Pose coordinate calibration method for combined machining of laser / ultrasonic double industrial robots

Abstract

The invention belongs to the technical field of pose coordinate calibration, and particularly discloses a pose coordinate calibration method for laser / ultrasonic double industrial robot combined machining, which comprises the following steps: laser and ultrasonic robot world coordinate system calibration and tool coordinate system calibration; correcting absolute deviation of a tool coordinate system; measuring the deviation of the double-industrial-robot combined machining system; the whole combined machining process of the double robots is dynamically monitored in real time, and system deviation caused by self-repeated positioning deviation of the robots is compensated in a self-adaptive mode. By means of the laser / ultrasonic multi-energy-field auxiliary combined machining method, the repeated positioning precision problem of laser / ultrasonic multi-energy-field auxiliary double-robot combined machining is solved in a breakthrough mode, and the laser / ultrasonic multi-energy-field auxiliary combined machining quality of aero-engine high-precision parts is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pose coordinate calibration, and particularly relates to a pose coordinate calibration method for laser / ultrasonic dual industrial robot combined machining. BACKGROUND

[0002] In recent years, with the continuous improvement of modern aircraft performance indicators, the performance requirements of aerospace high-temperature parts are becoming higher and higher. In the case of the temperature resistance of nickel-based single crystal high-temperature alloy approaching the limit, silicon carbide ceramic matrix composite (SiC f / SiC) as a substitute material for high-temperature alloy will play an important role in the development of new-generation engine hot-end components (seal plate / regulator plate, inner cone, annular combustion chamber, turbine guide vane, etc.). SiCf / SiC composite material is a new strategic thermal structural composite material, which has the advantages of light weight, high strength, high temperature resistance and corrosion resistance, and is regarded by various countries as the development direction of the next generation of aero-engine thermal structural materials.

[0003] However, SiC f / SiC composite material has a hardness second only to diamond and cubic boron nitride, and is a typical anisotropic, hard and brittle, difficult-to-machine material. Existing mechanical machining needs to use special brazed diamond tools, and the tool wear is large and the cost is too high; long-pulse laser has high efficiency, but the heat-affected zone is large, which affects the mechanical properties and fatigue life of the material; ultrashort pulse laser machining efficiency is too low and the cost is high.

[0004] The latest / optimal machining method is laser / ultrasonic assisted composite machining, which first uses laser for rough machining and then uses ultrasonic assisted tool cutting for finishing machining. In order to meet the needs of actual production and machining, dual industrial robots are currently used to load laser and ultrasonic for flexible combined machining, but the problems of pose coordinate calibration and repeated positioning of dual industrial robot combined machining, such as how to ensure the accuracy within 50 μm, are still urgent and difficult.

[0005] In the prior art, the method for single industrial robot pose coordinate calibration, such as patents CN115741712B and CN115946124B, uses a laser tracker to measure the motion of a target ball installed at the end of the robot to identify the kinematic parameters of the robot, and then obtains the angle values of each joint of the robot and the pose transformation matrix. Patent CN115741720B uses a vision sensor to measure each joint of the industrial robot and calibrate the zero coordinate; the pose calibration method for dual industrial robot combined machining, such as patents CN117921685B and CN118617420B, measures the base coordinates and the pose positioning of each joint of the two robots in the world coordinate system, and reduces the error of the collaborative work of the robots through an algorithm.

[0006] But these pose calibration generally exist following several problems, and can not solve the repeat positioning problem of multi-ability field auxiliary composite machining. 1) The current robot pose coordinate calibration generally focuses on the industrial robot base coordinate, joint transformation and world coordinate system, mainly considers the relationship between the robot and the environment / structure, and does not pay attention to the end effector, however, in the machining of ceramic matrix composite components of aero-engine, people are more concerned about the repeat positioning accuracy of laser spot and tool center, and the manufacturing and installation deviation of devices such as ultrasonic head and galvanometer loaded on the end effector will bring great trouble to the design requirement of 100 microns machining accuracy. 2) Laser is not a solid, unlike a tool, a sensor can be attached to the surface, laser must be measured by reflecting light source, and the special attribute of industrial robot loading laser is not considered in the current robot calibration. 3) The size of the gas film cooling hole of the hot end part of the aero-engine is a micro hole below 1mm, and the positioning deviation of laser spot and tool center needs to be considered for the design requirement of 50 microns precision deviation, how to accurately find the center of laser spot and the center of tool machining is a difficult problem that cannot be solved at present.

