Ultrasonic Nondestructive Testing Probe Self-Collimation Device Based on Manipulator and Working Method

Abstract

The present invention relates to an ultrasonic non-destructive testing probe self-collimation device and working method based on a manipulator, which is applicable to industrial and mining enterprises. An ultrasonic non-destructive testing probe self-collimation device is provided at the front end of a six-degree-of-freedom articulated manipulator. It includes a bolt base, on which there are a plurality of bolt holes for connecting with the front end of the six-degree-of-freedom articulated manipulator. The center of the bolt base is provided with an elastic connection mechanism, and an ultrasonic probe is connected to the elastic connection mechanism through a probe clamping mechanism. A plurality of laser range sensors are respectively arranged around the elastic connection mechanism. When it comes into contact with a curved surface during use, the spring in the elastic connection mechanism adaptively adjusts to make the ultrasonic probe closely adhere to the surface of the workpiece to be measured, and then ultrasonic scanning starts. Its structure is compact, the operation is convenient, and the use effect is good, having wide practicability in the technical field.

Description

Technical Field

[0001] The invention relates to an ultrasonic probe self-collimation device, in particular to an ultrasonic non-destructive testing probe self-collimation device based on a manipulator used in industrial and mining enterprises. Background Art

[0002] With the rapid development of modern industrial technology, the use of automated equipment to replace manual methods for flaw detection of curved workpieces has become a more advanced detection method. The manipulator can automatically complete specific operations according to internal programs, so it can replace manual labor to complete some heavy, complex, and dangerous detection operations, and has the advantages of high motion accuracy, high work efficiency, and low operating costs. Ultrasonic non-destructive testing technology, as a widely used detection technology in the industrial field, is an important means to ensure the quality of workpiece processing and the reliability of in-service workpieces. The automated detection method that combines the manipulator with ultrasonic non-destructive testing technology is an important future development direction of non-destructive testing technology.

[0003] When using ultrasound for nondestructive testing of curved workpieces, the acoustic axis of the ultrasonic transducer needs to coincide with the surface normal direction of the workpiece being tested close to the probe, so as to ensure that the ultrasonic wave propagates inside the workpiece at the most favorable angle for testing. In order to realize the automated testing of workpieces with complex curved surfaces, the position and posture of the ultrasonic transducer need to be accurately located.

[0004] The existing method usually knows the surface CAD model in advance, uses special software to plan the detection path according to the workpiece CAD model, automatically generates the detection trajectory, and the ultrasonic probe tracks the workpiece according to the pre-planned trajectory. This detection method can only detect surfaces with known contours, which makes the system less flexible and applicable and cannot meet special requirements. Summary of the invention

[0005] In view of the shortcomings of the above-mentioned technology, the purpose of the present invention is to provide a robot-based ultrasonic non-destructive testing probe self-alignment device. The device can obtain the contour information of the curved surface, guide the robot to reach the correct posture, and realize ultrasonic non-destructive testing of any curved surface.

[0006] In order to achieve the above technical objectives, a self-aligning device for an ultrasonic non-destructive testing probe based on a manipulator of the present invention is arranged to be used at the front end of a six-degree-of-freedom articulated manipulator. The six-degree-of-freedom articulated manipulator is arranged on a workbench. The six-degree-of-freedom articulated manipulator is connected to an industrial control computer through a wire. A water tank is also arranged on the workbench. A coupling agent is arranged in the water tank. A workpiece clamping device is immersed in the coupling agent. A workpiece to be tested is also immersed in the coupling agent above the workpiece clamping device. It is characterized in that: a self-aligning device for an ultrasonic non-destructive testing probe is arranged at the front end of the six-degree-of-freedom articulated manipulator, which includes a bolt base. A plurality of bolt holes for connecting to the front end of the six-degree-of-freedom articulated manipulator are arranged on the bolt base. An elastic connection mechanism is arranged at the center of the bolt base. An ultrasonic probe is connected to the elastic connection mechanism through a probe clamping mechanism. A plurality of laser range sensors are respectively arranged around the elastic connection mechanism.

[0007] The elastic connection mechanism includes a cylindrical sleeve, a connecting rod and a spring. The spring is arranged in the sleeve in a compressed state. The tail of the connecting rod is provided with a piston structure and is placed above the spring in the sleeve. The sleeve, the spring and the connecting rod form a spring piston structure. The tail of the connecting rod is pressed against the sleeve by the pressure of the spring. The head of the connecting rod is fixedly connected to the probe clamping mechanism. The bottom of the sleeve is fixedly connected to the bolt base.

