Feeding speed planning method and device for NURBS tool path and storage medium

Abstract

The invention discloses a feeding speed planning method and device for an NURBS tool path and a storage medium, and the method comprises the steps: obtaining a sub-curve in the tool path and an initial feeding speed curve corresponding to each segment of sub-curve, judging whether the initial feeding speed curve corresponding to the sub-curve meets a constraint condition or not for each segment of sub-curve, and determining whether the initial feeding speed curve corresponding to the sub-curve meets the constraint condition or not; when the initial feeding speed curve does not meet the constraint condition, adjusting the initial feeding speed curve to obtain an adjusted feeding speed curve and a corresponding transition interval feeding speed curve, and forming a new feeding speed curve; when the initial feeding speed curve meets the constraint condition, the initial feeding speed curve is determined to be the feeding speed curve corresponding to the sub-curve, and finally, the feeding speed curves corresponding to all the sub-curves are sequentially combined according to the sequence of the sub-curves in the tool path to obtain a complete planned feeding speed curve. According to the scheme, reasonable and efficient feeding speed planning can be achieved, and the efficiency and quality in the machining process are ensured.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of numerical control machine tools, and particularly relates to a method, device, and storage medium for planning the feed rate of a NURBS tool path. Background Art

[0002] In modern numerical control machining, high-speed and high-precision machining are the core objectives. For complex workpiece surfaces, the linear / arc interpolation processing of traditional numerical control systems can cause frequent acceleration and deceleration of the machine tool system, while parametric interpolation can provide a smoother motion curve, so it is increasingly being adopted. Common parametric interpolation methods include spline curves, Bezier curves, B-spline curves, and NURBS (Non-Uniform Rational B-Spline) curves, etc. NURBS curves have significant advantages in processing analytical functions and model shapes due to their flexibility and accuracy, and are widely used in fields such as mold manufacturing, automobile manufacturing, and aerospace. To achieve efficient high-speed machining, methods such as NURBS tool path fitting are often used to improve path continuity and reduce computational complexity.

[0003] Feed rate planning is a crucial step because it directly affects machining time and surface quality, and is essential for ensuring machining efficiency, smoothness, and motion accuracy. Therefore, it is crucial to implement an efficient and reasonable feed rate planning scheme for NURBS tool paths. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail in this document. This overview is not intended to limit the scope of protection of the claims.

[0005] Embodiments of this application provide a method, device, and storage medium for planning the feed rate of a NURBS tool path, which can achieve reasonable and efficient feed rate planning.

[0006] An embodiment of this application provides a method for planning the feed rate of a NURBS tool path, including:

[0007] Dividing the tool path into multiple sub-curves according to the curvature values of the points on the tool path;

[0008] Generating an initial feed rate curve corresponding to the sub-curve according to the allowable feed rate of the starting point and the allowable feed rate of the ending point of each sub-curve;

[0009] For each sub - curve, determine whether the initial feed - rate curve corresponding to the sub - curve meets the constraint conditions. When the initial feed - rate curve does not meet the constraint conditions, adjust the initial feed - rate curve to obtain the adjusted feed - rate curve and the corresponding feed - rate curve in the transition interval, and obtain the feed - rate curve corresponding to the sub - curve according to the adjusted feed - rate curve and the feed - rate curve in the transition interval; when the initial feed - rate curve meets the constraint conditions, determine the initial feed - rate curve as the feed - rate curve corresponding to the sub - curve;

[0010] Combine the feed - rate curves corresponding to all sub - curves in the order of the sub - curves in the tool path to obtain a complete planned feed - rate curve.

[0011] An embodiment of the present application further provides a feed - rate planning device for a NURBS tool path, including: a memory and a processor;

[0012] The memory is used to store a program for feed - rate planning of the NURBS tool path;

[0013] The processor is used to read the program for feed - rate planning of the NURBS tool path and execute the feed - rate planning method for the NURBS tool path as described in any embodiment of the present application.

[0014] An embodiment of the present application further provides a non - transient computer - readable storage medium, where the computer - readable storage medium stores a computer program, and when the computer program is executed by a processor, it can implement the feed - rate planning method for the NURBS tool path as described in any embodiment of the present application.

[0015] Compared with the related art, a feed - rate planning method, device and storage medium for a NURBS tool path provided by the embodiments of the present application determine the constraint conditions for the initial feed - rate curve corresponding to each sub - curve, adjust the initial feed - rate curve that does not meet the constraint conditions, and achieve smooth transition through a transition interval during adjustment, so that the finally generated planned feed - rate curve meets the requirements and is efficient and reasonable, thereby ensuring the efficiency and quality of the machining process.

[0016] Other features and advantages of the present application will be described in the subsequent specification, and part of them will become obvious from the specification, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained through the solutions described in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide an understanding of the technical solution of the present application and form a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation to the technical solution of the present application.

[0018] Figure 1 It is a brief flowchart of the feed rate planning method for the NURBS tool path of the present application;

[0019] Figure 2 It is a specific flowchart of the feed rate planning method for the NURBS tool path of the present application;

[0020] Figure 3a It is a schematic diagram of the NURBS tool path of the first embodiment of the present application;

[0021] Figure 3b It is a schematic diagram of the allowable feed rate curve and the planned feed rate curve after feed rate planning in the first embodiment of the present application;

[0022] Figure 3c It is a schematic diagram of the normal acceleration after feed rate planning in the first embodiment of the present application;

[0023] Figure 3d It is a schematic diagram of the normal jerk after feed rate planning in the first embodiment of the present application;

[0024] Figure 4a It is a schematic diagram of the NURBS tool path of the second embodiment of the present application;

[0025] Figure 4b It is a schematic diagram of the allowable feed rate curve and the planned feed rate curve after feed rate planning in the second embodiment of the present application;

[0026] Figure 4c It is a schematic diagram of the normal acceleration after feed rate planning in the second embodiment of the present application;

[0027] Figure 4d It is a schematic diagram of the normal jerk after feed rate planning in the second embodiment of the present application;

[0028] Figure 5 It is a schematic diagram of the feed rate planning device for the NURBS tool path of the present application. Detailed implementation manners

[0029] This application describes multiple embodiments, but the description is exemplary rather than restrictive, and it will be apparent to those of ordinary skill in the art that there can be more embodiments and implementation solutions within the scope of the embodiments described in this application. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically restricted, any feature or element of any embodiment can be combined with any other feature or element in any other embodiment, or can replace any other feature or element in any other embodiment.

