Water turbine runner chamber inner wall in-place robot automatic grinding method based on three-dimensional measurement

Abstract

The invention belongs to the field of water turbine in-place robot automatic grinding and machining, and particularly provides a water turbine runner chamber inner wall in-place robot automatic grinding method based on three-dimensional measurement, which comprises the following steps: setting the circumferential width of a single grinding area, dividing the surface of the inner wall into a plurality of grinding areas, arranging identification bodies at equal intervals, the positions and postures of the moving trolley and the mechanical arm in each area are calculated; the mobile trolley and the mechanical arm are controlled to carry out scanning measurement of a single area, measurement data are simplified, geometric features of the identification body are extracted, and a coordinate system is established at the identification body; according to the measuring point cloud data, a polishing track is calculated and generated; and the operation is repeated to obtain the grinding tracks of all the grinding areas, then according to mutual conversion of the identification body coordinate systems in the areas, the tracks of the two adjacent grinding areas are spliced, and the robot conducts grinding according to the spliced grinding tracks. The method realizes large-breadth polishing and repairing operation on the inner wall of the water turbine, and improves the maintenance efficiency of the water turbine.

Description

Technical Field

[0001] The invention belongs to the field of on-site robot automatic grinding processing of water turbines, and in particular, relates to an on-site robot automatic grinding method for the inner wall of a water turbine runner chamber based on three-dimensional measurement. Background Art

[0002] As the core component of hydroelectric power generation equipment, the turbine is affected by the impact of water flow, wear and corrosion during long-term operation, which may cause cracks or damage to the blades or the inner wall of the runner chamber, thus affecting the power generation efficiency and operation stability of the turbine. Traditional maintenance methods usually require shutting down the turbine and then manually inspecting and repairing the problem, which is not only time-consuming and labor-intensive, but may also affect the stable operation of the generator set.

[0003] In order to improve the efficiency and quality of turbine maintenance and reduce maintenance costs, an automated robot system was introduced to perform regular inspection, maintenance and repair of the runner. The automated polishing method under this technical background uses a robot system to operate inside the turbine, accurately locate surface damage and cracks, and perform efficient polishing and repair work. By setting up automated equipment inside the turbine, the robot can move to each polishing area in sequence along a preset path. Automated polishing under this technical background requires the ability to generate a polishing trajectory in order to perform automatic polishing. The prior art has not yet disclosed an automated polishing method using an automated robot system. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an on-site robot automatic grinding method for the inner wall of a turbine runner chamber based on three-dimensional measurement, so as to realize large-scale grinding and repair operations on the inner wall of the turbine and improve the maintenance efficiency of the turbine.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for automatic grinding of the inner wall of a turbine runner chamber by an in-situ robot based on three-dimensional measurement, comprising the following steps:

[0006] S1. Design multiple markers, evenly distribute them along the circumferential direction of the inner wall of the turbine runner chamber, set the circumferential width of a single grinding area according to the working radius of the robotic arm, divide the inner wall surface into multiple grinding areas, arrange the markers at equal intervals, and calculate the position and posture of the mobile car and the robotic arm in each area;

[0007] S2, control the mobile car and the mechanical arm to move to the designated position in sequence, perform scanning measurement of a single area, simplify the measurement data, extract the geometric features of the marker, and establish a coordinate system at each marker;

[0008] S3, calculating and generating a grinding trajectory according to the measured point cloud data of a single area of ​​the inner wall;

[0009] S4, repeating steps S2 and S3 to obtain the grinding trajectories of all grinding areas, and then splicing the trajectories of two adjacent grinding areas according to the mutual conversion of the coordinate systems of the markers in the area, and the robot performs grinding according to the spliced ​​grinding trajectories.