[0008] When the ultrasonic probe touches the surface of the object to be tested obliquely, under the action of pressure, the spring undergoes non-axial deformation and the connecting rod tilts, so that the ultrasonic probe fits perfectly with the surface of the object to be measured.

[0009] The ultrasonic probe is a conventional liquid immersion double crystal probe. When the piezoelectric wafer of the ultrasonic probe receives an electrical pulse excitation, mechanical vibration will be generated. This vibration propagates in the medium as ultrasonic waves. During the propagation of ultrasonic waves, water or other liquids must be used as the coupling medium between the ultrasonic probe and the workpiece to be tested.

[0010] There are four probe clamping mechanisms in total, which are respectively arranged in four directions of the elastic connection mechanism. When installing, it should be ensured that the four laser range sensors are on a cross section, and the cross section is perpendicular to the propagation direction of the ultrasonic wave. The model of the laser range sensor is the OD2-P250W150I0 displacement measurement sensor of Sick Company. The detection range is 100mm - 400mm, and the repeatability accuracy is 75um.

[0011] A working method of a self-aligning device for an ultrasonic non-destructive testing probe based on a manipulator is as follows:

[0012] First, establish a world coordinate system with the center point of the base of the six-degree-of-freedom articulated manipulator as the origin, and establish a tool coordinate system with the intersection point of the axis of the ultrasonic probe and the plane where the laser sensor is located as the origin. When the ultrasonic non-destructive testing probe self-collimation device at the front end of the six-degree-of-freedom articulated manipulator moves to the detection point one, the four laser sensors on the ultrasonic non-destructive testing probe self-collimation device respectively measure the distance information from each laser sensor to the workpiece to be measured. According to the arrangement position of the laser sensors, the measured distance information can be divided into two groups. Through trigonometric relationship calculation, the rotation angles of the ultrasonic probe around the X-axis and Y-axis directions of the tool coordinate system are obtained respectively; through this rotation angle, the rotation matrix between the current tool coordinate system and the target tool coordinate system is calculated, and the rotation matrix of the ultrasonic non-destructive testing probe self-collimation device at the front end of the six-degree-of-freedom articulated manipulator is obtained; through the current posture of the robotic arm and the rotation matrix, the posture and position information of the next point of the six-degree-of-freedom articulated manipulator are obtained, and then the position of the ultrasonic non-destructive testing probe self-collimation device is adjusted, and it feeds along the Z-axis direction of the tool coordinate system towards the surface of the workpiece to be measured until it contacts the surface of the workpiece to be measured as the object to be measured. Then, through the spring in the elastic connection mechanism for adaptive adjustment, the ultrasonic probe is made to closely adhere to the surface of the workpiece to be measured, and then ultrasonic scanning starts.

[0013] Define the world coordinate system as {A}, the tool coordinate system as {B}, the origin P of the tool coordinate system {B}, and the coordinate of any point in the world coordinate system {A} is a 3×1 position vector. In the world coordinate system {A}, the position of the origin P of the tool coordinate system {B} can be expressed by the position vector where P x 、P y 、P z are the position coordinates of point P in the world coordinate system respectively; the position and posture of the six-degree-of-freedom articulated manipulator are described by the pose matrix of the tool coordinate system in the world coordinate system.

[0014] The posture of the tool coordinate system {B} is represented by three unit vectors in the direction of the main axis of the tool coordinate system {B}. Denote the three unit vectors in the direction of the main axis of the tool coordinate system {B} as In the world coordinate system {A}, it is denoted as Arrange these three unit vectors in sequence to obtain the rotation matrix of the tool coordinate system relative to the world coordinate system

[0015]

[0016] Through the previous position description and posture description, the pose of the manipulator can be described as:

[0017]

[0018] The homogeneous transformation matrix from the tool coordinate system to the world coordinate system is:

[0019]

[0020] The calculation method for the rotation angles of the self-collimation device of the ultrasonic non-destructive testing probe at the front end of the six-degree-of-freedom articulated manipulator around the X-axis and Y-axis of the tool coordinate system is as follows: Define the origin of the tool coordinate system as P, and the positions where the laser sensors are arranged are defined as four positions A, A1, B, and B1. The distances from the four laser sensors to point P are equal, and the distance is L. According to the shape and size of the surface to be measured, the vertical incidence detection method or the oblique incidence detection method can be used for calculation.

