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

Abstract

The application relates to the technical field of numerical control machining, and discloses a five-axis linkage numerical control machining precision control system and method, wherein the method comprises the following steps: performing program segment pose synchronous analysis and adjacent program segment pose change prediction on a five-axis numerical control machining instruction to obtain pose synchronous error data; performing program segment length adjustment and double-mode weight distribution to obtain an expected motion track of a tool center point and a non-tool center point; generating a servo control signal according to the expected motion track, and outputting the servo control signal to a five-axis linkage machine tool to execute tool center point and non-tool center point cooperative precision machining. The method dynamically optimizes the program segment length according to actual machining requirements based on an adaptive program segment length adjustment mechanism of a pose change sensitivity coefficient, overcomes the limitation that a traditional fixed program segment length cannot adapt to complex geometric characteristics, improves machining precision while taking into account machining efficiency, and further improves the numerical stability of attitude control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of numerical control machining, and in particular to a five-axis linkage numerical control machining precision control system and method. BACKGROUND

[0002] Traditional five-axis linkage numerical control machining faces the technical problem of pose mutation at the program segment connection when processing complex curved surface workpieces. This mutation will cause discontinuity of the tool path, seriously affecting the machining surface quality and machining precision. The existing technology usually adopts a single control mode, either based on tool center point (TCP) control or non-tool center point (non-TCP) control, and cannot dynamically switch and cooperatively optimize according to the actual needs in the machining process. When machining small program segment instructions, the fixed program segment length setting often cannot adapt to the geometric feature changes of complex curved surfaces, causing difficulty in chord error control and a decrease in trajectory tracking precision. SUMMARY

[0003] The present application provides a five-axis linkage numerical control machining precision control system and method. Based on the adaptive program segment length adjustment mechanism of the pose change sensitivity coefficient, the program segment length is dynamically optimized according to the actual machining needs, overcoming the limitations of traditional fixed program segment length that cannot adapt to complex geometric features. The machining precision is improved while the machining efficiency is taken into account, thereby improving the numerical stability of the attitude control.

[0004] In a first aspect, the present application provides a five-axis linkage numerical control machining precision control method, which comprises:

[0005] Program segment pose synchronous analysis is performed on the five-axis numerical control machining instructions to obtain pose synchronous kinematic parameters, and adjacent program segment pose change prediction is performed based on the pose synchronous kinematic parameters to obtain pose synchronous error data;

[0006] Program segment length adjustment is performed based on the pose synchronous error data to obtain target program segment parameters, and the target program segment parameters are subjected to bimodal weight distribution to obtain an expected motion trajectory of the tool center point and the non-tool center point in cooperation;

[0007] Bimodal quaternion number sliding mode control is performed according to the expected motion trajectory to obtain a servo control signal, and the servo control signal is output to a five-axis linkage machine tool to perform tool center point and non-tool center point cooperative precision machining.

[0008] In combination with the first aspect, in a first implementation manner of the first aspect of the present application, the program segment pose synchronous analysis of the five-axis numerical control machining instructions to obtain pose synchronous kinematic parameters, and the adjacent program segment pose change prediction based on the pose synchronous kinematic parameters to obtain pose synchronous error data, comprises:

[0009] establishing a coordinate transformation matrix based on the five-axis numerical control machining instruction, taking the program segment coordinate system origin as a reference;

[0010] performing pose separation on tool motion information in a program segment based on the coordinate transformation matrix to obtain a tool center point displacement vector and a non-tool center point attitude quaternion;

[0011] performing coupled kinematic modeling based on the tool center point displacement vector and the non-tool center point attitude quaternion to obtain a kinematic equation set;

[0012] synchronously mapping five-axis joint angles and pose parameters according to the kinematic equation set to obtain pose synchronous kinematic parameters;

[0013] predicting pose changes of adjacent program segments based on the pose synchronous kinematic parameters to obtain pose synchronous error data.

[0014] In a second implementation manner of the first aspect, the coupled kinematic modeling based on the tool center point displacement vector and the non-tool center point attitude quaternion to obtain the kinematic equation set comprises:

[0015] performing rotation matrix conversion on the non-tool center point attitude quaternion to obtain a three-dimensional rotation matrix, and calculating a program segment displacement transformation vector based on the tool center point displacement vector and a preset program segment length;

[0016] performing homogeneous transformation on the three-dimensional rotation matrix and the program segment displacement transformation vector to obtain a pose transformation matrix;

[0017] establishing a kinematic equation set of program segment pose correlation according to the pose transformation matrix and five-axis joint angle variables.

[0018] In a third implementation manner of the first aspect, the predicting pose changes of adjacent program segments based on the pose synchronous kinematic parameters to obtain the pose synchronous error data comprises:

[0019] calculating a tool center point position prediction component and a non-tool center point attitude prediction component based on the pose synchronous kinematic parameters;

[0020] calculating a TCP position error of a tool center point actual position and an expected position based on the tool center point position prediction component, and calculating a non-TCP attitude error of a non-tool center point actual attitude and an expected attitude based on the non-tool center point attitude prediction component;

[0021] calculating a pose synchronization time error when switching between the tool center point control mode and the non-tool center point control mode according to the TCP position error and the non-TCP pose error;

[0022] performing square root value operation on the TCP position error, the non-TCP pose error and the pose synchronization time error to obtain pose synchronization error data.