[0030] This application includes and contemplates combinations with features and elements known to those of ordinary skill in the art. The embodiments, features, and elements disclosed in this application can also be combined with any conventional features or elements to form unique inventive solutions. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this application can be implemented alone or in any suitable combination. Therefore, the embodiments are not subject to other limitations except those made in accordance with the appended claims and their equivalents. In addition, various modifications and changes can be made within the scope of the appended claims.

[0031] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not depend on the specific order of the steps described herein, the method or process should not be limited to the specific order of steps described. As will be understood by those of ordinary skill in the art, other step orders are possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation on the claims. In addition, the claims directed to the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can easily understand that these orders can vary and still remain within the spirit and scope of the embodiments of this application.

[0032] The feed rate of the tool path directly affects the machining time and surface quality, and is crucial for ensuring machining efficiency, smoothness, and motion accuracy. For example, when there are many intervals in the tool path where the feed rate is lower than the programmed feed rate, the feed efficiency will be greatly affected; for another example, when the acceleration conversion of the feed rate curve corresponding to the tool path is discontinuous, it will cause considerable vibration and impact, affecting the machining process and the achievement of precise control, and thus affecting the machining quality. Therefore, a reasonable and efficient feed rate planning scheme for NURBS tool paths is crucial for machining efficiency and machining quality.

[0033] An embodiment of the present application provides a method for planning the feed rate of a NURBS tool path, as Figure 1 shown, which may include the following steps:

[0034] Step S110: Divide the tool path into multiple sub-curves according to the curvature values of the points on the tool path;

[0035] Step S120: Generate an initial feed rate curve corresponding to the sub-curve according to the allowable feed rate of the starting point and the allowable feed rate of the ending point of each sub-curve;

[0036] Step S130: For each sub-curve, determine whether the initial feed rate curve corresponding to the sub-curve meets the constraint conditions. When the initial feed rate curve does not meet the constraint conditions, adjust the initial feed rate curve to obtain an adjusted feed rate curve and a corresponding feed rate curve in the transition interval, and obtain the feed rate curve corresponding to the sub-curve according to the adjusted feed rate curve and the feed rate curve in the transition interval; when the initial feed rate curve meets the constraint conditions, determine the initial feed rate curve as the feed rate curve corresponding to the sub-curve;

[0037] Step S140: Combine the feed rate curves corresponding to all sub-curves in the order of the sub-curves in the tool path to obtain a complete planned feed rate curve.

[0038] In the method for planning the feed rate of the NURBS tool path in this embodiment, after obtaining the sub-curves in the tool path and the initial feed rate curve corresponding to each sub-curve, for each sub-curve, determine whether the initial feed rate curve corresponding to the sub-curve meets the constraint conditions. When the initial feed rate curve does not meet the constraint conditions, adjust the initial feed rate curve to obtain an adjusted feed rate curve and a corresponding feed rate curve in the transition interval, and obtain the feed rate curve corresponding to the sub-curve according to the adjusted feed rate curve and the feed rate curve in the transition interval; when the initial feed rate curve meets the constraint conditions, determine the initial feed rate curve as the feed rate curve corresponding to the sub-curve. Finally, combine the feed rate curves corresponding to all sub-curves in the order of the sub-curves in the tool path to obtain a complete planned feed rate curve. This solution judges the constraint conditions for the initial feed rate curve corresponding to each sub-curve, adjusts the initial feed rate curve that does not meet the constraint conditions, and realizes smooth transition through the transition interval during adjustment, so that the finally generated planned feed rate curve meets the requirements and is efficient and reasonable, thereby ensuring the efficiency and quality of the machining process.

[0039] In an exemplary embodiment, the dividing the tool path into multiple sub-curves according to the curvature values of the points on the tool path includes:

[0040] Adopt a method combining global rough scanning and local precise scanning to determine multiple curvature maximum points on the tool path;

[0041] Divide the tool path according to the curvature maximum points to obtain multiple sub-curves.

[0042] In the feed speed planning method of the NURBS tool path in this embodiment, the tool path is divided into multiple sub-curves through the curvature maximum points, and then the initial feed speed curve corresponding to each sub-curve is generated according to the allowable feed speed at the starting point and the allowable feed speed at the ending point of each sub-curve. In this way, it can be ensured that the points that do not meet the constraint conditions in the initial feed speed curve are located on the starting side or the ending side (the starting side refers to the side where the starting point of the sub-curve is located, and the ending side refers to the side where the ending point of the sub-curve is located), laying a foundation for the subsequent adjustment of the starting point and / or the ending point of the sub-curve.

[0043] In an exemplary embodiment, before generating the initial feed speed curve corresponding to each sub-curve according to the allowable feed speed at the starting point and the allowable feed speed at the ending point of each sub-curve, it further includes: generating the allowable feed speed curve corresponding to the tool path according to geometric, normal driving ability constraints, and programmed feed speed constraints.

[0044] In an example of this embodiment, generating the allowable feed speed curve corresponding to the tool path according to geometric, normal driving ability constraints, and programmed feed speed constraints includes:

[0045] Determine multiple preset interpolation positions in the tool path based on a preset interpolation period;

[0046] For each interpolation position, obtain the first feed speed, the second feed speed, the third feed speed, and the programmed feed speed at this position, and select the minimum value from the first feed speed, the second feed speed, the third feed speed, and the programmed feed speed as the allowable feed speed at this position; wherein, the first feed speed refers to the feed speed at this position under the constraint of the maximum chord height error, the second feed speed refers to the feed speed at this position under the normal acceleration constraint, the third feed speed refers to the feed speed at this position under the jerk constraint, and the programmed feed speed refers to the maximum feed speed determined by the user during the machining process, which is reflected in the G code of the numerical control machine tool;

[0047] Generate the allowable feed speed curve according to the allowable feed speeds of all interpolation positions.

[0048] Exemplarily, the calculation formula of the first feed speed under the constraint of the maximum chord height error can be as follows:

[0049]

[0050] Among them, T is the interpolation period, ρ is the radius of curvature of the tool path curve, and δ max is the set limit value of the bow height error.