[0021] When the radius of curvature of the surface to be measured of the workpiece to be tested ≥ 20L, the area to be detected can be approximated as a plane, and at this time, the vertical incidence detection method is used for detection:

[0022] According to the arrangement positions of the laser sensors, the laser sensors at the four positions A, A1, B, and B1 are divided into two groups in the X-axis direction and Y-axis direction of the tool coordinate system. Among them, A and B are in the X-axis direction, and A1 and B1 are in the Y-axis direction. The rotation angles in the two directions are calculated respectively by the same method:

[0023] Taking the X-axis direction as an example to calculate the rotation angle α, points A and B are the positions where the two laser sensors are located, points C and D are the projections of the lasers of the two laser sensors A and B on the surface of the workpiece to be tested, L1 and L2 are the projections of the plane where the laser sensors are located and the surface to be measured of the workpiece to be tested in the X-axis direction respectively. Connect points C and D to form line segment CD, connect points B and D to form line segment BD, and use point A as the starting point to draw an auxiliary line parallel to line segment CD. The intersection point of the auxiliary line and line segment BD is point F, forming line segment AF; the distances from the two laser sensors A and B to point P are both L, and the lengths of line segments AC and BD are measured as a and b respectively;

[0024] It can be known from the Pythagorean theorem that:

[0025]

[0026] It can be known from the cosine theorem that:

[0027]

[0028] In the Y-axis direction, the rotation angle β is calculated by the same method, and finally the rotation angles α and β of the tool coordinate system in the two directions are obtained respectively;

[0029] When the curvature radius of the measured surface of the workpiece to be measured ≤ 20L, adjust the incident angle θ of the laser emitted by the laser sensor. After adjustment, the curvature radius of the measured surface should be ≥ 10 times the maximum distance between any two of the four laser points on the surface of the workpiece to be measured. The detected area is approximately a plane. At this time, the oblique incidence detection method is adopted:

[0030] Taking the X-axis direction as an example to calculate the rotation angle α. Points A and B are the positions of the laser sensors. Points C and D are the projections of the lasers of the two laser sensors A and B on the surface of the workpiece to be measured. L1 and L2 are the projections of the plane where the laser sensors are located and the surface of the workpiece to be measured in the X-axis direction respectively; Extend the line segments AC and BD to intersect at point G, and draw an auxiliary line AF parallel to the line segment CD and intersect the line segment BD at point F. The distances from the two laser sensors to point P are both L, the incident angle of the light is θ, and the lengths of the line segments AC and BD measured by the laser sensors A and B are a and b respectively.

[0031] According to the sine theorem:

[0032]

[0033] CG = AG - AC = AG - a

[0034] DG = BG - BD = BG - b

[0035] According to the cosine theorem:

[0036]

[0037] According to the sine theorem:

[0038]

[0039]

[0040] α = ∠BAF = ∠BAG - ∠FAG = β - ∠DCG

[0041] In the Y-axis direction, calculate the rotation angle β in the same way, and finally obtain the rotation angles α and β of the tool coordinate system in the two directions respectively.

[0042] According to the rotation angles α and β around the X-axis and Y-axis of the tool coordinate system, the basic rotation matrix can be obtained as:

[0043]

[0044] The overall rotation matrix of the self-collimation device of the ultrasonic non-destructive testing probe at the front end of the six-degree-of-freedom articulated manipulator is:

[0045]

[0046] Map the pose of the tool coordinate system in the world coordinate system after rotating by angles α and β around its own X and Y axes to:

[0047]

[0048] where R is the rotation matrix and B' is the tool coordinate system after rotation.

[0049] The pose of the six-degree-of-freedom articulated manipulator after rotating the tool coordinate system by angles α and β around its own X and Y axes is:

[0050] Beneficial effects:

[0051] The present invention solves the problems of positioning and pose adjustment at the end of the manipulator during ultrasonic inspection of an arbitrary curved surface manipulator, ensuring that the acoustic axis direction of the ultrasonic transducer in the ultrasonic probe coincides with the surface normal direction of the workpiece close to the probe, so that ultrasonic waves propagate inside the workpiece at the most favorable angle for detection. It has a compact structure, convenient operation, good use effect, and wide practicability in the technical field. Description of the drawings

[0052] Figure 1 is a schematic structural diagram of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator of the present invention.