[0023] In a fourth implementation manner of the first aspect, the program segment length adjustment based on the pose synchronization error data to obtain target program segment parameters, and the double-mode weight distribution of the target program segment parameters to obtain the expected motion trajectory of the tool center point and the non-tool center point in cooperation comprises:

[0024] extracting the five-axis joint angle variation between adjacent program segments according to the pose synchronization error data and calculating the maximum pose variation between program segments;

[0025] performing product operation on the maximum pose variation and a pose variation sensitive coefficient and adding a preset program segment length to obtain a first program segment length;

[0026] calculating an error adjustment factor based on the pose synchronization error data and a preset error threshold, and multiplying the error adjustment factor and the first program segment length to obtain a second program segment length;

[0027] calculating a chord error compensation amount according to the second program segment length and a machining trajectory curvature radius, and performing geometric correction on program segment endpoint coordinates of the second program segment length based on the chord error compensation amount to obtain target program segment parameters;

[0028] generating the expected motion trajectory of the tool center point and the non-tool center point in cooperation according to the target program segment parameters.

[0029] In a fifth implementation manner of the first aspect, the generating the expected motion trajectory of the tool center point and the non-tool center point in cooperation according to the target program segment parameters comprises:

[0030] calculating a tool center point weight component and a non-tool center point weight component based on the pose synchronization error data and a weight balance point error value;

[0031] constructing a TCP control mode reference trajectory of the tool center point control mode and a non-TCP control mode reference trajectory of the non-tool center point control mode based on the target program segment parameters respectively;

[0032] multiplying the tool center point weight component with the TCP control mode reference trajectory and adding the product of the non-tool center point weight component and the non-TCP control mode reference trajectory, to obtain a fused motion trajectory;

[0033] performing cubic spline interpolation on the fused motion trajectory to obtain an expected motion trajectory of the tool center point and the non-tool center point in coordination.

[0034] In a sixth implementation form of the first aspect, the performing cubic spline interpolation on the fused motion trajectory to obtain an expected motion trajectory of the tool center point and the non-tool center point in coordination comprises:

[0035] setting position-velocity-acceleration continuity boundary conditions based on the fused motion trajectory to construct a cubic spline interpolation constraint equation set;

[0036] establishing position first derivative continuity and second derivative continuity constraints at a connection position of adjacent program segments according to the cubic spline interpolation constraint equation set to obtain a spline continuity coefficient matrix;

[0037] solving based on the spline continuity coefficient matrix to obtain cubic spline interpolation coefficients between the program segments;

[0038] performing cubic polynomial reconstruction on the fused motion trajectory based on the cubic spline interpolation coefficients to obtain the expected motion trajectory of the tool center point and the non-tool center point in coordination.

[0039] In a seventh implementation form of the first aspect, the performing dual-mode quaternion sliding mode control according to the expected motion trajectory to obtain a servo control signal and outputting the servo control signal to a five-axis linkage machine tool to perform tool center point and non-tool center point coordinated precision machining comprises:

[0040] performing quaternion transformation on the expected motion trajectory to obtain a quaternion transformation matrix;

[0041] calculating a TCP position deviation and a non-TCP attitude deviation based on the expected motion trajectory and a pose state of the five-axis linkage machine tool respectively, and combining the TCP position deviation and the non-TCP attitude deviation and integral terms thereof to establish a dual-mode sliding surface equation;

[0042] designing a quaternion sliding mode control law according to the dual-mode sliding surface equation;

[0043] performing inverse mapping of the quaternion sliding mode control law through the quaternion transformation matrix to obtain a servo control signal, and outputting the servo control signal to the five-axis linkage machine tool to perform tool center point and non-tool center point coordinated precision machining.

[0044] With reference to the first aspect, in an eighth implementation form of the first aspect of the present application, the four-element number sliding mode control law is designed according to the double-mode sliding surface equation, including:

[0045] The equivalent control component is obtained by performing dynamic inverse solution calculation based on the double-mode sliding surface equation and position acceleration information of the expected motion trajectory;

[0046] The sign function control item and the proportional control item are calculated according to the double-mode sliding surface equation, and the switching control component is obtained by adding the negative value of the sign function control item and the proportional control item;

[0047] The predicted control component is obtained by multiplying the program segment pose synchronous prediction information and the predicted control gain;

[0048] The equivalent control component, the switching control component and the predicted control component are subjected to vector addition operation to obtain the four-element number sliding mode control law.

[0049] In a second aspect, the present application provides a five-axis linkage numerical control machining precision control system, which comprises:

[0050] A pose change prediction module is configured to perform program segment pose synchronous analysis on five-axis numerical control machining instructions to obtain pose synchronous kinematics parameters, and perform adjacent program segment pose change prediction based on the pose synchronous kinematics parameters to obtain pose synchronous error data;

[0051] A program segment length adjustment module is configured to perform program segment length adjustment based on the pose synchronous error data to obtain target program segment parameters, and perform double-mode weight distribution on the target program segment parameters to obtain an expected motion trajectory of the tool center point and the non-tool center point cooperation;

[0052] A cooperative precision machining module is configured to perform double-mode four-element number sliding mode control according to the expected motion trajectory to obtain a servo control signal, and output the servo control signal to a five-axis linkage machine tool to perform tool center point and non-tool center point cooperative precision machining.

[0053] 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.

[0054] 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.

[0055] 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

[0056] Figure 1 This is a schematic diagram of an embodiment of the five-axis linkage CNC machining accuracy control method of the present invention;

[0057] 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

[0058] 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.

[0059] 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.

