一、前言用开环特性求闭环特性有多种方法,这里介绍尼柯尔斯线图求法。尼柯尔斯线图法应用起来简单,特别是当改变伺服系统的开环增益时,它能迅速并容易地求出闭环特性。二、使用尼柯尔斯线图法根据开环特性求闭环特性图1是电液伺服的方框图。图2为图1伺服系统的传递函数(频率特性)。图3是尼 I. INTRODUCTION There are many ways to find closed-loop characteristics with open-loop characteristics. Here we introduce Nichols diagram. The Nichols diagram method is simple to apply, especially when changing the open-loop gain of a servo system, it quickly and easily determines the closed-loop behavior. Second, the use of Nichols diagram method based on open-loop characteristics of closed-loop characteristics Figure 1 is a block diagram of electro-hydraulic servo. Figure 2 is the transfer function (frequency characteristics) of the servo system of Figure 1. Figure 3 is a niche