CN114942615B - Equal-bow-height error interpolation method, device and storage medium - Google Patents

Abstract

The interpolation method of the present invention needs to analyze the curvature change of the free curve in advance, divide the curve to be processed into sections according to the curvature change rate, and use different strategies to calculate the interpolation points in each section. For sections with stable curvature, the traditional geometric method is preferred for calculation, and the calibration function is discarded to improve calculation efficiency as much as possible; for sections with obvious curvature fluctuations, the curvature change needs to be strictly monitored, and the step size is automatically adjusted according to the error to ensure that the machining accuracy meets the requirements. The new interpolation method based on the curvature partition strategy solves the problems of error overrun and step size overconservation in the traditional contour height error method on the basis of flexible parameter control, fast, stable and reliable calculation.

Description

A contour height error interpolation method, device and storage medium

technical field

The invention relates to the technical field of numerical control machining motion control, in particular to a method, equipment, device and computer storage medium for interpolating contour height errors.

Background technique

The continuous advancement of the industrialization process has put forward higher requirements for the design and manufacture of products, and free-form surfaces have also emerged as the times require. As the main method of free-form surface machining, numerical control technology is also developing in the direction of high speed, high precision and reliability, and the interpolation method of free-form curve is a key technology that affects the quality of free-form surface machining.

At present, the most widely used methods in engineering are equidistant step method, equal parameter step method, parameter screening method and equal bow height error method. The equidistance method uses equal distances to interpolate the tool paths. In order to meet the approximation error, the value is relatively conservative, thus generating more redundant tool paths. The equal parameter step method divides the curve parameters equidistantly to obtain several discrete parameter nodes, which are used as the interpolation points for actual processing. Due to the nonlinear relationship between the parameter equation and the curve equation, the error between the interpolation points fluctuates greatly, and the processing The quality is not uniform, and even large approximation errors may occur locally. The parameter screening method requires that the initial discrete points be sufficiently dense, so the calculation amount is large and the calculation speed is slow. Moreover, the error of the bow height obtained by this method is uneven, which affects the precision of the processed surface. The equal bow height error method takes into account the change of curvature, which is a better improvement than the previous method, but the essence is still to use the arc to calculate the step size, which leads to the need to repeatedly verify the error, which reduces the calculation performance, and the verification results It is still possible to exceed the tolerance range of error. However, there are still some defects in the existing improvement schemes: (1) The calculation of the error value of the bow height between adjacent tangent points is improved by means of space vectors. Although a more accurate error value of the bow height can be obtained, to a certain extent Improve the accuracy of free curve interpolation, but it does not solve the problem of error overrun and step size too conservative caused by sudden curvature changes; Optimum step length value does not consider the curve situation, and blindly calculates to ensure that the bow height error meets the requirements, resulting in some redundant calculations and reducing the execution efficiency of the algorithm.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the problems of low calculation efficiency and inaccurate calculation in the prior art.

In order to solve the above technical problems, the present invention provides a contour height error interpolation method, equipment, device and computer storage medium, including:

Calculate the parameter expression of the Bezier curve according to the control vertex data of the curve to be processed;

Calculating the curvature of the Bezier curve to obtain the rate of change of the curvature as the curve parameters change;

If the rate of change of the current section is not greater than the reference value, the minimum radius of curvature in the current section is calculated by using the geometric relationship, and the interpolation step is calculated with the minimum radius of curvature as the radius of the arc;

If the rate of change of the current section is greater than the reference value, the geometric relationship is used to calculate the radius of curvature of the initial point of the current section, and the initial step is obtained by approximating the radius of curvature of the initial point as the arc radius, Iteratively updating the initial step size until an optimal step size meeting the bow height error requirement is obtained;

Calculate the corresponding interpolation end point according to the optimal step length, so as to judge whether the calculation of the current section is completed. If the calculation is not completed, update the initial point to the interpolation end point, and return to perform the above-mentioned optimal solution. Step by step;

When all sections are calculated, the discrete interpolation points are merged to obtain a complete discrete point path.

