说明：  通过对PID控制器中的积分时间常数Ti的研究，研究积分时间常数Ti的大小变化对PID控制器的影响，并绘制出不同的积分时间常数Ti下的单位阶跃响应图，进行比较。
(Through the study of the integral time constant Ti in the PID controller, the influence of the size variation of the integral time constant Ti on the PID controller is studied, and the unit step response diagram under the different integration time constant Ti is drawn, and the comparison is made.)