Five-axis linkage numerical control machining precision control system and method

Abstract

The invention relates to the technical field of numerical control machining, and discloses a five-axis linkage numerical control machining precision control system and method.The method comprises the steps that program segment pose synchronous analysis and adjacent program segment pose change prediction are conducted on a five-axis numerical control machining instruction, and pose synchronous error data are obtained; performing program segment length adjustment and bimodal weight distribution to obtain an expected movement track of cooperation of the tool center point and the non-tool center point; and a servo control signal is generated according to the expected movement track, and the servo control signal is output to a five-axis linkage machine tool to execute tool center point and non-tool center point cooperative precision machining. According to the method, the program segment length is dynamically optimized according to actual machining requirements on the basis of a self-adaptive program segment length adjusting mechanism of the pose change sensitivity coefficient, the limitation that the traditional fixed program segment length cannot adapt to complex geometrical characteristics is overcome, and the machining efficiency is considered while the machining precision is improved; therefore, the numerical stability of attitude control is improved.

Description

Technical Field

[0001] This invention relates to the field of CNC machining technology, and in particular to a five-axis linkage CNC machining accuracy control system and method. Background Technology

[0002] Traditional five-axis CNC machining faces the technical challenge of abrupt pose changes at program segment transitions when handling complex curved surfaces. These abrupt changes lead to discontinuous tool paths, severely impacting surface quality and machining accuracy. Existing technologies typically employ a single control mode, either based on the tool center point (TCP) or non-TCP, failing to dynamically switch and optimize based on actual machining requirements. When machining minute program segments, fixed segment lengths often cannot adapt to the geometric variations of complex surfaces, resulting in difficulties in chord error control and decreased trajectory tracking accuracy. Summary of the Invention

[0003] This invention provides a five-axis linkage CNC machining accuracy control system and method. The adaptive program segment length adjustment mechanism based on the pose change sensitivity coefficient dynamically optimizes the program segment length according to the actual machining requirements, overcoming the limitation of the traditional fixed program segment length being unable to adapt to complex geometric features. It improves machining accuracy while taking into account machining efficiency, thereby improving the numerical stability of posture control.

[0004] In a first aspect, the present invention provides a method for controlling the accuracy of five-axis linkage CNC machining, the method comprising: The pose synchronization of the five-axis CNC machining command is analyzed to obtain the pose synchronization kinematic parameters, and the pose change of adjacent program segments is predicted based on the pose synchronization kinematic parameters to obtain the pose synchronization error data. Based on the pose synchronization error data, the program segment length is adjusted to obtain the target program segment parameters, and the target program segment parameters are weighted in a dual-modal manner to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. Based on the desired motion trajectory, dual-modal quaternion sliding mode control is performed to obtain a servo control signal, and the servo control signal is output to a five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point.

[0005] In conjunction with the first aspect, in a first implementation of the first aspect of the present invention, the step of performing program segment pose synchronization analysis on the five-axis CNC machining instructions to obtain pose synchronization kinematic parameters, and predicting pose changes between adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data, includes: A coordinate transformation matrix is ​​established based on the origin of the program segment coordinate system, using five-axis CNC machining instructions as the reference. Based on the coordinate transformation matrix, the tool motion information within the program segment is separated into poses to obtain the displacement vector of the tool center point and the quaternion of the non-tool center point pose. Based on the coupled kinematic modeling of the displacement vector of the tool center point and the quaternion of the non-tool center point attitude, a set of kinematic equations is obtained. Based on the kinematic equations, the five-axis joint angles and pose parameters are synchronously mapped to obtain the pose synchronization kinematic parameters. Based on the pose synchronization kinematic parameters, pose changes between adjacent program segments are predicted to obtain pose synchronization error data.

[0006] In conjunction with the first aspect, in a second implementation of the first aspect of the present invention, the coupled kinematic modeling based on the displacement vector of the tool center point and the quaternion of the non-tool center point attitude to obtain a set of kinematic equations includes: The non-tool center point orientation quaternion is transformed by rotation matrix to obtain a three-dimensional rotation matrix, and the displacement transformation vector between program segments is calculated based on the tool center point displacement vector and the preset program segment length. A homogeneous transformation is performed on the three-dimensional rotation matrix and the displacement transformation vector between the program segments to obtain the pose transformation matrix. Based on the pose transformation matrix and the five-axis joint angle variables, a set of kinematic equations relating pose to program segments is established.

[0007] In conjunction with the first aspect, in a third implementation of the first aspect of the present invention, the step of predicting pose changes between adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data includes: Based on the pose synchronization kinematic parameters, calculate the tool center point position prediction component and the non-tool center point pose prediction component; The TCP position error between the actual and expected positions of the tool center point is calculated based on the tool center point position prediction component, and the non-TCP attitude error between the actual and expected attitudes of the non-tool center point is calculated based on the non-tool center point attitude prediction component. Calculate the pose synchronization time error when switching between tool center point control mode and non-tool center point control mode based on the TCP position error and the non-TCP posture error; The pose synchronization error data is obtained by performing a square root operation on the TCP position error, the non-TCP attitude error, and the pose synchronization time error.

[0008] In conjunction with the first aspect, in the fourth implementation of the first aspect of the present invention, the step of adjusting the program segment length based on the pose synchronization error data to obtain target program segment parameters, and then performing dual-modal weight allocation on the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center points, includes: Based on the pose synchronization error data, extract the five-axis joint angle change between adjacent program segments and calculate the maximum pose change between program segments. The product of the maximum attitude change and the attitude change sensitivity coefficient is added to the preset program segment length to obtain the first program segment length. The error adjustment factor is calculated based on the pose synchronization error data and the preset error threshold, and the error adjustment factor is multiplied by the length of the first program segment to obtain the length of the second program segment; The chord error compensation amount is calculated based on the length of the second program segment and the radius of curvature of the machining trajectory, and the coordinates of the endpoints of the program segment of the second program segment length are geometrically corrected based on the chord error compensation amount to obtain the target program segment parameters; Generate the desired motion trajectory of the tool center point and non-tool center points in coordination based on the target program segment parameters.

