Robot grinding and polishing process and track synchronous planning method and system for fixed margin removal

Abstract

The invention belongs to the technical field of robot path planning, and particularly discloses a fixed margin removal robot grinding and polishing process and track synchronous planning method and system. Comprising the steps that a robot smooth end face grinding and polishing material removal profile is constructed; the machining allowance of the workpiece is determined, and the curved surface of the surface of the workpiece is subjected to curved surface reconstruction based on the maximum tolerance limitation; with the machining residual height and the smoothness of the technological parameters as targets, force-speed-position machining information of robot grinding is planned on the reconstructed curved surface, and discrete machining point positions and the technological parameters are obtained; expanding the reconstructed curved surface to a four-dimensional form, obtaining a composite track fusing a position component and a process component, and carrying out adaptive interpolation on the composite track to meet the process precision and the motion precision of a processing point; and obtaining a normal vector of the interpolated composite trajectory, and optimizing a tail end redundancy degree of freedom to obtain process parameters and processing poses of synchronous planning. According to the method, matching and optimization of a track field and a process field in robot grinding are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of robot path planning, and more specifically, relates to a method and system for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal. Background Art

[0002] With the rapid development of the high-end equipment manufacturing industry, robotic end-face grinding and polishing technology has gradually replaced manual and machine-based grinding and polishing to become the mainstream for grinding and polishing large, complex components, thanks to its flexible contact, large working range, and high flexibility. The machining and manufacturing of large, complex components, such as high-speed rail locomotives, are characterized by complex surface curvatures and uneven stock distribution. This, coupled with inconsistencies between trajectory planning and process parameter planning during robotic grinding and polishing, makes it difficult to control the removal accuracy of robotic grinding and polishing, affecting the contour accuracy and consistency of the workpiece surface and limiting the further development of robotic grinding and polishing in the field of high-precision manufacturing of large, complex components.

[0003] To solve the above problems, Chinese patent CN115213901B proposes a robot grinding and polishing force-position-speed collaborative process planning method. By jointly planning the contact force and feed speed of different processing positions of the workpiece, force-position-speed collaborative process planning is realized, and high-efficiency and high-precision complex surface grinding and polishing is achieved; Chinese patent CN117620782A proposes a robot adaptive grinding and polishing method and system for complex surfaces. Based on the contact model, force-position trajectory planning is performed on the workpiece surface, and the feed speed is calculated according to the real-time grinding and polishing amount of the workpiece and the expected allowance, so as to achieve compliant and collaboratively controlled grinding and polishing of the workpiece surface. Although the above schemes all achieve adaptive high-precision processing of complex surfaces, the above methods all first perform full coverage path planning based on the workpiece surface geometry, and then perform process parameter planning at different processing positions in combination with the removal allowance distribution. This results in the generated trajectory ignoring the consideration of process requirements, failing to achieve consistency between the robot process parameters and trajectory planning, and still leaving the situation where the robot grinding and polishing removal accuracy is difficult to control with high precision.

[0004] Therefore, this field urgently needs to propose a method for synchronous planning of process parameters and trajectories based on the fusion of robot grinding force-speed-position information, which can overcome the problem of the influence of process requirements on robot process parameters and trajectory planning in the existing technology by fusing and interpolating the robot grinding trajectory with the process parameters. Summary of the Invention

[0005] To address the aforementioned shortcomings or improvements in existing technologies, a method and system for synchronously planning process parameters and trajectories based on the fusion of robotic grinding force, velocity, and position information has been developed. This method comprehensively considers the relationship between the robot's compliant end-face grinding and polishing mechanism, workpiece geometry, machining allowance distribution, and trajectory planning algorithms, achieving matching and optimization of the trajectory field and process field during robotic grinding.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for synchronously planning a robot grinding and polishing process and trajectory with fixed allowance removal is proposed, comprising the following steps:

[0007] Step 1: Constructing the robot's flexible end face grinding and polishing material removal profile;

[0008] Step 2: determine the machining allowance of the workpiece and reconstruct the surface of the workpiece based on the maximum tolerance limit;

[0009] Step 3: With the goal of achieving smoothness of machining residual height and process parameters, the force-speed-position machining information of robot grinding is planned on the reconstructed surface to obtain the discrete machining point positions and process parameters.