[0060] To facilitate the understanding of the present embodiment, first of all, a five-axis linkage numerical control machining precision control method disclosed by the embodiment of the present application is introduced in detail. As shown in the figure, the method comprises the following steps: Figure 1

[0061] 101. Program segment pose synchronous analysis is performed on the five-axis numerical control machining instructions to obtain pose synchronous kinematics parameters, and adjacent program segment pose change prediction is performed based on the pose synchronous kinematics parameters to obtain pose synchronous error data;

[0062] In the present embodiment, based on the trajectory planning data and attitude control information contained in the five-axis numerical control machining instructions, a homogeneous coordinate transformation matrix with the program segment coordinate system origin as the reference is constructed for each program segment. The homogeneous coordinate transformation matrix adopts an improved D-H modeling method. By taking the local coordinate system origin of the program segment as the reference system, a rotation matrix and a displacement vector are constructed by combining the direction vector of the tool movement path, the cutting point position information and the machining segment time parameter to form a unified transformation relationship. On the basis of the established coordinate transformation, pose separation processing is performed on the tool movement data within the program segment to extract the linear movement amount and the rotation axis attitude information in the numerical control instructions as the three-dimensional displacement vector of the tool center point and the attitude quaternion of the non-tool center point, respectively. Based on the tool center point displacement vector and the attitude quaternion, a coupled kinematics equation set is constructed. The kinematics model simultaneously introduces the program segment execution time, the segment length and the five-axis joint angle vector to realize the coupled expression of the tool center point control channel and the non-tool center point control channel in the homogeneous transformation structure, and form a time-varying pose constraint model considering the continuity and time sequence between program segments. On the basis of the kinematics modeling result, the obtained displacement vector and attitude quaternion are synchronously mapped to the specific five-axis joint angle output and the pose state parameters within the program segment through reverse solving and parameter mapping mechanism to obtain the pose synchronous kinematics description quantity. Combined with the pose synchronous kinematics parameters, the pose change trend between adjacent program segments is estimated in advance by constructing a program segment pose synchronous prediction model, and the deviation between the actual tool path and the ideal interpolation trajectory in the position, attitude and time sequence dimensions is calculated to obtain the pose synchronous error data including the tool center point position error, the non-tool center point attitude error and the control channel synchronous delay.

[0063] 102. Program segment length adjustment is performed based on the pose synchronous error data to obtain target program segment parameters, and the target program segment parameters are subjected to bimodal weight distribution to obtain the expected motion trajectory of the tool center point and the non-tool center point in cooperation;

[0064] ​In this embodiment, the five-axis joint angle change values between adjacent program segments are extracted from the pose synchronization error data, and the set of angle changes are analyzed item by item, and the angle difference with the largest change amplitude in the current time interval is selected as the key variable representing the degree of pose change between program segments, i.e. the maximum pose change, which is used to measure the complexity of the machining path and the intensity of the pose transition. The maximum pose change is multiplied by the pose change sensitivity coefficient calibrated through experiments to reflect the dynamic adjustment effect of the pose intensity on the program segment length, and the product value is added to the preset basic program segment length to obtain the first program segment length, which reflects 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. According to the comparison between the current pose synchronization error data and the error threshold set in the system, the error adjustment factor is calculated to describe the change trend of the current error level relative to the system tolerance, and the error adjustment factor is multiplied by the first program segment length to obtain the second program segment length. According to the second program segment length, the chord error analysis is carried out in combination with the local curvature radius of the machining path, the deviation of the program segment endpoint caused by the change of curvature is estimated, and the corresponding chord error compensation amount is calculated. The chord error compensation amount is used to fine-tune and geometrically correct the spatial position of the program segment endpoint determined by the second program segment length, to generate the target program segment parameters meeting the actual trajectory topography requirements. Based on the target program segment parameters, the linear motion requirements of the tool center point and the pose change trajectory of the non-tool center point are jointly considered, and the cooperative trajectory generation operation is performed to form the expected motion trajectory under the cooperative control of the tool center point and the non-tool center point.

[0065] 103. Perform bimodal quaternion sliding mode control according to the expected motion trajectory to obtain servo control signals, and output the servo control signals to the five-axis linkage machine tool to perform cooperative precision machining of the tool center point and the non-tool center point.

[0066] In this embodiment, the desired motion trajectory is processed by quaternion transformation, which converts the attitude information contained in the trajectory from Euler angles or direction cosine matrix representation to quaternion form, and constructs the corresponding quaternion transformation matrix based on quaternion algebra. The desired motion trajectory is compared with the current real-time pose state of the five-axis linkage machine tool step by step, and the spatial deviation value of the tool center point position and the attitude deviation information of the non-tool center point are extracted respectively. The position deviation is obtained by the vector difference between the expected position and the measured position, and the attitude deviation is obtained by the product difference between the expected quaternion and the actual quaternion. The spatial deviation value of the tool center point position and the attitude deviation information of the non-tool center point are combined with the first derivative and time integral term to construct a double-mode sliding surface equation. The double-mode sliding surface represents the state deviation trend of the TCP position control channel and the non-TCP attitude control channel, and has anti-interference and adaptive adjustment capability. Based on the sliding surface definition, a corresponding quaternion sliding mode control law is designed, which consists of equivalent items, switching items and prediction items, to ensure that the system state converges to the sliding surface and provides feedforward compensation for sudden changes between program segments, thereby effectively improving the tracking accuracy and stability of the controller in the dynamic response stage. The output result of the control law is subjected to inverse mapping operation through the quaternion transformation matrix, so that the virtual control quantity output by the controller is projected into the servo execution coordinate system of the machine tool, and servo control signals with physical meaning and execution significance are obtained, which include the velocity command, position command of the tool center point and the attitude adjustment command of the non-tool center point. The servo control signals are transmitted to the drive system of the five-axis linkage machine tool through the real-time control channel, and the linear axes and rotary axes are driven to run cooperatively, completing the synchronous tracking of the tool center point and the non-tool center point on the spatial trajectory and attitude target, and realizing the whole-process collaborative precision machining control.