[0009] In conjunction with the first aspect, in a fifth implementation of the first aspect of the present invention, the step of generating the desired motion trajectory of the tool center point and non-tool center points in coordination with the target program segment parameters includes: Calculate the tool center point weight component and the non-tool center point weight component based on the pose synchronization error data and the weight balance point error value; Based on the target program segment parameters, the TCP control mode reference trajectory for the tool center point control mode and the non-TCP control mode reference trajectory for the non-tool center point control mode are constructed respectively. The fused motion trajectory is obtained by multiplying the tool center point weight component with the TCP control mode reference trajectory and then adding the product of the non-tool center point weight component and the non-TCP control mode reference trajectory. Cubic spline interpolation is performed on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points working together.

[0010] In conjunction with the first aspect, in a sixth implementation of the first aspect of the present invention, the step of performing cubic spline interpolation on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points collaboratively includes: Based on the boundary conditions for the continuity of position, velocity and acceleration of the fused motion trajectory, a set of cubic spline interpolation constraint equations is constructed. Based on the set of cubic spline interpolation constraint equations, establish the positional first derivative continuity and second derivative continuity constraints at the junction of adjacent program segments, and obtain the spline continuity coefficient matrix; The cubic spline interpolation coefficients between each program segment are obtained by solving the spline continuity coefficient matrix. Based on the cubic spline interpolation coefficients, the fused motion trajectory is reconstructed using a cubic polynomial to obtain the desired motion trajectory of the tool center point and non-tool center points working together.

[0011] In conjunction with the first aspect, in the seventh implementation of the first aspect of the present invention, the step of performing dual-modal quaternion sliding mode control based on the desired motion trajectory to obtain a servo control signal, and outputting the servo control signal to a five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point, includes: The desired motion trajectory is subjected to quaternion transformation to obtain a quaternion transformation matrix; Based on the desired motion trajectory and the pose state of the five-axis linkage machine tool, the TCP position deviation and non-TCP attitude deviation are calculated respectively. The TCP position deviation and the non-TCP attitude deviation and their integral terms are combined to establish the bimodal sliding surface equation. Design a quaternion sliding mode control law based on the bimodal sliding surface equation; The quaternion sliding mode control law is inversely mapped through the quaternion transformation matrix to obtain the servo control signal, and the servo control signal is output to the five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point.

[0012] In conjunction with the first aspect, in the eighth implementation of the first aspect of the present invention, the step of designing a quaternion sliding mode control law based on the bimodal sliding surface equation includes: Based on the dual-mode sliding surface equation and the position and acceleration information of the desired motion trajectory, inverse dynamics calculation is performed to obtain the equivalent control components. The sign function control term and the proportional control term are calculated based on the bimodal sliding surface equation, and the negative values ​​of the sign function control term and the proportional control term are added together to obtain the switching control component. The predictive control component is obtained by multiplying the program segment pose synchronization prediction information with the predictive control gain. The equivalent control component, the switching control component, and the predictive control component are vector-added to obtain the quaternion sliding mode control law.

[0013] Secondly, the present invention provides a five-axis linkage CNC machining accuracy control system, the five-axis linkage CNC machining accuracy control system comprising: The pose change prediction module is used to perform program segment pose synchronization parsing on five-axis CNC machining instructions to obtain pose synchronization kinematic parameters, and to predict the pose change of adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data. The program segment length adjustment module is used to adjust the program segment length based on the pose synchronization error data, obtain the target program segment parameters, and perform dual-modal weight allocation on the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. The collaborative precision machining module is used to perform dual-modal quaternion sliding mode control according to the desired motion trajectory, obtain servo control signals, and output the servo control signals to a five-axis linkage machine tool to perform collaborative precision machining of the tool center point and non-tool center point.

[0014] The technical solution provided by this invention establishes a program segment pose synchronization prediction mechanism, which can accurately predict the pose change pattern between adjacent program segments, effectively solving the technical problem that traditional methods cannot predict pose abrupt changes at program segment connections. An adaptive program segment length adjustment mechanism based on the pose change sensitivity coefficient dynamically optimizes the program segment length according to actual machining requirements, overcoming the limitation of traditional fixed program segment lengths being unable to adapt to complex geometric features, thus improving machining accuracy while also considering machining efficiency. A dual-modal weight allocation mechanism enables intelligent switching and collaborative operation between the tool center point control mode and the non-tool center point control mode, ensuring smooth control mode switching through an S-shaped smooth transition function. The use of a quaternion sliding mode control law avoids the singularity problem of traditional Euler angle representation, improving the numerical stability of attitude control.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an embodiment of the five-axis linkage CNC machining accuracy control method of the present invention; Figure 2 This is a schematic diagram of an embodiment of the five-axis linkage CNC machining accuracy control system of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0020] To facilitate understanding of this embodiment, a detailed description of a five-axis linkage CNC machining accuracy control method disclosed in this embodiment of the invention will be provided first. For example... Figure 1 As shown, this method includes the following steps: 101. Perform program segment pose synchronization analysis on the five-axis CNC machining instructions to obtain pose synchronization kinematic parameters, and predict the pose change of adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data. In this embodiment, based on the trajectory planning data and attitude control information contained in the five-axis CNC machining instructions, a homogeneous coordinate transformation matrix is ​​constructed for each program segment, with the origin of the program segment coordinate system as the reference. The homogeneous coordinate transformation matrix adopts an improved DH modeling method, using the local coordinate system origin of the program segment as the reference frame, and combining the direction vector of the tool motion path, the cutting point position information, and the machining segment time parameters to construct a rotation matrix and a displacement vector, forming a unified transformation relationship. Based on the established coordinate transformation, the tool motion data within the program segment is subjected to pose separation processing. The coupled linear movement and rotation axis attitude information in the CNC instructions are extracted as a three-dimensional displacement vector of the tool center point and an attitude quaternion of the non-tool center point, respectively. Based on the tool center point displacement vector and attitude quaternion, a coupled kinematic equation system is constructed. The kinematic model also incorporates the program segment execution time, segment length, and five-axis joint angle vectors, realizing the coupled expression of the tool center point control channel and the non-tool center point control channel in the homogeneous transformation structure, forming a time-varying pose constraint model that considers the continuity and temporal sequence between program segments. Based on the kinematic modeling results, the obtained displacement vectors and attitude quaternions are synchronously mapped to specific five-axis joint angle outputs and pose state parameters within the program segment through a reverse solving and parameter mapping mechanism, thus obtaining the pose synchronization kinematic description. Combining the pose synchronization kinematic parameters, a program segment pose synchronization prediction model is constructed to prospectively estimate the attitude change trend between adjacent program segments. The deviations between the actual toolpath and the ideal interpolation trajectory in the dimensions of position, attitude, and timing are calculated, yielding pose synchronization error data including tool center point position error, non-tool center point attitude error, and control channel synchronization delay.