[0010] Step 4: Based on the force-speed-position processing information, the reconstructed surface is expanded to a four-dimensional form, a composite trajectory integrating the position component and the process component is obtained, and the composite trajectory is adaptively interpolated to meet the process accuracy and motion accuracy of the processing point;

[0011] Step 5: Obtain the normal vector of the interpolated composite trajectory, optimize the redundant degrees of freedom at the end, and obtain the synchronously planned process parameters and machining posture.

[0012] As a further preferred method, in step 1, based on the Hertz contact theory and the macroscopic contact pressure of the workpiece, the normal force model of a single conical abrasive is derived, the joint probability density function of the abrasive height and cone angle is established, and the microscopic penetration depth of the abrasive is calculated by the macro-microscopic normal force balance, thereby constructing the macro-scale flexible end face grinding and polishing material removal profile φ(x, F n , v w ).

[0013] As a further preferred embodiment, in step 2, based on the maximum tolerance limit, the discrete point cloud is fitted into a smooth 4th-order NURBS surface S(u, v):

[0014]

[0015] Where, d ij is the surface control point, w ij is the control point weight, N i,3 (u),N j,3 (v) are the cubic basis functions with respect to u and v respectively.

[0016] As further preferred, step three includes the following steps:

[0017] (31) Construct the initial path, discretize the initial path using the equal chord height error method, and calculate the corresponding processing points of two adjacent paths. and Position interpolation is performed on the surface part of ;

[0018] (32) Based on the average value of the absolute deviation between the residual height of the interpolation point and the average residual height, the total processing residual height index after polishing the i-th and i+1-th paths is constructed;

[0019] (33) Based on the consideration of the degree of variation of process parameters at different processing positions on the same path, assuming that there are n processing points on each path, the overall objective function of the smoothness of the robot's normal force and feed speed is constructed.

[0020] As a further preferred embodiment, in step (31), the calculation model of the position interpolation includes:

[0021]

[0022] Where, is the position of the mth interpolation point between the jth processing point on path i and path i+1, and k is the number of interpolation points.

[0023] Preferably, in step (32), the calculation model of the total processing residual height index includes:

[0024]

[0025] Where, It represents the residual height index of the jth point after the i+1th path grinding, expressed as the normal force F with respect to the line spacing Δu n and feed speed v w Function

[0026] Preferably, in step (33), the calculation model of the overall objective function includes:

[0027]

[0028] Where ω1, ω2, and ω3 are the weights of machining residual height index, normal force fluctuation, and feed speed fluctuation, respectively.

[0029] As a further preferred embodiment, in step 4, the step of expanding the reconstructed surface into a four-dimensional form includes: expanding the curve into a four-dimensional form, integrating the normal force F of the robot processing n , feed speed v w And the surface position parameters (u, v):

[0030]

[0031] Where α is the parameter of the curve, C1(α) and C2(α) represent the position component and process component of the composite trajectory respectively, and w iis the weight of the NURBS curve, d i are the curve control points.

[0032] As a further preferred embodiment, in step 4, the adaptive interpolation of the composite trajectory includes:

[0033] (41) Obtain the initial calculation point C(α0)=C(0) on the composite trajectory;

[0034] (42) Determine the initial value of the interpolation step Δα i ;

[0035] (43) According to the interpolation step Δα i Calculate the trajectory of the next point and the process parameter C(α i +Δα i );

[0036] (44) Determine the interpolation step length Δα i Whether the process constraint ε is met Re , tangent plane chord height error ε δ and the surface discretization error constraint ε d If satisfied, proceed to step (45); otherwise, adjust the interpolation step size and return to step (43);

[0037] (45) Determine the next parameter α i+1 =α i +Δα i Is it greater than or equal to 1? If so, output the interpolation point sequence {α i}, otherwise, let i=i+1 and return to step (42).

[0038] As a further preferred embodiment, in step 4, the adaptive interpolation of the composite trajectory includes: performing margin calculation on the points within the interpolation step, and defining the margin error as the maximum difference between the margin between the interpolation points and the margin of the next point:

[0039]

[0040] Where, ΔRe j is the margin difference, Re(α) is the point α j The margin error, Re(α j+1 ) is point α j+1 The margin error;

[0041] Preferably, in step 4, the adaptive interpolation of the composite trajectory further comprises: assuming that the two endpoints of the interpolation trajectory are Q j , Q j+1 , select any position Q between two points j，m , ask Q j，m To straight line segment Q jQ j+1 The projection point M, and find the point Q based on the NURBS surface information j,m Normal vector at Then the chord height error on the tangent plane can be expressed as:

[0042]

[0043] Preferably, in step 4, the adaptive interpolation of the composite trajectory further comprises: limiting the comprehensive deviation caused by the composite trajectory interpolation, that is:

[0044]

[0045] In the formula, C′(α j ) is the first-order derivative of the composite trajectory, C"(α j ) is the second-order derivative of the composite trajectory, and Δα is the interpolation step size.

