针对反向响应时滞系统，将Smith预估控制和内模控制相结合，提出一种二自由度
控制方法. 设定值跟随控制器采用Smith预估器形式，可使系统具有良好的设定值跟随特性，
而干扰抑制控制器则采用内模控制器设计方法，可改进系统的干扰抑制性能和鲁棒性，克服
传统Smith预估器的不足. 通过两种不同的方法(直接分解和全通分解)，把过程对象的传递
函数分解为最小相位部分和非最小相位部分，相应导出了两种不同控制器的设计方法，并给
出了系统满足鲁棒稳定性的充要条件. 理论分析和仿真对比研究表明，该方法可使系统具有良
好的设定值跟随性能、干扰抑制性能和鲁棒性.

For a system with inverse response to time delay, we propose a two-degreeof-
freedom (2-DOF) control method by combining the Smith predict or control with the
internal model control (IMC). The structure of Smith predict or control is used to obtain a
set-point tracking controller for good set-point tracking performance. In addition, a disturbance
rejection controller uses the method of internal model control to improve disturbance
rejection performance and robustness, overcoming the drawback of the traditional Smith
predictor. The transfer function of the process model is decomposed in to a minimum
phase part and a non-minimum phase part using direct decomposition and full decomposition
methods. Thus, two different methods for controller design are derived. Necessary and
sufficient conditions for the system robust stability are discussed. Theoretical analysis and
simulation results show that the proposed method has good set-point tracking response,
disturbance rejection response and robustness.