A method, system, device, and storage medium for multi-axis trajectory planning and interpolation consistency control based on Z-axis feed contribution weight.

Abstract

This invention discloses a multi-axis trajectory planning and interpolation consistency control method, system, device, and storage medium based on Z-axis feed contribution weight, belonging to the field of multi-axis linkage CNC machining technology. The invention first acquires trajectory coordinates, attitude angles, feed speed, and interpolation cycle; calculates the displacement increment of each axis in the current interpolation segment and determines the Z-axis feed contribution weight ω_z; based on this weight, multi-axis speed allocation is performed and Z-axis priority constraints are applied, achieving synchronous interpolation between axes within the interpolation cycle. Simultaneously, the synchronization effect is evaluated in real-time using the interpolation consistency index E_cons; through contour error closed-loop feedback, the weight and speed commands are adaptively corrected, solving the problems of unquantified Z-axis contribution, poor interpolation synchronization, insufficient high-speed machining accuracy, and insufficient disclosure in existing technologies. This invention can significantly improve contour accuracy, interpolation consistency, and machining stability, and is suitable for high-precision and high-efficiency machining of complex curved surfaces in five-axis linkage.

Description

Technical Field

[0001] This invention belongs to the field of multi-axis linkage CNC machining technology, specifically relating to a multi-axis trajectory planning and interpolation consistency control method, system, equipment and storage medium based on Z-axis feed contribution weight for high-speed, high-precision complex surface machining. Background Technology

[0002] Multi-axis CNC machining is a core method for manufacturing complex curved surface parts such as aerospace, precision molds, and impeller blades. Trajectory planning and interpolation control directly determine the machining contour accuracy, surface quality, motion stability, and machining efficiency. The Z-axis is responsible for cutting depth, sudden load changes, and normal attitude correction, and its dynamic response and interpolation synchronization are key to machining quality.

[0003] However, the existing technology has the following technical defects:

[0004] It is impossible to simultaneously achieve both "feed stability of XY-dominated process" and "true length expression of Z-dominated motion".

[0005] The inability to maintain the same set of feed semantics across the three levels of geometry construction, velocity planning, and interpolation output results in inconsistencies between planning and execution outcomes.

[0006] The inability to manage Z-axis participation as a segment-level modal parameter results in local strategies in hybrid process paths not being able to take effect independently.

[0007] In extreme cases, such as when the user sets the weight to 0 and the path segment is mainly composed of Z displacements, significant distortions in length, speed, and time estimations can easily occur. Summary of the Invention

[0008] To address the current limitations of existing technologies in simultaneously ensuring both "feed stability in XY-dominated processes" and "true length representation of Z-dominated motion," it's crucial to understand how they fail to maintain a consistent set of feed semantics across geometry construction, velocity planning, and interpolation output, leading to inconsistencies between planning and execution results. Furthermore, the inability to manage Z-axis participation as a segment-level modal parameter prevents local strategies in hybrid process paths from taking effect independently. In extreme cases, such as when the user sets the weight to 0 and the path segment primarily consists of Z-displacements, significant distortions in length, velocity, and time estimations can easily occur.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight, characterized in that it includes:

[0011] S1: Obtain multi-axis machining trajectory parameters, including trajectory point coordinates, attitude angle, commanded feed rate v_cmd, and interpolation cycle T;

[0012] S2: Calculate the increments Δx, Δy, Δz, ΔA, and ΔC for each axis in the current interpolation segment, and calculate the Z-axis feed contribution weight according to the formula:

[0013] ω_z = |Δz| / (|Δx| + |Δy| + |Δz| + |ΔA| + |ΔC|);

[0014] S3: Perform multi-axis velocity allocation based on ω_z, apply priority velocity constraints to the Z-axis, and generate reference velocities v for each axis. x 、vᵧ、v_z、v_A、v_C;

[0015] S4: Perform multi-axis synchronous interpolation within the interpolation period T to ensure that the position increment synchronization and interpolation consistency are maintained.

[0016] S5: Real-time detection of contour error e, using the error as feedback to adaptively correct ω_z and speed commands.

[0017] As a further aspect of the present invention, the multi-axis synthesis speed in S3 satisfies:

[0018] v = √(v x ² + vᵧ² + v_z² + (k_A・v_A)² + (k_C・v_C)²) ≤ v_limit;

[0019] Where k_A and k_C are the equivalent conversion coefficients from the rotation axis to the linear axis, and v_limit is the upper limit of the synthesis velocity.

[0020] As a further aspect of the present invention, the Z-axis priority constraint in S3 is:

[0021] v_z = ω_z・v_limit;

[0022] The remaining velocity is allocated to the XY axes: v_xy = (1−ω_z)・v_limit・k_xy, where k_xy is the XY axis allocation coefficient.

[0023] As a further aspect of this invention, the interpolation consistency in S4 is evaluated using the index E_cons:

[0024] E_cons = max (|e x |,|eᵧ|,|e_z|) / T;

[0025] Control E_cons to be less than or equal to a preset threshold to ensure inter-axis synchronization.

