Kinematics equations and kinematic equations of dynamic models are the basis for building dynamic models. For the shape of the fixed and moving platform of the parallel machine tool, as shown, the coordinate system o'x'y'z' and oxyz are respectively established on the upper and lower platforms, wherein the o' and o points are respectively the centroids of two hexagons. The ox and o'x' axes take the perpendiculars of the two short sides A1A6 and B1B6, oz and o'z' are perpendicular to the two platforms, respectively, and the directions of oy and o'y' are determined according to the right-hand rule. 1 Parallel machine tool structure diagram 2 The coordinate system of the upper and lower platforms is set to r1 and r2 respectively for the circumscribed circle radius corresponding to the upper and lower platforms, and Α1 and Α2 are respectively the central angle corresponding to the two hexagonal short sides, {xoi 'yoi'zoi'} is the i-th hinge point of the upper platform. In the o'x'y'z' coordinate, since the o' point is active, it is the relative coordinate, and {xi'yi'zi'} is the coordinate of the i-th hinge point of the upper platform in oxyz, that is, absolute Coordinates, {xoi Yoi Zoi} is the coordinates of the i-th hinge point of the lower platform in oxyz. Then the cosine matrix from the coordinate system o'x'y'z' to the oxyz coordinate system is Α, Β, Χ are the angles of the upper platform around the z, y, and x axes. xP, yP, and zP are the absolute coordinates of the geometric center point of the upper platform. {Vi}, {Ui} can be calculated from the geometric parameters of the machine tool. When given the location of the active platform {xP When yPzPΑΒΧ}, the inverse solution equation of the platform mechanism is si=ViDi(2), where {Di}={xoiyoizoi1}, from which the length of each branch can be obtained. Because si=f(xPyPzPΑΒΧ), the first derivative of si is obtained to obtain the inverse relationship of the speed of the parallel machine tool. The application of Matlab in dynamic model calculation Matlab provides a mathematical system environment for human-computer interaction, and uses matrix as the basic data structure. It is not easy to implement symbolic operations on the VC platform, but Matlab provides two sub-toolboxes for basic symbolic operations and extended symbolic operations. With the help of these two sub-toolboxes, you can write your own M files and M functions, and it is convenient to establish the various symbol variables and their relationship in the dynamic model. The program is easy to modify at a glance. Matlab not only provides commands for creating symbolic equations, but also provides commands for solving linear and nonlinear equations, saving time in pure VC programming. (1) The parameter input module is responsible for accepting the necessary parameters such as structural parameters and initial conditions of the mechanism, then opens the Matlab engine and passes the parameters to Matlab. (2) Call the model operation module to perform symbol derivation, numerical calculation and drawing of kinematics and dynamics models. This module is represented by a M function with parameters, which is the core part of the whole programming. From the M function, it can output the transformation matrix of symbolic representation, influence the system matrix, dynamic positive problem and dynamic inverse problem. (3) The operation information display module displays the text result, the prompt error and the warning information calculated by the model. The visual simulation results returned by the Matlab engine to the application are easily compared with the measured results to find out the factors affecting the dynamic characteristics of the parallel machine tool system. (4) The trajectory planning module optimizes the designed motion trajectory so that there is no singular position in the workspace, and then solves the kinematic problem together with the transformation matrix and the influence coefficient matrix. The kinematics equation and the dynamic positive problem can be Used for kinetic control. Complex operations such as matrix operations, symbol derivation, solution linear or nonlinear differential equations involved in these modules can be implemented in Matlab, and interface, parameter input and operation information display can be completed on the VC platform. Conclusion (1) Using the VC and Matlab interface engine method to call Matlab functions or commands in the VC application, you can make full use of Matlab's powerful matrix calculation, symbol derivation and convenient drawing function to complete the parallel machine tool dynamics model operation and Simulation, to reduce the workload and debugging difficulties of pure VC programming, to ensure the reliability and accuracy of the calculation. (2) VC and Matlab interface technology makes the program inherit a good user interface, can directly input parameters, get the required text results, and facilitate comparison with instrument measurement results. (3) Introducing the influence coefficient method to bring convenience to programming. Each module in the above box can be independently programmed, and a corresponding data interface is established between each module. These interfaces can be interactively performed through the interface, thereby embodying the C language. 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The application of the new control in the joint lathe system