[0051] Exemplarily, the calculation formula for the second feed rate under the normal acceleration constraint can be as follows:

[0052]

[0053] Among them, ρ is the radius of curvature of the tool path curve, and a n,max is the set limit value of the normal acceleration.

[0054] Exemplarily, the calculation formula for the third feed rate under the normal jerk constraint can be as follows:

[0055]

[0056] Among them, ρ is the radius of curvature of the tool path curve, and j n,max is the set limit value of the normal jerk.

[0057] Exemplarily, the calculation formula for selecting the minimum value from the first feed rate, the second feed rate, the third feed rate, and the programmed feed rate as the allowable feed rate at this position can be as follows:

[0058] v lim = min{v δ , v a , v j , v p};

[0059] Among them, v δ represents the first feed rate, v a represents the second feed rate, v j represents the third feed rate, and v p represents the programmed feed rate.

[0060] In the feed rate planning method for the NURBS tool path of this embodiment, the minimum value is selected from the first feed rate under the bow height error limit constraint, the second feed rate under the normal acceleration constraint, the third feed rate under the normal jerk constraint, and the programmed feed rate as the allowable feed rate (that is, the obtained allowable feed rate satisfies all constraint conditions), and then the allowable feed rate is used to judge the initial feed rate in the initial feed rate curve, so as to adjust the initial feed rate curve, so that the feed rates in the finally obtained planned feed rate curve will not exceed the limit.

[0061] In an example of this embodiment, after generating the allowable feed rate curve corresponding to the tool path according to geometric, normal driving ability constraints, and programmed feed rate constraints, the following steps are further included:

[0062] For each sub-curve, under the tangential driving ability constraint, through reverse scanning during the deceleration process and forward scanning during the acceleration process, determine the optimal allowable feed rate at the starting point and the optimal allowable feed rate at the ending point of the sub-curve;

[0063] Update the allowable feed rate at the starting point of the sub-curve to the optimal allowable feed rate at the starting point, and update the allowable feed rate at the ending point of the sub-curve to the optimal allowable feed rate at the ending point.

[0064] Exemplarily, the steps of determining the optimal allowable feed rate at the starting point and the ending point of each sub-curve through scanning can refer to the following steps: (1) Digitally process the curve to obtain discretized data points; (2) Forward scanning: Gradually increase the position from the starting point to the ending point of the curve, analyze the local curvature change to determine possible starting and ending points; (3) Reverse scanning: Gradually decrease the position from the ending point to the starting point of the curve, and also analyze the local curvature change to confirm possible starting and ending points; (4) Curvature calculation: Calculate the curvature values of each local section according to the local curvature information obtained during the scanning process; (5) Feed rate adjustment: Combine the tangential driving ability constraint, and according to the curvature information and process requirements, adjust the feed rate of each sub-curve to ensure that the machining efficiency is maximized without exceeding the tolerable range of the machine tool or workpiece; (6) Optimization evaluation: Evaluate the adjusted feed rate plan, including considering factors such as machining time, quality requirements, and machine tool stability; (7) Iterative optimization: Repeatedly perform scanning and adjustment according to the actual situation until the optimal feed rate plan is found.

[0065] In the feed rate planning method of the NURBS tool path in this embodiment, after determining the optimal allowable feed rate at the starting point and the optimal allowable feed rate at the ending point of the sub-curve, update the allowable feed rate at the starting point of the sub-curve to the optimal allowable feed rate at the starting point, and update the allowable feed rate at the ending point of the sub-curve to the optimal allowable feed rate at the ending point. Then, use the optimal allowable feed rate at the starting point and the optimal allowable feed rate at the ending point to generate the initial feed rate curve corresponding to the sub-curve, making the initial feed rate curve better. In this way, on the one hand, the efficiency of feed rate planning can be improved; on the other hand, it can also make the planned feed rate curve obtained based on the initial feed rate curve better, thus ensuring the efficiency and quality of the machining process.

[0066] In an exemplary embodiment, generating an initial feed rate curve corresponding to the sub-curve according to the allowable feed rate at the starting point and the allowable feed rate at the ending point of each sub-curve includes:

[0067] Obtaining the duration of each acceleration stage according to the tangential acceleration, tangential jerk, starting point feed rate, and ending point feed rate. The duration of each acceleration stage includes: jerk duration, uniform acceleration duration, and deceleration duration;

[0068] Obtaining the initial feed rate curve corresponding to the sub-curve according to the starting point feed rate, tangential jerk, duration of each acceleration stage, and maximum acceleration. The maximum acceleration refers to the maximum acceleration within the range from the starting point to the ending point of the sub-curve.

[0069] It can be seen from the feed rate planning method of the NURBS tool path in this embodiment that the acceleration of the initial feed rate curve generated in this embodiment is continuous, which makes the finally obtained planned feed rate change smoothly, solving the problem of "causing a relatively large vibration and impact, which affects the machining process and further affects the machining quality due to the discontinuous acceleration conversion", and realizing an efficient and reasonable feed rate planning.

[0070] In an exemplary embodiment, determining whether the initial feed rate curve corresponding to the sub-curve meets the constraint conditions includes: when the feed rate at any point in the initial feed rate curve of the sub-curve exceeds the allowable feed rate corresponding to that point, it is confirmed that the initial feed rate curve does not meet the constraint conditions; when the feed rates of all points in the initial feed rate curve of the sub-curve do not exceed the allowable feed rate corresponding to that point, it is confirmed that the initial feed rate curve meets the constraint conditions;

[0071] The initial feed rate curve of each sub-curve includes a complete rising and falling trend. Adjusting the initial feed rate curve to obtain an adjusted feed rate curve includes: when there is an over-limit point on the starting side of the sub-curve, all points between the starting point and the last over-limit point on the starting side are over-limit, and the starting point of the sub-curve is updated to the position where the last over-limit point on the starting side of the sub-curve is located; when there is an over-limit point on the ending side of the sub-curve, all points between the first over-limit point on the ending side and the ending point are over-limit, and the ending point of the sub-curve is updated to the position where the first over-limit point on the ending side of the sub-curve is located; generating the adjusted feed rate curve according to the allowable feed rate at the starting point and the allowable feed rate at the ending point of the updated sub-curve. Wherein, the starting side refers to the side where the starting point of the sub-curve is located, and the ending side refers to the side where the ending point of the sub-curve is located;

[0072] The feed rate curve of the transition interval includes a starting transition interval feed rate curve and an ending transition interval feed rate curve; obtaining the adjusted feed rate curve and the corresponding feed rate curve of the transition interval includes: taking the transition interval between the starting point of the adjusted sub-curve and the starting point of the sub-curve before adjustment as the starting transition interval, taking the feed rate at the starting point of the adjusted feed rate curve as the feed rate of the starting transition interval, and generating a constant-speed starting transition interval feed rate curve; taking the transition interval between the ending point of the adjusted sub-curve and the ending point of the sub-curve before adjustment as the ending transition interval, taking the feed rate at the ending point of the adjusted feed rate curve as the feed rate of the ending transition interval, and generating a constant-speed ending transition interval feed rate curve.

