【作者】 刘艳艳；

【导师】 莫德举；

【作者基本信息】 北京化工大学 ， 检测技术与自动化装置， 2007， 硕士

【摘要】 目前市场上的超声波液位计品种多样，大多采用温度补偿方法对超声波传播速度进行校正，以提高仪表测量精度。此方法需在系统外加一个温度测量单元，通过测量环境温度，获得实际声速；由此也引进了温度测量误差，从而限制了系统精度的进一步提高。课题设计了一种利用参考声速法实现声速校正的超声液位测量系统。设计中采用气介测量方式，将一个反射性能良好的参考挡板固定在超声波探头与液面之间距离一定的位置，通过测量挡板回波的时间，实现精确的声速校正；并用单片机双定时器对挡板反射回波和液而反射回波进行精确计时，从而大大提高了液位测量精度。此系统不但继承了传统超声波液位计的优点，而且由于无需采集环境温度，避免了由于测温误差引起的系统误差，还简化系统结构，降低了生产成本，进一步提高了系统精度。论文研究了设置参考挡板进行声速校正的特点，通过理论分析，得出了探头安装角度、安装距离、挡板安装位置、挡板大小与测量量程之间的关系，及其对测量结果的影响，并通过实验进行了验证。系统选用AT89S52型单片机作为系统控制核心，以超声波测距原理为理论依据，完成对液体液位的连续测量、实时液位数据显示和远程通讯等功能。课题研究中完成了软硬件设计，对系统进行了整体调试，对理论推导进行了很好的验证。这种新型声速校正方法相对于传统的温度补偿方法，性能更加优越，是今后超声液位测量的发展方向，具有广阔的发展前景。更多还原

【Abstract】 Today, the ultrasonic liquid level meters are diversiform. Most of them use the instrument of temperature compensation to obtain the real ultrasonic velocity in order to improve the measurement precision. But it needs a temperature measurement unit, so the error is added.In this thesis, a new way of ultrasonic liquid level measurement, which is based on the compensation of ultrasonic velocity by a baffle reflecting the ultrasonic, is studied. It is timed that the ultrasonic transmitted by AT89 series single chip microcomputer. The liquid level can be measured exactly by this kind of instrument. It has advantages as the former meters, and simplifies the system, improves the precision and reduces the cost.The characteristic of ultrasonic velocity compensation by a baffle reflecting the ultrasonic is studied in this thesis. And it is talked where and how the ultrasonic sensor and the baffle are installed, and whether they would affect the measurement result.In the system, AT89S52 single chip microcomputer controls the entire system which based on the principle of ultrasonic reflecting on barrier. It can measure the liquid level, display the data and implement communication function. In the study, it accomplishes the design in hardware and software, in addition the system debugging. This kind of ultrasonic liquid level meter will apply widely and have a bright future.更多还原