温控

一般是令Ti=0、Td=0。输入设定为系统允许的最大值的60%~70%，由0逐渐加大比例增益P，直至系统出现振荡；再反过来，从此时的比例增益P逐渐减小，直至系统振荡消失，记录此时的比例增益P，设定PID的比例增益P为当前值的60%~70%。(t control

An integral term increases action in relation not only to the error but also the time for which it has persisted. So, if applied force is not enough to bring the error to zero, this force will be increased as time pass. A pure "I" controller could bring the error to zero, however, it would be both slow reacting at the start (because action would be small at the beginning, needing time)