Magnetorheological finishing tool mark suppression method based on multi-tool head cooperation

Abstract

The present application relates to the technical field of optical processing, and more particularly to a magnetorheological polishing tool mark suppression method based on multi-tool head cooperation, comprising the following steps: building a cooperative polishing system of double mechanical arms carrying double magnetorheological polishing tool heads, so that the two tool heads cooperatively process along the same processing track at a preset included angle; calculating the safe number of rows according to the minimum safe distance of the two tool heads, constructing a cooperative material removal model according to the removal function and the workpiece surface form error, and solving the residence time; comparing the processing progress of the two tool heads in real time, adjusting the hierarchical residence time and reversely compensating the polishing process parameters to maintain the constant total material removal amount; and finally compiling the mechanical arm control file to complete the cooperative polishing. The present application cooperatively processes two magnetorheological polishing tool heads at different removal function angles on the same track, which can effectively suppress the periodic tool mark generated in the processing process, improve the overall processing efficiency, and strictly ensure the processing convergence accuracy of the optical surface.

Description

Technical Field

[0001] This invention belongs to the field of optical processing technology, and in particular relates to a magnetorheological polishing mark suppression method based on multi-tool head collaboration. Background Technology

[0002] With the rapid development of modern optical technology, new optical systems are increasingly demanding higher imaging quality, posing a more severe challenge to the deterministic manufacturing of optical components. Magnetorheological polishing, as an advanced deterministic polishing process, is often used in the final polishing stage of precision optical components. Due to its advantages such as controllable material removal, low subsurface damage, and high surface convergence efficiency, it has become one of the key technologies for high-precision optical component processing.

[0003] However, the high determinism of magnetorheological polishing also makes its results highly susceptible to the coupling effects of complex factors such as tool path planning, feed motion parameters, and machine tool dynamics. This can easily introduce periodic residual lines, i.e., machining marks, onto the machined surface. In existing magnetorheological polishing processes, a multi-round iterative machining strategy is typically employed to efficiently converge surface shape errors. However, existing technologies generally suffer from the limitation that tool marks can overlap and reinforce each other during multi-round machining. That is, using fixed or simple cyclic tool paths in multi-round machining leads to a high degree of spatial frequency correlation in the tool marks generated in each round, easily resulting in the superposition of marks at the same frequency, thus strengthening composite tool marks in specific frequency bands. Furthermore, because multiple rounds of machining are required to suppress tool marks, it is often impossible to balance tool mark and surface shape convergence, necessitating multiple iterations and significantly extending the machining time. Summary of the Invention

[0004] In view of this, the present invention aims to provide a magnetorheological polishing tool mark suppression method based on multi-tool head collaboration. By using two magnetorheological polishing tool heads to process collaboratively at different removal function angles, periodic tool marks can be effectively suppressed, achieving collision-free and efficient processing.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A magnetorheological polishing mark suppression method based on multi-tool head collaboration includes the following steps: S1: Construct a dual-arm collaborative polishing system, with a magnetorheological polishing tool head mounted at the end of each arm. The spatial relative pose of the two magnetorheological polishing tool heads is calibrated so that the two magnetorheological polishing tool heads are arranged at a preset angle along the normal of the workpiece surface to be processed, and the removal function of the two magnetorheological polishing tool heads is obtained. S2: Plan a machining trajectory for the workpiece surface to be machined, and obtain the trajectory gauge. Based on the physical dimensions of the two magnetorheological polishing tool heads, a minimum safe distance is set when the two magnetorheological polishing tool heads move collaboratively along the same machining trajectory. Combined with track gauge and minimum safe distance Calculate the number of safe rows for two magnetorheological polishing tool heads. ; S3: Based on the removal functions of the two magnetorheological polishing tool heads and the workpiece surface shape error distribution obtained by detection, a collaborative material removal model of the two magnetorheological polishing tool heads is constructed. The dwell time of each trajectory dwell point is solved by the constrained optimization algorithm, and the total dwell time of each magnetorheological polishing tool head on all path points is calculated. S4: Combine with safe row count Calculate the dwell time difference between the two magnetorheological polishing tool heads. When the dwell time difference is greater than zero, it is determined that there is a risk of collision. The graded dwell time adjustment strategy is activated, and the polishing process parameters are adjusted to compensate the instantaneous volume removal rate of the magnetorheological polishing tool head in reverse, so as to ensure that the total amount of material removed at each trajectory dwell point is constant. S5: Based on the adjusted dwell time and polishing process parameters in step S4, and combined with the processing trajectory, compile into a synchronous motion control file executable by the dual robotic arms, drive the two magnetorheological polishing tool heads to maintain a safe distance on the same processing trajectory to complete the collaborative polishing operation and suppress the generation of tool marks.

