机械控制5-6.doc

Chap 5 System Representation系统的描述 5.1 Introduction引言 5.2 Block diagrams方框图 5.3 Determination of the overall transfer function 总传递函数的确定 5.4 Standard block diagram terminology 标准的方框图术语 5.5 The simplification of block diagrams 方框图的简化 5.7 Signal flow graphs 信号流图 5.8 Summary 总结 5.1 Introduction引言 System representation： Block diagram: feedback 方框图：反馈 Signal flow graph (SFG): intercoupled relationships 信号流图：相互耦合的关系 Simulation diagrams: overall differential equation is known仿真图：全部微分方程是已知的 State-diagram: initial conditions in the SFG are included 状态图：包括信号流图中的初始条件 5.2 Block diagrams方框图 The representation of physical components by blocks is shown in Chapter 2. For each block the transfer function provides the dynamic mathematical relationship between the input and output quantities. Feedback is used to achieve a better response of a control system to a command input. 在第二章中给出了用方框图描述物理成份的方法。对于每一个方框，传递函数提供了输入量和输出量之间的动态数学关系式。为了使控制系统在指令输入下达到最好的响应就要利用反馈。 The blocks represent the functions performed rather than the components of the system. 方框图表示的是它所完成的功能，而不是系统的成份。 FIG 5.1 An industrial process temperature control system. 工业过程温度控制系统 The voltage r, obtained from a potentiometer（电位计）, is calibrated（校准） in terms of the desired temperature θcomm to be produced within the tank. This voltage represents the input quantity to the feedback control system. 根据容器中液体的期望温度θcomm来设定电压路上的电压，该电压是反馈控制系统的输入量。 The actual temperature θ, the output quantity, is measured by means of a thermocouple（热电偶） immersed in the tank.用插入容器中的热电偶测量液体的实际温度θ，作为输出量。 The voltage eth produced in the thermocouple is proportional to θ. The voltage eth is amplified to produce a voltage b, which is the feedback quantity. 在热电偶中产生的电压eth与θ成正比，该电压放大后产生一个电压b即为反馈量。 The voltage e=r-b is the actuating signal and is amplified to produce the solenoid voltage e1. 电压e=r-b为激励信号，并经放大后作为线圈的输入电压e1。 The current is in the solenoid, which results from applying e1，produces a proportional force fs that acts on t