[0053] Figure 2 is a schematic structural diagram of the ultrasonic non-destructive testing probe self-collimation device of the present invention.

[0054] Figure 3 is a schematic plan view of the ultrasonic non-destructive testing probe self-collimation device of the present invention.

[0055] Figure 4 is a schematic structural diagram of the elastic connection device of the present invention.

[0056] Figure 5 is a schematic diagram of the laser ranging sensor and the probe position of the present invention.

[0057] Figure 6 is a schematic diagram of the principle of the vertical incidence method of the present invention.

[0058] Figure 7 is a schematic diagram of the principle of the oblique incidence method of the present invention.

[0059] Figure 8 is a schematic diagram of the working process of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator of the present invention.

[0060] In the figure: 1 - Six - degree - of - freedom articulated manipulator, 2 - Ultrasonic non - destructive testing probe self - collimation device, 3 - Water tank, 4 - Workpiece to be tested, 5 - Workpiece clamping device, 6 - Coupling agent, 7 - Workbench, 8 - Bolt base, 9 - Laser ranging sensor, 10 - Probe clamping mechanism, 11 - Ultrasonic probe, 12 - Elastic connection mechanism, 13 - Bolt hole, 14 - Link, 15 - Spring, 16 - Sleeve, 17 - Industrial control computer.

[0061] Embodiment

[0062] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0063] As Figure 1 shown, the ultrasonic non - destructive testing probe self - collimation device based on a manipulator of the present invention is arranged to be used at the front end of a six - degree - of - freedom articulated manipulator 1. The six - degree - of - freedom articulated manipulator 1 is arranged on a workbench 7. The six - degree - of - freedom articulated manipulator 1 is connected to an industrial control computer 17 through a wire. There is also a water tank 3 on the workbench 7. There is a coupling agent 6 in the water tank 3. The workpiece clamping device 5 is immersed in the coupling agent 6. Above the workpiece clamping device 5, there is a workpiece to be tested 4 which is also immersed in the coupling agent 6;

[0064] As Figure 2 and Figure 3 shown, at the front end of the six - degree - of - freedom articulated manipulator 1, there is an ultrasonic non - destructive testing probe self - collimation device 2, which includes a bolt base 8. There are a plurality of bolt holes 13 on the bolt base 8 for connecting to the front end of the six - degree - of - freedom articulated manipulator 1. At the center of the bolt base 8, there is an elastic connection mechanism 12. An ultrasonic probe 11 is connected to the elastic connection mechanism 12 through a probe clamping mechanism 10. A plurality of laser ranging sensors 9 are respectively arranged around the elastic connection mechanism 12. When the ultrasonic probe 11 touches the surface of the object to be measured obliquely, under the action of pressure, the spring 15 undergoes non - axial deformation, and the link 14 inclines, so that the ultrasonic probe 11 fits perfectly with the surface of the object to be measured. The ultrasonic probe 11 is a conventional liquid - immersion double - crystal probe. When the piezoelectric wafer of the ultrasonic probe 11 receives an electrical pulse excitation, it will generate mechanical vibration. This vibration propagates in the medium as ultrasonic waves. During the propagation of ultrasonic waves, water or other liquids must be used as the coupling medium between the ultrasonic probe 11 and the workpiece to be tested 4. There are a total of four probe clamping mechanisms 10, which are respectively arranged in four directions of the elastic connection mechanism 12. When installing, it should be ensured that the four laser ranging sensors 9 are on a cross - section, and the cross - section is perpendicular to the propagation direction of the ultrasonic waves. The model of the laser ranging sensor 9 is the OD2 - P250W150I0 type displacement measurement sensor of Sick Company, with a detection range of 100mm - 400mm and a repeatability accuracy of 75um.