Preferably, according to the control vertex data of the curve to be processed, the calculated parameter expression of the Bezier curve includes:

According to the given control vertex data P of the curve to be processed, calculate the Bezier curve L;

Calculate the basis function expression of the Bezier curve according to the number of control vertices n:

Among them, i=0,1,2,...,n, the curve parameter u∈[0,1], thus the parameter expression of the Bezier curve L is calculated:

Preferably, the calculation of the curvature of the Bezier curve to obtain the rate of change of the curvature as the curve parameter changes comprises:

Calculate the curvature of the Bezier curve Wherein c (u) is the parametric expression of described Bezier curve, c ' (u) is the curve first-order derivative, and c " (u) is the curve second-order derivative;

Computes the rate of change of curvature as a function of a curve parameter

Preferably, the iteratively updating the initial step size until an optimal step size that meets the bow height error requirement is obtained includes:

Step a: Calculate the maximum bow height error value between adjacent interpolation points when the current step value is obtained;

Step b: Calculate the absolute value of the difference between the maximum bow height error value of the current step length and the processing allowable maximum bow height error value, and compare it with the iterative error;

Step c: if the absolute value is greater than the iterative error, jump to step d; if the absolute value is not greater than the iterative error, skip the iterative calculation and use the current step size as the optimal step size;

Step d: If the maximum bow height error value of the current step size is not greater than the processing allowable maximum bow height error value, then increase the parameter increment of the free curve, update the current step size value, jump to step a, and set The current step size is the optimal step size, otherwise, reduce the parameter increment of the free curve, update the current step size value, and jump to step a until the maximum bow height error value of the current step size is not greater than the specified The above processing allowable maximum bow height error value.

Preferably, the optional increase or decrease of the parameter increment of the free curve Δu=(1±α)Δu, where α is a preset step size automatic adjustment coefficient.

Preferably, the updated current step value is s _i =c'(u _i )Δu _i , where c(u) is a parameter expression of the Bezier curve, i=0,1,2 ,...,n,u∈[0,1];

The corresponding end point of the interpolation segment is calculated as c(u _i+1 )=c(u _i +Δu _i ).

Preferably, when the calculation obtains the current step length value, the maximum bow height error value e ₀ =||T ₂ ||sinθ between adjacent interpolation points;

Among them, the angle between the two vectors is a vector composed of two adjacent interpolation points, /> It is the vector formed from the starting point of the interpolation segment to any point on the curve segment.

The present invention also provides a device for interpolating contour height errors, including:

The curve parameter expression calculation module is used to calculate the parameter expression of the Bezier curve according to the control vertex data of the curve to be processed;

Curve rate of change calculation module, used to calculate the curvature of the Bezier curve, to obtain the rate of change of the curvature as the curve parameter changes;

The smooth section interpolation step calculation module is used to calculate the minimum curvature radius in the current section by using the geometric relationship, and calculate the interpolation step with the minimum curvature radius as the arc radius;

The optimal step size calculation module of the fluctuation section is used to calculate the curvature radius of the initial point of the current section by using the geometric relationship, and use the curvature radius of the initial point as the arc radius to obtain the initial step size by approximate calculation , iteratively updating the initial step size until the optimal step size meeting the bow height error requirement is obtained;

The judging module for whether the calculation of the fluctuation section is completed is used to calculate the corresponding interpolation end point according to the optimal step length, so as to judge whether the calculation of the current section is completed, and if the calculation is not completed, update the initial point to the The end point of the interpolation is described, and the step of performing the above-mentioned solution to the optimal step size is returned;

The discrete interpolation point merging module is used to merge the discrete interpolation points to obtain a complete discrete point path after all sections are calculated.

The present invention also provides a device for contour height error interpolation, including:

The memory is used to store the computer program; the processor is used to realize the steps of the above-mentioned contour error interpolation method when executing the computer program.

The present invention also provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned contour error interpolation method are realized.