[0026] As a further aspect of the present invention, the error feedback correction rule in S5 is as follows:

[0027] When the contour error e > e0, increase ω_z; when e < e1, decrease ω_z; e0 is the upper limit threshold of the error, and e1 is the lower limit threshold of the error.

[0028] As a further aspect of the present invention, look-ahead preprocessing is also included:

[0029] Pre-calculate the ω_z sequence for N consecutive interpolation segments and apply acceleration / deceleration constraints in advance.

[0030] As a further aspect of the present invention, a multi-axis trajectory planning and interpolation consistency control system based on Z-axis feed contribution weight includes:

[0031] The parameter acquisition module, weight calculation module, speed allocation module, synchronous interpolation module, and error feedback module are used to execute the method described in any one of claims 1-6.

[0032] As a further aspect of the present invention, a multi-axis CNC device includes a processor and a memory. The memory stores a program, and the processor executes the program to implement a multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight.

[0033] As a further aspect of the present invention, a computer-readable storage medium is provided for storing a computer program, which, when executed, implements the method described in any one of claims 1-6.

[0034] As a further aspect of the present invention, ω_z is normalized to [0,1]. The higher the Z-axis feed ratio, the larger ω_z is, and the higher the accuracy priority.

[0035] The beneficial effects of this invention are:

[0036] With configurable Z-axis feed contribution weights, it is possible to flexibly express various process semantics such as XY dominance, three-dimensional equalization, and partial Z compensation.

[0037] The protection mechanism of automatically restoring standard three-dimensional weights through the Z-dominant segment avoids zero-length segments, velocity distortion, and time estimation distortion.

[0038] By using a segmented modal snapshot mechanism, different Z weights can be applied to different path segments to meet the requirements of composite process paths.

[0039] By implementing a consistency algorithm synchronously in the geometry construction layer, velocity planning layer, and interpolation output layer, the consistency between the "defined feed semantics" and the "executed velocity semantics" is ensured.

[0040] It is applicable to various geometric segments such as straight lines, spirals, splines, Akima, and quintic curves, and has good versatility and engineering feasibility.

[0041] It is largely transparent to the underlying actuators, requires no modification to the drive-side protocol, and is easy to integrate and deploy in existing control systems. Attached Figure Description

[0042] The invention will now be further described with reference to the accompanying drawings.

[0043] Figure 1. Overall flowchart of the present invention;

[0044] Figure 2. Schematic diagram of segmented modal snapshots of Z-axis feed weights;

[0045] Figure 3. Schematic diagram of weighted arc length and effective weight protection mechanism;

[0046] Figure 4. Schematic diagram of constraint scaling in velocity planning layer;

[0047] Figure 5. Schematic diagram of tangential correction for interpolation output layer;

[0048] Figure 6 shows a schematic diagram of the application scenario. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are intended to fully disclose the technical solutions of the present invention, enabling those skilled in the art to implement the present invention, and are not intended to limit the scope of protection of the present invention.

[0050] Example 1: Five-axis linkage mold surface finishing

[0051] Equipment and parameters

[0052] Machine tool type: XYZAC five-axis linkage machining center

[0053] Interpolation period: T = 1 ms

[0054] Commanded feed rate: v_cmd = 5 m / min

[0055] Speed ​​limit: v_limit = 6 m / min

[0056] Equivalent coefficients for the rotation axis: kA = 0.02 mm / °, kC = 0.02 mm / °

[0057] Error thresholds: e0 = 0.01 mm, e1 = 0.003 mm

[0058] Control steps

[0059] Read the coordinates (X,Y,Z,A,C) of the trajectory points;

[0060] Calculate the increments Δx, Δy, Δz, ΔA, and ΔC for each axis;

[0061] Calculate the Z-axis weight:

[0062] ω_z = |Δz| / (|Δx|+|Δy|+|Δz|+|ΔA|+|ΔC|)

[0063] Speed ​​is allocated according to ω_z: v_z = ω_z・v_limit;

[0064] Interpolation is performed based on the synthesis rate constraint;

[0065] Calculate the consistency index E_cons = max (|ex|,|ey|,|ez|) / T;

[0066] Real-time error feedback, dynamically adjusting ω_z.

[0067] Effect

[0068] Contour accuracy: ±0.005 mm

[0069] Surface roughness: Ra ≤ 0.8 μm

[0070] Interpolation consistency error: ≤ 0.5 μm / ms

[0071] No vibration, no knife marks.

[0072] Example 2: Side milling of aerospace aluminum alloy structural parts

[0073] Equipment and parameters

[0074] Machine tool: XYZBC five-axis machine tool

[0075] Interpolation period: T = 1 ms

[0076] Feed rate: v_cmd = 8 m / min

[0077] Equivalent coefficients: kB = 0.015 mm / °, kC = 0.015 mm / °

[0078] Error thresholds: e0 = 0.012 mm, e1 = 0.004 mm

[0079] Control steps

[0080] Similar to Example 1, a look-ahead N=20 segments of pre-calculated ω_z sequence are used to advance acceleration and deceleration constraints.

[0081] Effect

[0082] Contour accuracy improved by 25%.

[0083] Processing efficiency improved by 10%.

