【作者】 归金娟；

【导师】 张自嘉；

【作者基本信息】 南京信息工程大学 ， 系统分析与集成， 2011， 硕士

【摘要】 降水量是一种重要的气象要素,降水的观测无论是对于气象、水文、海洋、环境的观测还是对航空、铁路交通的安全都具有重要的意义。雨量计是观测降水量的重要仪器,它的准确度直接关系到所测量数据的可靠性,特别在人工降雨的效果检验和气象科研方面,其测量的准确度显得尤为重要。要保证雨量计的精度和可靠性,对雨量计进行校验是非常必要的。目前对雨量计的校验主要是利用标准容器或者精度较高的翻斗式雨量计,也有用手工方法通过量杯进行校验,整个过程工作效率低,而且易造成人为误差,所以需要一种能自动产生所需雨量的校验仪器。论文设计了一种可设置和自动调节流速、流量,用于现场校验的便携式雨量计校验仪。该校验装置由储水室、超声波液位测量单元、阀门、步进电机、人机交互界面等部分组成。储水室通过阀门与排水管道和外界相通,阀门的开度受步进电机控制,通过控制阀门开度来调节水的流速,并控制在一定时间段内水的流量；利用位于储水室上部的收发一体的超声波探头来测量液位高度,并以此来判断水的流量和流速。校验时,通过人机交互界面来设置模拟雨强和模拟降水量,系统根据设定的雨强计算出步进电机转动的步数后控制步进电机转动,调节阀门开度,同时利用超声波实时检测当前液位,通过反馈的方式不断调节水的流量,使流量更均匀、准确。在未达到设定的降水量时保持排水状态,当达到设定的降水量时,控制步进电机反向转动,关闭阀门。最后通过对比雨量计读数判断其是否符合精度要求。为保证测量精度,选用了频率较高的超声波传感器,传感器频率为200KHz；处理器则选用了具有32位定时器及计时频率达50MHz的ARM7芯片,其特有的定时器外部捕获和快中断功能,可以提高超声波脉冲边缘的检测精度和系统的反应时间,从而有助于提高整机的测量精度。与传统的校验方法相比,雨量计自动校验仪避免了人工手动操作带来的不确定因素,可以保持水流量的均匀。此外,该仪器体积小,操作方便,可以用可充电电池供电,便于户外对雨量计进行现场校验,有着较好的应用前景。更多还原

【Abstract】 Precipitation is an important meteorological element. It is significant to measure precipitation not only for the observation of meteorological phenomena, hydrology, marine climate and environment but also for the traffic safety of aviation and railway. Pluviometer is an important instrument to measure precipitation. Its accuracy directly affects the reliability of the measurement data, especially for testing the effect of artificial precipitation and meteorological research, so its measurement accuracy is very important. In order to make sure the precision and reliability of pluviometer, it is very necessary to check the pluviometer. Currently the calibration method for pluviometer is mainly using standard containers or a high accuracy tilting bucket rain-gauge, or through manual method using measuring cup to check out. The entire process is inefficient, and could easily introduce human errors, so we need a calibrator for pluviometer which can generate the desired rainfall automatically.In the paper, a portable automatic calibrator for pluviometer which can be set simulative rainfall intensity and precipitation was designed. It can automatically adjust the current velocity and the flow of water. The calibrator for pluviometer consists of a water container, a unit of ultrasonic liquid level measurement, a valve, a stepper motor and the man-machine interface. The water container connect with outside through the valve and a drainage pipe. The valve opening is controlled by stepper motor to regulate the current velocity. The ultrasonic transducer above the water container is used to measure the current liquid level and then to estimate the current velocity and the flow of water. The instrument can be set simulative rainfall intensity and precipitation through the man-machine interface. According to the simulative rainfall intensity, the system calculates the number of steps which the stepper motor should move to adjust the valve opening. At the same time, the system uses ultrasonic to detect the current liquid level and then controls the stepper motor regulating the current velocity and the flow of water automatically by way of feedback to keep the water flow evenly and accurately. When the flow of water dose not reach the desired precipitation, the valve maintains the drainage state. When the flow of water reaches the set precipitation, the processor controls stepper motor rotate reversely to close the valve. Different rainfall intensity and precipitation can be set to simulate the real rainfall via the man-machine interface. Finally, by comparing with the pluviometer readings, we judge whether it meets the precision demand. To ensure the precision, we use a high-frequency ultrasonic transducer whose frequency is 200KHz and the processor is selected with ARM7 chip which has a 32-bit timer and the clock frequency of CPU reaches 50MHZ. The unique function of external capture and fast timer interruption can enhance detection accuracy of the ultrasonic pulse edge and improve system response time, thus helping to improve accuracy of the calibrator for pluviometer.Compared with traditional calibration methods, automatic calibrator for pluviometer can avoid the uncertain factors by manual operation. It can maintain the water flow evenly, in addition, the equipment is small, easy to operate and can use rechargeable batteries. So it is convenient for checking the pluviometer in the open air and has a good prospect.更多还原