[0010] In a preferred embodiment, step S1 includes the following steps:

[0011] S11, three standard balls with different diameters {S small , S medi , S large} are installed on the same base to form an identification body I;

[0012] S12, determine the circumferential area of ​​the inner wall of the turbine runner chamber that needs to be polished, start from a fixed starting point on the circumference, arrange the marking bodies one by one in an evenly spaced manner, and divide the polishing area {A1, A2, ..., A n}, and at the same time ensure that each polishing area has two left and right markings {I left ,I right};

[0013] S12. Design the spacing between the marking bodies according to the working radius of the robot arm To ensure that the position of the trolley on the circular guide rail can cover the markers on both sides of the area during measurement. left ,I right};

[0014] S13, the three-dimensional measuring instrument is installed at the end of the robotic arm, and the robotic arm is fixed on a mobile trolley platform that moves along a circular guide rail. For a single-block grinding area, the center position of the mobile trolley platform is designed to be located on the central vertical plane of the arc area;

[0015] S14. Use the robot virtual simulation software to teach the measurement posture of the robot arm to ensure that the robot arm can complete the scanning measurement of the marking bodies on both sides while the mobile car remains stationary, and obtain the {A i |i=1~n} and the measured position and posture of the mobile car and the robotic arm.

[0016] In a preferred solution, in step S2, the measurement data is simplified, the geometric features of the markers are extracted, and a coordinate system is established at each marker, which includes the following steps:

[0017] S21, perform hand-eye calibration on the three-dimensional measuring instrument installed at the end of the robot arm, use the hand-eye matrix and coordinate transformation to obtain point cloud data in the robot base coordinate system after each measurement, remove noise interference points and perform point cloud filtering on the scanning measurement data, and obtain streamlined single-area point cloud data;

[0018] S22. In the CAD model of the logo, the standard ball S large The center of the ball is the origin of the coordinate system, is the X-axis direction of the coordinate system, For the Y-axis direction of the coordinate system, a theoretical coordinate system of the marker is constructed;

[0019] S23, using the theoretical CAD model of the marker as a reference model, extracting the feature point cloud of all the markers in the measurement data through a template matching algorithm, and calculating the transformation matrix of the actual marker in the machine base coordinate system;

[0020] S24. For the initial polishing circumferential area A1, the measurement data only includes a right-side identification feature and the corresponding coordinate system. For other areas i |i=2~n}, the measurement data includes the features of the left and right sides of the marker and the corresponding coordinate system

[0021] In a preferred embodiment, step S3 comprises the following steps:

[0022] S31, for each polishing area {A i |i=1~n}, the coordinate system of the right marker in the area is used as the reference coordinate system Calculate the grinding trajectory in a single area;

[0023] S32, based on the reference coordinate system of the right identification body in the single area And the length and width of the area, intercept the point cloud data in the area And set the Y axis of the reference coordinate system as the tool feed direction;

[0024] S33, point cloud data Construct a kd-tree index of the surface point cloud, determine the range of points, traverse the point cloud to find the initial point, search for nearby points, take the centroid of multiple points to get the control point, and re-solve the point cloud normal based on the control point;

[0025] S34, determine the tool inclination angle and the grinding disc radius based on the grinding process parameters, solve the tool axis vector based on the tool tip point position and the normal line, take the tool axis vector as the Z axis and the trajectory point feed direction as the X axis, generate the grinding posture at the tool tip point, and calculate the multi-segment grinding trajectory in a single area. The trajectory points are expressed in matrix form as follows:

[0026]

[0027] Among them, i represents the polishing track of the i-th area, j represents the number of track segments in the area, and k represents the number of track points contained in a single polishing track.

[0028] In a preferred solution, in step S4, the trajectories of two adjacent polishing areas are spliced ​​according to the mutual conversion of the coordinate systems of the markers in the area, which includes the following steps:

[0029] S41, for each area of ​​measurement data, according to step S2, obtain the coordinate system of the left and right markers And calculate the change matrix

[0030] S42, in the starting grinding area A1, The coordinate system is used as a reference. According to step S3, the grinding trajectory points in the area are generated and expressed in matrix form as follows:

[0031]

[0032] Wherein, i represents the polishing track of the i-th area, j1 represents the number of track segments in the polishing area A1, and k represents the number of track points contained in a single polishing track;

[0033] S43, for adjacent grinding area {A i |i=2~n-1}, the measurement data in this area includes the left and right marker coordinate systems The left side logo is the same as the right side logo of the previous area, so Through the coordinate transformation matrix Convert the end point of each trajectory in the i-1 area to the i area, that is:

[0034]

[0035] Taking the end point of each track segment in the i-1th area as the starting point of each track segment in the i-th area, according to step S3, the grinding track points in the area are generated;

[0036] S44, for the final polishing area A n , the left marker in this area is the same as the right marker in the n-1th area. Therefore, the end point of each track in the n-1th area is used as the starting point of each track in the nth area, and the starting point of each track in the 1st area is used as the end point of each track in the nth area to calculate the polishing track of the final area. The expression is:

[0037]

[0038] S45. According to steps S41 to S45, the robot automatically repeats the same processing flow by splicing the path points in the upper and lower areas along the circumference of the inner wall of the turbine runner chamber to complete the grinding of multiple circular surfaces.

[0039] The invention provides an on-site robot automatic grinding method for the inner wall of a turbine runner chamber based on three-dimensional measurement, which has the following beneficial effects:

[0040] 1. The large-scale automated grinding and repair operation of the inner wall of the turbine runner chamber has been realized, which significantly improves the maintenance efficiency of the turbine.

[0041] 2. Through the design of the marker and coordinate system, precise positioning and trajectory splicing of multiple grinding areas are achieved, ensuring the continuity and uniformity of grinding.

[0042] 3. High degree of automation reduces manual participation, reduces labor intensity, and improves operation safety. It can adapt to the complex curved surface of the inner wall of the turbine runner chamber and achieve full coverage grinding operations.

[0043] 4. Through digital and automated methods, the accuracy and consistency of turbine maintenance are improved, maintenance downtime is reduced, the utilization rate of turbines is increased, and more stable equipment guarantee is provided for hydropower generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0045] Figure 1 is a flow chart of the present invention;

[0046] Figure 2 is a schematic diagram of the identification body;

[0047] Figure 3 It is the layout diagram of the logo body;

[0048] Figure 4 It is the location map of the mobile car and robot;

[0049] Figure 5 It is the theoretical identification body model and reference coordinate system;

[0050] Figure 6 It is a simulation diagram of the identification body feature template matching and feature extraction;

[0051] Figure 7 It is the relationship diagram of regional coordinate system;

[0052] Figure 8 It is a schematic diagram of the grinding trajectory of a single area;

[0053] Fig. 9 is the path point distribution map;

[0054] Fig.10 It is a mosaic of trajectories of adjacent areas;

[0055] Fig.11 This is a schematic diagram of the robot's single-area grinding trajectory;

[0056] Fig.12 Schematic diagram of trajectory stitching of point clouds in adjacent processing areas. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0058] like Figures 1 to 12 As shown, a method for automatic grinding of the inner wall of a turbine runner chamber by an on-site robot based on three-dimensional measurement is applied to the repair processing of the inner wall of a turbine runner chamber, comprising the following steps:

[0059] S1. Design multiple markers and evenly distribute them along the circumference of the inner wall of the turbine runner chamber. According to the working radius of the robot arm, set the circumference width of a single grinding area, divide the inner wall surface into multiple grinding areas, arrange the markers at equal intervals, and calculate the position and posture of the mobile car and the robot arm in each area. Specifically:

[0060] S11, such as Figure 2 As shown, three standard balls with different diameters {S small , S me , S large} are installed on the same base to form an identification body I.

[0061] S12, such as Figure 3 As shown in the figure, the circumferential area of ​​the turbine runner chamber wall that needs to be polished is determined, and starting from a fixed starting point on the circumference, the markers are arranged one by one in an equidistant manner to divide the polishing area {A1, A2, …, A n}, and at the same time ensure that each area has two left and right markers {I left ,I right}.

[0062] S12. Design a reasonable spacing between markers based on the working radius of the robot arm To ensure that the position of the trolley on the circular guide rail can cover the markers on both sides of the area during measurement. left ,I right}.

[0063] In this embodiment, for the Xinsong robot GCR20-1100, its working radius is 1100mm. According to the robot working height and the ball space radius, the distance between the markers is designed to be about L I =800mm.

