说明：  本人自己琢磨着弄了一个整型变量来实现了PID算法，由于是用整型数来做的，所以也不是很精确，但是对于很多的使用场合，这个精度也够了
(I wondered make a an integer to realize PID algorithm, because be in integer to do, so also is not very accurate, but for a lot of use, the precision also enough occasion)