[0006] Furthermore, in step S1, a preset included angle is set. The range of values ​​is .

[0007] Furthermore, in step S2, the machining trajectory is an equally spaced trajectory with a trajectory gauge of [missing information]. Smaller than the effective polishing diameter of the magnetorheological polishing tool head.

[0008] Furthermore, in step S2, the number of safe rows The calculation formula is: ; in, Represents logarithmic values Perform the floor operation.

[0009] Furthermore, in step S3, the material removal model is: ; in, The workpiece surface shape error is discretely distributed. For the first i Removal matrix of a magnetorheological polishing tool head For the first i The dwell time vector corresponding to each magnetorheological polishing tool head; The constrained optimization algorithm takes minimizing the workpiece surface shape error as the optimization objective and uses equality constraints and physical non-negativity constraints as constraints. Among them, the equality constraint is that the total material removal amount under the combined action of the two magnetorheological polishing tool heads matches the target removal amount corresponding to the surface shape error of the workpiece. The physical non-negativity constraint is that the dwell time of each magnetorheological polishing tool head at each trajectory dwell point is not less than zero.

[0010] Furthermore, in step S4, the tiered dwell time adjustment strategy includes level 1 adjustment, level 2 adjustment, and level 3 adjustment; firstly, level 1 adjustment is initiated; if level 1 adjustment cannot eliminate the collision risk, level 2 adjustment is initiated; if the collision risk still exists after level 2 adjustment, level 3 adjustment is initiated. Level 1 adjustment: Shorten the dwell time of the magnetorheological polishing tool head that is ahead in the processing progress to reduce the processing time difference between the two magnetorheological polishing tool heads; Secondary adjustment: The dwell time of the two magnetorheological polishing tool heads is adjusted together to increase the processing progress difference; Level 3 adjustment: Add virtual dwell points outside the processing trajectory to make up for the processing time of the magnetorheological polishing tool head that is lagging behind in the processing progress.

[0011] Furthermore, the specific adjustment method for the tiered stay time adjustment strategy is as follows: The magnetorheological polishing tool head with the earlier processing progress is defined as the first tool head, and the magnetorheological polishing tool head with the later processing progress is defined as the second tool head. For the processing trajectory... m Line, define the first toolhead in the first... m The total dwell time at all path points is denoted as The second tool head is in the first m The total dwell time at all path points is denoted as ; Construct the dwell time difference between the first toolhead and the second toolhead ,when At that time, the tiered dwell time adjustment strategy will be activated; Level 1 Adjustment: Adjust the first tool head in the... m Duration of stay The calculation formula is: ; in, The maximum value selection function selects the maximum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. The minimum dwell time under the constraints of the robotic arm's motion performance; The first tool head is in the... m The dwell time vector of the row; This represents the reciprocal of the upper limit ratio coefficient. This upper limit ratio coefficient corresponds to the first tool head, which, through processing parameter adjustment, can have its removal function volume removal rate increased to the maximum value within the adjustable range. A constant that is greater than 0 and less than 1; For the first tool head in the first m The adjustment weight vector for line processing dwell time, and satisfying ; After the first-level adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ; in, This is a vector summation function used to calculate the sum of all elements within a vector; if the condition is met... If so, a secondary adjustment will be initiated; Secondary adjustment: The dwell time of the two magnetorheological polishing tool heads is adjusted jointly, and the dwell time of the second tool head is adjusted in the second stage. Duration of stay The calculation formula is: ; in, The minimum value selection function selects the minimum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. Indicates the second tool head in the first... The maximum allowed stay time for the line, and meets the following requirements. ; For the second tool head in the first The dwell time vector of the row; This represents the reciprocal of the lower limit proportional coefficient. This lower limit proportional coefficient corresponds to the second tool head, which, through processing parameter adjustment, can lower its removal function volume removal rate to the minimum value within the adjustable range. It is a constant greater than 1; For the second tool head in the first Adjusted weight vector for processing dwell time; After the secondary adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ; If the judgment condition is met If so, a level three adjustment will be initiated; Level 3 adjustment: (Second tool head) A virtual dwell point is added to the safety area outside the machining trajectory on the end extension line of the machining trajectory. The removal function at this virtual dwell point will not remove material from the workpiece machining area. The dwell time of this virtual dwell point is set as follows: .