[0065] As Figure 4As shown, the elastic connection mechanism 12 includes a sleeve 16 with a columnar structure, a connecting rod 14, and a spring 15. The spring 15 is arranged in a compressed state within the sleeve 16. The tail of the connecting rod 14 is provided with a piston structure and is placed above the spring 15 within the sleeve 16. The sleeve 16, the spring 15, and the connecting rod 14 form a spring-piston structure. Relying on the pressure of the spring 15, the tail of the connecting rod 14 is pressed tightly against the sleeve 16. The head of the connecting rod 14 is fixedly connected to the probe clamping mechanism 10, and the bottom of the sleeve 16 is fixedly connected to the bolt base 8;

[0066] As Figure 8 shown, a working method of an ultrasonic non-destructive testing probe self-collimation device based on a manipulator is as follows:

[0067] First, establish a world coordinate system with the center point of the base of the six-degree-of-freedom articulated manipulator 1 as the origin, and establish a tool coordinate system with the intersection point of the ultrasonic probe axis and the plane where the laser sensor is located as the origin. When the ultrasonic non-destructive testing probe self-collimation device 2 at the front end of the six-degree-of-freedom articulated manipulator 1 moves to the detection point one, the four laser sensors 9 on the ultrasonic non-destructive testing probe self-collimation device 2 respectively measure the distance information from each laser sensor 9 to the workpiece to be measured 4. According to the arrangement positions of the laser sensors 9, the measured distance information can be divided into two groups. Through triangular relationship calculation, the rotation angles of the ultrasonic probe 11 around the X-axis and Y-axis directions of the tool coordinate system are respectively obtained; the rotation matrix between the current tool coordinate system and the target tool coordinate system is calculated through this rotation angle, and the rotation matrix of the ultrasonic non-destructive testing probe self-collimation device 2 at the front end of the six-degree-of-freedom articulated manipulator 1 is obtained; the pose and position information of the next point of the six-degree-of-freedom articulated manipulator 1 are obtained through the current pose of the robotic arm and the rotation matrix, and then the position of the ultrasonic non-destructive testing probe self-collimation device 2 is adjusted, and it is fed along the Z-axis direction of the tool coordinate system towards the surface of the workpiece to be measured 4 until it contacts the surface of the workpiece to be measured 4 as the object to be measured. Then, through the spring self-adaptation adjustment in the elastic connection mechanism 12, the ultrasonic probe 11 is pressed tightly against the surface of the workpiece to be measured 4, and then ultrasonic scanning is started.

[0068] As Figure 5 shown, define the world coordinate system as {A}, the tool coordinate system as {B}, the origin P of the tool coordinate system {B}, and the coordinate of any point in the world coordinate system {A} is a 3×1 position vector. In the world coordinate system {A}, the position of the origin P of the tool coordinate system {B} can be expressed by the position vector where P x 、P y 、P z are respectively the position coordinates of point P in the world coordinate system; the position and pose of the six-degree-of-freedom articulated manipulator 1 are described through the pose matrix of the tool coordinate system in the world coordinate system.

[0069] The posture of the tool coordinate system {B} is represented by three unit vectors in the direction of the spindle of the tool coordinate system {B}. Denote the three unit vectors in the direction of the spindle of the tool coordinate system {B} as In the world coordinate system {A}, it is denoted as Arranging these three unit vectors in sequence can obtain the rotation matrix of the tool coordinate system relative to the world coordinate system

[0070]

[0071] Through the previous position description and posture description, the pose of the manipulator can be described as:

[0072]

[0073] The homogeneous transformation matrix from the tool coordinate system to the world coordinate system is:

[0074]

[0075] The calculation method of the rotation angles of the ultrasonic non-destructive testing probe self-collimation device 2 at the front end of the six-degree-of-freedom articulated manipulator 1 around the X-axis and Y-axis of the tool coordinate system is as follows: Define the origin of the tool coordinate system as P, and the positions where the laser sensors 9 are arranged are defined as four positions A, A1, B, and B1. The distances from the four laser sensors 9 to point P are equal, and the distance is L. According to the different shapes and sizes of the measured curved surface, the vertical incidence detection method or the oblique incidence detection method can be used for calculation.

[0076] As Figure 6 shown, when the radius of curvature of the measured curved surface of the workpiece 4 to be measured ≥ 20L, the measured area can be approximated as a plane. At this time, the vertical incidence detection method is used for detection:

[0077] According to the arrangement positions of the laser sensors 9, the laser sensors 9 at the four positions A, A1, B, and B1 are divided into two groups in the X-axis direction and Y-axis direction of the tool coordinate system. Among them, A and B are in the X-axis direction, and A1 and B1 are in the Y-axis direction. Use the same method to calculate the rotation angles in the two directions respectively:

[0078] Taking the X-axis direction as an example to calculate the rotation angle α, points A and B are the positions where two laser sensors 9 are located, points C and D are the projections of the lasers of the two laser sensors 9 of A and B on the surface of the workpiece 4 to be measured, L1 and L2 are the projections of the plane where the laser sensor 9 is located and the measured surface of the workpiece 4 to be measured in the X-axis direction respectively. Connect points C and D to form line segment CD, connect points B and D to form line segment BD, use point A as the starting point to draw an auxiliary line parallel to line segment CD, and the intersection point of the auxiliary line and line segment BD is point F, forming line segment AF; the distances from the two laser sensors 9 of A and B to point P are both L, and the lengths of line segments AC and BD are measured as a and b respectively;

[0079] According to the Pythagorean theorem:

[0080]

[0081] According to the cosine theorem:

[0082]

[0083] In the Y-axis direction, use the same method to calculate the rotation angle β, and finally obtain the rotation angles α and β of the tool coordinate system in the two directions respectively;

[0084] When the radius of curvature of the measured curved surface of the workpiece 4 ≤ 20L, adjust the incident angle θ of the laser emitted by the laser sensor 9. After adjustment, the radius of curvature of the measured curved surface should be ≥ 10 times the maximum distance between any two of the four laser points on the surface of the workpiece to be measured. The detected area is approximately a plane. At this time, the oblique incidence detection method is adopted:

[0085] Similarly, taking the X-axis direction as an example to calculate the rotation angle α, points A and B are the positions where the laser sensor 9 is located, points C and D are the projections of the lasers of the two laser sensors 9 of A and B on the surface of the workpiece 4 to be measured, L1 and L2 are the projections of the plane where the laser sensor 9 is located and the surface of the workpiece 4 to be measured in the X-axis direction respectively; extend line segments AC and BD to intersect at point G, and draw an auxiliary line AF parallel to line segment CD and intersecting line segment BD at point F. The distances from the two laser sensors 9 to point P are both L, the incident angle of the light is θ, and the lengths of line segments AC and BD measured by laser sensors A and B are a and b respectively.

[0086] According to the sine theorem:

[0087]

[0088] CG = AG - AC = AG - a

[0089] DG = BG - BD = BG - b

[0090] According to the cosine theorem:

[0091]

[0092] According to the sine theorem:

[0093]

[0094] α = ∠BAF = ∠BAG - ∠FAG = β - ∠DCG

[0095] In the Y-axis direction, the rotation angle β is calculated in the same way, and finally the rotation angles α and β of the tool coordinate system in the two directions are obtained respectively.

[0096] As Figure 7 shown, according to the rotation angles α and β around the X-axis and Y-axis of the tool coordinate system, the basic rotation matrix can be obtained as:

[0097]

[0098] The overall rotation matrix of the self-collimation device 2 of the ultrasonic non-destructive testing probe at the front end of the six-degree-of-freedom articulated manipulator 1 is:

[0099]

[0100] The pose of the tool coordinate system in the world coordinate after rotating by the rotation angles α and β around its own X-axis and Y-axis is mapped as:

[0101]

[0102] In the formula, R is the rotation matrix, and B' is the tool coordinate system after rotation.

[0103] The pose of the six-degree-of-freedom articulated manipulator 1 after rotating by the rotation angles α and β around its own X-axis and Y-axis is:

[0104]

