说明：  这个是我机械工程课程的大作业。题目是钢板磁悬浮的控制设计。本文主要是利用PID对悬浮钢板进行平衡控制。
(This is my major courses in mechanical engineering operations. Entitled to control the design of magnetic steel. This article is mainly on the use of PID control to balance the suspension plate.)