The above technical solution of the present invention has the following advantages compared with the prior art:

The invention proposes a contour height error interpolation method in curve processing based on curvature partition. This interpolation method needs to analyze the curvature change of the free curve in advance, divide the curve to be processed into sections according to the curvature change rate, and use different strategies to calculate the interpolation points in each section. For sections with stable curvature, the traditional geometric method is preferred for calculation, and the calibration function is discarded to improve calculation efficiency as much as possible; for sections with obvious curvature fluctuations, the curvature change needs to be strictly monitored, and the step size is automatically adjusted according to the error to ensure that the machining accuracy meets the requirements.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

Fig. 1 is the realization flowchart of contour height error interpolation method of the present invention;

Fig. 2 is a schematic diagram of calculating the interpolation step length by the geometric method;

Fig. 3 is a schematic diagram of the automatic adjustment step size mechanism according to the curvature change;

Fig. 4 is a flow chart of a method for interpolating contour height errors in an embodiment of the present invention;

Fig. 5 is the schematic diagram of free curve to be processed;

Fig. 6 is the schematic diagram of the curvature change of the selected free curve to be processed;

Figure 7(a) is the discrete knife contact after the interpolation calculation by the equal bow height error method;

Figure 7(b) shows the error distribution after the interpolation calculation by the contour error method;

Fig. 8(a) is the discrete knife contact after the interpolation calculation based on the curvature partition equal bow height error interpolation method;

Figure 8(b) shows the error distribution after the interpolation calculation based on the curvature partition-based contour height error interpolation method;

Fig. 9 is a structural block diagram of a contour height error interpolation device provided by an embodiment of the present invention.

Detailed ways

The core of the present invention is to provide a method, device, equipment and computer storage medium for interpolation of contour height errors. According to the curvature change rate, the curve to be processed is divided into sections, and each section adopts different strategies to calculate the interpolation points, so as to improve calculation accuracy and efficiency.

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Fig. 1, Fig. 1 is the realization flowchart of the contour height error interpolation method provided by the present invention; The specific operation steps are as follows:

The given parameters of the system include: the control vertex data P of the curve to be processed, the tool radius r of the ball nose cutter used for processing, the maximum bow height error e allowed for processing, the curvature change rate reference value μ of the divided section, and the step size automatic adjustment Coefficient α;

S101: According to the control vertex data of the curve to be processed, calculate the parameter expression of the Bezier curve;

According to the given control vertex data P of the curve to be processed, calculate the Bezier curve L;

Calculate the basis function expression of the Bezier curve according to the number of control vertices n:

Among them, i=0,1,2,...,n, the curve parameter u∈[0,1], thus the parameter expression of the Bezier curve L is calculated:

The first and second derivatives of Bezier curves:

S102: Calculate the curvature of the Bezier curve to obtain the rate of change of the curvature as the curve parameters change;

Assuming that the parameter expression of a curve is c(u), the curvature k at a point on the curve is only related to the curve parameter u, the first order derivative c′(u) and the second order derivative c″(u) of the curve:

Then the rate of change of the curvature with the change of the curve parameters is obtained

S103: If the rate of change of the current section is not greater than the reference value, calculate the minimum curvature radius in the current section by using the geometric relationship, and use the minimum curvature radius as the radius of the arc to calculate the interpolation step size;

If the change rate of the current segment is not greater than the reference value μ ₀ ≤ μ, it means that the curvature of the current curve segment changes slightly, and the interference to the interpolation step calculation can be ignored;

As shown in Figure 2, the minimum radius of curvature in the current interpolation segment is obtained by using the geometric relationship between the radius of curvature and the reciprocal of the curvature And use this as the arc radius to calculate the interpolation step length /> Then realize the discrete approximation of the curve segment;

The time variable parameter t is introduced, and the second-order Taylor expansion is performed on the curve parameter u at t=t _i :

Substituting the first and second derivatives t′ and t″ of the curve parameter u to the time parameter t into the above formula, and expanding and simplifying, the relationship between the interpolation step s _i and the parameter increment Δu _i can be obtained: s _i = c'(u _i )Δu _i ;

After calculating the step length of the current interpolation point, it is necessary to find the position of the next interpolation point, that is, the intersection point between the interpolation line segment and the curve. However, it is very complicated to directly calculate the intersection point. The parameter increment is used to realize the recursive calculation of interpolation points, that is, c(u _i+1 )=c(u _i +Δu _i ), so that all interpolation points in the current interpolation section can be recursively calculated, Complete the interpolation calculation for the curvature stable segment.

