Method and device for achieving pose transition of five-axis machine tool

Abstract

According to the method and device for achieving pose transition of the five-axis machine tool, the inflection point position is selected in a self-adaptive mode, and the coupling problem of a tool nose and the tool axis direction is fully considered; spline control parameters are selected in a self-adaptive mode, and transition sufficiency is ensured with a harsh track as a benchmark; the double-track synchronous control points are arranged, the track matching and pose coordination ability is improved, smooth and continuous pose transition is achieved in the five-axis machine tool, and the transition quality and the machining precision are ensured. The embodiment of the invention has good engineering feasibility, is suitable for fairing treatment of various five-axis machining paths, and is particularly suitable for machining of workpieces with complex curvatures and posture changes.

Description

TECHNICAL FIELD

[0001] The present application relates to, but is not limited to, the technical field of numerical control machining, and particularly relates to a method and device for realizing pose transition of a five-axis machine tool. BACKGROUND

[0002] A numerical control program of a numerical control machine tool is usually generated by computer-aided manufacturing (CAM) software and is composed of multiple instruction segments. Between these instruction segments, there are often problems such as unsmooth trajectory transition and insufficient curvature continuity. For two-axis or three-axis machine tools, the numerical control program mainly contains position instructions, and such trajectory transition problems can usually be solved by methods such as spline fitting.

[0003] However, in a five-axis machine tool, the numerical control program not only contains position instructions but also includes attitude instructions (such as tool axis direction). Due to the simultaneous change of position and attitude, how to realize smooth and continuous pose transition has become a technical problem that needs to be solved. SUMMARY

[0004] The present application provides a method and device for realizing pose transition of a five-axis machine tool, which can realize smooth and continuous pose transition in a five-axis machine tool and ensure transition quality and machining precision.

[0005] The present application provides a method for realizing pose transition of a five-axis machine tool, which comprises:

[0006] The five-axis trajectory is decomposed, each tool position is converted into a tool tip point trajectory and a tool axis direction point trajectory, and the tool axis direction point and the tool tip point have a distance length;

[0007] The inflection point positions in the five-axis trajectory are determined by respectively detecting the inflection points of the tool tip point trajectory and the tool axis direction point trajectory;

[0008] For each inflection point, the spline control parameters at the inflection point are determined according to the trajectory with higher error control requirements in the tool tip point trajectory and the tool axis direction point trajectory;

[0009] For each inflection point, the tool tip point trajectory and the tool axis direction point trajectory are set synchronously based on the trajectory with higher error control requirements as the reference trajectory, so that the two trajectories remain consistent in the spline control point distribution structure;

[0010] The tool tip point trajectory spline curve and the tool axis direction point trajectory spline curve are respectively generated according to the determined inflection point positions and control point information, and the trajectory of the five-axis machine tool is constructed based on the two generated spline curves.

[0011] In an exemplary embodiment, the distance length is a characteristic length cl related to a machining characteristic of the current tool tip trajectory on the current trajectory segment, and the characteristic length cl is calculated according to an average cutting depth of the tool tip trajectory within the current trajectory segment and an inclination angle of the tool axis relative to the surface of the current trajectory segment.

[0012] In an exemplary embodiment, the inflection point detection on the tool tip trajectory and the tool axis direction trajectory respectively comprises:

[0013] For each tool position, the sag error of the tool tip trajectory and the tool axis direction trajectory is calculated respectively, and the continuity of the tool tip trajectory and the tool axis direction trajectory corresponding to the tool position is checked;

[0014] If the sag error of the tool tip trajectory or the tool axis direction trajectory of the tool position exceeds a preset threshold, the tool position is determined as an inflection point.

[0015] In an exemplary embodiment, for each inflection point, the spline control parameter at the inflection point is determined according to the trajectory with higher error control requirement between the tool tip trajectory and the tool axis direction trajectory, comprising:

[0016] At each inflection point, the spline control parameter range is calculated according to the local continuity requirement and error tolerance of the trajectory for the tool tip trajectory and the tool axis direction trajectory respectively.

[0017] In an exemplary embodiment, the spline control parameter range is calculated according to the local continuity requirement and error tolerance of the trajectory, and an upper limit of the control point spacing is determined, comprising:

[0018] At each inflection point, control points are arranged before and after the inflection point along the trajectory direction respectively, and at least n+2 control points required for fitting an n-order spline are constructed;

[0019] Based on the fitting error between the control points and the spline curve, and the variation characteristics of the control points before and after the trajectory direction, the maximum value range of the spline control parameter is determined.

[0020] In an exemplary embodiment, a quintic B-spline is used as the trajectory fitting curve for the fitting.