[0021] 102. Adjust the program segment length based on the pose synchronization error data to obtain the target program segment parameters, and perform dual-modal weight allocation on the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. In this embodiment, the five-axis joint angle change values ​​between adjacent program segments are extracted from the pose synchronization error data. Each angle change is analyzed, and the angle difference with the largest change amplitude within the current time interval is selected as the key variable characterizing the severity of pose changes between program segments, namely the maximum pose change, used to measure the complexity of the machining path and the intensity of pose transitions. The maximum pose change is multiplied by an experimentally calibrated pose change sensitivity coefficient to reflect the dynamic adjustment effect of pose severity on program segment length. The product value is added to a preset base program segment length to obtain the first program segment length, reflecting the requirement of pose change on the distribution density of machining segments. The greater the pose change, the smaller the first program segment length, and vice versa. The current pose synchronization error data is compared with the error threshold set in the system to calculate an error adjustment factor, which describes the changing trend of the current error level relative to the system tolerance. The error adjustment factor is multiplied by the first program segment length to obtain the second program segment length. Based on the length of the second program segment, chord error analysis is performed using the local radius of curvature of the machining path. The deviation of the program segment endpoints is estimated through curvature changes, and the corresponding chord error compensation is calculated. The chord error compensation is then used to fine-tune and geometrically correct the spatial position of the program segment endpoint, determined by the length of the second program segment, generating target program segment parameters that meet the actual trajectory morphology requirements. Based on the target program segment parameters, considering both the linear motion requirements of the tool center point and the attitude change trajectory of non-tool center points, a collaborative trajectory generation operation is performed to form the desired motion trajectory under the collaborative control of the tool center point and non-tool center points.

[0022] 103. Perform dual-modal quaternion sliding mode control according to the desired motion trajectory to obtain servo control signals, and output the servo control signals to the five-axis linkage machine tool to perform collaborative precision machining between the tool center point and non-tool center point.

[0023] In this embodiment, the desired motion trajectory undergoes quaternion transformation processing, unifying the attitude information contained in the trajectory from Euler angles or direction cosine matrix expressions to quaternion form, and constructing the corresponding quaternion transformation matrix based on quaternion algebra. The desired motion trajectory is progressively compared with the current real-time pose state of the five-axis CNC machine tool, extracting the spatial deviation value of the tool center point position and the attitude deviation information of non-tool center points. The position deviation is obtained by the vector difference between the desired position and the measured position, while the attitude deviation is constructed by the difference between the product of the desired quaternion and the actual quaternion. The spatial deviation value of the tool center point position and the attitude deviation information of non-tool center points are combined with their first derivatives and time integral terms for structured combination to construct a bimodal sliding surface equation. The bimodal sliding surface simultaneously represents the state offset trend of the TCP position control channel and the non-TCP attitude control channel, and has anti-interference and adaptive adjustment capabilities. Based on the definition of a sliding surface, a corresponding quaternion sliding surface control law is designed. The control law consists of equivalent terms, switching terms, and predictive terms, ensuring that the system state converges towards the sliding surface and providing feedforward compensation for abrupt changes between program segments, thereby effectively improving the tracking accuracy and stability of the controller during the dynamic response phase. The output of the control law is inversely mapped using a quaternion transformation matrix, reprojecting the virtual control quantity output by the controller onto the servo execution coordinate system of the machine tool, obtaining servo control signals with physical and execution meaning, including speed and position commands for the tool center point and attitude adjustment commands for non-tool center points. The servo control signals are transmitted to the drive system of the five-axis linkage machine tool through a real-time control channel, driving the linear and rotary axes to operate collaboratively, completing the synchronous tracking of the tool center point and non-tool center points on the spatial trajectory and attitude target, and achieving coordinated precision machining control throughout the entire process.

[0024] In one specific embodiment, the process of performing step 101 may specifically include the following steps: A coordinate transformation matrix is ​​established based on the origin of the program segment coordinate system, using five-axis CNC machining instructions as the reference. Based on the coordinate transformation matrix, the tool motion information within the program segment is separated into poses to obtain the displacement vector of the tool center point and the quaternion of the non-tool center point pose. Coupled kinematic modeling is performed based on the displacement vector of the tool center point and the quaternion of the non-tool center point attitude to obtain a set of kinematic equations. Synchronous mapping of five-axis joint angles and pose parameters is performed based on the kinematic equations to obtain the pose synchronization kinematic parameters. Based on the kinematic parameters of pose synchronization, the pose change of adjacent program segments is predicted to obtain pose synchronization error data.

