1. Introduce problems
在PLC+变频器+三相异步电机的控制结构下，如何实现被控制对象速度、位置的平滑过渡，并减少对机械系统造成的冲击？
本次项目采用西门子S7_1500、丹佛斯变频器FC302、SEW三相异步电机；程序的实现是基于 Sinx*Sinx 的 S 型速度曲线的生成并仿真测试运行 ，其有以下优点：
①由于 Sinx*Sinx 曲线具有的一阶二阶连续性，加速度和加加速度都符合正/余弦特性，相比传统的S曲线其加加速度并不连续而系统柔性受到一定限制的特点，尽可能的保证了加减速过程的平滑稳定。
②同时由于Sinx*Sinx 曲线加速度先增加后减小到的特征，整条曲线不用再分成七段或五段计算而采用传统速度曲线的三段速。
2. Pre-knowledge
Preface: The essence of interpolation is to approximate the curve with tiny straight segments in the execution link.
1. Data sampling interpolation is also called time division method: its principle is to divide the processing time of a curve into several equal interpolation cycles. After an interpolation cycle, an interpolation operation is performed, and the speed word of the inverter in the interpolation cycle is calculated. —This project directly uses the curve itself to interpolate, and the interpolation cycle is 1ms.
2. Since the integrals of ∫sinx*sinxdx and ∫(2/π)xdx in [0,π /2] are equal, the trapezoidal acceleration and the S-shaped acceleration can be equivalently converted, namely S_a=T_a * 2/Π (Π=3.1415926)
3. Vmin: the minimum operating speed to ensure reliable stopping of the stacker
4. Glide distance: the low-speed uniform running distance before the equipment approaches the target point
5. Calculation formula:
5.1、电机参数计算公式：（默认起始速度为0，加速度==减速度）
电机执行机构速度 m/s：ÿ