[0067] In a specific embodiment, the process of step 101 can specifically include the following steps:

[0068] Based on the five-axis numerical control machining instructions, a coordinate transformation matrix is established with the program segment coordinate system origin as the reference;

[0069] Based on the coordinate transformation matrix, the tool motion information in the program segment is separated by position and attitude to obtain the tool center point displacement vector and the non-tool center point attitude quaternion;

[0070] Based on the tool center point displacement vector and the non-tool center point attitude quaternion, coupled kinematics modeling is performed to obtain a set of kinematics equations;

[0071] According to the set of kinematics equations, the five-axis joint angle and the synchronous kinematics parameters are mapped to obtain the synchronous kinematics parameters;

[0072] The pose synchronization error data is obtained by predicting pose changes of adjacent program segments based on pose synchronization kinematics parameters.

[0073] In this embodiment, taking five-axis numerical control machining instructions as input basis, the position control information, attitude adjustment amount, segment length parameter and time span contained in each segment interpolation instruction are taken as variable inputs, a local coordinate system is established segment by segment, the starting position of each program segment is taken as the origin of the local coordinate system of the segment, each segment coordinate system is projected to the global parent coordinate system, a coordinate transformation matrix describing the geometric relationship between the local and the global is constructed, the coordinate transformation matrix contains a direction matrix describing rotation and a displacement vector describing translation, and the spatial configuration modeling at the program segment level is completed by analyzing and solving the characteristic parameters such as the trajectory direction, cutting depth and rotation axis state contained in the program segment. Based on the coordinate transformation matrix, the complex information in each segment tool motion instruction is calculated separately, the translational control part of the linear axis is extracted as the tool center point displacement vector to describe the translation behavior of the actual machining point in the three-dimensional space, and the attitude control part of the rotary axis is converted into the unit quaternion expression form to describe the overall direction orientation composed of the rotation of the tool attitude around the multi-axis, thereby completing the motion state separation of the tool center point control content and the non-tool center point control content. The tool center point displacement vector and the non-tool center point attitude quaternion are input into the coupled kinematics modeling framework as joint variables, and the kinematics equation set is established in combination with the joint configuration of the five-axis linkage machine tool, the inter-axis constraint relationship and the D-H parameter model. The kinematics equation set is used to perform solving operation, the synchronous mapping between the joint angle variable and the tool end desired pose parameter is realized in each control period through the forward forward solution or the inverse reverse solution, and the comprehensive pose synchronization kinematics parameters including all joint control amounts, displacement vectors and attitude quaternions are output. Based on the pose synchronization kinematics parameters, by introducing the program segment time sequence and the adjacent feature between segments, a multi-segment continuous prediction model is constructed to deduce the pose transition behavior caused by trajectory mutation, attitude switching or segment length adjustment between adjacent program segments, predict the trend of changes of each control variable in the future time window, and calculate the difference between the actual trajectory and the predicted trajectory in the three dimensions of position, attitude and control time sequence in combination with the real-time feedback pose data in the machining process, to obtain the pose synchronization error data reflecting the coordination between segments and the system dynamic response capability.

[0074] In a specific embodiment, the process of performing coupled kinematics modeling based on the tool center point displacement vector and the non-tool center point attitude quaternion to obtain the kinematics equation set can specifically include the following steps:

[0075] The non-tool center point attitude quaternion is converted into a three-dimensional rotation matrix, and a displacement transformation vector between program segments is calculated based on the tool center point displacement vector and the preset program segment length;

[0076] The three-dimensional rotation matrix and the displacement transformation vector between program segments are subjected to homogeneous transformation to obtain a pose transformation matrix;

[0077] A kinematics equation set of the pose correlation between program segments is established according to the pose transformation matrix and the five-axis joint angle variable.

[0078] In this embodiment, the quaternion expression form adopted for the non-tool center point pose information is converted, and the non-tool center point pose quaternion is unfolded into a three-dimensional rotation matrix structure by using the mapping relationship between the quaternion and the three-dimensional space rotation matrix. The three-dimensional rotation matrix has the ability to describe the rotation of a rigid body around any space axis, can represent the rotation state of the tool pose in the program segment, and the conversion process does not need to rely on Euler angles or direction cosine matrix, avoiding the singular point and gimbal lock problem, and is suitable for continuous interpolation and high dynamic pose adjustment scenarios. After the rotation matrix is constructed, the geometric displacement relationship between the program segments is quantitatively modeled by combining the displacement vector of the tool center point and the segment length parameter set for the current program segment. The displacement transformation vector between the program segments is obtained by normalizing the displacement vector in the unit direction and multiplying the program segment length. The three-dimensional rotation matrix and the displacement transformation vector between the program segments are subjected to homogeneous transformation to construct the three-dimensional rotation matrix and the displacement transformation vector between the program segments as two core components of a four-dimensional homogeneous matrix. The three-dimensional rotation matrix is filled into the upper left three-order sub-matrix as the rotation part, and the displacement transformation vector between the program segments is filled into the fourth column vector as the translation part, to construct the pose transformation matrix describing the comprehensive change relationship between the position and the pose between the program segments. The pose transformation matrix is introduced as a coupling variable into the kinematics modeling framework, and combined with the joint configuration structure of the five-axis linkage machine tool, the specific physical topological structure of the rotation axis and the translation axis, and the joint angle variable, the kinematics equation set between the program segments is constructed. The kinematics equation set encapsulates and constrains the mapping relationship between the spatial pose state of the tool end and the joint angles through matrix equations in form, which describes the coordination between each joint in time sequence and the pose change, and supports two modeling directions of forward direct solution and inverse solution.

