迴路整形法的設計概念，在於利用 控制理論的強健性能條件在波德圖面上形成限制，以求得符合條件的迴路轉移函數，進而得到控制器，並將控制器的設計過程圖形化。而在設計的過程上我們可以發現此種方法存在了一些缺點：(1)通常受控體的階數越高，所求出來的控制器階數也會越高，這使得不管是利用程式或者是電路來實現控制器都是一種負擔。(2)在波德圖上調整迴路轉移函數 使其滿足強健性能條件，這通常需經由不斷地嘗試錯誤來獲得，此將消耗較多的時間，況且是否有解並不可事先預知。(3)對於使用迴路整形法求出來的控制器 雖然滿足強健性能，但卻不一定會使公稱受控體 穩定。
本論文將PID控制器導入迴路整形法中，形成PID迴路整形方法來改善這些缺點。最後我們使用PID迴路整形方法來設計撓性臂系統的定位控制系統，藉以驗證PID迴路整形方法的可行性。並將其定位性能與Ziegler-Nichols方法所設計的PID控制器的性能作一比較。

The design concept of loop shaping is to determine the loop transfer function to satisfy performance design constrains on the Bode plot. However, the conventional loop shaping method suffers from the following drawbacks: (1) It usually happens that when the order of plant is higher, and the order of the resulting controller will become higher, too. This becomes a burden for implementing a controller by the programming languages or circuits. (2) Adjusting the loop transfer function for satisfying the robust performance condition on the Bode plot usually goes through a lot of trial and error. That is highly time-consuming, moreover the existence of the solution can’t be known beforehand. (3) The resulting controller may not be able to guarantee closed-loop stability.
The main idea of this study is to use the PID controller in loop shaping method to improve those drawbacks of conventional loop shaping. Finally, we used the proposed PID loop shaping to achieve positioning control of a flexible beam, and to show feasibility of the proposed method in practice. A comparison between performance of the proposed PID loop shaping method and that of the Ziegler-Nichols method is also given.

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