[0073] In the feed rate planning method of the NURBS tool path in this embodiment, when there are over-limit points in the initial feed rate curve corresponding to the sub-curve, the starting point and / or the ending point of the sub-curve are adjusted and the feed rate curve corresponding to the adjusted sub-curve (i.e., the adjusted feed rate curve) is generated; then, taking the transition interval between the starting point of the adjusted sub-curve and the starting point of the sub-curve before adjustment as the starting transition interval, taking the feed rate at the starting point of the adjusted feed rate curve as the feed rate of the starting transition interval, and generating a constant-speed starting transition interval feed rate curve; taking the transition interval between the ending point of the adjusted sub-curve and the ending point of the sub-curve before adjustment as the ending transition interval, taking the feed rate at the ending point of the adjusted feed rate curve as the feed rate of the ending transition interval, and generating a constant-speed ending transition interval feed rate curve; finally, combining all the adjusted feed rate curves and the feed rate curves of the transition interval (the starting transition interval feed rate curve and / or the ending transition interval feed rate curve) in the order of the sub-curves in the tool path to obtain a complete planned feed rate curve. In this way, it can not only ensure that all the feed rates in the planned feed rate curve do not exceed the limit, but also ensure that the speed is as large and smooth as possible, realizing an efficient and reasonable feed rate planning and ensuring the efficiency and quality of the machining process.

[0074] In an example of this embodiment, before generating the initial feed rate curve corresponding to each sub-curve according to the allowable feed rate at the starting point and the allowable feed rate at the ending point of each sub-curve, it further includes: determining a plurality of parameter adjustment intervals according to the relationship between the allowable feed rate and the programmed feed rate of the points on the tool path; each parameter adjustment interval is composed of a plurality of consecutive points on the curve where the allowable feed rate is less than the programmed feed rate, and each parameter adjustment interval contains only one point with a maximum curvature value; Exemplarily, the determining a plurality of parameter adjustment intervals according to the relationship between the allowable feed rate and the programmed feed rate of the points on the tool path can be achieved through the following steps: adopting a method combining global rough scanning and local precise scanning, selecting several points on the NURBS tool path to form a point sequence, scanning the point sequence to determine whether the allowable feed rate of the point is less than the programmed feed rate, if the allowable feed rate of the point is less than the programmed feed rate, then the point belongs to the parameter adjustment interval; otherwise the point does not belong to the parameter adjustment interval; finally, a plurality of parameter adjustment intervals are obtained;

[0075] When there is an overrun point on the starting side of the sub-curve, updating the starting point of the sub-curve to the position where the last overrun point on the starting side of the sub-curve is located; when there is an overrun point on the ending side of the sub-curve, updating the ending point of the sub-curve to the position where the first overrun point on the ending side of the sub-curve is located, includes:

[0076] Determining the parameter adjustment interval to which the position of the point that does not meet the constraint conditions in the sub-curve belongs;

[0077] When the position of the point that does not meet the constraint conditions in the sub-curve is within the parameter adjustment interval corresponding to the sub-curve, updating the position where the starting point of the sub-curve is located according to the preset adjustment parameter; when the position of the point that does not meet the constraint conditions in the sub-curve is within the next parameter adjustment interval corresponding to the sub-curve, updating the position where the ending point of the sub-curve is located according to the preset adjustment parameter;

[0078] Exemplarily, when there is an overrun point on the sub-curve, judging the parameter adjustment interval to which the overrun point belongs; when the overrun point is within the parameter adjustment interval on the starting side of the sub-curve, increasing the starting point parameter of the sub-curve by a preset adjustment parameter until all positions on the starting side of the sub-curve meet the constraints; when the overrun point is within the parameter adjustment interval on the ending side of the sub-curve, decreasing the ending point parameter of the sub-curve by a preset adjustment parameter until all positions on the ending side of the sub-curve meet the constraints.

[0079] Wherein, the preset adjustment parameter should be selected as a relatively small quantity, such as 0.001, for the purpose of fine-tuning, so as to achieve that the finally obtained planned feed rate curve is optimal.

[0080] Exemplarily, if the overrun position is within the i-th parameter adjustment interval, then u i,start = u i,start + λ; if the overrun position is within the (i + 1)-th parameter adjustment interval, then u i,end = u i,end - λ, where λ is the introduced adjustment parameter. For example, suppose the curve parameters corresponding to the second sub-curve are [0.2, 0.3] (representing the starting point parameter is 0.2 and the ending point parameter is 0.3). If there is a speed overrun position on the sub-curve and the curve parameter u of the overrun position is 0.205, if 0.205 belongs to the second parameter adjustment interval, then the starting parameter of the sub-curve is increased; if the curve parameter u of the overrun position is 0.293, if 0.293 belongs to the third parameter adjustment interval, then the ending parameter of the sub-curve is decreased.

[0081] In the feed rate planning method of the NURBS tool path in this example, when there is an overrun point in the initial feed rate curve, by judging the parameter adjustment interval where the overrun point is located, and determining whether to adjust the starting point or the ending point of the sub-curve according to the parameter adjustment interval where the overrun point is located; then, according to the preset adjustment parameter, update the positions of the starting point and / or the ending point of the sub-curve, and re-plan the speed according to the updated sub-curve, ensuring that the finally generated planned feed rate curve has no overrun position and meets the processing requirements.