S104: If the rate of change of the current section is greater than the reference value, calculate the radius of curvature of the initial point of the current section using the geometric relationship, and use the radius of curvature of the initial point as the radius of the arc to approximate the calculation to obtain the initial step is long, update the initial step size iteratively until the optimal step size that meets the bow height error requirement is obtained;

S105: Calculate the corresponding interpolation end point according to the optimal step length, so as to judge whether the calculation of the current section is completed, if not, update the initial point to the interpolation end point, and return to execute the above solution The step with the optimal step size;

S106: After all sections are calculated, merge the discrete interpolation points to obtain a complete discrete point path.

The contour height error interpolation method model constructed by the present invention includes two main steps: section division and interpolation calculation.

Segment division refers to the use of the control vertex data P of the curve to be processed to fit the Bezier curve, and calculate the curvature of the curve obtained after fitting, by comparing the change rate of the curve curvature with the curve parameter change μ ₀ and The size relationship between the curvature change rate reference value μ used for section division, so as to realize the section division of the free curve to be processed, and the obtained curvature change characteristics in each section should remain basically the same.

Interpolation calculation refers to the calculation of interpolation points by using different calculation strategies for the sections with different curvature change characteristics obtained after the free curve is divided into sections. Free curves can generally be divided into three types of sections: stable curvature, increasing curvature, and decreasing curvature. Each type of section has a corresponding interpolation calculation strategy. The segment with stable curvature uses the geometric relationship to find the minimum curvature radius in the interpolation segment, and uses it as the radius of the arc to approximate the curve segment. Because the curvature in the segment remains stable, in order to improve the efficiency of the algorithm, the calibration can be ignored. test part. The two types of sections with increased curvature and decreased curvature can be combined into a section with obvious curvature change. In this type of section, it is necessary to monitor the change of the curvature of the curve at each position in real time. By comparing the actual value of the discrete back bow error with the given The size relationship between the values is automatically adjusted for the step size, and after a certain number of iterative calculations, the maximum step size that satisfies the given bow height error is found. This can ensure that even if the curvature of the curve changes drastically, the processing accuracy can meet the requirements, the surface error after processing can be kept uniform, and the number of steps required for processing is small, and the processing efficiency is high.

When the interpolation model is determined, the free curve to be processed is divided into multiple sections, and an appropriate calculation strategy is used for subsequent interpolation calculations according to the curvature change characteristics of each section.

As shown in Figure 3, based on the above embodiment, this embodiment will further describe steps S104-S105 in detail, as follows:

Step a: Calculate the maximum bow height error value e ₀ between adjacent interpolation points when the current step value is obtained =||T ₂ ||sinθ;

Among them, the angle between the two vectors is a vector composed of two adjacent interpolation points, /> It is the vector formed from the starting point of the interpolation segment to any point on the curve segment.

Step b: Calculate the absolute value of the difference between the maximum bow height error value of the current step length and the processing allowable maximum bow height error value e, and compare it with the iteration error δ;

Step c: If the absolute value is greater than the iteration error |e ₀ -e|>δ, it means that the difference between the maximum bow height error value e ₀ generated by the current step size and the bow height error e allowed by processing does not meet the iteration accuracy If required, judge the size relationship between the maximum bow height error value of the current step length and the processing allowable maximum bow height error value, if the absolute value is not greater than the iteration error |e ₀ -e|≤δ, then jump out of the iterative calculation, and set The current step size is used as the optimal step size;

Step d: If the maximum bow height error value of the current step is not greater than the allowable maximum bow height error value e ₀ ≤ e, jump out of the iterative calculation, and use the current step size as the optimal step size, if the current step size When the maximum bow height error value is greater than the processing allowable maximum bow height error value e ₀ >e, reduce the parameter increment of the free curve, update the current step value, and jump to step a until the current step The maximum bow height error value is not greater than the processing allowable maximum bow height error value.