[0012] Furthermore, in step S4, the polishing process parameters are at least one of the following: polishing wheel speed, polishing working gap, and polishing fluid flow rate; the method for reverse compensation of the instantaneous volume removal rate of the magnetorheological polishing tool head is as follows: when the dwell time of the trajectory dwell point decreases, the polishing process parameters at that trajectory dwell point are adjusted to increase the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head; when the dwell time of the trajectory dwell point increases, the polishing process parameters at that trajectory dwell point are adjusted to decrease the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head, ensuring that the total amount of material removed at each trajectory dwell point remains constant.

[0013] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention employs two magnetorheological polishing tool heads to collaboratively process along the same trajectory at different removal function angles. This actively suppresses periodic machining marks from a physical perspective, improving the surface finish of the workpiece. A graded dwell time adjustment strategy is used to collaboratively control the dwell time of the two magnetorheological polishing tool heads at various trajectory points. Furthermore, the polishing process parameters are adjusted to compensate for the instantaneous volume removal rate of the material, ensuring collision-free, safe, and stable operation of the multi-tool head collaborative processing and precisely maintaining a constant total material removal at each trajectory dwell point. Leveraging the advantages of parallel processing with multiple tool heads improves overall processing efficiency while strictly preserving the high-precision convergence characteristics of deterministic magnetorheological polishing. Attached Figure Description

[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic flowchart of the magnetorheological polishing tool mark suppression method based on multi-tool head collaboration described in the embodiments of the present invention; Figure 2 A schematic diagram of the removal function rotation described in the embodiment of the present invention; Figure 3 This is a schematic diagram of the grating processing trajectory described in an embodiment of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, the multi-tool head collaborative magnetorheological polishing tool mark suppression method of this invention includes the following steps: S1: Construct a dual-robotic arm collaborative polishing system. Equip the end of each robotic arm with a magnetorheological polishing tool head. Calibrate the spatial relative pose of the two magnetorheological polishing tool heads, arranging them at a preset angle along the normal to the workpiece surface to be machined. Obtain the removal function of the two magnetorheological polishing tool heads. Step S1 includes the following steps: S11: Construct a dual-arm collaborative polishing system with two magnetorheological polishing tool heads, wherein the first tool head is mounted at the end of the first arm and the second tool head is mounted at the end of the second arm; establish a unified workpiece coordinate system and define tool coordinate systems for the first and second tool heads respectively; ensure that there is no rotation between the workpiece coordinate system and the tool coordinate system through calibration, that is, ensure that the removal function orientation of the two magnetorheological polishing tool heads is consistent.

[0021] S12: Calibrate the removal functions of the dual robotic arms to obtain the first tool head removal function. With the second tool head removal function .

[0022] S13: Determine the fixed relative spatial orientation of the two magnetorheological polishing tool heads in the machining plane, and rotate the tool coordinate system of the second tool head relative to the tool coordinate system of the first tool head around the z-axis by a preset angle. Preset angle The range of values ​​is This step allows the major axis angle of the removal function of the two magnetorheological polishing tool heads to be [value missing]. The second toolhead removal function at this time is And ensure rotational alignment accuracy through calibration, such as Figure 2 As shown in the figure, TOOL1 represents the first tool head removal function, TOOL2 represents the second tool head removal function, and point O represents the trajectory dwell point.

[0023] Magnetorheological polishing marks are generated when a magnetorheological polishing tool head processes the workpiece surface according to a predetermined trajectory and machining path. Based on the "plowing" model of magnetorheological marks, a periodic structure corresponding to the machining path forms on the surface. When two removal functions have an angle between them, the influence ranges of the different removal functions overlap, thereby disrupting the aforementioned periodic structure and suppressing the marks. The angle between the two removal functions depends on the actual machining parameters, the machining environment, and the parameters of the removal functions used. It is usually determined through actual experiments to find the optimal angle that can effectively suppress the marks under the current machining conditions.

[0024] S2: Plan a machining trajectory for the workpiece surface to be machined, and obtain the trajectory gauge. Based on the physical dimensions of the two magnetorheological polishing tool heads, a minimum safe distance is set when the two magnetorheological polishing tool heads move collaboratively along the same machining trajectory. Combined with track gauge and minimum safe distance Calculate the number of safe rows for two magnetorheological polishing tool heads. .