[0064] S13, such as Figure 4 As shown in the figure, the 3D measuring instrument is installed at the end of the robot arm, and the base of the robot arm is fixed on a mobile trolley platform that can move along the circular guide rail. In order to ensure that the 3D measuring instrument can measure the marking bodies on both sides, for the single-block grinding area, the center position of the mobile trolley platform is designed to be located on the central vertical plane of the arc area.

[0065] S14. Use the robot virtual simulation software to teach the measurement posture of the robot arm and simulate the reachability of the robot arm to ensure that the robot arm can complete the scanning measurement of the marking bodies on both sides when the mobile trolley remains stationary. i |i=1~n}, the measured position and posture of the mobile car and the robotic arm.

[0066] S2, control the mobile car and the mechanical arm to move to the specified position in turn, and automatically perform scanning measurement of a single area. Then, the measurement data is streamlined, the geometric features of the marker are extracted, and a coordinate system is established at each marker. Specifically:

[0067] S21. Perform hand-eye calibration on the 3D measuring instrument installed at the end of the robot arm. Using the hand-eye matrix and coordinate transformation, point cloud data in the robot base coordinate system can be obtained after each measurement. Noise interference points are removed and point cloud filtering is performed on the scanning measurement data to obtain streamlined single-area point cloud data.

[0068] In this embodiment, a statistical outlier filter is used to remove noise points, and then a voxel filter is applied to downsample to reduce the amount of data. Then, a bilateral filter is used to smooth the point cloud while maintaining edge features. Finally, the point cloud normal vector is estimated by the PCA method and optimized using the moving least squares method to improve the accuracy of subsequent feature extraction and grinding trajectory generation.

[0069] S22, such as Figure 5 As shown, in the CAD model of the logo, the standard ball S large The center of the ball is the origin of the coordinate system, is the X-axis direction of the coordinate system, Construct the theoretical coordinate system of the marker in the Y-axis direction of the coordinate system.

[0070] S23, such as Figure 6As shown, the theoretical CAD model of the marker is used as a reference model, the feature point cloud of all the markers in the measurement data is extracted through the template matching algorithm, and the transformation matrix of the actual marker in the machine base coordinate system is calculated.

[0071] The template matching algorithm used in this embodiment may be an iterative closest point algorithm (ICP) or an improved version based on the iterative closest point algorithm, which is an existing technology widely used in point cloud registration.

[0072] S24, such as Figure 7 As shown, for each grinding circumference area A i The measurement data includes the left and right side marker features and the corresponding coordinate system

[0073] S3. Calculate and generate the grinding trajectory based on the measured point cloud data of a single area of ​​the inner wall. Specifically:

[0074] S31, such as Figure 8 As shown, for each polishing area {A i |i=1~n}, the coordinate system of the right marker in the area is used as the reference coordinate system To calculate the grinding trajectory in a single area.

[0075] S32, based on the reference coordinate system of the right identification body in the single area And the length and width of the area, intercept the point cloud data in the area And set the Y axis of the reference coordinate system as the tool feed direction.

[0076] S33, such as Fig. 9 As shown, point cloud data Construct a kd-tree index for the surface point cloud, determine the point range, traverse the point cloud to find the initial point, search for nearby points, obtain the centroid of multiple points to obtain the control point, and re-solve the point cloud normal based on the control point.

[0077] S34, determine the tool inclination angle and the radius of the grinding disc based on the grinding process parameters, solve the tool axis vector based on the tool tip point position and normal, take the tool axis vector as the Z axis and the trajectory point feed direction as the X axis, generate the grinding posture at the tool tip point, and thus calculate the multi-segment grinding trajectory in a single area, and the trajectory points are expressed in matrix form

[0078]

[0079] Among them, i represents the polishing track of the i-th area, j represents the number of track segments in the area, and k represents the number of track points contained in a single polishing track.