[0025] In this embodiment, five-axis CNC machining commands are used as the input basis. The position control information, attitude adjustment amount, segment length parameter, and time span contained in each interpolation command are used as variable inputs. A local coordinate system is established segment by segment, and the starting position of each program segment is used as the origin of the local coordinate system of that segment. The coordinate system of each segment is projected uniformly onto the global parent coordinate system to construct a coordinate transformation matrix describing the geometric relationship between the local and global coordinates. The coordinate transformation matrix contains a direction matrix describing rotation and a displacement vector describing translation. The spatial configuration modeling at the program segment level is completed by analytically solving the feature parameters such as trajectory direction, cutting depth, and rotation axis state contained in the program segment. Based on the coordinate transformation matrix, the composite information in each tool motion command is separated and calculated. The translation control part of the linear axis is extracted as the displacement vector of the tool center point to describe the translation behavior of the actual machining point in three-dimensional space. At the same time, the attitude control part of the rotation axis is converted into a unit quaternion expression to describe the overall orientation of the tool attitude around the multi-axis rotation. This completes the separation of the motion state of the tool center point and non-tool center point control content. The tool center point displacement vector and the non-tool center point posture quaternions are input as joint variables into the coupled kinematic modeling framework. A set of kinematic equations is established by combining the joint configuration, inter-axis constraints, and DH parameter model of the five-axis CNC machine tool. The kinematic equations are solved using forward or inverse kinematics methods to achieve synchronous mapping between joint angle variables and the desired tool end-effector pose parameters within each control cycle. A comprehensive pose synchronization kinematic parameter set, including all joint control quantities, displacement vectors, and posture quaternions, is output. Based on the pose synchronization kinematic parameter set, a multi-segment continuous prediction model is constructed by introducing program segment time series and inter-segment adjacency characteristics. This model extrapolates the pose transition behavior caused by trajectory abrupt changes, posture switching, or segment length adjustments between adjacent program segments, predicting the changing trends of each control variable within future time windows. Combined with real-time pose data feedback during machining, the differences between the actual trajectory and the predicted trajectory in three dimensions—position, posture, and control timing—are calculated to obtain pose synchronization error data reflecting inter-segment coordination and system dynamic response capability.

[0026] In one specific embodiment, the process of performing coupled kinematic modeling based on the displacement vector of the tool center point and the quaternions of the non-tool center point orientation to obtain a set of kinematic equations can specifically include the following steps: The non-tool center point orientation quaternion is transformed by rotation matrix to obtain a three-dimensional rotation matrix, and the displacement transformation vector between program segments is calculated based on the tool center point displacement vector and the preset program segment length. A homogeneous transformation is performed on the 3D rotation matrix and the displacement transformation vector between program segments to obtain the pose transformation matrix; A set of kinematic equations relating pose to program segments is established based on the pose transformation matrix and the five-axis joint angle variables.

[0027] In this embodiment, the quaternion representation of the non-tool center point attitude information is transformed. The mapping relationship between quaternions and a three-dimensional rotation matrix is ​​used to expand the non-tool center point attitude quaternion into a three-dimensional rotation matrix structure. This three-dimensional rotation matrix can describe the rotation of a rigid body around any spatial axis, characterizing the rotational state of the tool attitude within a program segment. Furthermore, the transformation process does not rely on Euler angles or direction cosine matrices, avoiding singularity and gimbal lock-up issues, making it suitable for continuous interpolation and high-dynamic attitude adjustment scenarios. After constructing the rotation matrix, the geometric displacement relationship between program segments is quantitatively modeled by combining the displacement vector of the tool center point with the segment length parameter set in the current program segment. By normalizing the displacement vector in the unit direction and multiplying it by the program segment length, the actual displacement transformation vector existing in space from the end point of the previous program segment to the start point of the current program segment is obtained. Homogeneous transformations are performed on the 3D rotation matrix and the inter-program segment displacement transformation vectors to construct two core components of a 4D homogeneous matrix. The 3D rotation matrix is ​​used as the rotation component and filled into the top-left 3D submatrix, while the inter-program segment displacement transformation vectors are used as the translation component and filled into the fourth column vector. This completes the pose transformation matrix, which describes the comprehensive relationship between the position and attitude changes between program segments. The pose transformation matrix is ​​introduced as a coupling variable into the kinematic modeling framework. Combined with the joint configuration structure of the five-axis CNC machine tool, the specific physical topology of the rotation and translation axes, and the joint angle variables, a set of kinematic equations between program segments is constructed. Formally, the kinematic equations encapsulate and constrain the mapping relationship between the spatial pose state of the tool end and each joint angle through matrix equations. This includes a description of the synergy between the temporal sequence and pose changes of each joint and supports both forward and inverse modeling directions.

[0028] In one specific embodiment, the process of performing pose synchronization error data by predicting pose changes between adjacent program segments based on pose synchronization kinematic parameters can specifically include the following steps: The predicted components of the tool center point position and the predicted components of the non-tool center point attitude are calculated based on the kinematic parameters of the pose synchronization. The TCP position error between the actual and expected positions of the tool center point is calculated based on the tool center point position prediction component, and the non-TCP attitude error between the actual and expected attitudes of the non-tool center point is calculated based on the non-tool center point attitude prediction component. Calculate the pose synchronization time error when switching between tool center point control mode and non-tool center point control mode based on TCP position error and non-TCP attitude error; The pose synchronization error data is obtained by performing a square root operation on the TCP position error, non-TCP attitude error, and pose synchronization time error.