[0025] In the workpiece coordinate system, plan a machining trajectory for the surface to be machined on the workpiece. This machining trajectory is a grating machining trajectory. ,like Figure 3 As shown, the track gauge is defined as... s The processing starts at point A.

[0026] To ensure that the two magnetorheological polishing tool heads do not touch each other during any machining posture while moving collaboratively along the same machining trajectory, the minimum safe distance between the centers of the two magnetorheological polishing tool heads is set based on their physical dimensions. .

[0027] Safe number of lines The calculation formula is: ; in, Represents logarithmic values x Perform a floor function (round up) to calculate the number of safe rows. This means the number of rows the first toolhead precedes the second toolhead is greater than or equal to 1. To prevent collisions, the following steps control the difference in the number of machining rows between the two magnetorheological polishing tool heads to equal the safe number of rows, thus improving processing efficiency. .

[0028] S3: Based on the removal functions of the two magnetorheological polishing tool heads and the workpiece surface shape error distribution obtained from detection, a collaborative material removal model for the two magnetorheological polishing tool heads is constructed. A constrained optimization algorithm is used to solve for the dwell time at each trajectory dwell point, and the total dwell time at all path points of each magnetorheological polishing tool head is calculated. Step S3 includes the following steps: S31: Perform optical interferometry on the surface of the workpiece to be machined to obtain the surface shape data of the surface to be machined. ,in and Establish the workpiece coordinate system. Based on the surface shape data. Based on actual processing requirements, the discrete distribution of surface shape error of the workpiece surface to be processed is obtained. and convert it into vector form. This refers to the total amount of material that needs to be removed.

[0029] S32: Construct the removal matrix, which is formed by... M OK N The columns are composed of, among which M Discrete distribution of surface shape error The number of discrete points, N For processing trajectory The total number of trajectory dwell points. The matrix of the first... k OK j The column elements represent the magnetorheological polishing tool head when... The j When the trajectory represented by the line is stationary, the magnetorheological polishing tool head removes the function for... The k The removal rate is generated for each data point. Based on the above principles, the removal functions are used respectively. and Constructing the removal matrix of two magnetorheological polishing tool heads and Therefore, the following collaborative material removal model is established: ; in, For the first i The dwell time vector corresponding to each magnetorheological polishing tool head.

[0030] S33: Solve the equation in step S32 using constrained least squares or other constrained optimization algorithms to obtain the polishing dwell time. and This sequence ensures that the total material removal amount under the combined action of the two magnetorheological polishing tool heads matches the target material removal amount corresponding to the workpiece surface shape error, i.e., it is closest to the target material removal amount. Meanwhile, the dwell time of each magnetorheological polishing tool head at all trajectory dwell points meets the requirements. Physical nonnegativity constraints.

[0031] S34: Using Track Gauge trajectory Perform row splitting, using the intervals between adjacent trajectory points y The difference in direction coordinates is used as the basis for judgment, when Δy Greater than or equal to s When a point is considered a line break, all trajectory points are divided into corresponding line sequences, resulting in... K An ordered set of line trajectories: Correspondingly, the first tool head is in the 1st to the 2nd... K The dwell time vectors of the rows are respectively The second tool head is in the first to the second K The dwell time vectors of the rows are respectively For the processing trajectory, the first... m Okay, the first tool head is in the first... m The total dwell time at all path points is denoted as The second tool head is in the first m The total dwell time at all path points is denoted as .

[0032] S4: Combine with safe row count Calculate the dwell time difference between the two magnetorheological polishing tool heads. If the dwell time difference is greater than zero, a collision risk is identified, a graded dwell time adjustment strategy is initiated, and polishing process parameters are adjusted to compensate for the instantaneous volume removal rate of the magnetorheological polishing tool head, ensuring a constant total material removal at each trajectory dwell point. Step S4 includes the following steps: S41: Comparison and ,in Classify the results accordingly: like Then it is considered that the second tool head is in the first m The processing progress of the row will not catch up with the first tool head, and processing can be carried out according to the original dwell time of this row; like Then there exists a second toolhead in the process of completing the first... After processing, the first tool head still has not completed the first step. m Processing may lead to collision risks, necessitating a reallocation of dwell time. The first level of the tiered dwell time adjustment strategy is initiated, using the following formula to calculate the difference in dwell time between the first and second toolheads at this point. : ; The first tool head is calculated using the following formula at the 1st twentieth ... m Adjustment weight vector for processing dwell time for: ; The first tool head was subsequently updated in [the following section]. m The length of stay for the trip is And calculate the actual adjustment value: ; in, The maximum value selection function selects the maximum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. The minimum dwell time under the constraints of the robotic arm's motion performance; The first tool head is in the... m The dwell time vector of the row; This represents the reciprocal of the upper limit ratio coefficient. This upper limit ratio coefficient corresponds to the first tool head, which, through processing parameter adjustment, can have its removal function volume removal rate increased to the maximum value within the adjustable range. It is a constant greater than 0 and less than 1.

