自动控制原理课件——时域分析法.pptVIP

Chapter 3 Time-Domain Analysis of Control Systems 3.1 Introduction Since time is used as an independent variable in most control systems, it is usually of interest to evaluate the output response with respect to time, or simply, the time response. In the analysis problem, a reference input signal is applied to a system, and the performance of the system is evaluated by studying the system response in the time domain. The time response of a control system is usually divided into two parts: the transient response and the steady–state response. 3.2 Typical test signals for the time response of control systems 3.2 Typical Test Signals for The Time Response of Control Systems 3.2 Typical Test Signals For The Time Response of Control Systems Typical unit - step response of a control system * * The inputs to many practical control systems are not exactly known ahead of time. In many cases, the actual inputs of a control system may vary in random fashion with respect to time. (For instance, in a radar tracking system for anti- aircraft missiles) It is difficult to design a control system so that it will perform satisfactorily to all possible forms of input signals. For the purpose of analysis and design, it is necessary to assume some basic types of test inputs so that the performance of a system can be evaluated. By selecting these basic test signals properly, not only is the mathematical treatment of the problem systematized, but the response due to these inputs allows the prediction of the system’s performance to other more complex inputs. In design problem, performance criteria may be specified with respect to those test signals and the system may be designed to meet the criteria. Step-Function Input: The step function is very useful as a signal since its initial instantaneous jump in amplitude reveals a great deal about a system’s quickness in respond- ing to inputs with abrupt changes. 3.2 Typical Test Signals For The Time Response of Control Sys