[0046] As a further preferred method, the interpolation step length Δα j Need to meet the following requirements at the same time:

[0047]

[0048] Where, ε Re is the process constraint, ε δ is the plane chord height error constraint, ε d is the curve discretization error constraint.

[0049] According to another aspect of the present invention, a robot grinding and polishing process and trajectory synchronization planning system for fixed allowance removal is provided, comprising the following steps:

[0050] The first main control module is used to build the robot's flexible end face grinding and polishing material removal profile;

[0051] The main control module is used to determine the machining allowance of the workpiece and reconstruct the surface of the workpiece based on the maximum tolerance limit;

[0052] The third main control module is used to plan the force-speed-position processing information of robot grinding on the reconstructed surface with the goal of smoothing the residual height and process parameters, and obtain the discrete processing point positions and process parameters;

[0053] a fourth main control module, configured to expand the reconstructed surface into a four-dimensional form based on the force-speed-position processing information, obtain a composite trajectory integrating the position component and the process component, and perform adaptive interpolation on the composite trajectory to meet the process accuracy and motion accuracy of the processing point;

[0054] The fifth main control module is used to obtain the normal vector of the interpolated composite trajectory, optimize the redundant degrees of freedom at the end, and obtain the synchronously planned process parameters and machining posture.

[0055] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0056] 1. The present invention achieves synchronization and consistency between process and trajectory planning by fusing and interpolating the trajectory of robot grinding with process parameters, and realizes high-precision removal of non-uniform allowances on the workpiece surface.

[0057] 2. The present invention generates robot grinding force-speed-position information for specific allowance removal by optimizing the residual height between paths and process smoothness.

[0058] 3. The present invention expands the NURBS curve to a four-dimensional form, and fully expresses the position information and process information of the robot processing point through a single variable function.

[0059] 4. The present invention adaptively calculates the interpolation step size based on the margin error, the tangent plane chord height error and the curve discrete error, thereby meeting the process accuracy and motion accuracy of trajectory planning. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a flow chart of a method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to an embodiment of the present invention;

[0061] Figure 2 1 is a schematic structural diagram of a robot compliant grinding system according to an embodiment of the present invention;

[0062] Figure 3 is a flow chart of force-speed-position information generation based on specific margin removal according to an embodiment of the present invention;

[0063] Figure 4 This is a flow chart of the fusion and adaptive interpolation of force-speed-position information involved in an embodiment of the present invention;

[0064] Figure 5 is a flow chart of a NURBS-based composite trajectory adaptive interpolation algorithm according to an embodiment of the present invention;

[0065] Figure 6 (a) is a schematic diagram comparing the method of the present invention with the constant parameter processing area, Figure 6 (b) is a comparison diagram of the residual distribution after the method of the present invention and constant parameter processing. DETAILED DESCRIPTION

[0066] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0067] like Figure 1 As shown, an embodiment of the present invention provides a method for synchronous planning of a robot grinding and polishing process and trajectory for fixed allowance removal, which is implemented based on an ABB4400 robot and an electric power-controlled actuator (of course, the above is only one model of robot involved in the embodiment of the present invention, and other models of robots or actuators that can implement the control method of the present invention are also applicable to the present invention). Figure 2 The main steps are as follows:

[0068] (1) In order to obtain a more accurate material removal profile, the macroscopic contact pressure between the tool and the workpiece is analyzed based on the Hertz contact theory, the normal force model of a single conical abrasive is derived, and the joint probability density function of the abrasive height and cone angle is established. The microscopic penetration depth of the abrasive is calculated by the balance of macroscopic and microscopic normal forces, and then the macroscopic-scale flexible end face grinding and polishing material removal profile φ(x, F n , v w ).

[0069] (2) In order to determine the machining allowance of the workpiece, a laser tracker is used to obtain high-precision point cloud data. Since the scanned point cloud often has defects such as outliers and noise points, and has extremely high density and a large number, it is necessary to remove outliers, filter and downsample. The processed point cloud theoretical model is aligned, and the machining allowance is estimated by calculating the distance of the aligned point cloud, and the interpolation method is used to express it as a distribution function MA(x, y, z) in cubic Euclidean space. At the same time, based on the maximum tolerance limit, the discrete point cloud is fitted into a smooth 4th-order NURBS surface S(u, v), which is expressed as:

[0070]

[0071] Where, d ij is the surface control point, w ij is the control point weight, N i，3 (u), N j，3 (v) are the cubic basis functions with respect to u and v respectively.