[0079] In a specific embodiment, the process of performing step of predicting the pose change between adjacent program segments based on the pose synchronization kinematics parameters to obtain the pose synchronization error data can specifically include the following steps:

[0080] Calculating the tool center point position prediction component and the non-tool center point pose prediction component based on the pose synchronization kinematics parameters;

[0081] Calculating the TCP position error between the actual position and the expected position of the tool center point based on the tool center point position prediction component, and calculating the non-TCP pose error between the actual pose and the expected pose of the non-tool center point based on the non-tool center point pose prediction component;

[0082] According to the TCP position error and the non-TCP attitude error, a pose synchronization time error is calculated when the tool center point control mode and the non-tool center point control mode are switched;

[0083] The TCP position error, the non-TCP attitude error and the pose synchronization time error are subjected to square and root value operations to obtain pose synchronization error data.

[0084] In this embodiment, the pose synchronization kinematics parameters include five-axis joint angle states mapped by the coupled kinematics model in each control period, displacement vectors, attitude quaternions, velocity vectors and acceleration estimates in the current program segment, and depend on the forward kinematics and the continuous transformation of the local coordinate system. By establishing a prediction time window, forward extrapolation operation is performed on the pose synchronization kinematics parameters. 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, and the position is estimated by taking the time increment as the propulsion variable to obtain the predicted position of the tool center point in the future period of time, reflecting the continuous motion trend of the TCP channel in the program segment propulsion process. For the attitude prediction component of the non-tool center point, the exponential mapping prediction is performed based on the current attitude quaternion and the angular velocity component, and the nonlinear rotation behavior is forward propagated through the attitude integral or rotation accumulation model to obtain the predicted quaternion value of the attitude direction, which is regarded as the non-TCP reference attitude when the program segment is propelled to the next time frame, and is used to describe the attitude change trend of the non-end control point. After obtaining the above prediction components, the predicted value of the tool center point position is compared with the actual observed position at the corresponding time node, and the spatial deviation between the two is quantified by the spatial Euclidean distance calculation method to obtain the TCP position error of the tool center point, reflecting the linear deviation degree of the actual path relative to the ideal predicted path. At the same time, the predicted quaternion of the non-tool center point attitude is compared with the measured quaternion, and the nonlinear difference in the rotation domain is obtained through the quaternion comparison or the attitude angle calculation method to obtain the non-TCP attitude error, which is used to measure the directional deviation ability of the non-rigid end in the attitude control mode. According to the TCP position error and the non-TCP attitude error, the cooperative time difference when the control mode is switched between TCP and non-TCP is analyzed, the absolute time difference between the two control channels at the time when the error response or state switching event occurs is calculated to obtain the time difference error, and the time difference error is normalized by the error weight coefficient to form the pose synchronization time error. The TCP position error, the non-TCP attitude error and the pose synchronization time error are added after being squared, and the square root of the sum is taken to obtain the pose synchronization error data.

[0085] In a specific embodiment, the process of step 102 can specifically include the following steps:

[0086] extracting a five-axis joint angle variation between adjacent program segments according to the pose synchronization error data and calculating a maximum pose variation between the program segments;

[0087] multiplying the maximum pose variation by a pose variation sensitivity coefficient and adding a preset program segment length to obtain a first program segment length;

[0088] calculating an error adjustment factor based on the pose synchronization error data and a preset error threshold, and multiplying the error adjustment factor by the first program segment length to obtain a second program segment length;

[0089] calculating a chord error compensation amount according to the second program segment length and a machining trajectory curvature radius, and geometrically correcting program segment endpoint coordinates of the second program segment length based on the chord error compensation amount to obtain target program segment parameters;

[0090] generating an expected motion trajectory of a tool center point and a non-tool center point in cooperation according to the target program segment parameters.

[0091] In this embodiment, the five-axis joint angle information between each pair of adjacent program segments is extracted from the pose synchronization error data, the item-by-item difference of the joint angles of adjacent program segments is calculated, a five-axis angle change vector is constructed, the component with the largest numerical magnitude 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, and the local peak behavior of the pose disturbance in the machine tool motion is reflected. The maximum pose change quantity is multiplied by the pose change sensitivity coefficient obtained through the machining environment calibration to quantify the influence degree of the pose change on the machining segment granularity control, and the product value is added to the preset basic program segment length to generate a first program segment length. When the pose change is large, the first program segment length is compressed to improve the local resolution of the trajectory control, and vice versa to optimize the execution efficiency. Based on the first program segment length, the deviation of the current machining state from the system tolerance range is calculated in combination with the error threshold set in the control system and the pose synchronization error data, and an error adjustment factor is constructed through interpolation or a segmented function. 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 tends to 1 and does not affect the segment length. When the error exceeds the warning threshold, the adjustment factor is significantly less than 1, so that the segment length is further compressed to enhance the control precision. The error adjustment factor is multiplied by the first program segment length to obtain a second program segment length that integrates the pose intensity and the error level. Based on the second program segment length, the curvature radius of the machining path is introduced as an auxiliary judgment parameter, and the chord error compensation quantity is calculated through the functional relationship between the local curvature of the path and the segment length to evaluate the geometric deviation caused by the linear interpolation approximation of the endpoint of the program segment. When the trajectory curvature is large or the segment length is too long, the chord error compensation quantity increases, and the spatial endpoint coordinates of the current segment are geometrically corrected by adjusting the endpoint along the local normal direction to generate target program segment parameters that meet the trajectory continuity and curvature constraints. According to the target program segment parameters, the position vector of the tool center point and the attitude quaternion of the non-tool center point are matched in time and space through trajectory reconstruction and interpolation algorithms, and a coordinated expected motion trajectory with adaptive segment length adjustment capability and precision compensation mechanism is generated in combination with the synchronization requirements of the translation and rotation control channels.