[0084] No loss of footing or shaking at high speeds.

[0085] Example 3: Machining of Complex Curved Surfaces Like Blades with Changed Posture

[0086] Equipment and parameters

[0087] Machine tool: Five-axis blade special machine tool

[0088] Interpolation period: T = 0.5 ms

[0089] Feed rate: v_cmd = 3 m / min

[0090] The key is to ensure the accuracy of the Z-axis normal feed.

[0091] Control steps

[0092] Calculate the Z-axis contribution percentage based on the normal vector;

[0093] The Z-axis velocity weight is forcibly increased in the high ω_z segment;

[0094] Strictly limit E_cons ≤ 0.4 μm / ms.

[0095] Effect

[0096] Blade profile accuracy: ±0.003 mm

[0097] No tool marks were found across the entire stance phase.

[0098] Example 4: Heavy cutting machining of high-rigidity mold steel

[0099] Equipment and parameters

[0100] Machine tool: Heavy-duty five-axis machining center

[0101] Interpolation period: T = 1 ms

[0102] Feed rate: v_cmd = 2 m / min

[0103] The load fluctuates greatly, and the Z-axis experiences significant stress.

[0104] Control steps

[0105] Real-time acquisition of Z-axis load;

[0106] ω_z is automatically increased when the load increases to enhance stability;

[0107] Consistency index E_cons is used for real-time closed-loop control.

[0108] Effect

[0109] Cutting vibration reduced by 30%.

[0110] Dimensional stability improved by 40%.

[0111] Tool life is extended.

[0112] Comparative example (existing technology: fixed weights)

[0113] The conditions are exactly the same as in Examples 1–4;

[0114] A fixed weight ω_z = 0.2 is used;

[0115] No real-time adaptive designation, no Z-axis priority allocation;

[0116] result:

[0117] The contour error is 3 times greater;

[0118] Poor interpolation consistency;

[0119] Significant vibration and poor surface quality;

[0120] It is prone to exceeding tolerances under high-speed / variable posture / heavy cutting conditions.

[0121] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight, characterized in that, include: S1: Obtain multi-axis machining trajectory parameters, including trajectory point coordinates, attitude angle, commanded feed rate v_cmd, and interpolation cycle T; S2: Calculate the increments Δx, Δy, Δz, ΔA, and ΔC for each axis in the current interpolation segment, and calculate the Z-axis feed contribution weight according to the formula: ω_z = |Δz| / (|Δx| + |Δy| + |Δz| + |ΔA| + |ΔC|); S3: Perform multi-axis velocity allocation based on ω_z, apply priority velocity constraints to the Z-axis, and generate reference velocities v for each axis. x 、vᵧ、v_z、v_A、v_C; S4: Perform multi-axis synchronous interpolation within the interpolation period T to ensure that the position increment synchronization and interpolation consistency are maintained. S5: Real-time detection of contour error e, using the error as feedback to adaptively correct ω_z and speed commands.

2. The multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight according to claim 1, characterized in that, The multi-axis synthesis speed in S3 satisfies: v = √(v x ² + vᵧ² + v_z² + (k_A・v_A)² + (k_C・v_C)²) ≤ v_limit; Where k_A and k_C are the equivalent conversion coefficients from the rotation axis to the linear axis, and v_limit is the upper limit of the synthesis velocity.

3. The multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight according to claim 1, characterized in that, The priority constraint for the Z-axis in S3 is: v_z = ω_z・v_limit; The remaining velocity is allocated to the XY axes: v_xy = (1−ω_z)・v_limit・k_xy, where k_xy is the XY axis allocation coefficient.

4. The multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight according to claim 1, characterized in that, In S4, interpolation consistency is evaluated using the metric E_cons. E_cons = max (|e x |,|eᵧ|,|e_z|) / T; Control E_cons to be less than or equal to a preset threshold to ensure inter-axis synchronization.

5. The multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight according to claim 1, characterized in that, The error feedback correction rule for S5 is as follows: When the contour error e > e0, increase ω_z; when e < e1, decrease ω_z; e0 is the upper limit threshold of the error, and e1 is the lower limit threshold of the error.

6. The multi-axis trajectory planning and interpolation consistency control method based on Z-axis feed contribution weight according to claim 1, characterized in that, It also includes prospective preprocessing: Pre-calculate the ω_z sequence for N consecutive interpolation segments and apply acceleration / deceleration constraints in advance.

7. A multi-axis trajectory planning and interpolation consistency control system based on Z-axis feed contribution weight, characterized in that, include: The parameter acquisition module, weight calculation module, speed allocation module, synchronous interpolation module, and error feedback module are used to execute the method described in any one of claims 1-6.

8. A multi-axis CNC machine, characterized in that, It includes a processor and a memory, the memory stores a program, and the processor executes the program to implement the method of any one of claims 1-6.

9. A computer-readable storage medium for storing a computer program, characterized in that, When the program is executed, it implements the method described in any one of claims 1-6.

10. The method according to claim 1, characterized in that, ω_z is normalized to [0,1]. The higher the proportion of Z-axis feed, the larger ω_z is, and the higher the precision priority.

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