[0033] After the first-level adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ; in, Represents a vector x Summing all elements in the , due to the operation of taking the maximum value, the ... m The actual adjustment of the line It should be less than or equal to ,when If the condition is met, continue with step S42; otherwise, proceed directly to step S44.

[0034] S42: When the dwell time adjustment of the first toolhead cannot meet the requirements, a joint adjustment of the first and second toolheads is required, i.e., the second-level adjustment of the hierarchical dwell time adjustment strategy is initiated. The following formula is used to calculate the second toolhead at the [missing information - likely a date or time]. Adjustment weight vector for processing dwell time for: ; The second toolhead was then updated in [the following section]. The length of stay for the trip is And calculate the actual adjustment value: ; in, The minimum value selection function selects the minimum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. Indicates the second tool head in the first... The maximum allowed stay time for the line, and meets the following requirements. Its value is equal to the original residence time vector multiplied by the scaling factor. ; For the second tool head in the first The dwell time vector of the row; This represents the reciprocal of the lower limit proportional coefficient. This lower limit proportional coefficient corresponds to the second tool head, which, through processing parameter adjustment, can lower its removal function volume removal rate to the minimum value within the adjustable range. It is a constant greater than 1.

[0035] After the secondary adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ; This coefficient is influenced by a combination of factors, including modulation capability, physical limitations, and security risks. If at this time... If the condition is met, proceed to step S43; otherwise, proceed to step S44.

[0036] S43: When the joint adjustment of the first toolhead and the second toolhead still fails to meet the requirements, initiate the third-level adjustment of the hierarchical dwell time adjustment strategy, in the second toolhead's... A virtual dwell point is added to the safety area on the end extension line, outside the machining trajectory, to ensure that the removal function at this virtual dwell point will not remove material from the workpiece machining area. The dwell time of this virtual dwell point is set as follows: .

[0037] S44: For trajectory lines with dwell time adjustments, compensate for the instantaneous volume removal rate of the first toolhead removal function: obtain the original dwell time for this line. Adjusted stay time , for the g Given a trajectory dwell point, solve for the scaling factor. : ; Therefore, when the first toolhead stops at this trajectory dwell point, its removal function at this point should be adjusted to... Use the following formula to calculate: .

[0038] Similarly, if this line is a joint adjustment line for the first and second tool heads, then compensation is made for the instantaneous volume removal rate of the second tool head: obtain the original residence time. Adjusted stay time (If a virtual dwell point is added in step S45, remove it and keep it) and (Two vectors of equal dimension), for the first g Given a trajectory dwell point, solve for the scaling factor. : ; Therefore, when the second toolhead stops at this trajectory dwell point, its removal function at this point should be adjusted to... Calculate using the following formula : .

[0039] The method for compensating for the instantaneous volume removal rate of the magnetorheological polishing tool head is as follows: when the residence time at a trajectory dwell point decreases, the polishing process parameters at that dwell point are adjusted to increase the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head; when the residence time at a trajectory dwell point increases, the polishing process parameters at that dwell point are adjusted to decrease the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head, ensuring that the total amount of material removed at each trajectory dwell point remains constant. The polishing process parameters include at least one of the following: polishing wheel speed, polishing working gap, and polishing fluid flow rate.

[0040] Since adjusting the polishing process parameters to change the instantaneous volume removal rate of the magnetorheological polishing tool head is an existing technology, it will not be described in detail in this invention.

[0041] S45: Perform steps S41 to S44 on all lines of the machining trajectory to obtain all adjusted dwell times and polishing process parameters.