[0092] In a specific embodiment, the process of generating the expected motion trajectory of the tool center point and the non-tool center point according to the target program segment parameters can specifically include the following steps:

[0093] Based on the pose synchronization error data and the weight balance point error value, the tool center point weight component and the non-tool center point weight component are calculated;

[0094] Based on the target program segment parameters, the TCP control mode reference trajectory of the tool center point control mode and the non-TCP control mode reference trajectory of the non-tool center point control mode are constructed respectively;

[0095] multiplying the tool center point weight component with the TCP control mode reference trajectory and adding the product of the non-tool center point weight component and the non-TCP control mode reference trajectory to obtain a fused motion trajectory;

[0096] performing cubic spline interpolation on the fused motion trajectory to obtain an expected motion trajectory of the tool center point and the non-tool center point in cooperation.

[0097] In the embodiment, the pose synchronization error data includes position error of the tool center point, attitude error of the non-tool center point, and control response time difference between the two, a weight balance point error value is introduced as a judgment standard based on the pose synchronization error data, and the weight component of the tool center point control mode and the weight component of the non-tool center point control mode are calculated by using a smooth transition function according to the relative deviation between the current error level and the weight balance point, to form a bimodal weight vector reflecting the current control center of the system. When the pose synchronization error is small, the tool center point control strategy is preferred, at this time, the tool center point weight component tends to 1, and the non-tool center point weight component tends to 0; on the contrary, when the error increases, the system control strategy tends to be mainly attitude maintenance, at this time, the non-tool center point weight component rises, and the tool center point weight component correspondingly decreases. According to the target program segment parameters obtained in the current stage, a TCP control mode reference trajectory for describing the linear interpolation behavior of the tool center point and a non-TCP control mode reference trajectory for expressing the attitude following behavior of the non-tool center point are constructed, wherein the TCP reference trajectory is derived from the program segment starting point, end point, speed instruction and interpolation mode, and is used to control the spatial position accuracy; and the non-TCP reference trajectory is formed based on the quaternion attitude interpolation or angular velocity extrapolation method, and is used to maintain the continuity and control stability of the machine tool attitude transition. The tool center point weight component is multiplied with the TCP control mode reference trajectory element by element, and the result is added with the product of the non-tool center point weight component and the non-TCP control mode reference trajectory point by point to generate a composite trajectory of double fusion of spatial position and attitude direction. The composite trajectory has the response ability to different control strategies in the time domain and the joint fitting ability to multi-axis states in the spatial domain. The fused motion trajectory is interpolated in the position, velocity and acceleration dimensions, the discrete trajectory points of the fused trajectory are overall curve fitted by the cubic spline interpolation algorithm, so that the fused motion trajectory meets the requirements of continuous first and second derivatives in the entire time period, to obtain an expected motion trajectory.

[0098] In a specific embodiment, the process of performing cubic spline interpolation on the fused motion trajectory to obtain an expected motion trajectory of the tool center point and the non-tool center point in cooperation can specifically include the following steps:

[0099] The position, velocity, and acceleration continuity boundary conditions are set based on the fused motion trajectory, and a cubic spline interpolation constraint equation set is constructed;

[0100] The position and first derivative continuity and second derivative continuity constraints of the adjacent program segment junction are established according to the cubic spline interpolation constraint equation set, and a spline continuity coefficient matrix is obtained;

[0101] The cubic spline interpolation coefficients between the program segments are obtained by solving the spline continuity coefficient matrix;

[0102] The cubic polynomial reconstruction is performed on the fused motion trajectory based on the cubic spline interpolation coefficients, and an expected motion trajectory of the tool center point and the non-tool center point is obtained.

[0103] In this embodiment, the position, velocity, and acceleration continuity boundary conditions are set based on the fused motion trajectory. The continuity boundary conditions of the position, velocity, and acceleration of the fused trajectory at each interpolation point are set, that is, the generated trajectory is required to be continuous not only in position value but also in first derivative and second derivative at the start and end points of each program segment, so as to avoid sudden jumps or oscillations when the trajectory switches. Based on the boundary conditions, a constraint equation set of the cubic spline function is constructed in each interpolation interval, wherein the trajectory function of each interval is composed of four unknown coefficients, which are used to describe the cubic polynomial coefficients on the path, and the functions of all spline intervals need to be connected to each other at the interpolation points and meet the derivative continuity requirements. The continuity matching equation is introduced in the constraint equation set, the derivative continuity between adjacent program segments is converted into algebraic constraint conditions, and the continuity matching equation is uniformly written into the coefficient matrix of the entire interpolation system, so as to construct a linear equation set containing all unknown interpolation coefficients, that is, a spline continuity coefficient matrix. The spline continuity coefficient matrix is solved by a numerical method, and the cubic polynomial coefficient set corresponding to each interpolation interval is obtained, that is, 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 the cubic polynomial curve is generated according to the time or parameterized path variable, so as to fit and reconstruct the spatial path of the tool center point and the attitude path of the non-tool center point, respectively, and obtain a coordinated expected motion trajectory with displacement, velocity, and acceleration continuity in the entire machining process.

[0104] In a specific embodiment, the process of performing step 103 can specifically include the following steps:

[0105] The quaternion transformation matrix is obtained by performing quaternion transformation on the expected motion trajectory;

[0106] The TCP position deviation and the non-TCP attitude deviation are calculated based on the expected motion trajectory and the pose state of the five-axis linkage machine tool, respectively, and the TCP position deviation and the non-TCP attitude deviation and their integral terms are combined to establish a dual-mode sliding mode surface equation.

