各章习题及答案
第一章 绪论
1 .举例说明什么是测控?
答:(1) 测控例子:
为了确定一端固定的悬臂梁的固有频率,我们可以采用锤击法对梁进行激振,再利用压电传感器、电荷放大器、波形记录器记录信号波形,由衰减的振荡波形便可以计算出悬臂梁的固有频率。 (2)结论:
由本例可知:测控是指确定被测对象悬臂梁的属性—固有频率的全部操作,是通过一定的技术手段—激振、拾振、记录、数据处理等,获取悬臂梁固有频率的信息的过程。
2. 测控技术的任务是什么?
答:测控技术的任务主要有:
通过模型试验或现场实测,提高产品质量; 通过测控,进行设备强度校验,提高产量和质量; 监测环境振动和噪声,找振源,以便采取减振、防噪措施; 通过测控,发现新的定律、公式等;
通过测控和数据采集,实现对设备的状态监测、质量控制和故障诊断。
3. 以方框图的形式说明测控系统的组成,简述主要部分的作用。
测控系统方框图如下:
(2)各部分的作用如下:
? 传感器是将被测信息转换成某种电信号的器件;
? 信号的调理是把来自传感器的信号转换成适合传输和处理的形式; ? 信号处理环节可对来自信号调理环节的信号,进行各种运算、滤波
和分析;
? 信号显示、记录环节将来自信号处理环节的信号显示或存贮。 ? 模数(A/D)转换和数模(D/A)转换是进行模拟信号与数字信号相互转换,以
便用计算机处理。
4.测控技术的发展动向是什么?
传感器向新型、微型、智能型方向发展;
测控仪器向高精度、多功能、小型化、在线监测、性能标准化和低价格
发展;
参数测量与数据处理向计算机为核心发展;
5. A precise optional signal source can control the output power level to within 1%. A laser is controlled by an input current to yield the power output. A microprocessor controls the input current to
the laser. The microprocessor compares the desired power level with a measured signal proportional to the laser power output obtained from a sensor. Complete the block diagram representing this closed-loop control system shown in Fig E1.1, identifying the output, input, and measured variables and the control device.
答:
6. many luxury automobiles have thermostatically controlled air-conditioning system(恒温空调系统) for the comfort of the passengers. Sketch a block diagram of an air-condition temperature on a dashboard panel(仪表盘). Identify the function of each element of the thermostatically controlled cooling system. 答:
7. In the past, control systems used a human operator as part of a closed-loop control system. Sketch the block diagram of the valve control system shown in Fig. P1.2.
答:
8. The student-teacher learning process is inherently a feedback process intended to reduce the system error back model of the learning process and identify each block of the system. 答:
9. Automatic control of water level using a float level was used in the Middle East for a water clock. The water clock was used from sometime before Christ until the seventeenth century. Discuss the operation of the water clock, and establish how the float provides a feedback control that maintains the accuracy of the clock. Sketch a block diagram of the feedback system.
答:
第二章 信号与系统分析基础
1 求周期方波的傅立叶级数(复指数函数形式),画出|cn|-?和?-?图。
解:(1)方波的时域描述为:
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