Claims

1. A working method of an ultrasonic non-destructive testing probe self-collimation device based on a manipulator, characterized in that, The robotic manipulator-based ultrasonic non-destructive testing probe self-collimation device includes an ultrasonic non-destructive testing probe self-collimation device (2) provided at the front end of a six-degree-of-freedom articulated robotic manipulator (1). The six-degree-of-freedom articulated robotic manipulator (1) is arranged on a workbench (7). The six-degree-of-freedom articulated robotic manipulator (1) is connected to an industrial control computer (17) through a wire. A water tank (3) is also provided on the workbench (7). A coupling agent (6) is provided in the water tank (3). A workpiece clamping device (5) is immersed in the coupling agent (6). A workpiece to be tested (4) that is also immersed in the coupling agent (6) is provided above the workpiece clamping device (5). The ultrasonic non-destructive testing probe self-collimation device (2) includes a bolt base (8). A plurality of bolt holes (13) for connecting to the front end of the six-degree-of-freedom articulated robotic manipulator (1) are provided on the bolt base (8). An elastic connection mechanism (12) is provided at the center of the bolt base (8). An ultrasonic probe (11) is connected to the elastic connection mechanism (12) through a probe clamping mechanism (10). A plurality of laser range sensors (9) are respectively arranged around the elastic connection mechanism (12). The elastic connection mechanism (12) includes a cylindrical sleeve (16), a connecting rod (14), and a spring (15). The spring (15) is arranged in a compressed state in the sleeve (16). The tail of the connecting rod (14) is provided with a piston structure and is placed below the spring (15) in the sleeve (16). The sleeve (16), the spring (15), and the connecting rod (14) form a spring piston structure. The tail of the connecting rod (14) is pressed tightly against the sleeve (16) by the pressure of the spring (15). The head of the connecting rod (14) is fixedly connected to the probe clamping mechanism (10). The bottom of the sleeve (16) is fixedly connected to the bolt base (8). There are four laser range sensors (9) in total, which are respectively arranged in four directions of the elastic connection mechanism (12). During installation, it should be ensured that the four laser range sensors (9) are on one cross-section, and the cross-section is perpendicular to the propagation direction of the ultrasonic wave. The specific steps of the working method are as follows: First, establish a world coordinate system with the center point of the base of the six-degree-of-freedom articulated manipulator (1) as the origin, and establish a tool coordinate system with the intersection point of the ultrasonic probe axis and the plane where the laser range sensor is located as the origin. When the ultrasonic non-destructive testing probe self-collimation device (2) moves to the first detection point, the distance information from each laser range sensor (9) to the workpiece to be measured (4) is measured respectively. According to the arrangement position of the laser range sensor (9), the measured distance information is divided into two groups. Through triangular relationship calculation, the rotation angles of the ultrasonic probe (11) around the X-axis and Y-axis of the tool coordinate system are obtained respectively; through this rotation angle, the rotation matrix between the current tool coordinate system and the target tool coordinate system is calculated, and the rotation matrix of the ultrasonic non-destructive testing probe self-collimation device (2) is obtained; through the current posture of the robotic arm and the rotation matrix of the ultrasonic non-destructive testing probe self-collimation device (2), the posture and position information of the next point of the six-degree-of-freedom articulated manipulator (1) are obtained, and then the position of the ultrasonic non-destructive testing probe self-collimation device (2) is adjusted, and it feeds along the Z-axis direction of the tool coordinate system towards the surface of the workpiece to be measured (4) until it contacts the surface of the workpiece to be measured (4), and then through the spring in the elastic connection mechanism (12) for adaptive adjustment, so that the ultrasonic probe (11) is closely attached to the surface of the workpiece to be measured (4), and then ultrasonic scanning starts; The calculation method for the rotation angles of the ultrasonic non-destructive testing probe self-collimation device (2) at the front end of the six-degree-of-freedom articulated manipulator (1) around the X-axis and Y-axis of the tool coordinate system is as follows: Define the origin of the tool coordinate system as P, and the positions where the laser range sensors (9) are arranged are defined as four positions A, A1, B, and B1. The distances from the four laser range sensors (9) to point P are equal, and the distance is L. The vertical incidence detection method or the oblique incidence detection method is used for calculation according to the size of the workpiece to be measured.

2. The working method of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator according to claim 1, characterized in that: When the ultrasonic probe (11) touches the surface of the workpiece to be measured obliquely, under the action of pressure, the spring (15) undergoes non-axial deformation, and the connecting rod (14) tilts, so that the ultrasonic probe (11) fits the surface of the workpiece to be measured.

3. The working method of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator according to claim 1, characterized in that: The ultrasonic probe (11) is a liquid-immersed double-crystal probe. When the piezoelectric wafer of the ultrasonic probe (11) receives an electrical pulse excitation, mechanical vibration will be generated. This vibration propagates in the medium as ultrasonic waves. During the propagation of ultrasonic waves, water or other liquids must be used as the coupling medium between the ultrasonic probe (11) and the workpiece to be measured (4).

4. The working method of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator according to claim 1, characterized in that: Define the world coordinate system as {A}, the tool coordinate system as {B}, the origin of the tool coordinate system {B} is P, and the coordinates of any point in the world coordinate system {A} are a 3×1 position vector. In the world coordinate system {A}, the position of the origin P of the tool coordinate system {B} is expressed by the position vector where P x , P y , P z are the position coordinates of point P in the world coordinate system respectively; the position and attitude of the six-degree-of-freedom articulated manipulator (1) are described by the pose matrix of the tool coordinate system in the world coordinate system.