[0021] In an exemplary embodiment, the tool tip trajectory and the tool axis direction trajectory are set synchronously, comprising:

[0022] Taking the trajectory with smaller upper limit of the spline control parameter as a reference trajectory, the positions of the spline control points on the reference trajectory are set;

[0023] The positions of the spline control points on the other trajectory are set synchronously using the same proportional relationship as the reference trajectory, so as to realize the consistency of the two trajectories in the spline control point distribution structure.

[0024] The embodiment of the present application further provides a computer readable storage medium, which stores computer executable instructions, and the computer executable instructions are used for executing the method for realizing pose transition of a five-axis machine tool.

[0025] The embodiment of the present application further provides a computer device, which comprises a memory and a processor, wherein the memory stores instructions executable by the processor, and the instructions are used for executing the steps of the method for realizing pose transition of a five-axis machine tool.

[0026] The embodiment of the present application further provides a device for realizing pose transition of a five-axis machine tool, which comprises a decomposition module, a inflection point determination module, a selection processing module, a synchronous processing module and a construction module, wherein,

[0027] The decomposition module is used for decomposing a five-axis trajectory, converting each tool position into a tool tip point trajectory and a tool axis direction point trajectory, and the tool axis direction point has a distance length from the tool tip point.

[0028] The inflection point determination module is used for respectively detecting inflection points in the tool tip point trajectory and the tool axis direction point trajectory to determine the positions of the inflection points in the five-axis trajectory.

[0029] The selection processing module is used for determining the spline control parameters at each inflection point according to the trajectory with higher error control requirement between the tool tip point trajectory and the tool axis direction point trajectory.

[0030] The synchronous processing module is used for setting the tool tip point trajectory and the tool axis direction point trajectory synchronously based on the trajectory with higher error control requirement as a reference trajectory, so that the two trajectories are consistent in the spline control point distribution structure.

[0031] The construction module is used for respectively generating a tool tip point trajectory spline curve and a tool axis direction point trajectory spline curve according to the determined inflection point positions and control point information, and constructing a five-axis machine tool trajectory based on the two generated spline curves.

[0032] The method for realizing pose transition of a five-axis machine tool based on double splines provided by the embodiment of the present application adaptively selects the positions of the inflection points, fully considers the coupling problem of the tool tip and the tool axis direction, adaptively selects the spline control parameters, ensures the transition sufficiency based on the harsh trajectory, sets the synchronous control points of the two trajectories, improves the trajectory matching and pose coordination ability, realizes smooth and continuous pose transition in the five-axis machine tool, and ensures the transition quality and machining precision. The embodiment of the present application has good engineering feasibility, is suitable for fairing processing of various five-axis machining paths, and is especially suitable for machining of workpieces with complex curvature and attitude change.

[0033] Other features and advantages of the present application will be set forth in the following specification, and in part will be apparent from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings are included to provide a further understanding of the technical scheme of the application and constitute a part of the specification, which serve to explain the technical scheme of the application together with the embodiments of the application, and do not constitute a limitation on the technical scheme of the application.

[0035] Figure 1 A flowchart of a method for realizing pose transition of a five-axis machine tool in an embodiment of the application;

[0036] Figure 2 A trajectory schematic diagram of milling a quadrangular prism in an embodiment of the application;

[0037] Figure 3 A display schematic diagram of five-axis trajectory decomposition and inflection point position determination in an embodiment of the application;

[0038] Figure 4 A display schematic diagram of determining an inflection point in an embodiment of the application;

[0039] Figure 5 A schematic diagram of arranging control points around an inflection point in an embodiment of the application;

[0040] Figure 6 A local enlarged view of a three-dimensional path after a five-axis trajectory is subjected to spline transition processing in an embodiment of the application;

[0041] Figure 7 A schematic diagram of a typical five-axis hybrid machine tool structure;

[0042] Figure 8(a) is a schematic diagram of a whole trajectory comparison based on an Xw axis instruction in an embodiment of the application; Figure 7 A schematic diagram of a whole trajectory comparison by comparison of an Xw axis instruction;

[0043] Figure 8(b) is a local enlarged schematic diagram of figure 8(a) in an embodiment of the application;

[0044] Figure 9 A schematic diagram of a composition structure of a device for realizing pose transition of a five-axis machine tool in an embodiment of the application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the application more clear, the embodiments of the application will be described in detail below with reference to the drawings. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0046] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0048] It is understood that the terms "first" and "second" used in this application are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0049] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0050] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0051] The steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be performed in an order different from that shown here.