[0082] In an exemplary embodiment, after obtaining the complete planned feed rate curve, it may further include:

[0083] Obtaining a planned feed rate sequence corresponding to the tool path according to the planned feed rate curve;

[0084] Performing online interpolation on the tool path based on the parameter-corrected second-order Runge-Kutta method (second-order Runge-Kutta method) according to the planned feed rate sequence.

[0085] In the feed rate planning method of the NURBS tool path in this embodiment, by performing online interpolation on the tool path based on the parameter-corrected second-order Runge-Kutta method, on the one hand, a smoother motion curve can be provided, thereby reducing the acceleration and deceleration frequency of the machine tool system and improving the machining accuracy; on the other hand, it can also ensure maintaining the best efficiency and stability during the machining process.

[0086] The following is a complete example of the feed rate planning method of the NURBS tool path in this application, as Figure 2 shown, which may include the following steps:

[0087] Step S210: Generate the allowable feed rate curve corresponding to the tool path according to geometric, normal driving ability constraints, and programmed feed rate constraints. Exemplarily, this step S210 may include the following steps S211 - S215:

[0088] Step S211: Calculate the first feed rate v at this position under the chord height error limit constraint δ ;

[0089] Exemplarily, the calculation formula may be as follows:

[0090]

[0091] where T is the interpolation period, ρ is the curve curvature radius, and δ max is the set chord height error limit value;

[0092] Step S212: Calculate the second feed rate v at this position under the normal acceleration constraint a ;

[0093] Exemplarily, the calculation formula may be as follows:

[0094]

[0095] where a n,max is the set normal acceleration limit value, and ρ is the curve curvature radius;

[0096] Step S213: Calculate the third feed rate v at this position under the jerk constraint j ;

[0097] Exemplarily, the calculation formula may be as follows:

[0098]

[0099] where j n,max is the set jerk limit value, and ρ is the curve curvature radius;

[0100] Step S214: Determine the programmed feed rate v p , and the programmed feed rate v p refers to the maximum speed determined by the user during the machining process, which is reflected in the G - code of the numerical control machine tool;

[0101] Step S215: Select the minimum value from the first feed rate v δ , the second feed rate v a , the third feed rate v j , and the programmed feed rate v p as the allowable feed rate v lim ;

[0102] Exemplarily, the formula may be as follows: v lim = min{v δ , v a , v j , v p}}。

[0103] Step S220: Obtain parameter adjustment intervals, where there are multiple parameter adjustment intervals.

[0104] Adopt a method combining global rough scanning and local precise scanning. Select several points on the NURBS tool path to form a point sequence, scan this point sequence, and determine whether the allowable feed rate of this point is less than the programmed feed rate. If the allowable feed rate of this point is less than the programmed feed rate, then this point belongs to the parameter adjustment interval; otherwise, this point does not belong to the parameter adjustment interval; finally, obtain multiple parameter adjustment intervals. Among them, the "parameter adjustment interval" is defined as the position on the curve where the allowable feed rate is lower than the programmed feed rate, and each parameter adjustment interval only contains one point with a maximum curvature value.

[0105] Step S230: Divide the tool path into multiple sub-curves according to the curvature values of the points on the tool path.

[0106] Exemplarily, this step may include: Adopt a method combining global rough scanning and local precise scanning to determine multiple points with maximum curvature values on the tool path; divide the tool path according to the points with maximum curvature values to obtain multiple sub-curves.

[0107] Step S240: According to the tangential driving ability constraint, adopt two-way scanning to update the allowable feed rates of the starting point and the ending point of each sub-curve on the tool path.

[0108] Exemplarily, this step may include: For each sub-curve, under the tangential driving ability constraint, through reverse scanning in the deceleration process and forward scanning in the acceleration process, determine the optimal allowable feed rate of the starting point and the optimal allowable feed rate of the ending point of this sub-curve; update the allowable feed rate of the starting point of this sub-curve to the optimal allowable feed rate of the starting point, and update the allowable feed rate of the ending point of this sub-curve to the optimal allowable feed rate of the ending point.

[0109] Exemplarily, the specific process of bidirectional scanning can be as follows: (1) Data acquisition and digitization: Digitize the curve to obtain discrete data points; (2) Forward scanning: Gradually increase the position from the starting point to the ending point of the curve, and analyze the local curvature change to determine the possible starting and ending points. (3) Reverse scanning: Gradually decrease the position from the ending point to the starting point of the curve, and also analyze the local curvature change to confirm the possible starting and ending points. (3) Curvature calculation: Calculate the curvature values of each local section according to the local curvature information obtained during the scanning process. (4) Feed speed adjustment: Combine the tangential driving ability constraint, and adjust the feed speed of each sub-curve according to the curvature information and process requirements to ensure that the machining efficiency is maximized without exceeding the tolerable range of the machine tool or workpiece. (5) Iterative optimization: Repeatedly perform scanning and adjustment according to the actual situation until the optimal feed speed scheme is found.

[0110] Step S250: Generate the initial feed speed curve corresponding to the sub-curve according to the allowable feed speed at the starting point and the allowable feed speed at the ending point of each sub-curve;

[0111] Exemplarily, the S-shaped acceleration and deceleration rule can be adopted to generate the initial feed speed curve of each sub-curve, and this step S250 may include the following steps S251 - step S252:

[0112] Step S251: Obtain the time of each acceleration stage according to the tangential acceleration, tangential jerk, starting point feed speed, and ending point feed speed. The time of each acceleration stage includes: jerk time, uniform acceleration time, and deceleration jerk time; the calculation formula can be as follows:

[0113] Under the constraint conditions of tangential acceleration and tangential jerk, the starting and ending feed speeds are v s and v e respectively, and the acceleration stage time is:

[0114]

[0115] t3 = t1;

[0116] where a t,max represents the set limit value of tangential acceleration, j t,max represents the set limit value of tangential jerk, v s represents the starting point feed speed, v e represents the ending point feed speed, t1 represents the jerk time, t2 represents the uniform acceleration time, and t3 represents the deceleration jerk time.

[0117] Step S252: Obtain the initial feed rate curve corresponding to the sub-curve according to the starting point feed rate, tangential jerk, the time of each acceleration stage, and the maximum acceleration. Exemplarily, the calculation formula can be as follows:

[0118]

[0119] where v s represents the starting point feed rate, v e represents the ending point feed rate, j t,max represents the set tangential jerk limit value, a max is the maximum acceleration during the acceleration / deceleration process, t1 represents the jerk time, t2 represents the constant acceleration time, t3 represents the deceleration jerk time, t5 represents the acceleration and deceleration time, t6 represents the constant deceleration time, and t7 represents the deceleration jerk time.