5. The working method according to claim 4, characterized in that: The orientation of the tool coordinate system {B} is represented by three unit vectors along the main axis direction of the tool coordinate system {B}. Denote the three unit vectors along the main axis direction of the tool coordinate system {B} as In the world coordinate system {A}, it is denoted as Arranging these three unit vectors in sequence can obtain the rotation matrix of the tool coordinate system relative to the world coordinate system Thus, the pose of the robotic arm is described as: The homogeneous transformation matrix from the tool coordinate system to the world coordinate system is:

6. The working method of the ultrasonic non-destructive testing probe self-collimation device based on a manipulator according to claim 1, characterized in that: When the curvature radius of the measured curved surface of the workpiece to be measured (4) ≥ 20L, the detected area is approximately a plane. At this time, the vertical incidence detection method is used for detection: According to the arrangement position of the laser range sensor (9), the laser range sensors (9) at the four positions A, A1, B, and B1 are divided into two groups in the X-axis direction and Y-axis direction of the tool coordinate system. Among them, A and B are in the X-axis direction, and A1 and B1 are in the Y-axis direction: Taking the X-axis direction as an example to calculate the rotation angle α, points A and B are the positions where two laser distance sensors (9) are located. Points C and D are the projections of the lasers of the two laser distance sensors (9) at A and B on the surface of the workpiece to be measured (4). L1 and L2 are the projections of the plane where the laser distance sensors (9) are located and the measured surface of the workpiece to be measured (4) in the X-axis direction. Connect points C and D to form line segment CD, connect points B and D to form line segment BD. Taking point A as the starting point, draw an auxiliary line parallel to line segment CD. The intersection point of the auxiliary line and line segment BD is point F, forming line segment AF. The distances from the two laser distance sensors (9) at A and B to point P are both L. The lengths of line segments AC and BD are measured as a and b respectively; It can be known from the Pythagorean theorem that: As can be seen from the cosine theorem: In the Y-axis direction, calculate the rotation angle β in the same way. Finally, obtain the rotation angles α and β of the tool coordinate system in the two directions respectively; When the radius of curvature of the measured curved surface of the workpiece to be measured (4) ≤ 20L, adjust the incident angle θ of the laser emitted by the laser distance sensor (9). After adjustment, the radius of curvature of the measured curved surface should be greater than or equal to 10 times the maximum distance between any two of the four laser points on the surface of the workpiece to be measured. The detected area is approximately a plane. At this time, the oblique incidence detection method is adopted: Taking the X-axis direction as an example to calculate the rotation angle α in the same way. Points A and B are the positions where the laser distance sensors (9) are located. Points C and D are the projections of the lasers of the two laser distance sensors (9) at A and B on the surface of the workpiece to be measured (4). L1 and L2 are the projections of the plane where the laser distance sensors (9) are located and the surface of the workpiece to be measured (4) in the X-axis direction; Extend line segments AC and BD to intersect at point G. Draw an auxiliary line AF parallel to line segment CD and intersect line segment BD at point F; The distances from the two laser distance sensors (9) to point P are both L, the incident angle of the light is θ, and the lengths of line segments AC and BD measured by laser distance sensors A and B are a and b respectively; It can be known from the sine theorem that: CG = AG - AC = AG - a DG = BG - BD = BG - b It can be known from the cosine theorem that: It can be known from the sine theorem that: α = ∠BAF = ∠BAG - ∠FAG = θ - ∠DCG In the Y-axis direction, calculate the rotation angle β in the same way. Finally, obtain the rotation angles α and β of the tool coordinate system in the two directions respectively.

7. The working method according to claim 6, characterized in that: According to the rotation angles α and β around the X-axis and Y-axis of the tool coordinate system, the basic rotation matrix is: The overall rotation matrix of the self-collimation device (2) of the ultrasonic non-destructive testing probe at the front end of the six-degree-of-freedom articulated manipulator (1) is: Map the posture of the tool coordinate system in the world coordinate system after rotating by the rotation angles α and β around its own X-axis and Y-axis to: In the formula, R is the rotation matrix, and B' is the tool coordinate system after rotation; After rotating the tool coordinate system by rotation angles α and β about its own X-axis and Y-axis, the pose of the six-degree-of-freedom articulated manipulator (1) is as follows:

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