Integral action is an essential component for offset-free response in many feedback control systems. Standard internal model control design rules ensure an offset-free response for open-loop stable plants. In this paper a linear feedback control structure is proposed that comprises an observer using an augmented plant model, state estimate feedback and disturbance estimate feedback. This allows internal model control design principles to be applied to unstable and marginally stable plants. Conditions are given for both nominal internal stability and offset-free action even in the case of plant-model mismatch. The Youla parameterization is recovered as a limiting case with reduced-order observers. The design is illustrated on a large scale non-square model with marginally stable dynamics.

积分作用是许多反馈控制系统中无偏移响应的重要组成部分。标准的内部模型控制设计规则可确保开环稳定工厂的无偏移响应。在本文中，提出了一种线性反馈控制结构，该结构包括使用增强型植物模型的观察者，状态估计反馈和干扰估计反馈。这允许将内部模型控制设计原理应用于不稳定和边缘稳定的工厂。给出了名义内部稳定性和无偏移作用的条件，即使在工厂模型不匹配的情况下也是如此。Youla参数化被恢复为具有减少顺序的观察者的极限情况。该设计在具有边际稳定动力学的大规模非正方形模型上进行了说明。