[0120] Step S260: For each sub-curve, determine whether the initial feed rate curve corresponding to the sub-curve meets the constraint conditions. When the initial feed rate curve does not meet the constraint conditions, adjust the initial feed rate curve to obtain the adjusted feed rate curve and the corresponding feed rate curve in the transition interval, and obtain the feed rate curve corresponding to the sub-curve according to the adjusted feed rate curve and the feed rate curve in the transition interval; when the initial feed rate curve meets the constraint conditions, determine the initial feed rate curve as the feed rate curve corresponding to the sub-curve; combine the feed rate curves corresponding to all sub-curves in the order of the sub-curves in the tool path to obtain the complete planned feed rate curve.

[0121] Exemplarily, this step S260 may include the following steps S261 - step S266:

[0122] Step S261: When the feed rate at any point in the initial feed rate curve of the sub-curve exceeds the allowable feed rate corresponding to this point, confirm that the initial feed rate curve does not meet the preset requirements, and transfer to step S262; when the feed rates at all points in the initial feed rate curve of the sub-curve do not exceed the allowable feed rate corresponding to this point, confirm that the initial feed rate curve meets the preset requirements, and transfer to step S265.

[0123] Step S262: Determine the parameter adjustment interval to which the position of the point that does not meet the constraint condition belongs in this sub-curve; when the position of the point that does not meet the constraint condition in this sub-curve is within the parameter adjustment interval corresponding to this sub-curve, update the position of the starting point of this sub-curve according to the preset adjustment parameter; when the position of the point that does not meet the constraint condition in this sub-curve is within the next parameter adjustment interval of the parameter adjustment interval corresponding to this sub-curve, update the position of the ending point of this sub-curve according to the preset adjustment parameter.

[0124] It should be noted that there is a corresponding relationship between the number of parameter adjustment intervals and the number of sub-curves. The number of sub-curves is equal to the number of parameter adjustment intervals plus 1.

[0125] Exemplarily, if the overrun position is within the i-th parameter adjustment interval, then u i,start = u i,start + λ; if the overrun position is within the (i + 1)-th parameter adjustment interval, then u i,end = u i,end - λ, where λ is the introduced adjustment parameter. For example, if the curve parameter corresponding to the second sub-curve is [0.2, 0.3] (representing that the starting point parameter is 0.2 and the ending point parameter is 0.3), if there is a speed overrun position on the sub-curve and the curve parameter u of the overrun position is 0.205, if 0.205 belongs to the second parameter adjustment interval, then increase the starting parameter of the sub-curve; if the curve parameter u of the overrun position is 0.293, if 0.293 belongs to the third parameter adjustment interval, then decrease the ending parameter of the sub-curve.

[0126] It should be noted that λ should be selected as a relatively small value, such as 0.001, for fine-tuning purposes, so as to ultimately obtain an optimal planned feed speed curve.

[0127] Step S263: Re-update the allowable feed speed of the starting point and the allowable feed speed of the ending point of the sub-curve by two-way scanning.

[0128] Step S264: Re-plan the speed of the adjusted sub-curve using the S-shaped acceleration and deceleration rule to generate an adjusted feed speed curve.

[0129] Step S265: For the transition interval between the starting point of the adjusted sub-curve and the starting point of the unadjusted sub-curve, and the transition interval between the ending point of the adjusted sub-curve and the ending point of the unadjusted sub-curve, perform constant speed planning using the allowable feed speeds of the starting point and the ending point obtained in Step S263 respectively to obtain transition interval curves.

[0130] Exemplarily, the transitional interval feed rate curve includes a starting transitional interval feed rate curve and an ending transitional interval feed rate curve. This step can specifically be: taking the transitional interval between the starting point of the adjusted sub-curve and the starting point of the unadjusted sub-curve as the starting transitional interval, taking the feed rate at the starting point of the adjusted feed rate curve (i.e., the allowable feed rate at the starting point obtained in step S263) as the feed rate of the starting transitional interval, and generating the starting transitional interval feed rate curve; taking the transitional interval between the ending point of the adjusted sub-curve and the ending point of the unadjusted sub-curve as the ending transitional interval, taking the feed rate at the ending point of the adjusted feed rate curve (i.e., the allowable feed rate at the ending point obtained in step S263) as the feed rate of the ending transitional interval, and generating the ending transitional interval feed rate curve.

[0131] Step S266: Combine all the adjusted sub-curves and transitional interval curves in sequence as the complete feed rate curve

[0132] Step S270: Perform online interpolation based on the parameter-corrected second-order Runge-Kutta method to accurately calculate the interpolation points on the NURBS tool path.

[0133] Online interpolation based on the parameter-corrected second-order Runge-Kutta method. This step S270 can include the following steps S271 - S274:

[0134] Step S271: Use the actual arc length and the arc length for the S-shaped acceleration and deceleration rule to correct the speed:

[0135]

[0136] Among them, {vi} represents the speed sequence on the sub-curve, l act represents the actual arc length of the sub-curve, l use represents the arc length used during S-shaped acceleration and deceleration.

[0137] It should be noted that when using S-shaped acceleration and deceleration for speed planning, the time obtained in each S-shaped acceleration and deceleration planning stage is an integer multiple of the interpolation period. However, in actual situations, the curve arc length can hardly be exactly utilized by the S-shaped acceleration and deceleration rule, and there will be a situation where the arc length used in the S-shaped acceleration and deceleration planning is greater than the actual curve arc length.

[0138] Step S272: According to the curve parameter u of the current interpolation point i and the feed rate v at the current position i , use the second-order Runge-Kutta method to calculate the initial value of the curve parameter of the next interpolation point; the calculation formula can be as follows:

[0139]

[0140] Among them, represents the initial value of the curve parameters of the next interpolation point. T is the interpolation period, and v ci represents the corrected feed rate, and u i represents the curve parameters of the current interpolation point, and C′(u i ) represents the first-order derivative of the curve at ui, and C′(u i +Tk1) represents the first-order derivative of the curve at ui+Tk1.