Step d: If the maximum bow height error value of the current step size is not greater than the processing allowable maximum bow height error value e ₀ ≤ e, it means that the current step size value is relatively conservative, then increase the parameter increment of the free curve Δu=(1 +α)Δu, update the current step value, jump to step a, take the current step as the optimal step, if e ₀ >e, it means the current step value is too large, reduce the free curve Parameter increment Δu=(1-α)Δu, update the current step value, jump to step a, until the current step maximum bow height error value is not greater than the processing allowable maximum bow height error value.

The interpolation method provided by the present invention can fit the control vertex data into a free curve according to the given parameters of the system, analyze the curvature change of the curve in advance, and divide the curve to be processed into zones according to the relationship between the curvature change rate and the reference value Each segment adopts different strategies to calculate the interpolation points. The section with stable curvature is preferentially calculated by traditional geometric method, and the calibration function is discarded to improve the calculation efficiency as much as possible; the section with obvious curvature fluctuation needs to strictly monitor the curvature change, and automatically adjust the step size according to the error to find the bow height error requirement. The optimal step length value to ensure that the machining accuracy meets the requirements. The new interpolation method based on the curvature partition strategy solves the problems of error overrun and step size overconservation in the contour height error method on the basis of flexible parameter control, fast, stable and reliable calculation.

As shown in Figure 4, based on the above embodiment, the present embodiment selects a free curve (as shown in Figure 5) in the free-form surface as the experimental object, specifically as follows:

Set the cutter radius r of the ball-end cutter used for processing to 5mm, the maximum allowable bow height error e to 0.01mm, the reference value μ of the curvature change rate of the divided section to 0.03, and the step length automatic adjustment coefficient α to 0.005.

Fitting the given control vertex data, the obtained Bezier curve, the curvature variation of the selected path to be processed is as shown in accompanying drawing 6;

When the curvature change is not greater than the reference value, the minimum curvature radius ρ in the current interpolation section is obtained by using the geometric relationship between the curvature radius and the curvature as the reciprocal of each other, and the interpolation step s is calculated as the arc radius , and then realize the discrete approximation of the curve segment;

If the curvature change is less than the reference value, the real-time monitoring of the change of the curvature of the curve at each position will automatically adjust the step size by comparing the actual value of the discretized bow height error with the given value.

The present invention pre-analyzes the curvature characteristics of the curve to be processed, and carries out corresponding partitions, so as to use different calculation strategies for the discrete calculation of the knife contact, effectively avoiding the problems of error overrun and step size overconservation in the equal bow height error method . From Figure 7(a), Figure 7(b) and Figure 8(a), Figure 8(b), it can be seen that the equal bow height error method has discretized a total of 41 knife contacts, and this method has discretized a total of 34 knife contacts. Compared with the equal bow height error method, the number of tool contacts is reduced by 17%, which effectively improves the efficiency of machining, and also greatly reduces the time-consuming aspect of program calculation. In terms of surface quality after processing, this method pre-analyzes the curvature change and uses the step size automatic adjustment mechanism reasonably to ensure that the algorithm can effectively track the curvature change. Compared with the equal bow height error method, it can effectively avoid the problem that the maximum bow height error exceeds the limit and the problem of too conservative step size caused by too small bow height error. Therefore, the surface residual error obtained after processing by this method is constant and is the allowable maximum value, which not only ensures the uniform surface quality after processing, but also greatly improves the processing efficiency, and at the same time avoids the interference of curvature factors on processing accuracy.