[0007] Therefore, there is an urgent need for a method to solve the pose coordinate calibration and high-precision machining problem of ceramic matrix composite laser / ultrasonic auxiliary machining. SUMMARY

[0008] In order to solve the problems in the prior art, the present application provides a laser / ultrasonic dual industrial robot combined machining pose coordinate calibration method, which can realize the secondary repeat positioning and high-precision machining of ceramic matrix composite laser / ultrasonic combined machining, and solve the problems mentioned in the background art.

[0009] In order to achieve the above purpose, the present application provides the following technical scheme: a laser / ultrasonic dual industrial robot combined machining pose coordinate calibration method, comprising the following steps: S1, laser and ultrasonic robot world coordinate system calibration: a dial gauge is installed on the end effector of the laser / ultrasonic dual robot, and the robot world coordinate system is preliminarily calibrated; S2, laser and ultrasonic robot tool coordinate system calibration: target points are installed on the galvanometer and ultrasonic head of the laser / ultrasonic dual robot respectively, and the pose coordinates in the tool coordinate system of the two industrial robots are calibrated by using a laser tracker; S3, tool coordinate system absolute deviation correction: the laser robot and the ultrasonic robot are respectively allowed to process cross lines on the test piece, and the two sets of cross lines are overlapped under a microscope; S4, dual industrial robot combined machining system deviation measurement: the two robots are moved to an arbitrary point far away in their respective tool coordinate systems, and the system accuracy deviation E' of the dual robot combined machining caused by the repeat positioning accuracy of the industrial robot itself is measured; S5, real-time calibration of pose coordinates and adaptive compensation.

[0010] Preferably, in step S1, specifically includes the following: S11, the xyz coordinate calibration of the mirror movement of the industrial robot loaded with laser, i.e. laser robot, is carried out to ensure that the mirror movement is parallel to the world coordinate system, the laser is parallel to the z axis, and the ground is perpendicular downward; S12, the xyz coordinate calibration of the ultrasonic head movement of the industrial robot loaded with ultrasonic, i.e. ultrasonic robot, is carried out to ensure that the ultrasonic head movement is parallel to the world coordinate system, the tool is parallel to the z axis, and the ground is perpendicular downward.

[0011] Preferably, in step S2, specifically includes the following: S21, the target point is installed on the laser robot, at this time at the zero point of the world coordinate system, i.e. point a, the laser robot tool coordinate system is placed, the robot is moved in parallel through x from point a to point b, and the robot is moved in parallel through y from point a to point c, to complete the placement of the laser robot tool coordinate system; S22, the target point is installed on the ultrasonic robot, at this time at the zero point of the world coordinate system, i.e. point a', the ultrasonic robot tool coordinate system is placed, the robot is moved in parallel through x from point a' to point b', and the robot is moved in parallel through y from point a' to point c', to complete the placement of the ultrasonic robot tool coordinate system; S23, the laser tracker records the positions of the three points a, b, and c of the laser robot in the world coordinate system, and the positions of the three points a', b', and c' of the ultrasonic robot in the world coordinate system; the absolute deviation values of points a and a', b and b', and c and c' in the world coordinate system are calculated, the tool coordinate system three points of the ultrasonic robot, i.e. a', b', and c', are moved in the minimum step to coincide with the three points a, b, and c of the laser robot, at this time the absolute coincidence of the tool coordinate systems of the starting points of the laser robot and the ultrasonic robot is realized in the world coordinate system.

[0012] Preferably, in step S3, specifically includes the following: S31, the laser on the laser robot is used to mark cross lines on the test workpiece; S32, the tool on the ultrasonic robot is used to mark cross lines on the test workpiece; S33, the deviation value E of the two sets of cross lines is observed and recorded under the microscope; S34, the ultrasonic robot is moved in the minimum step according to the deviation value; S35, the steps S31-S34 are repeated until the two sets of cross lines completely coincide; S36, the deviation value E is fed back to the tool coordinate system of the ultrasonic robot, at this time a' becomes a''.

[0013] Preferably, in step S4, specifically comprising: S41, the laser robot is stepped by x and y from the a point in the tool coordinate system to the end point d point in the working range, and the d, e and f three points of the tool coordinate system of the laser robot to be measured are placed at the d point; S42, the ultrasonic robot is stepped by x and y from the a'' point in the tool coordinate system to the end point d' point in the working range, and the d', e' and f' three points of the tool coordinate system of the ultrasonic robot to be measured are placed at the d' point; S43, the absolute deviation values of d and d', e and e', and f and f' points in the world coordinate system recorded by the laser tracker are calculated, and the deviation value is the systematic accuracy deviation E' of the laser / ultrasonic dual industrial robot combined machining.

