说明：  设计一超前校正环节，使得超调量为20 ，调节时间为1s。系统单位斜坡稳态响应误差为10 。并作出校正前后后的系统单位阶跃响应时域曲线加以比较。
(Design a lead correction link, so the overshoot is 20 , adjust the time of 1s. Steady-state response of the system unit error of the slope is 10 . Made before and after correction and after the system unit step response curves are compared in time domain.)