[0052] For the technical problem of position and attitude change in the trajectory transition process of five-axis machine tools, existing research attempts to make the attitude and position change simultaneously based on the position transition, so as to realize the smooth transition of the overall position and attitude. However, this method has certain limitations: in some cases, the position changes smoothly and does not need transition, but the attitude changes sharply and needs transition. Since this method completely depends on the position change for the attitude transition, it cannot effectively deal with the scene of smooth position and sudden attitude change, resulting in insufficient or discontinuous attitude transition. Some research attempts to represent the position and attitude as the positions of two space points (such as the tool position point and the tool axis direction point) respectively, and perform trajectory transition processing on the two points respectively. However, this method introduces new problems, such as how to keep the two point trajectories synchronized, how to determine the primary and secondary between the two points, and the coordination of the transition control logic of the two points, which will affect the transition quality and machining accuracy.

[0053] In order to realize smooth and continuous position and attitude transition and ensure the transition quality and machining accuracy, the embodiments of the present application provide a method for realizing position and attitude transition of a five-axis machine tool, as shown in Figure 1 , which can include:

[0054] Step 100: decompose the five-axis trajectory, convert each tool position point to a tool tip point trajectory and a tool axis direction point trajectory, and the tool axis direction point has a distance length from the tool tip point.

[0055] In the embodiments of the present application, the tool tip point (denoted as M point) represents the position of the tool at a certain time, and the tool axis direction point (denoted as N point) represents the attitude direction of the tool axis at that time. The tool axis direction point can be located at a position with a preset length from the tool tip point in the direction of the tool axis. Each tool position point j corresponds to a pair (M point, N point), that is: M j , N j .

[0056] In an exemplary example, the distance length is a characteristic length cl related to the machining characteristics of the current tool tip point (M point) trajectory in the current trajectory segment. The characteristic length cl can be calculated according to the average cutting depth a p of the M point trajectory in the current trajectory segment and the inclination angle a of the tool axis relative to the surface of the current trajectory segment. That is, the characteristic length cl is adaptively determined according to the local average cutting depth a p of the tool tip point trajectory and the tool axis inclination angle a. In an embodiment, In an embodiment, the position of the tool axis direction point can be calculated according to the following formula: N = M + Rcl, where N represents the coordinates (vector) of the tool axis direction point, M represents the coordinates (vector) of the tool tip point, and R represents the unit vector of the current tool axis direction (from M to the tool handle direction). That is, starting from the M point, along the current tool axis direction R, advancing a length of cl, the position of the attitude point N can be obtained.

[0057] As shown in the milling of a four-sided pyramid, the four sides of the four-sided pyramid have different inclination directions, i.e., each corner is a five-axis corner, as shown in FIG. 2, each thin straight line segment connects a pair of M points and N points, representing the pose vector at the tool position. All thin straight line segments are connected together to form the spatial pose trajectory (including position + attitude) of each tool position in the machining process. Figure 2 Figure 3 As shown in the milling of a four-sided pyramid, the four sides of the four-sided pyramid have different inclination directions, i.e., each corner is a five-axis corner, as shown in FIG. 2, each thin straight line segment connects a pair of M points and N points, representing the pose vector at the tool position. All thin straight line segments are connected together to form the spatial pose trajectory (including position + attitude) of each tool position in the machining process.

[0058] Step 101: Detecting the inflection points of the tool tip point trajectory and the tool axis direction point trajectory to determine the inflection point positions in the five-axis trajectory.

[0059] In an exemplary example, step 101 can include:

[0060] For each tool position j, the camber error is calculated respectively to check the continuity of the tool tip point (M point) trajectory and the continuity of the tool axis direction point (N point) trajectory corresponding to the tool position j.

[0061] If the camber error of the M point trajectory or the N point trajectory of the tool position j exceeds the preset threshold, it is determined that the tool position j is an inflection point.

[0062] In the embodiments of the present application, in order to identify the positions requiring transition processing in the five-axis trajectory, step 101 provides an implementation method for adaptive selection of inflection points. Step 101 mainly judges based on the geometric continuity of the tool tip point trajectory (M point trajectory) and the tool axis direction point trajectory (N point trajectory) to realize the unified processing of the coupled changes of position and attitude.

[0063] The M point trajectory and the N point trajectory before the transition are both composed of a series of discrete micro-segment trajectories, denoted as M1, M2, M3… and N1, N2, N3…, respectively, and each pair of M point and N point constitutes a tool position, for example, each tool position j corresponds to a pair of (M point, N point), i.e., M j , N j . For each tool position j, the M point trajectory and the N point trajectory corresponding thereto are detected respectively.