[0029] In this embodiment, the pose synchronization kinematic parameters include the five-axis joint angle states mapped by the coupled kinematic model within each control cycle, the displacement vector, attitude quaternion, velocity vector, and acceleration estimate within the current program segment, and depend on the continuous transformation between forward kinematics and the local coordinate system. By establishing a prediction time window, the pose synchronization kinematic parameters are extrapolated forward. For the predicted position component of the tool center point, an equivalent motion trajectory model is constructed based on the current position, velocity, and acceleration. Position estimation is performed using the time increment as the propagation variable to obtain the predicted position of the tool center point within a future period, reflecting the continuous motion trend of the TCP channel during program segment progression. For the attitude prediction component of non-tool center points, exponential mapping prediction is performed based on the current attitude quaternion and its angular velocity component. The nonlinear rotational behavior is propagated forward through an attitude integral or rotation accumulation model to obtain the predicted quaternion values ​​of the attitude direction. The predicted quaternion is regarded as the non-TCP reference attitude when the program segment progresses to the next time frame, used to describe the attitude change trend of non-endpoint control points. After obtaining the predicted components, the predicted position of the tool center point is compared with the actual observed position at the corresponding time node. The spatial deviation between the two is quantified by calculating the spatial Euclidean distance, resulting in the TCP position error of the tool center point, reflecting the degree of linear offset of the actual path relative to the ideal predicted path. Simultaneously, the predicted quaternion of the non-tool center point attitude is compared with the measured quaternion for attitude difference. The nonlinear difference in the rotation domain is obtained through quaternion comparison or attitude angle calculation, resulting in the non-TCP attitude error, used to measure the directional offset capability of the non-rigid end under attitude control mode. Based on the TCP position error and the non-TCP attitude error, the coordination time difference when switching between TCP and non-TCP control modes is analyzed. The time difference error is obtained by calculating the absolute time difference between the two control channels at the time of error response or state switching event, and normalized using the error weighting coefficient to form the pose synchronization time error. The TCP position error, non-TCP attitude error, and pose synchronization time error are squared, summed, and the square root of the sum is taken to obtain the pose synchronization error data.

[0030] In one specific embodiment, the process of performing step 102 may specifically include the following steps: Extract the five-axis joint angle changes between adjacent program segments based on the pose synchronization error data and calculate the maximum pose change between program segments. The first program segment length is obtained by multiplying the maximum attitude change amount and the attitude change sensitivity coefficient and then adding the product to the preset program segment length. The error adjustment factor is calculated based on the pose synchronization error data and the preset error threshold, and the error adjustment factor is multiplied by the length of the first program segment to obtain the length of the second program segment. The chord error compensation amount is calculated based on the length of the second program segment and the radius of curvature of the machining trajectory. Based on the chord error compensation amount, the coordinates of the endpoints of the program segment with the length of the second program segment are geometrically corrected to obtain the target program segment parameters. Generate the desired motion trajectory of the tool center point and non-tool center points in coordination based on the parameters of the target program segment.

[0031] In this embodiment, the five-axis joint angle information between each pair of adjacent program segments is extracted from the pose synchronization error data. By calculating the term-by-term difference of the joint angles of adjacent program segments, a five-axis angle change vector is constructed. The component with the largest numerical amplitude in the five-axis angle change vector is identified as the maximum pose change quantity describing the pose fluctuation intensity of the current program segment, reflecting the local peak behavior of the pose disturbance in the machine tool motion. The maximum pose change quantity is multiplied by the pose change sensitivity coefficient obtained through machining environment calibration to quantify the influence of pose change on the granular control of the machining segment. The product value is added to the preset basic program segment length to generate the first program segment length. When the pose change is large, the first program segment length is compressed to improve the local resolution of trajectory control; otherwise, the segment length is maintained or extended to optimize execution efficiency. Based on the first program segment length, combined with the pose synchronization error data and the error threshold set in the control system, the deviation of the current machining state from the system tolerance range is calculated. An error adjustment factor is constructed through interpolation or piecewise functions. The error adjustment factor represents the correction weight of the error level on the segment length distribution. When the error value is small, the adjustment factor approaches 1 and does not affect the segment length. When the error exceeds the warning threshold, the adjustment factor is significantly less than 1, thus further shrinking the segment length to enhance control accuracy. Multiplying the error adjustment factor by the first program segment length yields the second program segment length, which integrates both attitude severity and error level factors. Based on the second program segment length, the radius of curvature of the machining path is introduced as an auxiliary judgment parameter. The chord error compensation is calculated through the functional relationship between the local curvature of the path and the segment length, used to evaluate the geometric deviation caused by linear interpolation approximation at the program segment endpoints. When the trajectory curvature is large or the segment length is too long, the chord error compensation increases accordingly. At this time, the spatial endpoint coordinates of the current segment are geometrically corrected, and the endpoint is slightly adjusted along the local normal direction to generate target program segment parameters that meet trajectory continuity and curvature constraints. Based on the target program segment parameters, the tool center point position vector and the non-tool center point attitude quaternion are coordinated and matched temporally and spatially through trajectory reconstruction and interpolation algorithms. Combining the synchronization requirements of translation and rotation control channels, a cooperative desired motion trajectory with adaptive segment length adjustment capability and accuracy compensation mechanism is generated.

[0032] In one specific embodiment, the process of generating the desired motion trajectory of the tool center point and non-tool center points based on the target program segment parameters can specifically include the following steps: Calculate the weight components of the tool center point and the non-tool center point based on the pose synchronization error data and the weight balance point error value; Based on the target program segment parameters, the TCP control mode reference trajectory for the tool center point control mode and the non-TCP control mode reference trajectory for the non-tool center point control mode are constructed respectively. The fused motion trajectory is obtained by multiplying the tool center point weight component with the TCP control mode reference trajectory and then adding the product of the non-tool center point weight component and the non-TCP control mode reference trajectory. Cubic spline interpolation is performed on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points.

[0033] In this embodiment, the pose synchronization error data includes the position error of the tool center point, the attitude error of the non-tool center point, and the control response time difference between the two. Based on the pose synchronization error data, a weight balance point error value is introduced as a judgment criterion. According to the relative deviation between the current error level and the weight balance point, the weight components of the tool center point control mode and the non-tool center point control mode are calculated using a smooth transition function to form a bimodal weight vector reflecting the current control center of gravity of the system. When the pose synchronization error is small, the tool center point control strategy is preferred. At this time, the weight component of the tool center point approaches 1, while the weight component of the non-tool center point approaches 0. Conversely, when the error increases, the system control strategy tends to focus on attitude maintenance. At this time, the weight component of the non-tool center point increases, while the weight component of the tool center point decreases accordingly. Based on the target program segment parameters obtained at the current stage, a TCP control mode reference trajectory is constructed to describe the linear interpolation behavior of the tool center point, and a non-TCP control mode reference trajectory is constructed to express the attitude following behavior of the non-tool center point. The TCP reference trajectory is derived from the program segment start point, end point, speed command, and interpolation mode, and is used to control spatial position accuracy. The non-TCP reference trajectory is formed based on quaternion attitude interpolation or angular velocity extrapolation to maintain the continuity of machine tool attitude transition and control stability. The tool center point weight component is multiplied element-wise with the TCP control mode reference trajectory, and the result is summed point-by-point with the product of the non-tool center point weight component and the non-TCP control mode reference trajectory to generate a composite trajectory that integrates spatial position and attitude direction. The composite trajectory has the ability to respond to different control strategies in the time domain and the ability to jointly fit multi-axis states in the spatial domain. Interpolation processing is performed on the fused motion trajectory in the dimensions of position, velocity and acceleration. The discrete trajectory points of the fused trajectory are fitted as a whole using a cubic spline interpolation algorithm, so that the fused motion trajectory meets the requirements of continuous first and second derivatives throughout the entire time period, thus obtaining the desired motion trajectory.