[0014] Preferably, in step S5, specifically comprising: S51, the reference coordinate points of the tool coordinate system of the laser robot and the ultrasonic robot in the world coordinate system after each movement are captured in real time by using the laser tracker; S52, the deviation E' of the two robot reference coordinate points is calculated and compared with the preset deviation value E of the two tool coordinate system reference coordinate points through step S3; S53, the pose coordinates of the ultrasonic robot tool coordinate system zero point in the world coordinate system are adjusted according to the comparison result of step S52; S54, the steps S51-S53 are repeated to realize dynamic real-time coordinate monitoring of the dual robot combined machining, and the systematic deviation caused by the robot's own repeated positioning deviation is adaptively compensated.

[0015] Preferably, the test piece is SiC f / SiC ceramic matrix composite.

[0016] The beneficial effects of the present application are: the method focuses on the pose coordinate calibration and systematic positioning deviation measurement of the end effector of the laser / ultrasonic dual industrial robot combined machining for the first time; the laser tracker is used to measure the repeated positioning of the laser and tool combined machining for the first time; the tool microscope is used to correct the absolute deviation caused by target point installation, galvanometer and ultrasonic head manufacturing and installation for the first time; the systematic deviation of the dual industrial robot high-precision combined machining is measured for the first time; the dynamic real-time coordinate monitoring of the dual robot combined machining is realized for the first time, and the influence of the robot's own repeated positioning deviation on the combined machining accuracy is solved. The whole process of the dual robot combined machining is dynamically monitored in real time, the systematic deviation caused by the robot's own repeated positioning deviation is adaptively compensated, and the repeated positioning accuracy problem of the laser / ultrasonic multi-energy field assisted dual robot combined machining is solved, which greatly improves the quality of the laser / ultrasonic multi-energy field assisted combined machining of the high-precision parts of the aero-engine. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The flow chart of the pose coordinate calibration method of the laser / ultrasonic dual industrial robot combined machining. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0019] The present application first focuses on the pose coordinate calibration and systematic positioning deviation measurement of the end effector of the laser / ultrasonic dual industrial robot combined machining; first measures the combined machining repeated positioning of the laser and the tool by using the laser tracker; first corrects the absolute deviation caused by the target point installation, the galvanometer, and the manufacturing and installation of the ultrasonic head by using the tool setting microscope; first measures the systematic deviation of the dual industrial robot high-precision combined machining; and first realizes the dynamic real-time coordinate monitoring of the dual robot combined machining, and solves the influence of the repeated positioning deviation of the robot itself on the combined machining precision.

[0020] Please refer to Figure 1 The embodiments of the present application provide a method for calibrating the pose coordinates of a dual industrial robot for laser / ultrasonic auxiliary combined machining of SiC f ceramic matrix composite material, reducing the absolute accuracy deviation, and measuring the systematic deviation caused by the accumulation of the repeated positioning accuracy deviation of the robot itself, and the specific steps are as follows: S1, laser and ultrasonic robot world coordinate system calibration: a dial gauge is installed on the end effector of the laser / ultrasonic dual robot to preliminarily calibrate the robot world coordinate system, so that the xyz coordinate systems of the two robots are parallel to the world coordinate system, the laser and the tool are parallel to the z axis, and are perpendicular to the ground and downward. S11, xyz coordinate calibration of the galvanometer movement of the industrial robot loaded with the laser, i.e., the laser robot, to ensure that the galvanometer movement is parallel to the world coordinate system, the laser is parallel to the z axis, and is perpendicular to the ground and downward; S12, xyz coordinate calibration of the ultrasonic head movement of the industrial robot loaded with the ultrasonic, i.e., the ultrasonic robot, to ensure that the ultrasonic head movement is parallel to the world coordinate system, the tool is parallel to the z axis, and is perpendicular to the ground and downward.

[0021] S2, laser, ultrasonic robot tool coordinate system calibration: install target points on the galvanometer and ultrasonic head of the laser / ultrasonic dual robot respectively, and calibrate the pose coordinates in the tool coordinate system of the two industrial robots by using the laser tracker; specifically including the following: S21, install target points on the laser robot, at this time at the zero point of the world coordinate system, i.e. point a, place the laser robot tool coordinate system, move the robot 200mm through x from point a to point b, move the robot 200mm through y from point a to point c, complete the placement of the laser robot tool coordinate system; S22, install target points on the ultrasonic robot, at this time at the zero point of the world coordinate system, i.e. point a', place the ultrasonic robot tool coordinate system, move the robot 200mm through x from point a' to point b', move the robot 200mm through y from point a' to point c', complete the placement of the ultrasonic robot tool coordinate system; S23, the laser tracker records the positions of the three points a, b, c of the laser robot in the world coordinate system, and the positions of the three points a', b', c' of the ultrasonic robot in the world coordinate system; calculate the absolute deviation values of a and a', b and b', c and c' in the world coordinate system, and move the tool coordinate system of the ultrasonic robot with the minimum step to coincide with the three points a, b, c of the laser robot, at this time the absolute coincidence of the tool coordinate systems of the starting points of the laser robot and the ultrasonic robot is realized in the world coordinate system.