[0064] Taking the M point trajectory as an example, at the jth tool position, the two adjacent points M j-1 and M j+1 are selected, and a fitting circular arc is constructed through the three points. The maximum perpendicular distance δ1 between the straight line between M j-1 and M j and the circular arc is calculated, and the maximum perpendicular distance δ2 between M j and M j+1 is calculated. The maximum value of the two is taken as the camber error of the position, i.e., Similarly, the same method is used for the N point trajectory, and is calculated.

[0065] In the error judgment process, if the tool position j satisfies or That is, if the M-point trajectory or the N-point trajectory has a transition bow height error at the tool position j, then the j-th tool position is determined to be the inflection point. max Indicates the preset threshold (ie, error tolerance).

[0066] The detected inflection point position will be used as the key input for subsequent spline transition processing. Figure 2 As an example, the milling of the tetrahedron shown in the figure Figure 3 In the figure, all positions judged to be inflection points are marked with thick straight line segments. Figure 4 The geometric meaning of bow height error is illustrated, showing how to judge the continuity of trajectory by local arc fitting and straight line segment deviation evaluation. Figure 4 In the j-th tool position, a local arc is constructed and the maximum value is obtained after solving δ1 and δ2. Used to determine the inflection point position.

[0067] The embodiments of this application fully consider the synchronous changes in tool position and posture, enabling timely identification of inflection points when sudden changes occur in either direction, thus achieving coupled judgment of position and posture information. Compared to traditional methods that rely solely on the continuity of the tool tip trajectory for inflection point judgment, the embodiments of this application offer significant advantages in recognition accuracy and stability, avoiding the problems of missed or insufficiently processed sudden changes in posture, thereby improving trajectory transition quality and processing safety.

[0068] Step 102: For each inflection point, determine the spline control parameters at the inflection point according to the trajectory with higher error control requirements between the tool tip point trajectory and the tool axis direction point trajectory.

[0069] In one exemplary embodiment, step 102 may include:

[0070] At each inflection point, the spline control parameter range is calculated for the tool tip point trajectory (M-point trajectory) and the tool axis direction point trajectory (N-point trajectory) according to the local continuity requirements and error tolerance of the trajectory.

[0071] In one embodiment, the upper limit of the spline control parameter corresponding to each trajectory can be determined based on the calculated spline control parameter range; and the spline control parameter at the inflection point is set based on a trajectory with a smaller upper limit of the control point spacing.

[0072] In an exemplary embodiment, calculating a spline control parameter range based on the local continuity requirement and error tolerance of the trajectory and determining an upper limit of the spline control parameter may include:

[0073] At each inflection point (such as the jth point of the M-point trajectory), control points are arranged in front of and behind the inflection point along the trajectory direction, forming at least n+2 control points required for fitting the n-degree spline;

[0074] Based on the fitting error between the control point and the spline curve, as well as the changing characteristics of the trajectory direction before and after the control point, the maximum value range of the spline control parameters is determined to ensure fitting accuracy and trajectory continuity.

[0075] In one embodiment, determining the maximum value range of the spline control parameter may include:

[0076] Taking the central control point as the fitting point, the position deviation between the central control point and the spline curve fitting value is calculated as the error evaluation index;

[0077] Construct two direction vectors e1 and e2 before and after the control point, and calculate the value of the vector according to the preset threshold δ max The maximum allowable value of the distance between control points is determined by the constructed front-back direction vector;

[0078] The determined maximum allowed value is used as the upper limit of the spline control parameter l.

[0079] It should be noted that, in some embodiments, the control points can be arranged so that the spacing between adjacent control points is equal. In some embodiments, the control points can also be arranged so that the spacing between adjacent control points is not completely equal, that is, the distance between each segment can be different. These unequal spacings can be expressed based on the spline control parameter l. For example, assuming that 7 points are fitted, corresponding to 6 distance segments, the spacing can be 1, 1, 21, 21, 1, 1. It should be noted that other ratios are also possible and this application is not limited to this.

[0080] In a preferred embodiment, a quintic B-spline can be used as the trajectory fitting curve to obtain higher continuity and trajectory smoothing performance. It should be noted that, depending on actual processing requirements, a cubic, quartic or higher-order spline can also be used for fitting.

[0081] In this embodiment, after determining the inflection point, appropriate spline control parameters are set at each inflection point to achieve smooth transition fitting. Step 102 determines the spline control parameters for each inflection point based solely on the more restrictive trajectory of the tool tip point (the M-point trajectory) or the tool axis direction point (the N-point trajectory), thereby simplifying calculations and ensuring overall transition quality.