The interpolation method of the present invention can fit the control vertex data into a free curve according to the given parameters of the system, analyze the curvature change of the curve in advance, and divide the curve to be processed into sections according to the magnitude relationship between the curvature change rate and the reference value , each section adopts different strategies to calculate the interpolation points. The section with stable curvature is preferentially calculated by traditional geometric method, and the calibration function is discarded to improve the calculation efficiency as much as possible; the section with obvious curvature fluctuation needs to strictly monitor the curvature change, and automatically adjust the step size according to the error to find the bow height error requirement. The optimal step length value to ensure that the machining accuracy meets the requirements. The new interpolation method based on the curvature partition strategy solves the problems of error overrun and step size overconservation in the contour height error method on the basis of flexible parameter control, fast, stable and reliable calculation.

Please refer to Fig. 9, Fig. 9 is a structural block diagram of a contour error interpolation device provided by an embodiment of the present invention; the specific device may include:

The curve parameter expression calculation module 100 is used to calculate the parameter expression of the Bezier curve according to the control vertex data of the curve to be processed;

The curve rate of change calculation module 200 is used to calculate the curvature of the Bezier curve to obtain the rate of change of the curvature as the curve parameters change;

The smooth section interpolation step calculation module 300 is used to calculate the minimum radius of curvature in the current section by using the geometric relationship, and calculate the interpolation step with the minimum curvature radius as the radius of the arc;

The optimal step length calculation module 400 for the fluctuation section is used to calculate the curvature radius of the initial point of the current section by using the geometric relationship, and use the curvature radius of the initial point as the arc radius to obtain the initial step is long, update the initial step size iteratively until the optimal step size that meets the bow height error requirement is obtained;

The judging module 500 whether the calculation of the fluctuation section is completed is used to calculate the corresponding interpolation end point according to the optimal step size, so as to judge whether the calculation of the current section is completed, and if the calculation is not completed, update the initial point to The end point of the interpolation returns to the above-mentioned step of solving the optimal step size;

The discrete interpolation point merging module 600 is used for merging the discrete interpolation points to obtain a complete discrete point path after all sections are calculated.

The contour height error interpolation device of this embodiment is used to implement the aforementioned contour height error interpolation method, so the specific implementation of the contour height error interpolation device can be seen in the embodiment part of the contour height error interpolation method above. , For example, the curve parameter expression calculation module 100, the curve rate of change calculation module 200, the smooth section interpolation step calculation module 300, the fluctuation section optimal step calculation module 400, the fluctuation section calculation completion judgment module 500, The discrete interpolation point merging module 600 is respectively used to realize the steps S101, S102, S103, S104, S105 and S106 in the above-mentioned equal bow error interpolation method, so, its specific implementation can refer to the description of the corresponding parts of the embodiments , which will not be repeated here.

A specific embodiment of the present invention also provides a device for contour error interpolation, including: a memory for storing a computer program; a processor for implementing the above-mentioned contour error interpolation when executing the computer program method steps.

A specific embodiment of the present invention also provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the above-mentioned contour error interpolation method is implemented. step.

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

Apparently, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in various forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (10)