[0034] In one specific embodiment, the process of performing cubic spline interpolation on the fused motion trajectory to obtain the desired motion trajectory co-located between the tool center point and non-tool center points can specifically include the following steps: Based on the boundary conditions for the continuity of position, velocity, and acceleration in the fused motion trajectory, a set of cubic spline interpolation constraint equations is constructed. Based on the cubic spline interpolation constraint equations, the positional first derivative continuity and second derivative continuity constraints at the junction of adjacent program segments are established, and the spline continuity coefficient matrix is ​​obtained. The cubic spline interpolation coefficients between each program segment are obtained by solving the spline continuity coefficient matrix. Based on the cubic spline interpolation coefficients, a cubic polynomial reconstruction is performed on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points in coordination.

[0035] In this embodiment, continuity boundary conditions for position, velocity, and acceleration are set based on the fused motion trajectory. Continuity boundary conditions for position, velocity, and acceleration of the fused trajectory at each interpolation point are set, requiring that the generated trajectory not only has continuous position values ​​at the start and end points of each program segment, but also that its first and second derivatives remain continuous, to avoid abrupt jumps or oscillations during trajectory switching. Based on these boundary conditions, a set of constraint equations for cubic spline functions is constructed within each interpolation interval. The trajectory function for each interval consists of four unknown coefficients, describing the cubic polynomial coefficients along that path segment. The functions of all spline intervals must be interconnected at the interpolation points and satisfy the derivative continuity requirement. A continuity matching equation is introduced into the constraint equation set, transforming the derivative continuity between adjacent program segments into algebraic constraints segment by segment, and uniformly incorporating these constraints into the coefficient matrix of the entire interpolation system, constructing a linear equation set containing all unknown interpolation coefficients, i.e., the spline continuity coefficient matrix. The spline continuity coefficient matrix is ​​solved numerically to obtain the set of cubic polynomial coefficients corresponding to each interpolation interval, which are the trajectory reconstruction parameters of each program segment in the interpolation sense. The cubic polynomial coefficients are applied to each interpolation interval of the fused trajectory, and cubic polynomial curves are generated according to time or parameterized path variables. The spatial path of the tool center point and the attitude path of the non-tool center point are fitted and reconstructed respectively to obtain a cooperative desired motion trajectory with continuity of displacement, velocity and acceleration throughout the entire machining process.

[0036] In one specific embodiment, the process of performing step 103 may specifically include the following steps: The desired trajectory is transformed using quaternions to obtain the quaternion transformation matrix; Based on the desired motion trajectory and the pose state of the five-axis linkage machine tool, the TCP position deviation and non-TCP attitude deviation are calculated respectively. The TCP position deviation, non-TCP attitude deviation and their integral terms are combined to establish the bimodal sliding surface equation. Design a quaternion sliding mode control law based on the bimodal sliding surface equation; The quaternion sliding mode control law is inversely mapped through a quaternion transformation matrix to obtain the servo control signal, and the servo control signal is output to a five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point.

[0037] In this embodiment, the desired motion trajectory undergoes a standardized transformation. For the attitude component, a quaternion construction method is used to map the target attitude trajectory into a quaternion transformation matrix, describing the unit transformation, coordinate mapping, and attitude derivative characteristics during attitude rotation, and possessing algebraic characteristics for coupled execution with the control law. The desired motion trajectory in the current cycle is compared with the pose state fed back by the five-axis CNC machine tool in real time. The TCP position deviation is calculated through the position vector difference, and the non-TCP attitude deviation is calculated through the difference analysis of the product of the desired quaternion and the measured quaternion. These two deviations are structurally combined with their historical integrals to construct a set of dual-mode sliding surface equations with dual-channel error response capability. The dual-mode sliding surface equations are used to describe the unified state evolution trend of the control system under the two error dimensions of spatial displacement and attitude deflection, and provide a stable sliding mode approximation direction. Based on the bimodal sliding surface equation, a quaternion sliding mode control law is designed, comprising a proportional compensation term, a switching approach term, and a predictive feedforward term. The proportional term generates feedback adjustment based on the current error amplitude, the switching term rapidly propels the system into the sliding surface using an exponential approach, and the predictive term preemptively offsets sudden disturbances during machining based on look-ahead modeling. The quaternion sliding mode control law is converted into servo commands directly executable by a five-axis CNC machine tool. The control law results are inversely mapped using a quaternion transformation matrix, projecting the attitude and position control terms from a unified mathematical space back to the joint space and actuator drive space of the machine tool body, resulting in servo control signals with physical control significance. These signals include spatial position adjustment commands, rotational attitude target commands, and five-axis joint collaborative control parameters. The servo control signals are input to the real-time controller module via interpolation logic, enabling the CNC system to drive the five-axis CNC machine tool to synchronously execute precision collaborative machining tasks at both the tool center point and non-tool center points.