[0072] (3) Figure 3The computational process for force-velocity-position information for specific stock removal is demonstrated. Taking into account the interplay between the grinding process and the trajectory, and aiming for smoothness of the machining residual height and process parameters, the force-velocity-position information for robotic grinding is simultaneously planned on the reconstructed NURBS surface, obtaining discrete machining point locations and process parameters.

[0073] First, the boundary u=0 is used as the initial path and the equal chord height error method is used to discretize it. Then, for the corresponding processing points of two adjacent paths, and Interpolate the position of the surface part of :

[0074]

[0075] In order to more comprehensively reflect the uniformity of the overall processing and reduce the allowance fluctuation of subsequent finishing, the average value of the absolute deviation between the residual height of the interpolation point and the average residual height is considered. After grinding the i-th and i+1-th paths, the total processing residual height index can be expressed as:

[0076]

[0077] In the formula It means that after the i+1th path grinding, the processing residual height index corresponding to the jth point can be expressed as the normal force F with respect to the line spacing Δu n and feed speed v w Function At the same time, the degree of variation of process parameters at different processing positions on the same path is considered to improve the smoothness of the robot's normal force and feed rate. Assuming that there are n processing points on each path, the overall objective function can be written as:

[0078]

[0079] (4) Figure 4 The force-speed-position information fusion and adaptive interpolation process is demonstrated. First, the NURBS curve is expanded to a four-dimensional form, and the normal force F of the robot processing is integrated. n , feed speed v w and surface position parameters (u, v).

[0080]

[0081] Where α is a parameter of the NURBS curve. C1(α) and C2(α) represent the position component and process component of the composite trajectory, respectively. Using a four-dimensional NURBS curve, the trajectory and process information of robotic grinding can be integrated and represented as a single-parameter composite trajectory.

[0082] Then, the composite trajectory based on NURBS expression is adaptively interpolated according to the margin distribution, tangent plane chord height error and curve discrete error to meet the process accuracy and motion accuracy of the processing point. The specific algorithm flow is as follows Figure 5 The adaptive interpolation of the composite trajectory includes:

[0083] (41) Obtain the initial calculation point C(α0)=C(0) on the composite trajectory;

[0084] (42) Determine the initial value of the interpolation step Δα i ;

[0085] (43) According to the interpolation step Δα i Calculate the trajectory of the next point and the process parameter C(α i +Δα i );

[0086] (44) Determine the interpolation step length Δα i Whether the process constraint ε is met Re , tangent plane chord height error ε δ and the surface discretization error constraint ε d If satisfied, go to step (45); otherwise adjust the interpolation step size to half of the original Δα i =Δα i / 2, return to step (43);

[0087] (45) Determine the next parameter α i+1 =α i +Δα i Is it greater than or equal to 1? If so, output the interpolation point sequence {α i}, otherwise, let i=i+1 and return to step (42).

[0088] During the robot's interpolation execution, stable normal forces and feed rates can lead to relatively stable material removal depths. However, the asynchrony between process parameters and machining positions can lead to inconsistencies between theoretical material removal and non-uniform allowance distribution. In order for the interpolation of a single trajectory to meet the removal accuracy requirements, it is necessary to limit the change in allowance between adjacent interpolation points. The allowance is calculated for each point within the interpolation step, and the allowance error is defined as the maximum difference between the allowance between the interpolation points and the allowance of the next point:

[0089]

[0090] In smooth grinding and polishing, force control is often used for grinding. The normal displacement is adjusted according to the change of contact force, and the path tracking in the tangent plane is achieved based on the position controller. Therefore, the interpolation path error of smooth grinding and polishing trajectory planning often comes from the chord height error in the tangent plane, which needs to be limited to meet the trajectory accuracy requirements of the motion. Assume that the two endpoints of the interpolation trajectory are Q j , Q j+1 , select any position Q between two points j，m , ask Q j，m To straight line segment Q j Q j+1 The projection point M, and find the point Q based on the NURBS surface information j，m Normal vector at Then the chord height error on the tangent plane can be expressed as:

[0091]

[0092] Since the parameter α of the NURBS curve is converted to the composite trajectory information (u, v, F n , v m ) is a complex nonlinear relationship. Even a small discrete step length may lead to large parameter and position changes between trajectory points. It is necessary to limit the comprehensive deviation caused by composite trajectory interpolation, that is,

[0093]

[0094] For the above three accuracy constraints, the interpolation step size Δα j Need to meet the following requirements at the same time:

[0095]

[0096] (5) Calculate the normal vectors of the interpolation trajectory points on the NURBS surface and optimize the redundant degrees of freedom at the end to finally obtain the synchronously planned process parameters and machining posture.