[0042] S5: Based on the adjusted dwell time and polishing process parameters in step S4, and combined with the processing trajectory, compile into a synchronous motion control file executable by the dual robotic arms, drive the two magnetorheological polishing tool heads to maintain a safe distance on the same processing trajectory to complete the collaborative polishing operation and suppress the generation of tool marks.

[0043] Based on the adjusted dwell time and removal function in step S4, and combined with the machining trajectory and surface shape error of the surface to be machined planned in step S2, the adjusted dwell time, removal function parameters and path point coordinates are converted into a trajectory file and process parameter instruction set executable by the dual robotic arms. Synchronous motion control files for the robotic arms corresponding to the first tool head and the second tool head are generated respectively, driving the two magnetorheological polishing tool heads to maintain a safe distance on the same machining trajectory to complete the collaborative polishing operation and suppress the generation of tool marks.

[0044] Since the compilation and use of the robotic arm control file in step S5 is existing technology, it will not be described again in this invention.

[0045] It should be noted that when the workpiece has a large surface area to be machined and requires improved machining efficiency or further enhancement of tool mark suppression, more than two magnetorheological polishing tool heads can be used simultaneously for collaborative machining. This invention is also applicable to grating machining trajectories that require rotation. It only requires using a rotation matrix during planning to rotate the trajectory to the desired angle, and then using a rotation matrix of the same structure with parameters that are the opposite of the desired angle during the row processing in step S4 to rotate the trajectory back to the coordinate system of the grating lines and the workpiece. x The direction parallel to the axis is acceptable. Furthermore, if machining from the first tool head to the... m When the dwell time of the second tool head is greater than that of the first tool head, this difference can be recorded. This difference can then be used to reduce the dwell time of the next machining path where the dwell time of the first tool head is greater than that of the second tool head (i.e., the path requiring adjustment). This is to maximize efficiency and reduce the impact of adjusting residence time on removal volume.

[0046] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0047] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for suppressing tool marks in magnetorheological polishing based on multi-tool head collaboration, characterized in that, Includes the following steps: S1: Construct a dual-arm collaborative polishing system, with a magnetorheological polishing tool head mounted at the end of each arm. The spatial relative pose of the two magnetorheological polishing tool heads is calibrated so that the two magnetorheological polishing tool heads are arranged at a preset angle along the normal of the workpiece surface to be processed, and the removal function of the two magnetorheological polishing tool heads is obtained. S2: Plan a machining trajectory for the workpiece surface to be machined, and obtain the trajectory gauge. Based on the physical dimensions of the two magnetorheological polishing tool heads, a minimum safe distance is set when the two magnetorheological polishing tool heads move collaboratively along the same machining trajectory. Combined with track gauge and minimum safe distance Calculate the number of safe rows for two magnetorheological polishing tool heads. ; S3: Based on the removal functions of the two magnetorheological polishing tool heads and the workpiece surface shape error distribution obtained by detection, a collaborative material removal model of the two magnetorheological polishing tool heads is constructed. The dwell time of each trajectory dwell point is solved by the constrained optimization algorithm, and the total dwell time of each magnetorheological polishing tool head on all path points is calculated. S4: Combine with safe row count Calculate the dwell time difference between the two magnetorheological polishing tool heads. When the dwell time difference is greater than zero, it is determined that there is a risk of collision. The graded dwell time adjustment strategy is activated, and the polishing process parameters are adjusted to compensate the instantaneous volume removal rate of the magnetorheological polishing tool head in reverse, so as to ensure that the total amount of material removed at each trajectory dwell point is constant. S5: Based on the adjusted dwell time and polishing process parameters in step S4, and combined with the processing trajectory, compile into a synchronous motion control file executable by the dual robotic arms, drive the two magnetorheological polishing tool heads to maintain a safe distance on the same processing trajectory to complete the collaborative polishing operation and suppress the generation of tool marks.

2. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S1, the preset included angle The range of values ​​is .

3. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S2, the processing trajectory is an equally spaced trajectory with a track gauge of [missing information]. Smaller than the effective polishing diameter of the magnetorheological polishing tool head.

4. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S2, the number of secure rows The calculation formula is: ； in, Represents logarithmic values Perform the floor operation.

5. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S3, the material removal model is: ； in, The workpiece surface shape error is discretely distributed. For the first i Removal matrix of a magnetorheological polishing tool head For the first i The dwell time vector corresponding to each magnetorheological polishing tool head; The constrained optimization algorithm takes minimizing the workpiece surface shape error as the optimization objective and uses equality constraints and physical non-negativity constraints as constraints. Among them, the equality constraint is that the total material removal amount under the combined action of the two magnetorheological polishing tool heads matches the target removal amount corresponding to the workpiece surface shape error; the physical non-negativity constraint is that the dwell time of each magnetorheological polishing tool head at each trajectory dwell point is not less than zero.

6. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S4, the graded dwell time adjustment strategy includes first-level adjustment, second-level adjustment, and third-level adjustment; first-level adjustment is initiated, and if the first-level adjustment cannot eliminate the collision risk, second-level adjustment is initiated. If a collision risk still exists after the Level 2 adjustment, a Level 3 adjustment will be initiated. Level 1 adjustment: Shorten the dwell time of the magnetorheological polishing tool head that is ahead in the processing progress to reduce the processing time difference between the two magnetorheological polishing tool heads; Secondary adjustment: The dwell time of the two magnetorheological polishing tool heads is adjusted together to increase the processing progress difference; Level 3 adjustment: Add virtual dwell points outside the processing trajectory to make up for the processing time of the magnetorheological polishing tool head that is lagging behind in the processing progress.

7. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 6, characterized in that, The specific adjustment method for the tiered residence time adjustment strategy is as follows: The magnetorheological polishing tool head with the earlier processing progress is defined as the first tool head, and the magnetorheological polishing tool head with the later processing progress is defined as the second tool head. For the processing trajectory... m Line, define the first toolhead in the first... m The total dwell time at all path points is denoted as ; The second tool head is in the... m The total dwell time at all path points is denoted as ; Construct the dwell time difference between the first toolhead and the second toolhead ,when At that time, the tiered dwell time adjustment strategy will be activated; Level 1 Adjustment: Adjust the first tool head in the... m Duration of stay The calculation formula is: ； in, The maximum value selection function selects the maximum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. The minimum dwell time under the constraints of the robotic arm's motion performance; The first tool head is in the... m The dwell time vector of the row; This represents the reciprocal of the upper limit ratio coefficient. This upper limit ratio coefficient corresponds to the first tool head, which, through processing parameter adjustment, can have its removal function volume removal rate increased to the maximum value within the adjustable range. A constant that is greater than 0 and less than 1; For the first tool head in the first m The adjustment weight vector for line processing dwell time, and satisfying ; After the first-level adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ； in, This is a vector summation function used to calculate the sum of all elements within a vector; if the condition is met... If so, a secondary adjustment will be initiated; Secondary adjustment: The dwell time of the two magnetorheological polishing tool heads is adjusted jointly, and the dwell time of the second tool head is adjusted in the second stage. Duration of stay The calculation formula is: ； in, The minimum value selection function selects the minimum value among the corresponding elements of multiple equal-dimensional vectors or multiple numerical values. Indicates the second tool head in the first... The maximum allowed stay time for the line, and meets the following requirements. ; For the second tool head in the first The dwell time vector of the row; This represents the reciprocal of the lower limit proportional coefficient. This lower limit proportional coefficient corresponds to the second tool head, which, through processing parameter adjustment, can lower its removal function volume removal rate to the minimum value within the adjustable range. It is a constant greater than 1; For the second tool head in the first Adjusted weight vector for processing dwell time; After the secondary adjustment is completed, update the dwell time difference between the two magnetorheological polishing tool heads. for: ； If the judgment condition is met If so, a level three adjustment will be initiated; Level 3 adjustment: (Second tool head) A virtual dwell point is added to the safety area outside the machining trajectory on the end extension line of the machining trajectory. The removal function at this virtual dwell point will not remove material from the workpiece machining area. The dwell time of this virtual dwell point is set as follows: .

8. The magnetorheological polishing mark suppression method based on multi-tool head collaboration according to claim 1, characterized in that, In step S4, the polishing process parameters are at least one of the polishing wheel speed, polishing working gap, and polishing fluid flow rate; the instantaneous volume removal rate of the reverse-compensating magnetorheological polishing tool head is achieved by adjusting the polishing process parameters at the trajectory dwell point to increase the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head when the dwell time at the trajectory dwell point decreases; and by adjusting the polishing process parameters at the trajectory dwell point to decrease the instantaneous volume removal rate of the corresponding magnetorheological polishing tool head when the dwell time at the trajectory dwell point increases, thereby ensuring that the total amount of material removed at each trajectory dwell point remains constant.

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