[0080] S4, repeating steps S2 and S3, and splicing the trajectories of two adjacent polishing areas according to the mutual conversion of the coordinate systems of the markers in the area, such as Fig.10 As shown. Specifically:

[0081] S41: For the measurement data of each area, firstly obtain the coordinate system of the left and right markers according to the method of step S23. And calculate the change matrix

[0082] S42, at the start of grinding the circumferential area A1, This coordinate system is used as a reference. According to steps S31 to S34, the grinding trajectory points in the area are generated and expressed in matrix form as follows:

[0083]

[0084] S43, for adjacent grinding area {A i |i=2~n-1}, the measurement data in this area includes the left and right marker coordinate systems The left side logo is the same as the right side logo of the previous area, so Through the coordinate transformation matrix The end point of each trajectory in the i-1 area can be converted to the i area, that is:

[0085]

[0086] The end point of each track in the i-1th region is used as the starting point of each track in the i-th region, and the grinding track points in the region are generated according to steps S31 to S34. Fig.11 shown.

[0087] S44, for the final polishing area A n , the left marker in the area is the same as the right marker in the n-1th area, therefore, referring to step S43, the end point of each track in the n-1th area is used as the starting point of each track in the nth area, and the starting point of each track in the 1st area is used as the end point of each track in the nth area to calculate the polishing track of the final area. That is:

[0088]

[0089] S45, according to the above steps, by splicing the path points in the upper and lower areas along the circumference of the inner wall of the turbine runner chamber, such as Fig.12 As shown, the robot can automatically repeat the same processing process to complete the grinding of multiple circular surfaces.

[0090] The present invention provides an in-situ robot automatic grinding method for the inner wall of a turbine runner chamber based on three-dimensional measurement. By using three-dimensional measurement technology, the inner wall surface information can be obtained efficiently and accurately, greatly reducing the cost of manual measurement. This method not only improves the measurement efficiency, but also provides a reliable data basis for subsequent automatic grinding operations. By precisely controlling the grinding trajectory and parameters, the method can effectively repair damage to the inner wall surface and improve the surface quality while avoiding unnecessary damage to the turbine structure. This automated grinding method significantly improves the efficiency and quality of turbine maintenance.

[0091] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for automatic grinding of the inner wall of a turbine runner chamber by an on-site robot based on three-dimensional measurement, characterized in that: The following steps are involved: S1. Design multiple markers, evenly distribute them along the circumferential direction of the inner wall of the turbine runner chamber, set the circumferential width of a single grinding area according to the working radius of the robotic arm, divide the inner wall surface into multiple grinding areas, arrange the markers at equal intervals, and calculate the position and posture of the mobile car and the robotic arm in each area; S2, control the mobile car and the mechanical arm to move to the designated position in sequence, perform scanning measurement of a single area, simplify the measurement data, extract the geometric features of the marker, and establish a coordinate system at each marker; S3, calculating and generating a grinding trajectory according to the measured point cloud data of a single area of ​​the inner wall; S4, repeating steps S2 and S3 to obtain the grinding trajectories of all grinding areas, and then splicing the trajectories of two adjacent grinding areas according to the mutual conversion of the coordinate systems of the markers in the area, and the robot performs grinding according to the spliced ​​grinding trajectories.

2. The method for automatic grinding of the inner wall of a turbine runner chamber by an on-site robot based on three-dimensional measurement according to claim 1 is characterized in that: The step S1 includes the following steps: S11, three standard balls with different diameters {S small , S mediu , S large } are installed on the same base to form an identification body I; S12, determine the circumferential area of ​​the inner wall of the turbine runner chamber that needs to be polished, start from a fixed starting point on the circumference, arrange the marking bodies one by one in an evenly spaced manner, and divide the polishing area {A1, A2, ..., A n }, and at the same time ensure that each polishing area has two left and right markings {I left ,I right }; S12. Design the spacing between the marking bodies according to the working radius of the robot arm To ensure that the position of the trolley on the circular guide rail can cover the markers on both sides of the area during measurement. left ,I right }; S13, the three-dimensional measuring instrument is installed at the end of the robotic arm, and the robotic arm is fixed on a mobile trolley platform that moves along a circular guide rail. For a single-block grinding area, the center position of the mobile trolley platform is designed to be located on the central vertical plane of the arc area; S14. Use the robot virtual simulation software to teach the measurement posture of the robot arm to ensure that the robot arm can complete the scanning measurement of the marking bodies on both sides while the mobile car remains stationary, and obtain the {A i |i=1~n} and the measured position and posture of the mobile car and the robotic arm.

