中文说明：应用背景以BP + PID下控制器，若期望输出是单阶和余弦，那么仿真跟踪效果不错，但若期望输出凛（K）= 1700，那么BP输出KP，KI，KD都为南，关键技术这是什么原因啊？应该怎样改进，才能使实际输出你（K）跟期望输出一致仿真程序以下为MATLAB？
English Description：
The application background is BP + PID controller, if the expected output is single order and cosine, then the simulation tracking effect is good, but if the expected output Lin (k) = 1700, then the BP output KP, Ki, KD are all south, what is the reason for the key technology? How to improve, so that the actual output of you (k) is consistent with the expected output?