[0038] In one specific embodiment, the process of designing a quaternion sliding mode control law based on the bimodal sliding surface equation can specifically include the following steps: Based on the dual-mode sliding surface equation and the position and acceleration information of the desired motion trajectory, inverse dynamics calculation is performed to obtain the equivalent control components. The sign function control term and the proportional control term are calculated based on the equation of the dual-mode sliding surface, and the negative values ​​of the sign function control term and the proportional control term are added together to obtain the switching control component. The predictive control component is obtained by multiplying the program segment pose synchronization prediction information with the predictive control gain. The equivalent control component, the switching control component, and the predictive control component are vector-added to obtain the quaternion sliding mode control law.

[0039] In this embodiment, inverse dynamics calculation is performed based on the dual-mode sliding surface equations and the position and acceleration information of the desired motion trajectory. Combining the current sliding state value and the desired acceleration input, corresponding equivalent control components are constructed through the inverse dynamics model. These equivalent control components compensate for the inertial, acceleration feedforward, and attitude rotation coupling disturbances during the sliding surface error approach process, forming a dominant mechanical control quantity that guides the system towards the target state. While constructing the equivalent control channel, the system's forced convergence capability on the sliding surface is considered. Based on the current sliding surface value, a sign function control term and a linear proportional control term are calculated. The sign function term is used for rapid switching of the control direction, providing anti-disturbance saturation capability when the error nonlinearity increases, while the proportional control term performs linear compensation based on the sliding surface amplitude. The two are superimposed and then negative to form the actual control application direction, combining to form a set of switching control components with slope adjustment and rapid approximation capabilities. This enhances the intervention intensity in the early stages of the system response and the error convergence speed in the later stages. Based on the system's equivalent control and switching control, and considering the dynamic coupling characteristics between program segments, a program segment pose synchronization prediction matrix is ​​introduced. This matrix provides pose estimates for several program segments within a future time window, including spatial position trends and attitude change trends. A linear weighted calculation is then performed on the program segment pose synchronization prediction matrix using a set predictive control gain to generate a feedforward adjustment quantity reflecting the system's response to future disturbances, thus forming a forward-looking predictive control component. The equivalent control component, switching control component, and predictive control component are then superimposed according to the same dimensional structure of the control quantities to form a unified quaternion sliding mode control law.

[0040] The above describes the five-axis linkage CNC machining accuracy control method in the embodiments of the present invention. The following describes the five-axis linkage CNC machining accuracy control system in the embodiments of the present invention. Please refer to [link to relevant documentation]. Figure 2 One embodiment of the five-axis linkage CNC machining accuracy control system of the present invention includes: The pose change prediction module 201 is used to perform program segment pose synchronization analysis on five-axis CNC machining instructions to obtain pose synchronization kinematic parameters, and to predict the pose change of adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data. The program segment length adjustment module 202 is used to adjust the program segment length based on the pose synchronization error data, obtain the target program segment parameters, and perform dual-modal weight allocation on the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. The collaborative precision machining module 203 is used to perform dual-modal quaternion sliding mode control according to the desired motion trajectory, obtain servo control signals, and output the servo control signals to the five-axis linkage machine tool to perform collaborative precision machining of the tool center point and non-tool center point.

[0041] Through the collaborative efforts of the aforementioned components, and by establishing a program segment pose synchronization prediction mechanism, the pose change patterns between adjacent program segments can be accurately predicted, effectively solving the technical problem that traditional methods cannot predict abrupt pose changes at program segment connections. The adaptive program segment length adjustment mechanism based on the pose change sensitivity coefficient dynamically optimizes the program segment length according to actual machining requirements, overcoming the limitation of traditional fixed program segment lengths being unable to adapt to complex geometric features, thus improving machining accuracy while maintaining machining efficiency. The dual-modal weight allocation mechanism enables intelligent switching and collaborative operation between the tool center point control mode and the non-tool center point control mode, ensuring smooth control mode switching through an S-shaped smooth transition function. The use of a quaternion sliding mode control law avoids the singularity problem of traditional Euler angle representation, improving the numerical stability of attitude control.

[0042] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0043] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0044] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the accuracy of five-axis linkage CNC machining, characterized in that, include: The pose synchronization of the five-axis CNC machining command is analyzed to obtain the pose synchronization kinematic parameters, and the pose change of adjacent program segments is predicted based on the pose synchronization kinematic parameters to obtain the pose synchronization error data. Based on the pose synchronization error data, the program segment length is adjusted to obtain the target program segment parameters, and the target program segment parameters are weighted in a dual-modal manner to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. Based on the desired motion trajectory, dual-modal quaternion sliding mode control is performed to obtain a servo control signal, and the servo control signal is output to a five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point.

2. The five-axis linkage CNC machining accuracy control method according to claim 1, characterized in that, The process involves parsing the pose synchronization of five-axis CNC machining commands to obtain pose synchronization kinematic parameters, and then predicting pose changes between adjacent program segments based on these parameters to obtain pose synchronization error data, including: A coordinate transformation matrix is ​​established based on the origin of the program segment coordinate system, using five-axis CNC machining instructions as the reference. Based on the coordinate transformation matrix, the tool motion information within the program segment is separated into poses to obtain the displacement vector of the tool center point and the quaternion of the non-tool center point pose. Based on the coupled kinematic modeling of the displacement vector of the tool center point and the quaternion of the non-tool center point attitude, a set of kinematic equations is obtained. Based on the kinematic equations, the five-axis joint angles and pose parameters are synchronously mapped to obtain the pose synchronization kinematic parameters. Based on the pose synchronization kinematic parameters, pose changes between adjacent program segments are predicted to obtain pose synchronization error data.

3. The five-axis linkage CNC machining accuracy control method according to claim 2, characterized in that, The coupled kinematic modeling based on the displacement vector of the tool center point and the quaternion of the non-tool center point attitude yields a set of kinematic equations, including: The non-tool center point orientation quaternion is transformed by rotation matrix to obtain a three-dimensional rotation matrix, and the displacement transformation vector between program segments is calculated based on the tool center point displacement vector and the preset program segment length. A homogeneous transformation is performed on the three-dimensional rotation matrix and the displacement transformation vector between the program segments to obtain the pose transformation matrix. Based on the pose transformation matrix and the five-axis joint angle variables, a set of kinematic equations relating pose to program segments is established.

