The control method based on the equivalent‐input‐disturbance (EID) estimator and the Luenberger state observer has received much attention in recent years. However, the property of EID‐based control systems is still not well investigated. A number of design procedures were proposed but lacked sufficient theoretic justification. In this article, the two‐degree‐of‐freedom nature of an EID‐based control system is revealed. Specifically, the reference‐tracking is determined by an outer loop, while the disturbance rejection and robustness is determined by an inner loop consisting of the EID estimator and state observer. The bandwidth constraints on the inner loop are analyzed for plants having zeros or poles in the open right‐half plane by using the Bode and the Poisson integral formulas. These analyses provide a theoretic justification for conventional design procedures. Further, a coordinated design algorithm is provided for the EID‐based uncertain control systems. In addition, a comprehensive comparison of the EID‐based and the disturbance observer (DOB) based control systems is conducted in the system design aspect. Lastly, comparative studies of the EID‐based and DOB‐based control methods are given for various types of plants to validate the developed design algorithm.

中文翻译：

---

基于等效输入扰动的控制系统分析和不确定系统的协调设计算法

近年来，基于等效输入扰动（EID）估计器和Luenberger状态观测器的控制方法受到了广泛关注。但是，基于EID的控制系统的属性仍未得到很好的研究。提出了许多设计程序，但缺乏足够的理论依据。在本文中，揭示了基于EID的控制系统的两自由度性质。具体来说，参考跟踪由一个外部环路确定，而干扰抑制和鲁棒性则由一个由EID估计器和状态观测器组成的内部环路确定。通过使用Bode和Poisson积分公式，分析了在右半开放平面中具有零或极点的植物的内部环路带宽约束。这些分析为常规设计程序提供了理论依据。此外，为基于EID的不确定控制系统提供了一种协调设计算法。此外，在系统设计方面对基于EID和基于干扰观察器（DOB）的控制系统进行了全面比较。最后，针对各种类型的工厂对基于EID和基于DOB的控制方法进行了比较研究，以验证开发的设计算法。