基于单片机的超声测距系统设计

介绍一种基于单片机的脉冲反射式超声测距系统,提出了系统的总体构成,针对测距系统发射、接收、检测、显示部分的总体设计方案进行了论证,分析了系统各部分的硬件及软件实现。最后文中分析了误差产生的原因,并对系统完善提出了一些建议。     

Landscape irrigation scheduling efficiency and adequacy by various control technologies

Automated residential irrigation systems tend to result in higher water use than non-automated systems. Increasing the scheduling efficiency of an automated irrigation system provides the opportunity to conserve water resources while maintaining good landscape quality. Control technologies available for reducing over-irrigation include evapotranspiration (ET) based controllers, soil moisture sensor (SMS) controllers, and rain sensors (RS). The purpose of this research was to evaluate the capability of these control technologies to schedule irrigation compared to a soil water balance model based on the Irrigation Association (IA) Smart Water Application Technologies (SWAT) testing protocol. Irrigation adequacy and scheduling efficiency were calculated in 30-day running totals to determine the amount of over- or under-irrigation for each control technology based on the IA SWAT testing protocol. A time-based treatment with irrigation 2 days/week and no rain sensor (NRS) was established as a comparison. In general, the irrigation adequacy ratings (measure of under-irrigation) for the treatments were higher during the fall months of testing than the spring months due to lower ET resulting in lower irrigation demand. Scheduling efficiency values (measure of over-irrigation) decreased for all treatments when rainfall increased. During the rainy period of this testing, total rainfall was almost double reference evapotranspiration (ET_o) while in the remaining three testing periods the opposite was true. The 30-day irrigation adequacy values, considering all treatments, varied during the testing periods by 0-68 percentile points. Looking at only one 30-day testing period, as is done in the IA SWAT testing protocol, will not fully capture the performance of an irrigation controller. Scheduling efficiency alone was not a good indicator of controller performance. The amount of water applied and the timing of application were both important to maintaining acceptable turfgrass quality and receiving good irrigation adequacy and scheduling efficiency scores.     

缸内直喷汽油机旋流喷射喷雾特性影响因素的分析研究

为了研究影响缸内直喷汽油机高压旋流喷嘴喷雾特性的因素,对高压旋流喷射初始阶段运动进行了理论分析研究,确定了影响初始喷雾旋流体运动的无量纲参数。通过试验改变空心旋流体内外压差、初始旋流强度、旋流体油膜厚度,发现喷雾特性呈不同的变化趋势。随着旋流体内外压力差的增大,喷雾锥角明显减小而贯穿度变化不大;旋流强度增加,喷雾贯穿距离明显增加,而喷雾锥角变化不大;增加旋流体初始厚度,可以使喷雾在自由空间中外形尺寸增加。     

膜孔灌玉米农田尿素转化和分布特性研究

为了研究膜孔灌玉米农田尿素转化和分布特性,在测坑中进行了膜孔灌和畦灌施尿素试验,分析测定了施尿素后不同时间的土壤铵态氮和硝态氮含量。研究表明：膜孔灌尿素转化完全后,土壤中氮素的主要形态为硝态氮,可作为膜孔灌农田氮素水平评价的指标;基施尿素下,土壤中的硝态氮含量逐渐增大,分布范围以施肥点为中心呈大致成半圆形;灌水方式对尿...     

基于无线传感器网络的土壤信息采集系统

针对土壤信息采集的需要,提出了把无线传感器应用于土壤信息采集的思路,研究设计了一套基于无线传感器网络的土壤信息采集系统。节点设计采用低功耗MSP430单片机和CC2430 ZigBee无线射频芯片完成,可采集土壤温度、湿度和土壤含水率。系统网关设计基于ARM7系列S3C4480X、GPRS模块SIM100,搭建了农田中...     

基于霍尔传感器反馈的AVR单片机直流电机伺服系统设计

文章介绍了以ATmega8单片机作为核心控制芯片,采用PWM控制方式,应用PID控制算法,通过直流电机驱动芯片LM298和霍尔传感器实现的速度反馈闭环控制系统,给出了硬件电路和相应的软件设计.     

基于51单片机的会场人数监控仪

以单片机STC89C51为控制核心的检测装置,利用两对红外发送接收传感器分别检测进入会场和离开会场的人数,单片机通过外部中断实时检测红外传感器输入的电平信号,经过数据处理记录会场当前人数并显示在数码管上,同时可通过语音播放电路播放会场当前人数,通过串口通信将单片机中记录的人数信号传送给计算机并显示.此系统利用单片机控制,能实时检测并播报会场当前人数,具有实用价值,同时具有计算机上显示和语音播放人数等创新.     

基于Kalman滤波的田间导航车辆定位校正方法研究

以装载了RTK-DGPS导航系统的KUBOTASPU-68水田插秧机为试验平台,以姿态测量系统提供载体姿态信息,研究农业机械导航的姿态校正方法。在分析车载GPS倾斜误差产生原因基础上,提出了采用多传感器联合测量载体姿态角以提供校正信息。采用MEMS传感器集成模块ADIS16355作为惯性测量单元,卡尔曼滤波实现传感器信息融合以计算姿态角,设计了姿态测量系统。阐述了两种传感器融合测量实时姿态角的算法,基于ARM7Cotex-M3微处理器设计了姿态测量系统硬件。     

基于AT89S51的蔬菜大棚温控系统设计

以AT89S51单片机为控制核心,以数字温度传感器DS18B20为测温元件,采集温室内的温度信息。通过对当前温室环境的现状进行分析,对温室温度参数进行调节,以达到栽培作物生长发育的需要,为作物的生长提供最适宜的温度环境,大幅提高作物的产量和质量。     

水稻纸膜覆盖插秧机的设计

为加快纸膜覆盖水稻插秧技术的推广,提出设计水稻纸膜覆盖插秧机的基本思路,包括纸膜铺放机构、纸膜切断机构。该设计以期为以后生产样机和进一步优化设计水稻纸膜覆盖插秧机提供参考依据。