说明：  学习pid算法编写和控制，pid在工程应用很广，在自动化领域更广，可以自动调节使输出值跟设定值在一个位置上，有增量式PID和位置式PID
(Learning PID algorithm Writing and control, PID is widely used in engineering, in the field of automation more widely, can automatically adjust the output value with the set value in one position, there are incremental PID and position PID)