针对典型二阶系统状态方程，在有扰动情况下设计带有扩张状态观测器的自抗扰控制器，控制器设计方法参见韩京清先生的《自抗扰控制技术》。(According to the state equation of typical two order system, an active disturbance rejection controller (ADRC) is designed in the case of disturbance. The controller design method is de