[0107] designing a quaternion sliding mode control law according to the dual-mode sliding surface equation;

[0108] mapping the quaternion sliding mode control law through a quaternion transformation matrix to obtain a servo control signal, and outputting the servo control signal to the five-axis linkage machine tool to perform precision collaborative machining of the tool center point and the non-tool center point.

[0109] In this embodiment, the desired motion trajectory is standardized and transformed, wherein for the attitude part, the target attitude trajectory is mapped to a quaternion transformation matrix using a quaternion construction method to describe the unit transformation, coordinate mapping, and attitude derivative during attitude rotation, and has algebraic characteristics coupled with the control law for execution. The desired motion trajectory in the current period is compared with the real-time feedback pose state of the five-axis linkage machine tool, the TCP position deviation is calculated through the position vector difference, and the non-TCP attitude deviation is calculated through the product difference analysis of the desired quaternion and the measured quaternion. The two deviation quantities and their historical integral quantities are structured and combined to construct a dual-mode sliding surface equation with dual-channel error response capability. The dual-mode sliding surface equation is used to describe the unified state evolution trend of the control system under the two types of error dimensions of spatial displacement and attitude deflection, and to provide a stable sliding mode approximation direction. Based on the dual-mode sliding surface equation, a quaternion sliding mode control law is designed, which includes a proportional compensation term, a switching approaching term, and a predictive feedforward term. The proportional term generates a feedback adjustment quantity according to the current error amplitude, the switching term quickly pushes the system into the sliding surface inside in an exponential approaching manner, and the predictive term compensates for sudden disturbances in the machining process in advance based on forward modeling. The quaternion sliding mode control law is converted into a servo instruction that can be directly executed by the five-axis linkage machine tool. The control law result is inversely mapped through the quaternion transformation matrix to project the attitude control term and the position control term from the unified mathematical space back to the joint space and actuator driving space of the machine tool body, obtaining servo control signals with physical control significance, including spatial position adjustment instructions, rotational attitude target instructions, and five-axis joint collaborative control parameters. The servo control signal is input to the real-time controller module through the interpolation logic, and the five-axis linkage machine tool is driven by the numerical control system to synchronously execute the precision collaborative machining task of the tool center point and the non-tool center point.

[0110] In a specific embodiment, the process of designing a quaternion sliding mode control law according to the dual-mode sliding surface equation in the execution step can specifically include the following steps:

[0111] Based on the dual-mode sliding surface equation and the position acceleration information of the desired motion trajectory, perform dynamic inverse solution calculation to obtain equivalent control components;

[0112] The sign function control item and the proportional control item are calculated according to the dual-mode sliding mode surface equation, and the negative value of the sign function control item and the proportional control item is added to obtain the switching control component;

[0113] The prediction control component is obtained by multiplying the program segment pose synchronous prediction information and the prediction control gain;

[0114] The equivalent control component, the switching control component and the prediction control component are subjected to vector addition operation to obtain the quaternion sliding mode control law.

[0115] In the embodiment, the dynamics inverse solution is calculated based on the dual-mode sliding mode surface equation and the position and acceleration information of the expected motion trajectory. The corresponding equivalent control component is constructed by combining the current sliding mode state value and the expected acceleration input through the dynamics inverse solution model. The equivalent control component is used to compensate the inertia term, the acceleration feedforward term and the attitude rotation coupling disturbance of the system in the error approaching process of the sliding mode surface, and forms a dominant mechanical control quantity that makes the system tend to the target state. While constructing the equivalent control channel, the forced convergence ability of the system to the sliding mode surface is considered, and the sign function control item and the linear proportional control item are calculated based on the current sliding mode surface value. The sign function item is used for fast switching control direction, and provides anti-disturbance saturation ability when the error nonlinearity increases. The proportional control item is linearly compensated according to the sliding mode surface amplitude, and the actual control application direction is formed by taking the negative value of the superposition of the two. A switching control component with slope adjustment ability and fast approximation ability is combined, which is used to strengthen the intervention intensity in the early stage of system response and the error convergence speed in the middle and late stages. On the basis of the equivalent control and the switching control of the system, the program segment pose synchronous prediction matrix is introduced considering the dynamic coupling characteristics between the program segments. The matrix provides the pose estimation values of several program segments in the future time window, including the spatial position trend and the attitude change trend. The program segment pose synchronous prediction matrix is subjected to linear weighting operation combined with the set prediction control gain to generate a feedforward adjustment quantity reflecting the disturbance of the system in the future, and a predictive control component with foresight is constructed. The equivalent control component, the switching control component and the prediction control component are superimposed according to the same dimension structure of the control quantity to form a unified quaternion sliding mode control law.

[0116] The five-axis linkage numerical control machining precision control method in the embodiment of the application is described above, and the five-axis linkage numerical control machining precision control system in the embodiment of the application is described below, please refer to Figure 2 The five-axis linkage numerical control machining precision control system in the embodiment of the application includes one embodiment:

[0117] The pose change prediction module 201 is configured to perform program segment pose synchronous analysis on the five-axis numerical control machining instruction to obtain pose synchronous kinematics parameters, and perform adjacent program segment pose change prediction based on the pose synchronous kinematics parameters to obtain pose synchronous error data.

[0118] The program segment length adjustment module 202 is configured to perform program segment length adjustment based on the pose synchronization error data, obtain target program segment parameters, and perform bimodal weight distribution on the target program segment parameters to obtain an expected motion trajectory of the tool center point and the non-tool center point.

[0119] The collaborative precision machining module 203 is configured to perform bimodal quaternion sliding mode control according to the expected motion trajectory, obtain a servo control signal, and output the servo control signal to a five-axis linkage machine tool to perform collaborative precision machining of the tool center point and the non-tool center point.