[0097] (6) Taking the robot grinding process of the putty coating on the head of a high-speed railway as an example, the effects of the proposed method and the constant parameter processing are compared. Figure 6 As shown. During the constant parameter grinding process, due to the lack of adaptation and adjustment of the process to the allowance and curvature, uneven grinding marks appear, and even overcutting occurs in some parts. The proposed synchronous planning method realizes the matching and combination of the allowance distribution and the workpiece geometry, and can adjust the process parameters in time to achieve full coverage and precise removal of the processing area. After grinding with the proposed method, the mean and standard deviation of the surface residual height are 0.0461mm and 0.1693mm, respectively, which are significantly better than -0.1866mm and 0.3487mm under constant force and constant speed processing, improving the surface removal accuracy and reducing the fluctuation of the allowance.

[0098] Based on any of the above embodiments or a combination of multiple embodiments, this embodiment further provides a robot grinding and polishing process and trajectory synchronization planning system for fixed allowance removal, which is used to execute the method involved in any of the above embodiments, including:

[0099] The first main control module is used to build the robot's flexible end face grinding and polishing material removal profile;

[0100] The main control module is used to determine the machining allowance of the workpiece and reconstruct the surface of the workpiece based on the maximum tolerance limit;

[0101] The third main control module is used to plan the force-speed-position processing information of robot grinding on the reconstructed surface with the goal of smoothing the residual height and process parameters, and obtain the discrete processing point positions and process parameters;

[0102] a fourth main control module, configured to expand the reconstructed surface into a four-dimensional form based on the force-speed-position processing information, obtain a composite trajectory integrating the position component and the process component, and perform adaptive interpolation on the composite trajectory to meet the process accuracy and motion accuracy of the processing point;

[0103] The fifth main control module is used to obtain the normal vector of the interpolated composite trajectory, optimize the redundant degrees of freedom at the end, and obtain the synchronously planned process parameters and machining posture.

[0104] It will be easily understood by those skilled in the art that the above description is merely 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 scope of protection of the present invention.

Claims

1. A method for synchronous planning of robot grinding and polishing process and trajectory for fixed allowance removal, characterized in that: The following steps are involved: Step 1: Constructing the robot's flexible end face grinding and polishing material removal profile; Step 2: determine the machining allowance of the workpiece and reconstruct the surface of the workpiece based on the maximum tolerance limit; Step 3: With the goal of achieving smoothness of machining residual height and process parameters, the force-speed-position machining information of robot grinding is planned on the reconstructed surface to obtain the discrete machining point positions and process parameters. Step 4: Based on the force-speed-position processing information, the reconstructed surface is expanded to a four-dimensional form, a composite trajectory integrating the position component and the process component is obtained, and the composite trajectory is adaptively interpolated to meet the process accuracy and motion accuracy of the processing point; Step 5: Obtain the normal vector of the interpolated composite trajectory, optimize the redundant degrees of freedom at the end, and obtain the synchronously planned process parameters and machining posture.

2. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: In step 1, based on the Hertz contact theory and the macroscopic contact pressure of the workpiece, the normal force model of a single conical abrasive is derived, and the joint probability density function of the abrasive height and cone angle is established. The microscopic penetration depth of the abrasive is calculated by the balance of macroscopic and microscopic normal forces, and then the macroscopic-scale flexible end face grinding and polishing material removal profile φ(x, F n , v w ).

3. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: In step 2, based on the maximum tolerance limit, the discrete point cloud is fitted into a smooth 4th-order NURBS surface S(u, v): Where, d ij is the surface control point, w ij is the control point weight, N i，3 (u), N j，3 (v) are the cubic basis functions with respect to u and v respectively.

4. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: Step 3 includes the following steps: (31) Construct the initial path, discretize the initial path using the equal chord height error method, and calculate the corresponding processing points of two adjacent paths. and Position interpolation is performed on the surface part of (32) Based on the average value of the absolute deviation between the residual height of the interpolation point and the average residual height, the total processing residual height index after polishing the i-th and i+1-th paths is constructed; (33) Based on the consideration of the degree of variation of process parameters at different processing positions on the same path, assuming that there are n processing points on each path, the overall objective function of the smoothness of the robot's normal force and feed speed is constructed.

5. The method for synchronous planning of a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 4, characterized in that: In step (31), the calculation model of the position interpolation includes: Where, is the position of the mth interpolation point between the jth processing point on path i and path i+1, and k is the number of interpolation points. Preferably, in step (32), the calculation model of the total processing residual height index includes: Where, It represents the residual height index of the jth point after the i+1th path grinding, expressed as the normal force F with respect to the line spacing Δu n and feed speed υ ω Function Preferably, in step (33), the calculation model of the overall objective function includes: Where ω1, ω2, and ω3 are the weights of the machining residual height index, normal force fluctuation, and feed speed fluctuation, respectively.

6. The method for synchronous planning of a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: In step 4, the process of expanding the reconstructed surface into a four-dimensional form includes: expanding the curve into a four-dimensional form, integrating the normal force F of the robot processing n , feed speed v w And surface position parameters (u, v): Where α is the parameter of the curve, C1(α) and C2(α) represent the position component and process component of the composite trajectory respectively, and w i is the weight of the NURBS curve, d i are the curve control points.

7. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: In step 4, the adaptive interpolation of the composite trajectory includes: (41) Obtain the initial calculation point C(α0)=C(0) on the composite trajectory; (42) Determine the initial value of the interpolation step Δα i ; (43) According to the interpolation step Δα i Calculate the trajectory of the next point and the process parameter C(α i +Δα i ); (44) Determine the interpolation step length Δα i Whether the process constraint ε is met Re , tangent plane chord height error ε δ and the surface discretization error constraint ε d If satisfied, proceed to step (45); otherwise, adjust the interpolation step size and return to step (43); (45) Determine the next parameter α i+1 =α i +Δα i Is it greater than or equal to 1? If so, output the interpolation point sequence {α i }, otherwise, let i=i+1 and return to step (42).

8. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 1, characterized in that: In step 4, the adaptive interpolation of the composite trajectory includes: calculating the margin of the points within the interpolation step, and defining the margin error as the maximum difference between the margin between the interpolation points and the margin of the next point: Where, ΔRe j is the margin difference, Re(α) is the point α j The margin error, Re(α j+1 ) is point α j+1 The margin error; Preferably, in step 4, the adaptive interpolation of the composite trajectory further comprises: assuming that the two endpoints of the interpolation trajectory are Q j , Q j+1 , select any position Q between two points j，m , ask Q j，m To straight line segment Q j Q j+1 The projection point M, and find the point Q based on the NURBS surface information j，m Normal vector at Then the chord height error on the tangent plane can be expressed as: Preferably, in step 4, the adaptive interpolation of the composite trajectory further comprises: limiting the comprehensive deviation caused by the composite trajectory interpolation, that is: In the formula, C′(α j ) is the first-order derivative of the composite trajectory, C″(α j ) is the second-order derivative of the composite trajectory, and Δα is the interpolation step size.

9. The method for synchronously planning a robot grinding and polishing process and trajectory for fixed allowance removal according to claim 7, characterized in that: Interpolation step Δα j Need to meet the following requirements at the same time: Where, ε Re is the process constraint, ε δ is the plane chord height error constraint, ε d is the curve discretization error constraint.

10. A robot grinding and polishing process with fixed allowance removal and synchronous trajectory planning system, characterized in that: include: The first main control module is used to build the robot's flexible end face grinding and polishing material removal profile; The main control module is used to determine the machining allowance of the workpiece and reconstruct the surface of the workpiece based on the maximum tolerance limit; The third main control module is used to plan the force-speed-position processing information of robot grinding on the reconstructed surface with the goal of smoothing the residual height and process parameters, and obtain the discrete processing point positions and process parameters; a fourth main control module, configured to expand the reconstructed surface into a four-dimensional form based on the force-speed-position processing information, obtain a composite trajectory integrating the position component and the process component, and perform adaptive interpolation on the composite trajectory to meet the process accuracy and motion accuracy of the processing point; The fifth main control module is used to obtain the normal vector of the interpolated composite trajectory, optimize the redundant degrees of freedom at the end, and obtain the synchronously planned process parameters and machining posture.

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