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在测试技术中,经常应用电阻变化增量小的电阻应变片。由应变片将科学实验中的各种物理量,如压力、应力、应变等等,转换成电信号。而由应变片输出的电信号往往是几个毫伏的低电平信号。低电平信号由高增益的数据放大器进行放大和缓冲,然后进入数据采集子系统进行切换,模拟——数字转换等变换工作,再经过接口电路传输给微处理机进行处理。通常将电阻应变片接成电桥的测量电路,如图1所示。图中电桥的四个电阻可以都是电阻应变片(全桥);也可以只有两个是电阻应变片,两个是精密电阻(半桥);或者只有一个是电阻应变片,其余三个都是精密电阻(1/4桥)。为了补偿桥臂电阻值(即电阻应变片的阻值,精密电阻的阻值)的偏差所造成的初始不平衡,每一桥式测量
In testing techniques, resistance strain gauges with small incremental changes in resistance are often used. By the strain gauge will be scientific experiments in a variety of physical quantities, such as pressure, stress, strain, etc., into electrical signals. The electrical signal output by the strain gauge is often a few millivolts of low-level signal. The low-level signal is amplified and buffered by a high-gain data amplifier and then enters the data acquisition subsystem for switching, analog-to-digital conversion and other transformations, which are then transmitted to the microprocessor for processing via the interface circuit. The resistance strain gauges are usually connected to the bridge measurement circuit, as shown in Figure 1. The four resistances of the bridge can be both strain gages (full bridges); only two can be strain gages and two can be precision resistors (half-bridges); or only one can be a strain gage, and the remaining three Are precision resistors (1/4 bridge). In order to compensate for the initial unbalance caused by the deviation of the arm resistance (that is, the resistance of the strain gage and the resistance of the precision resistor), each bridge measurement