[0120] Through the cooperation of the above-mentioned components, the pose change rule between adjacent program segments can be accurately predicted by establishing a program segment pose synchronization prediction mechanism, effectively solving the technical problem that the traditional method cannot predict the pose mutation at the program segment junction. 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 limitations of the traditional fixed program segment length that cannot adapt to complex geometric features, improving the machining precision while taking into account the machining efficiency. The bimodal weight distribution mechanism realizes intelligent switching and collaborative work of the tool center point control mode and the non-tool center point control mode, and ensures the smoothness of the control mode switching through the S-shaped smooth transition function. The use of the quaternion sliding mode control law avoids the singular point problem of the traditional Euler angle representation method, improving the numerical stability of the attitude control.

[0121] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, system and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0122] The integrated unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0123] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling machining accuracy in five-axis NC machining, characterized by, The method comprises the following steps: program segment pose synchronization analysis is performed on five-axis NC machining instructions to obtain pose synchronization kinematics parameters, and adjacent program segment pose change prediction is performed based on the pose synchronization kinematics parameters to obtain pose synchronization error data; program segment length adjustment is performed based on the pose synchronization error data to obtain target program segment parameters, and the target program segment parameters are subjected to bimodal weight distribution to obtain expected motion trajectories of the tool center point and the non-tool center point; Specifically, the five-axis joint angle change amount between adjacent program segments is extracted according to the pose synchronization error data, and the maximum attitude change amount between program segments is calculated; the maximum attitude change amount is multiplied by a pose change sensitivity coefficient, and then added to a preset program segment length to obtain a first program segment length; an error adjustment factor is calculated based on the pose synchronization error data and a preset error threshold, and the error adjustment factor is multiplied by the first program segment length to obtain a second program segment length; a chord error compensation amount is calculated according to the second program segment length and a machining trajectory curvature radius, and the program segment endpoint coordinates of the second program segment length are geometrically modified based on the chord error compensation amount to obtain target program segment parameters; and expected motion trajectories of the tool center point and the non-tool center point are generated according to the target program segment parameters; Bimodal quaternion sliding mode control is performed according to the expected motion trajectories to obtain servo control signals, and the servo control signals are output to a five-axis linkage machine tool to perform tool center point and non-tool center point collaborative precision machining; specifically, quaternion transformation is performed on the expected motion trajectories to obtain a quaternion transformation matrix; TCP position deviation and non-TCP attitude deviation are calculated based on the expected motion trajectories and the pose state of the five-axis linkage machine tool, respectively, and the TCP position deviation and the non-TCP attitude deviation and their integral terms are combined to establish a bimodal sliding surface equation; a quaternion sliding mode control law is designed according to the bimodal sliding surface equation; the quaternion sliding mode control law is inversely mapped through the quaternion transformation matrix to obtain servo control signals, and the servo control signals are output to the five-axis linkage machine tool to perform tool center point and non-tool center point collaborative precision machining.

2. The five-axis NC machining precision control method according to claim 1, characterized by, The program segment pose synchronization analysis on the five-axis NC machining instructions to obtain the pose synchronization kinematics parameters, and the adjacent program segment pose change prediction based on the pose synchronization kinematics parameters to obtain the pose synchronization error data, comprises the following steps: A coordinate transformation matrix is established based on the five-axis NC machining instructions, with the program segment coordinate system origin as the reference; The pose of the tool center point and the non-tool center point is separated based on the coordinate transformation matrix to obtain a tool center point displacement vector and a non-tool center point attitude quaternion; Coupled kinematic modeling is performed based on the tool center point displacement vector and the non-tool center point attitude quaternion to obtain a kinematics equation set; Synchronous mapping of the five-axis joint angle and the pose parameters is performed according to the kinematics equation set to obtain pose synchronization kinematics 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 NC machining precision control method according to claim 2, characterized by, 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 NC machining precision control method according to claim 3, characterized by, 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 method of claim 1, wherein, 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.

6. The five-axis NC machining precision control method according to claim 5, characterized by, 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. Reconstruct the expected motion trajectory of the tool center point and the non-tool center point based on the cubic spline interpolation coefficient.

7. The method of claim 1, wherein, The four-element sliding mode control law is designed according to the double-mode sliding mode surface equation, which includes: Based on the position and acceleration information of the double-mode sliding mode surface equation and the expected motion trajectory, the dynamic inverse solution is calculated to obtain the equivalent control component; According to the double-mode sliding mode surface equation, the sign function control item and the proportional control item are calculated, and the negative value of the sign function control item and the proportional control item is added to obtain the switching control component; Based on the multiplication of the program segment pose synchronous prediction information and the prediction control gain, the prediction control component is obtained. The equivalent control component, the switching control component and the prediction control component are subjected to vector addition operation to obtain the four-element sliding mode control law.

8. A five-axis NC machining precision control system, characterized by, A method for performing the five-axis linkage numerical control machining precision control method according to any one of claims 1-7, comprising: A pose change prediction module for analyzing the five-axis numerical control machining instructions in program segment pose synchronous mode to obtain pose synchronous kinematics parameters, and predicting the pose change of adjacent program segments based on the pose synchronous kinematics parameters to obtain pose synchronous error data; A program segment length adjustment module for adjusting the program segment length based on the pose synchronous error data to obtain target program segment parameters, and performing double-mode weight distribution on the target program segment parameters to obtain the expected motion trajectory of the tool center point and the non-tool center point; A cooperative precision machining module for performing double-mode four-element sliding mode control according to the expected motion trajectory to obtain servo control signals, and outputting the servo control signals to the five-axis linkage machine tool to perform cooperative precision machining of the tool center point and the non-tool center point.

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