[0022] S3, tool coordinate system absolute deviation correction: respectively make the laser robot and the ultrasonic robot process cross lines on the test piece, and make the two sets of cross lines coincide under the microscope; to avoid the influence of the manufacturing and installation deviation of the galvanometer and the ultrasonic head, the absolute position deviation of the target point placement center distance, etc. on the actual machining precision. Specifically including the following: S31, use the laser on the laser robot to mark cross lines on the test piece; S32, use the tool on the ultrasonic robot to mark cross lines on the test piece; S33, observe and record the deviation value E of the two sets of cross lines under the microscope; S34, according to the minimum step of the ultrasonic robot; S35, repeat the steps of S31-S34 until the two sets of cross lines completely coincide; S36, feedback the deviation value E to the tool coordinate system of the ultrasonic robot, at this time a' becomes a''.

[0023] S4, dual industrial robot combined machining system deviation measurement: move the two robots to an arbitrary point far away in their respective tool coordinate systems, measure the system accuracy deviation E' of the dual robot combined machining caused by the repeat positioning accuracy of the industrial robot; specifically including: S41, step the laser robot from a point x in the tool coordinate system 600mm, y step 600mm to the end of the work range d point, place the laser robot tool coordinate system d, e, f three points to be measured at the d point; S42, step the ultrasonic robot from a point a'' in the tool coordinate system 600mm, y step 600mm to the end of the work range d' point, place the ultrasonic robot tool coordinate system d', e', f' three points to be measured at the d' point; S43, calculate the absolute deviation value of d and d', e and e', f and f' points in the world coordinate system recorded by the laser tracker, which is the systematic accuracy deviation E' of the laser / ultrasonic dual industrial robot combined machining. Caused by the accumulation of the robot's own repeatability deviation.

[0024] S5, real-time calibration and adaptive compensation of pose coordinates. Specifically, it includes: S51, use the laser tracker to capture the reference coordinate points of the tool coordinate system of the laser robot and the ultrasonic robot in the world coordinate system after each movement; S52, calculate the deviation E' of the two robot reference coordinate points, and compare it with the preset deviation value E of the two tool coordinate system reference coordinates; S53, step adjust the pose coordinates of the ultrasonic robot tool coordinate system zero point in the world coordinate system according to the comparison result of step S52; S54, repeat steps S51-S53 to realize dynamic real-time coordinate monitoring of dual robot combined machining, and adaptively compensate the systematic deviation caused by the robot's own repeatability deviation.

[0025] Further, the test piece is SiC f / SiC ceramic matrix composite material.

[0026] Further, the laser tracker used in the embodiment of the application is Leica AT403 laser tracker.

[0027] Further, the target coordinate measurement error of the laser tracker in the embodiment of the application is U （x，y，z） =±10μm.

[0028] Further, the metallographic microscope used in the embodiment of the application is CX40M.

[0029] Further, the tool setting microscope used in the embodiment of the application is er10 LS-20-90, with a resolution of 5.4μm.

[0030] The method breaks through the problem of repeated positioning accuracy in laser / ultrasonic multi-energy field assisted double-robot combined machining, and greatly improves the quality of laser / ultrasonic multi-energy field assisted combined machining of high-precision parts of an aero-engine.

[0031] It should be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0032] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0033] It should be understood that the term "and / or" used herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0034] Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (a stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detecting (a stated condition or event)" or "in response to detecting (a stated condition or event)".

