目的 设计基于STM32为控制核心的定长切割控制系统。方法 介绍了该系统的工作原理、硬件设计、外部中断跟踪程序的实现以及HMI人机界面的设计。同时，针对刀架以高速返回时的平稳性问题，提出了基于Sigmoid函数的S型算法，并将返回时的主要参数代入该函数中进行MATLAB仿真。结果 经测试，该控制系统满足工作要求。仿真结果表明，刀架返回时的频率曲线是连续平滑的。结论 该控制系统采用STM32替代PLC，成本低，功能稳定，实时性高，操作稳定，能够满足定长切割的精度要求。

The work aims to design a fixed-length cutting control system based on STM32 as the control core. The working principle, hardware design, realization of external interrupt tracking program and HMI design were introduced. In the meantime, aiming at the stationarity of tool holder when it returned at high speed, an S-type algorithm based on Sigmoid function was proposed, and the main parameters of tool holder during returning were substituted into the function for Matlab simulation. The test results showed that, the control system met the working requirements. The simulation results indicated that, the frequency curve was continuous and smooth when the tool holder returned. The control system adopting STM32 instead of PLC is featured by low cost, stable function, high real-time performance and stable operation, and can meet the precision requirements of fixed-length cutting.