1. A method for interpolating contour height errors, characterized in that it comprises: Calculate the parameter expression of the Bezier curve according to the control vertex data of the curve to be processed; Calculating the curvature of the Bezier curve to obtain the rate of change of the curvature as the curve parameters change; If the rate of change of the current section is not greater than the reference value, the minimum radius of curvature in the current section is calculated by using the geometric relationship, and the interpolation step is calculated with the minimum radius of curvature as the radius of the arc; If the rate of change of the current section is greater than the reference value, the geometric relationship is used to calculate the radius of curvature of the initial point of the current section, and the initial step is obtained by approximating the radius of curvature of the initial point as the arc radius, Iteratively updating the initial step size until an optimal step size meeting the bow height error requirement is obtained; Calculate the corresponding interpolation end point according to the optimal step length, so as to judge whether the calculation of the current section is completed. If the calculation is not completed, update the initial point to the interpolation end point, and return to perform the above-mentioned optimal solution. Step by step; When all sections are calculated, the discrete interpolation points are merged to obtain a complete discrete point path. 2. contour height error interpolation method according to claim 1, is characterized in that, described according to the control vertex data of curve to be processed, the parameter expression that calculates Bezier curve comprises: According to the given control vertex data of the curve to be processed , calculate the Bezier curve /> ; According to the number of control vertices Calculate the basis function expression of the Bezier curve: in, , curve parameter /> , thus calculating the Bezier curve /> The parameter expression for : . 3. the contour height error interpolation method according to claim 2, is characterized in that, described calculating the curvature of described Bezier curve, obtaining the rate of change of curvature along with curve parameter variation comprises: Calculate the curvature of the Bezier curve , where /> is the parameter expression of the Bezier curve, /> is the first derivative of the curve, /> is the second order derivative of the curve; Computes the rate of change of curvature as a function of a curve parameter . 4. The error interpolation method for contour height errors according to claim 1, wherein the iterative update of the initial step size until the optimum step size that meets the requirements of the bow height error is obtained includes: Step a: Calculate the maximum bow height error value between adjacent interpolation points when the current step value is obtained; Step b: Calculate the absolute value of the difference between the maximum bow height error value of the current step length and the processing allowable maximum bow height error value, and compare it with the iterative error; Step c: if the absolute value is greater than the iterative error, jump to step d; if the absolute value is not greater than the iterative error, skip the iterative calculation and use the current step size as the optimal step size; Step d: If the maximum bow height error value of the current step size is not greater than the processing allowable maximum bow height error value, then increase the parameter increment of the free curve, update the current step size value, jump to step a, and set The current step size is the optimal step size, otherwise, reduce the parameter increment of the free curve, update the current step size value, and jump to step a until the maximum bow height error value of the current step size is not greater than the specified The above processing allowable maximum bow height error value. 5. The contour height error interpolation method according to claim 4, characterized in that, said increasing or reducing the parameter increment of said free curve , among them, /> Automatically adjusts coefficients for preset step sizes. 6. The contour height error interpolation method according to claim 5, characterized in that, the current step size of the update is , where /> is the parameter expression of the Bezier curve, /> , /> ; Calculate the corresponding end point of the interpolation segment as . 7. The equal bow height error interpolation method according to claim 1, characterized in that, when the calculation obtains the current step value, the maximum bow height error value between adjacent interpolation points ; Among them, the angle between the two vectors , /> is a vector composed of two adjacent interpolation points, /> It is the vector formed from the starting point of the interpolation segment to any point on the curve segment. 8. A device for contour height error interpolation, characterized in that it comprises: The curve parameter expression calculation module is used to calculate the parameter expression of the Bezier curve according to the control vertex data of the curve to be processed; Curve rate of change calculation module, used to calculate the curvature of the Bezier curve, to obtain the rate of change of the curvature as the curve parameter changes; The smooth section interpolation step calculation module is used to calculate the minimum radius of curvature in the current section by using the geometric relationship if the rate of change of the current section is not greater than the reference value, and calculate the minimum radius of curvature as the arc radius interpolation step; The optimal step size calculation module of the fluctuation section, if the rate of change of the current section is greater than the reference value, is used to calculate the curvature radius of the initial point of the current section by using the geometric relationship, and use the curvature radius of the initial point The initial step size is calculated for the approximate approximation of the radius of the arc, and the initial step size is iteratively updated until the optimal step size that meets the bow height error requirement is obtained; The judging module for whether the calculation of the fluctuation section is completed is used to calculate the corresponding interpolation end point according to the optimal step length, so as to judge whether the calculation of the current section is completed, and if the calculation is not completed, update the initial point to the The end point of the interpolation is described, and the step of performing the above-mentioned solution to the optimal step size is returned; The discrete interpolation point merging module is used to merge the discrete interpolation points to obtain a complete discrete point path after all sections are calculated. 9. A device for contour height error interpolation, characterized in that it comprises: memory for storing computer programs; A processor, configured to implement the steps of a contour error interpolation method according to any one of claims 1 to 7 when executing the computer program. 10. A computer-readable storage medium, characterized in that, a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the computer program according to any one of claims 1 to 7 is implemented. The steps of the contour height error interpolation method.