[0082] like Figure 5 As shown in the figure, assuming that the j-th inflection point of the M-point trajectory needs to be smoothed, taking the 5-order B-spline curve fitting as an example, at M j-1 to M jControl points P0, P1, P2 are arranged in the segment, and control point P3 is arranged at M j point itself, M j to M j+1 Control points P4, P5, P6 are arranged in the segment. For simplicity of description, the control points are arranged at equal intervals, and the interval is the spline control parameter l. Taking the M-point trajectory as an example, ‖P0P1‖ = ‖P1P2‖ = ‖P2P3‖ = ‖P3P4‖ = ‖P4P5‖ = ‖P5P6‖ = l P , which indicates that the control points P0, P1, P2, P3, P4, P5, P6 are arranged at equal intervals.

[0083] For the M-point trajectory and the N-point trajectory, the maximum fitting error ε usually occurs at the control point P3, that is, ε = P3-P(0.5). According to the given error tolerance, the corresponding spline control parameter range can be solved, such as the spline control parameter range l P of the M-point trajectory as shown in formula (1):

[0084]

[0085] In formula (1), e1 and e2 represent the two direction vectors (i.e., the direction vectors of adjacent spline control points) in front and back of the current inflection point in the M-point trajectory.

[0086] Similarly, the spline control parameter range l Q of the N-point trajectory can also be calculated according to formula (1), and at this time, e1 and e2 represent the two direction vectors (i.e., the direction vectors of adjacent spline control points) in front and back of the current inflection point in the N-point trajectory, which will not be described here.

[0087] On this basis, only the spline control parameter of the trajectory with more stringent error control is selected. If the selectable parameter range of the M-point trajectory at the inflection point is smaller (i.e., the accuracy requirement is higher), the spline control parameter is set based on the M-point trajectory; otherwise, the spline control parameter is set based on the N-point trajectory. For example: when j = j1, the spline control parameter range of the M-point trajectory is smaller, that is, l P < l Q , and only the spline parameter of the M-point is set. If j = j2, the spline control parameter range of the N-point trajectory is smaller, that is, l Q < l P , and only the spline parameter of the N-point is set. The optimal control strategy in the embodiment of the application avoids repeated calculation, and also ensures that the continuity requirement of the key trajectory is met.

[0088] Step 103: Taking the trajectory with more stringent error control as the reference trajectory, the tool tip point trajectory and the tool axis direction point trajectory are set synchronously to keep the consistency of the two trajectories in the spline control point distribution structure.

[0089] In an example, the synchronously setting the tool tip point trajectory and the tool axis direction point trajectory can include:

[0090] Setting the positions of the spline control points on a reference trajectory, which is a trajectory with higher error control requirement;

[0091] Synchronously setting the positions of the spline control points on another trajectory with the same proportional relationship as the reference trajectory, to achieve the consistency of the two trajectories in the spline control point distribution structure.

[0092] In an example, the same proportional relationship as the reference trajectory means that when arranging the spline control points on the non-reference trajectory, the relative distribution law (distance and position proportion) of the control points arranged on the reference trajectory is referred to, to ensure the synchronization of the two trajectories in the spline control point structure. That is, if the reference trajectory arranges 7 spline control points (such as the n+2 control points commonly used in B-spline), then the other trajectory also arranges 7 spline control points; if the distance between the control points on the reference trajectory is l P , then the spline control points are also arranged on the non-reference trajectory in a manner proportional to the length or spatial position of the trajectory, such as: on the reference trajectory, the spline control points extend from M1 to M7, the total distance along the length of the trajectory is L, and the average distance between the control points is l P =L / 6; then on the N point trajectory, N1 to N7 are also evenly divided, so that each segment has a distance of l q =L′ / 6. For example, assuming that the reference trajectory (such as the M point trajectory) extends from position A to position B with a total length of 6 mm and arranges 7 spline control points, and the non-reference trajectory (such as the N point trajectory) extends from position C to position D with a total length of 4.8 mm, then the spline control points arranged by the M point trajectory have a distance of 1 mm (uniform); the N point trajectory is also divided into 6 segments, but each segment is 0.8 mm, and the spline control point distance and segment structure are kept in synchronization with the M point trajectory.

[0093] The synchronously setting the tool tip point trajectory and the tool axis direction point trajectory by step 103 ensures the synchronous evolution of the spline curves in space. When the M point trajectory enters a curved segment, the N point trajectory also undergoes a posture transition at the same structural position, ensuring the overall coordination and smoothness of the entire five-axis trajectory (position + posture).

[0094] Step 104: generating a tool tip point trajectory spline curve and a tool axis direction point trajectory spline curve based on the determined inflection point positions and control point information, and constructing a five-axis machine tool trajectory based on the two generated spline curves.

