说明：  在计算机控制系统中，使用的是数字PID控制器，数字PID控制算法通常又分为位置式和增量式控制算法。由于计算机控制是一种采样控制，它只能根据采样时刻的偏差值计算控制量，因此模拟式中的积分和微分项不能直接使用，需要进行离散化处理。以一系列的采样时刻点kT代表连续时间t,以和式代替积分，以增量代替微分，作近似变换。采样周期足够短，才能保证有足够的精度
(the computer control system, using the digital PID controller, digital PID control algorithm is usually divided into place- and incremental control algorithm. Computer control is a sample control, it can only be based on the time sampling error control volume terms, the analogue of integral and differential items not directly use, the need for discrete treatment. A series of sampling time point kT representatives consecutive time t, and- to replace integral to replace the differential increment for similar transformation. Sufficient short sampling period, in order to ensure a sufficient precision)