[0035] The "first / second" mentioned in the embodiments is only to distinguish similar objects, and does not represent the specific order of the objects. Understandably, the "first / second" can be interchanged with the specific order or sequence as allowed. It should be understood that the objects distinguished by "first / second" can be interchanged under appropriate circumstances, so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0036] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalent features, by those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pose coordinate calibration method for laser / ultrasonic dual industrial robot combined machining, characterized in that, Comprising the following steps: S1, laser, ultrasonic robot world coordinate system calibration: by installing a micrometer on the end effector of the laser / ultrasonic dual robot, the robot world coordinate system is preliminarily calibrated; S2, laser, ultrasonic robot tool coordinate system calibration: target points are installed on the galvanometer and ultrasonic head of the laser / ultrasonic dual robot respectively, and the pose coordinates of the tool coordinate system of the two industrial robots are calibrated by using a laser tracker; S3, tool coordinate system absolute deviation correction: respectively let the laser robot and the ultrasonic robot process cross lines on the test piece, and make the two sets of cross lines coincide under the microscope; S4, deviation measurement of the dual industrial robot combined machining system: move the two robots to an arbitrary point far away in their respective tool coordinate systems, and measure the system accuracy deviation E' of the dual robot combined machining caused by the repeatability of the industrial robot itself; S5, real-time calibration and adaptive compensation of the pose coordinates.

2. The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: In step S1, the following steps are included: S11, calibrate the xyz coordinates of the galvanometer movement of the laser-loaded industrial robot, i.e. the laser robot, to ensure that the galvanometer movement is parallel to the world coordinate system, the laser is parallel to the z-axis, and the ground is perpendicular downward; S12, calibrate the xyz coordinates of the ultrasonic head movement of the ultrasonic-loaded industrial robot, i.e. the ultrasonic robot, to ensure that the ultrasonic head movement is parallel to the world coordinate system, the tool is parallel to the z-axis, and the ground is perpendicular downward. 3.The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: In step S2, the following steps are included: S21, install a target point on the laser robot, at this time at the zero point of the world coordinate system, i.e. point a, place the laser robot tool coordinate system, move the robot from point a to point b through x parallel, and from point a to point c through y parallel, to complete the placement of the laser robot tool coordinate system; S22, install a target point on the ultrasonic robot, at this time at the zero point of the world coordinate system, i.e. point a', place the ultrasonic robot tool coordinate system, move the robot from point a' to point b' through x parallel, and from point a' to point c' through y parallel, to complete the placement of the ultrasonic robot tool coordinate system; S23, the laser tracker records the positions of points a, b, c of the laser robot and points a', b', c' of the ultrasonic robot in the world coordinate system; calculate the absolute deviation values of points a and a', b and b', c and c' in the world coordinate system, and make the tool coordinate system three points of the ultrasonic robot, i.e. a', b', c', coincide with the three points of the laser robot, i.e. a, b, c, at this time the absolute coincidence of the starting points of the tool coordinate systems of the laser robot and the ultrasonic robot in the world coordinate system is realized.

4. The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: In step S3, the following steps are included: S31, use the laser on the laser robot to mark a cross line on the test piece; S32, use the tool on the ultrasonic robot to mark a cross line on the test piece; S33, observe and record the deviation value E of the two sets of cross lines under the microscope; S34, according to the minimum step of the deviation value, move the ultrasonic robot; S35, repeat the steps of S31-S34 until the two sets of cross lines completely coincide; S36, feedback the deviation value E to the tool coordinate system of the ultrasonic robot, at this time a' becomes a''.

5. The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: In step S4, specifically comprising: S41, the laser robot is stepped by x and y from the a point in the tool coordinate system to the end point d in the working range, and the d, e and f points of the tool coordinate system of the laser robot to be measured are placed at the d point; S42, the ultrasonic robot is stepped by x and y from the a'' point in the tool coordinate system to the end point d' in the working range, and the d', e' and f' points of the tool coordinate system of the ultrasonic robot to be measured are placed at the d' point; S43, in the world coordinate system recorded by the laser tracker, the absolute deviation values of the d and d', e and e', and f and f' points in the world coordinate system are calculated, and the deviation value is the systematic accuracy deviation E' of the laser / ultrasonic dual industrial robot combined machining.

6. The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: In step S5, specifically comprising: S51, using the laser tracker, the reference coordinate points of the tool coordinate system of the laser robot and the ultrasonic robot in the world coordinate system after each movement are captured in real time; S52, the deviation E' of the reference coordinate points of the two robots is calculated and compared with the preset deviation value E of the reference coordinate points of the two tool coordinate systems in step S3; S53, according to the comparison result of step S52, the pose coordinates of the zero point of the tool coordinate system of the ultrasonic robot in the world coordinate system are adjusted step by step; S54, repeat steps S51-S53 to realize dynamic real-time coordinate monitoring of dual robot combined machining and self-adaptive compensation of the system deviation caused by the repeated positioning deviation of the robot itself.

7. The pose coordinate calibration method of laser / ultrasonic dual industrial robot combined machining according to claim 1, characterized in that: The test piece is SiC f / SiC ceramic matrix composite.

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