[0095] In an example, step 104 can include:

[0096] For each inflection point identified in step 101, a B-spline curve is constructed on the M-point trajectory and the N-point trajectory respectively according to the control points arranged in step 103. The B-spline is used for transition smoothing, and the curve expression of the B-spline calculation method is shown in formula (2):

[0097]

[0098] In formula (2), u ∈ [0, 1] is a spline parameter, p i is a spline control point, N i,n (u) is a basis function, as shown in formula (3):

[0099]

[0100] The recursive definition of the basis function and the node vector U are configured according to specific continuity requirements, and the node vector U = [0 0 0 0 0 0.5 1 1 1 1 1 1]. Under the commonly used uniform node design, the high-order continuous smooth trajectory is obtained near the inflection point by interpolation or approximation.

[0101] After the transition paths of the M-point and the N-point are generated by the above-mentioned B-spline curves, the complete pose of each tool position is restored by using the two paths, that is, the tool tip position is obtained from the M-point, and the tool shaft attitude is restored from the vector composed of the M-point and the N-point, that is, the trajectory of the corresponding five-axis machine tool is constructed based on the two generated spline curves, so as to realize the overall continuous transition of the spatial position and direction.

[0102] The method for realizing pose transition of the five-axis machine tool provided by the embodiment of the present application adaptively selects the inflection point position, fully considers the coupling problem of the tool tip and the tool shaft direction, adaptively selects the spline control parameter, ensures the transition sufficiency based on the harsh trajectory, sets the synchronous control points of the double trajectories, improves the trajectory matching and pose coordination ability, realizes the smooth and continuous pose transition in the five-axis machine tool, and ensures the transition quality and machining precision. The embodiment of the present application has good engineering feasibility, is suitable for the smoothing processing of various five-axis machining paths, and is especially suitable for the machining of workpieces with complex curvature and attitude change.

[0103] In actual application, the embodiment of the present application generates a transition section at the inflection point, that is, a plurality of transition poses are taken at the inflection point, smooth transition is realized, and the trajectory is smoother. As Figure 6 shown, a local enlarged view of the five-axis trajectory after the spline transition processing is shown, which focuses on a corner position. It can be clearly seen from the figure that the original trajectory is obviously discontinuous between the points at the position, and the spline section smoothly connects the front and rear trajectory sections, realizes the transition, that is, the discontinuous inflection point in the original trajectory is replaced by the continuous spline section, and a plurality of smooth trajectory points are generated by interpolation in the region. From the figure, it can be seen that the original trajectory is discontinuous at the inflection point, and the spline section smoothly connects the front and rear trajectory sections, realizes the transition, that is, the discontinuous inflection point in the original trajectory is replaced by the continuous spline section, and a plurality of smooth trajectory points are generated by interpolation in the region.Figure 6 It can be seen that the trajectory transition curve generated in the embodiment of the application, i.e., the M-point and N-point trajectories generated by the double spline, maintains the pose continuity in space, i.e., the tool tip position and the tool axis pose are continuous at the same time, thereby improving the trajectory quality and the smoothness of the machine tool operation.

[0104] Figure 7 A typical five-axis hybrid machine tool structure is shown, as shown in Figure 7 which has three parallel swing angle heads and two linear feed shafts, and can realize high-precision five-axis machining of complex surfaces. In an embodiment, the five-axis hybrid machine tool structure shown in Figure 7 is used to verify the effectiveness of the method for realizing pose transition of the five-axis machine tool provided in the embodiment of the application. Figure 8(a) shows the actual effect of the trajectory fairing in the embodiment of the application by comparing the instructions of the Xw axis, and Figure 8(a) is a comparison diagram of the overall trajectory. The original trajectory and the trajectory after fairing have the same overall path, but the sudden change at the inflection point is smoothed. Figure 8(b) is a local enlarged view. It can be seen that there is an obvious peak change in the original trajectory, while the transition of the trajectory after fairing is smoother at this point, significantly improving the continuity and machinability of the trajectory, and effectively improving the smoothness and machining quality of the five-axis trajectory.

[0105] Through the intuitive verification of the fairing effect, the method for realizing pose transition of the five-axis machine tool provided in the embodiment of the application has the following advantages: the inflection point position is adaptively selected, fully considering the coupling problem of the tool tip and the tool axis direction; the spline control parameter is adaptively selected, ensuring the sufficiency of the transition based on the harsh trajectory; the double trajectory synchronous control point is set, improving the trajectory matching and pose coordination ability. The embodiment of the application has good engineering feasibility, is suitable for fairing processing of various five-axis machining paths, and is especially suitable for machining of workpieces with complex curvature and attitude change.

[0106] The application also provides a computer-readable storage medium storing computer-executable instructions for executing the method for realizing pose transition of the five-axis machine tool.

[0107] The application further provides a computer device including a memory and a processor, wherein the memory stores instructions executable by the processor, for executing the steps of the method for realizing pose transition of the five-axis machine tool.