[0141] Step S273: Modify the second-order Runge-Kutta method and calculate the corrected value of the curve parameters. Exemplarily, the calculation formula can be as follows:

[0142]

[0143] Among them, Δu i+1 represents the corrected value of the curve parameters, v i represents the feed rate at the current position, T is the interpolation period, and u i represents the curve parameters of the current interpolation point, and u i+1 represents the curve parameters of the next interpolation point.

[0144] Step S274: Calculate the new interpolation point parameters of the NURBS tool path. The calculation formula can be as follows:

[0145]

[0146] Among them, u i+1 represents the curve parameters of the next interpolation point, represents the initial value of the curve parameters of the next interpolation point, and Δu i+1 represents the corrected value of the curve parameters.

[0147] Exemplarily, Figure 3a is a schematic diagram of the NURBS tool path of an embodiment of the present application. In the Figure 3a shown embodiment, the interpolation period T is 2 ms, the set maximum chord error limit value δ max is 1 μm, the set maximum normal acceleration limit value a n,max is 950 mm / s 2 , the set maximum jerk limit value j n,max is 18000 mm / s 3 , and the programmed feed rate is 70 mm / s. When planning the feed rate for the Figure 3a shown tool path, the schematic diagrams of the allowable feed rate curve and the planned feed rate curve in the process of this embodiment can be referred to Figure 3b , and the schematic diagram of the normal acceleration after feed rate planning can be referred toFigure 3c , a schematic diagram of the normal jerk after feed rate planning can be referred to Figure 3d .

[0148] Exemplarily, Figure 4a is a schematic diagram of the NURBS tool path of another embodiment of the present application. In Figure 4a the illustrated embodiment, the interpolation period T is 3 ms, and the set chord height error limit value δ max is 1 μm, and the set normal acceleration limit value a n,max is 50 mm / s 2 , and the set normal jerk limit value j n,max is 20000 mm / s 3 , and the programmed feed rate is 40 mm / s. When performing feed rate planning on the Figure 4a illustrated tool path, a schematic diagram of the allowable feed rate curve and the planned feed rate curve in the process of this embodiment can be referred to Figure 4b , a schematic diagram of the normal acceleration after feed rate planning can be referred to Figure 4c , a schematic diagram of the normal jerk after feed rate planning can be referred to Figure 4d .

[0149] In summary, the feed rate planning method for the NURBS tool path in this embodiment realizes the improvement of the feed efficiency while ensuring that the feed rate curve meets multiple constraints, and improves the interpolation accuracy.

[0150] An embodiment of the present application provides a feed rate planning device for a NURBS tool path, as Figure 5 shown, including: a memory and a processor;

[0151] The memory is used to store a program for feed rate planning of the NURBS tool path;

[0152] The processor is used to read the program for feed rate planning of the NURBS tool path and execute the feed rate planning method for the NURBS tool path as described in any embodiment of the present application.

[0153] An embodiment of the present application further provides a non-transitory computer-readable storage medium, and the computer-readable storage medium stores a computer program, wherein the computer program can implement the feed rate planning method for the NURBS tool path as described in any embodiment of the present application when executed by a processor.

[0154] In summary, the present application provides a method, an apparatus, and a storage medium for planning the feed rate of a NURBS tool path. The solution is as follows: First, the allowable feed rate is determined according to geometric and normal driving ability constraints, and the NURBS tool path is segmented into multiple sub-curves. Second, the allowable feed rate is updated according to the tangential driving ability constraint, and the S-shaped acceleration and deceleration rule is adopted to generate the initial feed rate. For any sub-curve that exceeds the allowable feed rate, the start point and end point parameters are adjusted, and the corresponding transition interval is created. During the online interpolation process, the modified second-order Runge-Kutta interpolation method is adopted to ensure the accurate calculation of the interpolation points. This solution combines two-way scanning with the adjustment of the start and end parameters of the NURBS sub-curve, solves the problem of achieving high-precision and high-efficiency feed rate planning in high-speed CNC machining, and significantly improves the machining efficiency and accuracy.

[0155] Those of ordinary skill in the art can understand that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and apparatuses, can be implemented as software, firmware, hardware, and appropriate combinations thereof. In the hardware implementation, the division between the functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be executed by several physical components in cooperation. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term "computer storage medium" includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassette, tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0156] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0157] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A feed rate planning method for a NURBS tool path, characterized in that: include: Dividing the tool path into multiple sub-curves according to the curvature values ​​of points on the tool path; According to the allowable feed speed at the starting point and the allowable feed speed at the ending point of each sub-curve, an initial feed speed curve corresponding to the sub-curve is generated; For each sub-curve, determine whether the initial feed speed curve corresponding to the sub-curve meets the constraint conditions; when the initial feed speed curve does not meet the constraint conditions, adjust the initial feed speed curve to obtain an adjusted feed speed curve and a corresponding transition interval feed speed curve; and obtain the feed speed curve corresponding to the sub-curve according to the adjusted feed speed curve and the transition interval feed speed curve; when the initial feed speed curve meets the constraint conditions, determine the initial feed speed curve as the feed speed curve corresponding to the sub-curve; The feed rate curves corresponding to all sub-curves are combined in sequence according to the order of the sub-curves in the tool path to obtain a complete planned feed rate curve.

2. The feed rate planning method of NURBS tool path according to claim 1, characterized in that: The step of dividing the tool path into multiple sub-curves according to the curvature values ​​of points on the tool path includes: A method combining global scanning and local scanning is used to determine multiple curvature maximum value points on the tool path; The tool path is divided according to the maximum curvature points to obtain multiple sub-curves.

3. The feed rate planning method of NURBS tool path according to claim 1, characterized in that: Before generating the initial feed rate curve corresponding to the sub-curve according to the allowable feed rate at the starting point and the allowable feed rate at the ending point of each sub-curve, the method further includes: generating the allowable feed rate curve corresponding to the tool path according to the geometric and normal drive capability constraints and the programmed feed rate constraints; The step of generating an allowable feed rate curve corresponding to the tool path according to the geometry, normal drive capability constraints and programmed feed rate constraints includes: determining a plurality of preset interpolation positions in the tool path based on a preset interpolation cycle; For each interpolation position, the first feed speed, the second feed speed, the third feed speed and the programmed feed speed of the position are obtained, and the minimum value among the first feed speed, the second feed speed, the third feed speed and the programmed feed speed is selected as the allowable feed speed of the position; wherein the first feed speed refers to the feed speed of the position under the constraint of the bow height error limit, the second feed speed refers to the feed speed of the position under the constraint of the normal acceleration, the third feed speed refers to the feed speed of the position under the constraint of the normal jerk, and the programmed feed speed refers to the maximum feed speed determined by the user during the processing; The allowable feed speed curve is generated according to the allowable feed speeds of all interpolation positions.

