Research On Control Strategy Of Embedded Multi-axis Linkage Interpolation System

As the core technology of CNC machine tools,multi-axis linkage interpolation system is the key to achieve high-speed and high-precision.Most traditional numerical control machine tools only support linear and circular interpolation,cannot directly process freeform curved surfaces.If NURBS curve interpolation technology is used,not only can the machining speed and accuracy of the machine tool be improved,but also the smoothness of the part surface can be improved.Therefore,this paper studies the NURBS interpolation algorithm.The main research content is as follows:The properties of NURBS curve and its parameter calculation method are studied.The Taylor formula is used to expand the NURBS parameter curve.The factors that affect the accuracy of NURBS curve interpolation,such as truncation error,curvature,normal acceleration,and bow height error,are analyzed.The constraint condition of the feedrate during the process are determined to ensures that the feedrate satisfies the system limitations and error requirements of the machine tool during the real-time interpolation of the NURBS algorithm.The characteristics and characteristics of the trapezoidal acceleration/deceleration algorithm,exponential acceleration/deceleration algorithm,and S-shaped acceleration/deceleration algorithm are compared.S-shaped acceleration/deceleration algorithms are selected to perform acceleration/deceleration planning for the feed rate of NURBS curve interpolation.According to the NURBS curve interpolation start speed and feed step,the S-shaped acceleration/deceleration algorithm modes are classified.The operation phases of S-shaped curve acceleration/deceleration in different modes are introduced in detail.The path length and feed speed solution calculation method in different modes are introduced.Based on this,combining with controllable bow height error control theory,a NURBS curve interpolation method based on S-shaped curve acceleration/deceleration planning is proposed.Based on the study of NURBS curve interpolation method based on S-shaped curve acceleration/deceleration planning,an embedded numerical control experimental platform designed.The architecture of ARM+FPGA adopted.ARM responsible for communication,exception handling and other functions.Modbus protocol used to communicate with touch screen.uC/OS used to schedule tasks and multi-tasking application message queues are designed to improve the efficiency of each task's access to data.The FPGA is responsible for the realization of functions such as interpolation calculation,speed planning,and motor drive,which reduces the load on the ARM processor and improves the system's real-time performance and interpolation accuracy.An experimental platform is built,the embedded numerical control experiment platform and MATLAB are used for experimental verification and data analysis.By analyzing the experimental results and the speed,acceleration and other data during the interpolation,it is proved that the proposed algorithm is correct and effective.