[0108] The embodiment of the application also provides a device for realizing pose transition of a five-axis machine tool, as shown in Figure 9 which can include a decomposition module, an inflection point determination module, a selection processing module, a synchronization processing module, and a construction module; wherein,

[0109] a decomposition module configured to decompose the five-axis trajectory, convert each tool position to a tool tip point trajectory and a tool axis direction point trajectory, and have a distance length between the tool axis direction point and the tool tip point;

[0110] a turning point determination module configured to detect turning points in the tool tip point trajectory and the tool axis direction point trajectory respectively to determine turning point positions in the five-axis trajectory;

[0111] a selection processing module configured to determine, for each turning point, a spline control parameter at the turning point according to a trajectory with higher error control requirement between the tool tip point trajectory and the tool axis direction point trajectory;

[0112] a synchronization processing module configured to set the tool tip point trajectory and the tool axis direction point trajectory based on a reference trajectory with higher error control requirement, so that the two trajectories are consistent in spline control point distribution structure;

[0113] a construction module configured to generate a tool tip point trajectory spline curve and a tool axis direction point trajectory spline curve according to the determined turning point positions and control point information, and construct a five-axis machine tool trajectory based on the two generated spline curves.

[0114] In an exemplary example, the distance length is a characteristic length cl related to a machining characteristic of the current tool tip point (M point) trajectory in the current trajectory segment.

[0115] In an exemplary example, the turning point determination module can be configured to:

[0116] For each tool position j, the continuity of the tool tip point (M point) trajectory and the continuity of the tool axis direction point (N point) trajectory corresponding to the tool position j are calculated respectively based on the sag error; if the sag error of the M point trajectory or the N point trajectory of the tool position j exceeds a preset threshold, it is determined that the tool position j is a turning point.

[0117] In the embodiments of the present application, the synchronous changes of the tool position and attitude are fully considered, the turning points can be identified in time when any aspect suddenly changes, and the coupling judgment of the position and attitude information is realized. Compared with the traditional method of judging the turning points based on the continuity of the tool tip trajectory, the embodiments of the present application have obvious advantages in identification accuracy and stability, avoid the problems of missing attitude mutation or insufficient processing, and thus improve the trajectory transition quality and machining safety.

[0118] In an exemplary example, the selection processing module can be configured to:

[0119] At each inflection point, the spline control parameter range is calculated according to the local continuity requirement and error tolerance for the tool tip point trajectory (M point trajectory) and the tool axis direction point trajectory (N point trajectory) respectively. In an embodiment, the upper limit of the spline control parameter corresponding to each trajectory can be determined according to the calculated spline control parameter range; and the spline control parameter at the inflection point is set according to the smaller one of the upper limit of the control point spacing.

[0120] In the embodiments of the present application, for each inflection point, the spline control parameter is determined only according to the more stringent one of the tool tip point trajectory (M point trajectory) and the tool axis direction point trajectory (N point trajectory), so that the calculation is simplified and the overall transition quality is ensured.

[0121] In an exemplary instance, the synchronization processing module can be configured to:

[0122] The position of the spline control point on the reference trajectory is set according to the trajectory with higher error control requirement; and the position of the spline control point on the other trajectory is set in the same proportional relationship as the reference trajectory, so as to realize the consistency of the two trajectories in the spline control point distribution structure.

[0123] The synchronization processing module is used to synchronize the tool tip point trajectory and the tool axis direction point trajectory, so as to ensure the synchronization evolution of the spline curve in space. When the M point trajectory enters a curved section, the N point trajectory also has a posture transition at the same structure position, so as to ensure the overall coordination and smoothness of the whole five-axis trajectory (position + posture).

[0124] The device for realizing the position and posture transition of the five-axis machine tool provided in the embodiments of the present application has the adaptive selection of the inflection point position, fully considers the coupling problem of the tool tip and the tool axis direction, has the adaptive selection of the spline control parameter, ensures the transition sufficiency according to the stringent trajectory as the reference, has the synchronization control point setting of the two trajectories, improves the trajectory matching and posture coordination capability, realizes the smooth and continuous position and posture transition in the five-axis machine tool, and ensures the transition quality and machining precision. The embodiments of the present application have good engineering feasibility, are suitable for the fairing processing of various five-axis machining paths, and are especially suitable for the machining of workpieces with complex curvature and posture changes.

[0125] Although the embodiments disclosed in the present application are as above, the content described above is only the embodiments adopted for the convenience of understanding the present application, and is not used to limit the present application. Any person skilled in the art of the present application can make any modification and change in the implementation form and details without departing from the spirit and scope of the present application, but the patent protection scope of the present application should be subject to the scope defined by the appended claims.