4. The feed rate planning method of NURBS tool path according to claim 3, characterized in that: After generating the allowable feed rate curve corresponding to the tool path according to the geometry, normal drive capability constraints and programmed feed rate constraints, the method further includes: For each sub-curve, under the constraint of tangential driving capacity, the optimal allowable feed speed at the starting point and the optimal allowable feed speed at the end point of the sub-curve are determined by reverse scanning during the deceleration process and forward scanning during the acceleration process; The allowable feed speed at the starting point of the sub-curve is updated to the optimal allowable feed speed at the starting point, and the allowable feed speed at the ending point of the sub-curve is updated to the optimal allowable feed speed at the ending point.

5. The feed rate planning method of NURBS tool path according to claim 1, characterized in that: The step of generating an initial feed speed curve corresponding to each sub-curve according to the allowable feed speed at the starting point and the allowable feed speed at the ending point of each sub-curve comprises: The duration of each acceleration stage is obtained according to the tangential acceleration, the tangential jerk, the starting point feed speed and the ending point feed speed, wherein the duration of each acceleration stage includes: the jerk duration, the uniform acceleration duration and the deceleration duration; The initial feed rate curve corresponding to the sub-curve is obtained according to the starting point feed rate, tangential jerk, duration of each acceleration stage and maximum acceleration; the maximum acceleration refers to the maximum acceleration within the range from the starting point to the end point of the sub-curve.

6. The feed rate planning method of NURBS tool path according to claim 3, characterized in that: The determining whether the initial feed speed curve corresponding to the sub-curve meets the constraint condition includes: when the feed speed of any point in the initial feed speed curve of the sub-curve exceeds the allowable feed speed corresponding to the point, confirming that the initial feed speed curve does not meet the constraint condition; when the feed speeds of all points in the initial feed speed curve of the sub-curve do not exceed the allowable feed speed corresponding to the point, confirming that the initial feed speed curve meets the constraint condition; The adjusting of the initial feed speed curve to obtain the adjusted feed speed curve includes: when there is an over-limit point located on the starting side of the sub-curve, all points between the starting point and the last over-limit point on the starting side are over-limited, and the starting point of the sub-curve is updated to the position of the last over-limit point on the starting side of the sub-curve; when there is an over-limit point located on the ending side of the sub-curve, all points between the first over-limit point on the ending side and the ending point are over-limited, and the ending point of the sub-curve is updated to the position of the first over-limit point on the ending side of the sub-curve; the adjusted feed speed curve is generated according to the updated starting point allowable feed speed and ending point allowable feed speed of the sub-curve; wherein the starting side refers to the side where the starting point of the sub-curve is located, and the ending side refers to the side where the ending point of the sub-curve is located; The transition interval feed speed curve includes a starting transition interval feed speed curve and an ending transition interval feed speed curve; the adjusted feed speed curve and the corresponding transition interval feed speed curve are obtained, including: taking the transition interval between the starting point of the adjusted sub-curve and the starting point of the sub-curve before adjustment as the starting transition interval, taking the starting point feed speed of the adjusted feed speed curve as the feed speed of the starting transition interval, and generating a constant-speed starting transition interval feed speed curve; taking the transition interval between the ending point of the adjusted sub-curve and the ending point of the sub-curve before adjustment as the ending transition interval, taking the ending point feed speed of the adjusted feed speed curve as the feed speed of the ending transition interval, and generating a constant-speed ending transition interval feed speed curve.

7. The feed rate planning method of NURBS tool path according to claim 6, characterized in that: Before generating the initial feed rate curve corresponding to the sub-curve according to the allowable feed rate of the starting point and the allowable feed rate of the ending point of each sub-curve, the method further includes: determining a plurality of parameter adjustment intervals according to the relationship between the allowable feed rate of the points on the tool path and the programmed feed rate; each parameter adjustment interval is composed of a plurality of consecutive points on the curve whose allowable feed rate is less than the programmed feed rate, and each parameter adjustment interval contains only one curvature maximum value point; When there is an over-limit point located at the starting side of the sub-curve, the starting point of the sub-curve is updated to the position of the last over-limit point located at the starting side of the sub-curve; when there is an over-limit point located at the ending side of the sub-curve, the ending point of the sub-curve is updated to the position of the first over-limit point located at the ending side of the sub-curve, including: Determine the parameter adjustment interval to which the position of the point that does not meet the constraint condition in the sub-curve belongs; When the position of the point that does not meet the constraint conditions in the sub-curve is located in the parameter adjustment interval corresponding to the sub-curve, the position of the starting point of the sub-curve is updated according to the preset adjustment parameters; when the position of the point that does not meet the constraint conditions in the sub-curve is located in the next parameter adjustment interval of the parameter adjustment interval corresponding to the sub-curve, the position of the end point of the sub-curve is updated according to the preset adjustment parameters.

8. The feed rate planning method of NURBS tool path according to claim 1, characterized in that: After the complete planned feed speed curve is obtained, the following steps are also included: Obtaining a planned feed speed sequence corresponding to the tool path according to the planned feed speed curve; According to the planned feed speed sequence, the tool path is interpolated online based on the parameter-corrected second-order Runge-Kutta method.

9. A feed rate planning device for a NURBS tool path, comprising: A memory and a processor, characterized in that: The memory is used to store a program for feed rate planning of a NURBS tool path; The processor is used to read the program for feed rate planning of the NURBS tool path and execute the feed rate planning method of the NURBS tool path as described in any one of claims 1 to 8.

10. A non-transitory computer-readable storage medium storing a computer program, wherein: When the computer program is executed by a processor, it is capable of implementing the feed rate planning method for a NURBS tool path as claimed in any one of claims 1 to 8.

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