3. The method for automatic grinding of the inner wall of a turbine runner chamber by an on-site robot based on three-dimensional measurement according to claim 1 is characterized in that: In the step S2, the measurement data is simplified, the geometric features of the markers are extracted, and a coordinate system is established at each marker, which includes the following steps: S21, perform hand-eye calibration on the three-dimensional measuring instrument installed at the end of the robot arm, use the hand-eye matrix and coordinate transformation to obtain point cloud data in the robot base coordinate system after each measurement, remove noise interference points and perform point cloud filtering on the scanning measurement data, and obtain streamlined single-area point cloud data; S22. In the CAD model of the logo, the standard ball S large The center of the ball is the origin of the coordinate system, is the X-axis direction of the coordinate system, For the Y-axis direction of the coordinate system, a theoretical coordinate system of the marker is constructed; S23, using the theoretical CAD model of the marker as a reference model, extracting the feature point cloud of all the markers in the measurement data through a template matching algorithm, and calculating the transformation matrix of the actual marker in the machine base coordinate system; S24. For the initial polishing circumferential area A1, the measurement data only includes a right-side identification feature and the corresponding coordinate system. For other areas i |i=2~n}, the measurement data includes the features of the left and right sides of the marker and the corresponding coordinate system 4. The method for automatic grinding of the inner wall of a turbine runner chamber by an on-site robot based on three-dimensional measurement according to claim 1 is characterized in that: The step S3 includes the following steps: S31, for each polishing area {A i |i=1~n}, the coordinate system of the right marker in the area is used as the reference coordinate system i=1~n, calculate the grinding trajectory in a single area; S32, based on the reference coordinate system of the right identification body in the single area And the length and width of the area, intercept the point cloud data in the area And set the Y axis of the reference coordinate system as the tool feed direction; S33, point cloud data Construct a kd-tree index of the surface point cloud, determine the range of points, traverse the point cloud to find the initial point, search for nearby points, take the centroid of multiple points to get the control point, and re-solve the point cloud normal based on the control point; S34, determine the tool inclination angle and the grinding disc radius based on the grinding process parameters, solve the tool axis vector based on the tool tip point position and the normal line, take the tool axis vector as the Z axis and the trajectory point feed direction as the X axis, generate the grinding posture at the tool tip point, and calculate the multi-segment grinding trajectory in a single area. The trajectory points are expressed in matrix form as follows: Among them, i represents the polishing track of the i-th area, j represents the number of track segments in the area, and k represents the number of track points contained in a single polishing track.

5. The method for automatic on-site robot grinding of the inner wall of a turbine runner chamber based on three-dimensional measurement according to claim 1 is characterized in that: In step S4, the trajectories of two adjacent polishing areas are spliced ​​according to the mutual conversion of the coordinate systems of the markers in the area, which includes the following steps: S41, for each area of ​​measurement data, according to step S2, obtain the coordinate system of the left and right markers And calculate the change matrix S42, in the starting grinding area A1, The coordinate system is used as a reference. According to step S3, the grinding trajectory points in the area are generated and expressed in matrix form as follows: Wherein, i represents the polishing track of the i-th area, j1 represents the number of track segments in the polishing area A1, and k represents the number of track points contained in a single polishing track; S43, for adjacent grinding area {A i |i=2~n-1}, the measurement data in this area includes the left and right marker coordinate systems The left side logo is the same as the right side logo of the previous area, so i=2~n-1; through coordinate transformation matrix Convert the end point of each trajectory in the i-1 area to the i area, that is: Taking the end point of each track segment in the i-1th area as the starting point of each track segment in the i-th area, according to step S3, the grinding track points in the area are generated; S44, for the final polishing area A n , the left marker in this area is the same as the right marker in the n-1th area. Therefore, the end point of each track in the n-1th area is used as the starting point of each track in the nth area, and the starting point of each track in the 1st area is used as the end point of each track in the nth area to calculate the polishing track of the final area. The expression is: S45. According to steps S41 to S45, the robot automatically repeats the same processing flow by splicing the path points in the upper and lower areas along the circumference of the inner wall of the turbine runner chamber to complete the grinding of multiple circular surfaces.

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