Claims

1. A method for achieving posture transition of a five-axis machine tool, characterized in that: include: Decompose the five-axis trajectory and convert each tool position into a tool tip point trajectory and a tool axis direction point trajectory. There is a distance between the tool axis direction point and the tool tip point. Perform inflection point detection on the tool tip point trajectory and tool axis direction point trajectory respectively to determine the inflection point position in the five-axis trajectory; For each inflection point, the spline control parameters at the inflection point are determined based on the trajectory with higher error control requirements between the tool tip point trajectory and the tool axis direction point trajectory; Taking a trajectory with higher error control requirements as the reference trajectory, the tool tip point trajectory and the tool axis direction point trajectory are synchronized so that the two trajectories are consistent in the spline control point distribution structure; According to the determined inflection point position and control point information, the tool tip point trajectory spline curve and the tool axis direction point trajectory spline curve are generated respectively, and the trajectory of the five-axis machine tool is constructed based on the two generated spline curves.

2. The method according to claim 1, wherein The distance length is a characteristic length cl related to the processing characteristics of the current tool tip point trajectory in the current trajectory segment. The characteristic length cl is calculated based on the average cutting depth of the tool tip point trajectory in the current trajectory segment and the inclination angle of the tool axis relative to the surface of the current trajectory segment.

3. The method according to claim 1, wherein The inflection point detection of the tool tip point trajectory and the tool axis direction point trajectory respectively includes: For each tool position point, the bow height error is calculated respectively, and the continuity of the tool tip point trajectory and the tool axis direction point trajectory corresponding to the tool position point are checked; If the bow height error of the tool tip point trajectory or the tool axis direction point trajectory of the tool position point exceeds a preset threshold, the tool position point is determined to be an inflection point.

4. The method according to claim 1, wherein For each inflection point, the spline control parameters at the inflection point are determined according to the trajectory with higher error control requirements between the tool tip point trajectory and the tool axis direction point trajectory, including: At each inflection point, the spline control parameter range is calculated for the tool tip point trajectory and the tool axis direction point trajectory respectively according to the local continuity requirement and error tolerance of the trajectory.

5. The method according to claim 4, wherein The calculation of the spline control parameter range based on the local continuity requirement and error tolerance of the trajectory and the determination of the upper limit of the control point spacing include: At each inflection point, control points are arranged in front of and behind the inflection point along the trajectory direction, with the inflection point as the center, to form at least n+2 control points required for fitting the n-degree spline; Based on the fitting error between the control point and the spline curve, and the changing characteristics of the trajectory direction before and after the control point, the maximum value range of the spline control parameter is determined.

6. The method according to claim 5, wherein: The fitting is performed using a quintic B-spline as a trajectory fitting curve.

7. The method according to claim 1, wherein The synchronous setting of the tool tip point trajectory and the tool axis direction point trajectory includes: Taking a trajectory with a smaller upper limit of the spline control parameter as a reference trajectory, setting the position of the spline control point on the reference trajectory; The positions of the spline control points on the other trajectory are synchronously set using the same proportional relationship as the reference trajectory to achieve consistency in the distribution structure of the spline control points of the two trajectories.

8. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method for achieving posture transition of a five-axis machine tool according to any one of claims 1 to 7.

9. A computer device comprising a memory and a processor, wherein: The memory stores the following instructions that can be executed by the processor: used to execute the steps of the method for achieving posture transition of a five-axis machine tool as described in any one of claims 1-7.

10. A device for realizing posture transition of a five-axis machine tool, characterized in that: include: Decomposition module, inflection point determination module, selection processing module, synchronization processing module, construction module; wherein, A decomposition module is used to decompose the five-axis trajectory and convert each tool position into a tool tip point trajectory and a tool axis direction point trajectory, where there is a distance between the tool axis direction point and the tool tip point; An inflection point determination module is used to perform inflection point detection on the tool tip point trajectory and the tool axis direction point trajectory respectively to determine the inflection point position in the five-axis trajectory; A selection processing module is used to determine, for each inflection point, a spline control parameter at the inflection point according to a trajectory with a higher error control requirement between the tool tip point trajectory and the tool axis direction point trajectory; A synchronization processing module is used to synchronize the tool tip point trajectory and the tool axis direction point trajectory using a trajectory with higher error control requirements as the reference trajectory, so that the two trajectories are consistent in the spline control point distribution structure; The construction module is used to generate a tool tip point trajectory spline curve and a tool axis direction point trajectory spline curve according to the determined inflection point position and control point information, and construct the trajectory of the five-axis machine tool based on the two generated spline curves.

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