and each instruction block includes 3 instructions:

Insert motion instructions to move the ray source and detector to the specified scan path point.

An instruction to start collecting signals is inserted, and the instruction is transmitted to the data acquisition system to notify the data acquisition system to start collecting.

Insert the input waiting command and wait for the data acquisition system to complete the acquisition.

After inserting all scan path points into the robot program, complete the programming process and save the program.

Specifically, the robotic arm control program is as follows:

S11, creating a robotic arm control program;

S12. Insert a motion command into the program to move the ray source and the detector to the scanning path point;

S13. Inserting a start signal command into the program to notify the data acquisition system to start collecting data;

S14. Inserting an input waiting instruction into the program, waiting for the data collection system to complete the collection;

S15. Judging whether the scanning path planning is completed, if not, return to step S2, and if yes, end.

S2. The control system controls the ray source and the detector to move to the i-th scanning path point, and the initial value of i is 1;

The scanning path points can be obtained by manual teaching, by specifying offsets, or by extracting path points through computer graphics based on the three-dimensional model of the workpiece.

Preferably, the method for extracting waypoints by computer graphics based on the three-dimensional model of the workpiece comprises the following steps:

S21. Obtain a three-dimensional model of the workpiece;

The 3D model is the grid representation of the workpiece, which exists in the form of files, and records the position coordinates of each grid point in the model (such as stl files) and topological information such as edges, faces, and bodies contained in the model (such as stp files). Display editing is usually performed with a computer or other video equipment. Anything that exists in physical nature can be represented by a three-dimensional model. The three-dimensional model of the workpiece can be obtained in the following ways: Created by 3D modeling software. Generally, the workpiece to be inspected will create a 3D model before production, and carry out production and processing according to the drawings generated by the 3D model; modeling.

S22, dividing the surface of the workpiece to be detected into a plurality of regions to be detected;

Specifically, in order to realize the full coverage detection of the workpiece surface, the surface of the workpiece can be divided into a series of quadrilateral grid areas, as shown in Figure 10(a); in order to realize the detection of the vertical weld on the workpiece, the direction of the weld along the workpiece can be Divide the workpiece surface where the weld seam is located into multiple quadrilateral mesh areas, as shown in Fig. 10(b).

S23. Obtain the center point position and normal direction of each area to be detected on the surface of the workpiece based on computer graphics;

In the 3D modeling software, the world coordinate system is defined at the center of the bottom surface of the workpiece, with the center of the bottom surface of the workpiece as the origin, the X axis horizontally to the right, and the Z axis vertically upward to establish a coordinate system, as shown in Figure 11.

According to computer graphics, the position and normal direction of any point on the workpiece surface can be obtained, so the position and normal direction of the center point of the area to be detected can be obtained.

S24. Determine the position and normal direction of the center point of the detector corresponding to each area according to the position and normal direction of the above-mentioned center point, wherein the normal direction of the detector is consistent with the normal direction of the area;

Specifically, the method of obtaining the position and normal direction of the detector center point is as follows:

According to the position and normal direction of the center point P of the area to be detected and the distance v from the detector to the workpiece surface, the position and normal direction of the detector center point D can be determined. As shown in Figure 11, the angle between the normal direction and the vertical direction between the center point P and the detector center point D is α, and the distance between the center point P and the detector center point D is v, then x, The z coordinates are

D _x ＝P _x -v·sin(α) (8)

D _z =P _z +v·cos(α) (9)

S25. Obtain the focus position of the ray source and the direction of the central beam according to the position of the center point of the detector and the normal direction, wherein the direction of the central beam is consistent with the normal direction of the detector;

Specifically, the acquisition method of the focus position of the ray source and the direction of the central beam is as follows:

According to the position and normal direction of the center point P of the area to be detected, the distance v from the detector to the workpiece surface, and the distance f from the focus point of the ray source to the detector, determine the position and normal direction of the focus point R of the ray source. As shown in Figure 11, the angle between the normal direction of the center point P, the central beam direction of the ray source focus R and the vertical direction is α, and the distance between the center point P and the ray source focus R is f-v, then the ray source focus R The x and z coordinates are respectively

R _x ＝P _x +(fv) sin(α) (10)

R _z =P _z -(fv)·cos(α) (11).

The center position and normal direction of the detector, the focus position of the ray source, and the direction of the center beam corresponding to each of the above regions to be detected are the acquired scanning path points.

The controller controls the first mechanical arm and the second mechanical arm, so that the detector and the radiation source arrive at the scanning path point corresponding to the area to be detected.

S3. The control system outputs an instruction to start collecting signals to the data acquisition system, then executes the input waiting instruction, and waits for the data acquisition system to complete data acquisition;

After the detector and the ray source arrive at the scanning path point, the control system sends an instruction to the data acquisition system to start collecting signals, and then executes the input waiting instruction, waiting for the data acquisition system to complete the acquisition. The acquisition completion signal emitted.

S4. After the data acquisition system receives the instruction to start collecting signals, it turns on the ray source and the detector, and collects the data output by the detectors, and outputs a collection completion signal to the control system after the collection is completed;

After the data acquisition system receives the instruction to start collecting signals, it turns on the switch of the radiation source to make the radiation source emit radiation, and at the same time controls the detector to start working, receives the radiation beam that penetrates the surface of the workpiece and reaches the detector, and images it; the detector The imaging data is transmitted to the data acquisition system through the data line, and after the data acquisition system completes the acquisition, it outputs an acquisition completion signal to the control system, and controls the ray source to be turned off;

S5. After the control system receives the collection completion signal, it judges whether the program is finished, if yes, completes the detection, if not, adds 1 to the value of i, and returns to step S2.