4. The five-axis linkage CNC machining accuracy control method according to claim 3, characterized in that, The prediction of pose change between adjacent program segments based on the pose synchronization kinematic parameters, to obtain pose synchronization error data, includes: Based on the pose synchronization kinematic parameters, calculate the tool center point position prediction component and the non-tool center point pose prediction component; The TCP position error between the actual and expected positions of the tool center point is calculated based on the tool center point position prediction component, and the non-TCP attitude error between the actual and expected attitudes of the non-tool center point is calculated based on the non-tool center point attitude prediction component. Calculate the pose synchronization time error when switching between tool center point control mode and non-tool center point control mode based on the TCP position error and the non-TCP posture error; The pose synchronization error data is obtained by performing a square root operation on the TCP position error, the non-TCP attitude error, and the pose synchronization time error.

5. The five-axis linkage CNC machining accuracy control method according to claim 1, characterized in that, The process of adjusting the program segment length based on the pose synchronization error data to obtain target program segment parameters, and then applying dual-modal weight allocation to the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center points, includes: Based on the pose synchronization error data, extract the five-axis joint angle change between adjacent program segments and calculate the maximum pose change between program segments. The product of the maximum attitude change and the attitude change sensitivity coefficient is added to the preset program segment length to obtain the first program segment length. The error adjustment factor is calculated based on the pose synchronization error data and the preset error threshold, and the error adjustment factor is multiplied by the length of the first program segment to obtain the length of the second program segment; The chord error compensation amount is calculated based on the length of the second program segment and the radius of curvature of the machining trajectory, and the coordinates of the endpoints of the program segment of the second program segment length are geometrically corrected based on the chord error compensation amount to obtain the target program segment parameters; Generate the desired motion trajectory of the tool center point and non-tool center points in coordination based on the target program segment parameters.

6. The five-axis linkage CNC machining accuracy control method according to claim 5, characterized in that, The step of generating the desired motion trajectory of the tool center point and non-tool center points in coordination based on the target program segment parameters includes: Calculate the tool center point weight component and the non-tool center point weight component based on the pose synchronization error data and the weight balance point error value; Based on the target program segment parameters, the TCP control mode reference trajectory for the tool center point control mode and the non-TCP control mode reference trajectory for the non-tool center point control mode are constructed respectively. The fused motion trajectory is obtained by multiplying the tool center point weight component with the TCP control mode reference trajectory and then adding the product of the non-tool center point weight component and the non-TCP control mode reference trajectory. Cubic spline interpolation is performed on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points working together.

7. The five-axis linkage CNC machining accuracy control method according to claim 6, characterized in that, The step of performing cubic spline interpolation on the fused motion trajectory to obtain the desired motion trajectory of the tool center point and non-tool center points includes: Based on the boundary conditions for the continuity of position, velocity and acceleration of the fused motion trajectory, a set of cubic spline interpolation constraint equations is constructed. Based on the set of cubic spline interpolation constraint equations, establish the positional first derivative continuity and second derivative continuity constraints at the junction of adjacent program segments, and obtain the spline continuity coefficient matrix; The cubic spline interpolation coefficients between each program segment are obtained by solving the spline continuity coefficient matrix. Based on the cubic spline interpolation coefficients, the fused motion trajectory is reconstructed using a cubic polynomial to obtain the desired motion trajectory of the tool center point and non-tool center points working together.

8. The five-axis linkage CNC machining accuracy control method according to claim 1, characterized in that, The process of performing dual-modal quaternion sliding mode control based on the desired motion trajectory to obtain a servo control signal, and outputting the servo control signal to a five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point, includes: The desired motion trajectory is subjected to quaternion transformation to obtain a quaternion transformation matrix; Based on the desired motion trajectory and the pose state of the five-axis linkage machine tool, the TCP position deviation and non-TCP attitude deviation are calculated respectively. The TCP position deviation and the non-TCP attitude deviation and their integral terms are combined to establish the bimodal sliding surface equation. Design a quaternion sliding mode control law based on the bimodal sliding surface equation; The quaternion sliding mode control law is inversely mapped through the quaternion transformation matrix to obtain the servo control signal, and the servo control signal is output to the five-axis linkage machine tool to perform coordinated precision machining of the tool center point and non-tool center point.

9. The five-axis linkage CNC machining accuracy control method according to claim 8, characterized in that, The design of the quaternion sliding mode control law based on the bimodal sliding surface equation includes: Based on the dual-mode sliding surface equation and the position and acceleration information of the desired motion trajectory, inverse dynamics calculation is performed to obtain the equivalent control components. The sign function control term and the proportional control term are calculated based on the bimodal sliding surface equation, and the negative values ​​of the sign function control term and the proportional control term are added together to obtain the switching control component. The predictive control component is obtained by multiplying the program segment pose synchronization prediction information with the predictive control gain. The equivalent control component, the switching control component, and the predictive control component are vector-added to obtain the quaternion sliding mode control law.

10. A five-axis linkage CNC machining accuracy control system, characterized in that, The method for controlling the accuracy of five-axis linkage CNC machining as described in any one of claims 1-9 includes: The pose change prediction module is used to perform program segment pose synchronization parsing on five-axis CNC machining instructions to obtain pose synchronization kinematic parameters, and to predict the pose change of adjacent program segments based on the pose synchronization kinematic parameters to obtain pose synchronization error data. The program segment length adjustment module is used to adjust the program segment length based on the pose synchronization error data, obtain the target program segment parameters, and perform dual-modal weight allocation on the target program segment parameters to obtain the desired motion trajectory of the tool center point and non-tool center point in coordination. The collaborative precision machining module is used to perform dual-modal quaternion sliding mode control according to the desired motion trajectory, obtain servo control signals, and output the servo control signals to a five-axis linkage machine tool to perform collaborative precision machining of the tool center point and non-tool center point.

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