There are multiple scanning path points in the program. After completing the detection of a scanning path point, the control system needs to judge whether the program is over. The end means that all the path points have been detected. For the detected waypoints, add 1 to the value of i to enter the next undetected waypoint until all the waypoints are detected, then the program ends.

In this automatic detection method, three control instructions corresponding to each path point are inserted into the program by writing the control program of the manipulator. According to the instructions, the control system controls the detector and the ray source to reach the position corresponding to the scanning path point, and controls the acquisition system to complete Data collection, automatic detection.

The method uses three-dimensional modeling of the workpiece, and uses computer graphics to obtain the position and normal direction of the center point of the area to be measured on the surface of the workpiece, and obtains the position and normal direction of the center point of the detector corresponding to each detection area according to the position and normal direction of the center point. direction, the focus position of the ray source and the direction of the central beam, and make the normal direction of the detector and the direction of the central beam of the ray source consistent with the normal direction of the area to be measured. The scanning path points obtained in this way can realize the vertical penetration of complex curved surfaces. The imaging quality and detection accuracy are improved.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

Claims (8)

1. An automatic detection method of a double-manipulator digital radiation detection device, characterized in that the device comprises a radiation source, a detector, a workpiece turntable, a first mechanical arm, a second mechanical arm, a control system and a data acquisition system; The first mechanical arm and the second mechanical arm are placed on both sides of the workpiece turntable, and the radiation source and detector are respectively installed on the first mechanical arm and the second mechanical arm; The workpiece to be tested is installed on the workpiece turntable; The data acquisition system is used to collect the imaging data of the detector; The control system changes the position and direction of the detector and the ray source by adjusting the movement axes of the first mechanical arm and the second mechanical arm, so as to realize the detection of the workpiece; the central beam of the ray source is always perpendicular to the surface of the detector and passes through the detection during scanning. device center point; The method comprises the steps of: S1. The control system runs the robotic arm control program; S2. The control system moves the ray source and the detector to the i-th scanning path point by controlling the mechanical arm, and the initial value of i is 1; Wherein, the scanning path point is extracted based on the three-dimensional model of the workpiece through computer graphics, including the following steps: S21. Acquiring a three-dimensional model of the workpiece; S22, dividing the surface of the workpiece into a plurality of regions to be detected; S23. Obtain the center point position and normal direction of each area to be detected on the surface of the workpiece based on computer graphics; S24. Determine the position and normal direction of the center point of the detector according to the position and normal direction of the center point above, wherein the normal direction of the detector is consistent with the normal direction of the area; S25. Obtain the focus position of the ray source and the direction of the central beam according to the position of the center point of the detector and the normal direction, wherein the direction of the central beam is consistent with the normal direction of the detector; The center position and normal direction of the detector, the focus position of the ray source and the direction of the center beam corresponding to the above-mentioned regions to be measured are the acquired scanning path points; S3. The control system outputs an instruction to start collecting signals to the data acquisition system, then executes the input waiting instruction, and waits for the data acquisition system to complete data acquisition; S4. After the data acquisition system receives the instruction to start collecting signals, it turns on the ray source and the detector, and collects the data output by the detectors, and outputs a collection completion signal to the control system after the collection is completed; S5. After the control system receives the collection completion signal, it judges whether the program is finished, if yes, completes the detection, if not, adds 1 to the value of i, and returns to step S2. 2 . The automatic detection method according to claim 1 , wherein the scanning path point can also be acquired by manual teaching and specifying an offset. 3 . 3. The automatic detection method according to claim 1, wherein the mechanical arm control program is specifically as follows: S11, creating a robotic arm control program; S12. Insert a motion command into the program to move the ray source and the detector to the scanning path point; S13. Inserting a start signal command into the program to notify the data acquisition system to start collecting data; S14. Inserting an input waiting instruction into the program, waiting for the data collection system to complete the collection; S15. Judging whether the scanning path planning is completed, if not, return to step S2, and if yes, end. 4. The automatic detection method of a double-manipulator digital radiation detection device according to claim 1, wherein the control system maintains the central beam of the radiation source by adjusting the movement axes of the first mechanical arm and the second mechanical arm. The direction does not change, so that the detector and the ray source perform synchronous translational movement along a certain direction, so as to realize the detection of different positions of the workpiece. 5. The automatic detection method of a dual-manipulator digital radiation detection device according to claim 1, wherein the control system maintains the position of the center point of the detector by adjusting the movement axes of the first mechanical arm and the second mechanical arm Make the detector rotate along the bisector in the horizontal or vertical direction of the detector without changing, and at the same time make the ray source rotate in an arc orbit with the center of the detector as the center and the distance from the center of the detector to the focus of the ray source as the radius , to realize the detection of different angles of the workpiece. 6. The automatic detection method of a dual-manipulator digital radiation detection device according to claim 1, wherein the control system adjusts the movement axes of the first mechanical arm and the second mechanical arm so that the detector and the radiation source Along the circle centered on a point to be measured in the workpiece, the radius of the detector is the distance from the center point of the detector to the point to be measured, and the radius of the ray source is the distance from the point to be measured to the focal point of the ray source, and the two work in opposite directions. The circular arc track rotates to realize the detection of different angles of the workpiece. 7. The automatic detection method of a double-manipulator digital radiation detection device according to any one of claims 1, 4-6, wherein the control system adjusts the movement of the first mechanical arm or the second mechanical arm axis, so that the detector or ray source moves along the direction of the line between the ray source and the detector, thereby changing the distance between the ray source and the detector, and realizing the detection of different magnification ratios of the workpiece. 8. The automatic detection method of a dual-manipulator digital radiation detection device according to any one of claims 1, 4-6, characterized in that the detection of different angles in the circumferential direction of the workpiece is realized by rotating the workpiece turntable.

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