Digital wheel slipmeter for agricultural 2WD tractors

A microcontroller based digital slipmeter was developed for agricultural two wheel drive (2WD) tractors. The actual and theoretical speeds of tractor were calculated by measuring the revolutions per minute (RPM) of front wheel and rear wheels, respectively, using optical slot sensors. A microcontroller was programmed to calculate the actual forward speed and wheel slip of the tractor. These measured values were digitally displayed on the tractor dashboard. The slipmeter was fabricated in such a way that it could be mounted on any make and model of 2WD tractor. The slipmeter was rigorously tested in the laboratory as well as in the field with different tractor-implement combinations. A maximum of ±2 per cent variation was observed between measured and indicated wheel slip.     

Using a vision sensor system for performance testing of satellite-based tractor auto-guidance

A vision sensing system for the measurement of auto-guidance pass-to-pass and long-term errors was implemented to test the steering performance of tractors equipped with auto-guidance systems. The developed test system consisted of an optical machine vision sensor rigidly mounted on the rear of the tested tractor. The center of the drawbar hitch pin point was used as the reference from which to measure the deviation of the tractor's actual travel path from its desired path. The system was built and calibrated to a measurement accuracy of better than 2 mm. To evaluate the sensor, two auto-guidance systems equipped with RTK-level GNSS receivers were tested and the results for different travel speeds compared. Pass-to-pass and long-term errors were calculated using the relative positions of a reference at a collocated point when the tractor was operated in opposite directions within 15 min and more than 1 h apart, respectively. In addition to variations in speed, two different auto-guidance steering stabilization distances allowed for comparison of two different definitions of steady-state operation of the system. For the analysis, non-parametric cumulative distributions were generated to determine error values that corresponded to 95% of the cumulative distribution. Both auto-guidance systems provided 95% cumulative error estimates comparable to 51 mm (2 in.) claims and even smaller during Test A. Higher travel speeds (especially 5.0 m/s) significantly increased measured auto-guidance error, but no significant difference was observed between pass-to-pass and long-term error estimates. The vision sensor testing system could be used as a means to implement the auto-guidance test standard under development by the International Standard Organization (ISO). Third-party evaluation of auto-guidance performance will increase consumer awareness of the potential performance of products provided by a variety of vendors.     

Tractor_PT: A traction prediction software for agricultural tractors

Traction prediction modelling, a key factor in farm tractor design, has been driven by the need to find the answer to this question without having to build physical prototypes. A wide range of theories and their respective algorithms can be used in such predictions.The “Tractors and Tillage” research team at the Polytechnic University of Madrid, which engages, among others, in traction prediction for farm tractors, has developed a series of programs based on the cone index as the parameter representative of the terrain. With the software introduced in the present paper, written in Visual Basic, slip can be predicted in two- and four-wheel drive tractors using any one of four models. It includes databases for tractors, front tyres, rear tyres and working conditions (soil cone index and drawbar pull exerted). The results can be exported in spreadsheet format.     

A program in Visual Basic for predicting haulage and field performance of 2WD tractors

A tractor drawbar performance program that predicts the performance of two-wheel-drive (2WD) tractors for haulage as well as field operations for both bias-ply and radial-ply tyres is developed to meet user requirements in educational and research organizations. The program is written in Visual Basic programming language. The program provides an intuitive user interface by linking databases such as tractor specifications, tyre data, implement and trailer specifications and traction equation coefficients to predict the performance of a selected tractor model. The program has been proven to be user friendly and efficient for various field operations under frictional–cohesive soils.     

水稻模拟模型研究与发展趋势

介绍了水稻模拟模型的主要功能与特征,综述了主要水稻模拟模型及其特点,分析了现有模拟模型的发展趋势,提出了水稻模拟模型研究存在的不足,并展望了今后的研究方向及应用前景。     

大豆生长模拟模型SOYGRO的引进、二次开发及应用

本文概括地介绍了美国大豆生长模拟模型SOYGRO的引进及基于此模型开发的、具有独立知识产权的“大豆生长模拟模型决策支持系统(SMD)”V1.0版本的开发、功能及应用情况。     

小麦生长模拟过程可视化软件的研究

本文介绍了小麦生长模拟过程可视化软件的设计思想和实现的关键技术，该软件具有通用性和独立于模型的特点，并通过器官库的支持来实现小麦的造型部分。最后讨论了实现的关键技术，包括器官库的构建技术、三维图形的绘制技术、用户交互技术。     

基于ADAMS的轮式拖拉机行驶平顺性研究

基于Pro/E软件平台,构建拖拉机-座椅悬架系统简化的几何模型,并将其导入ADAMS软件,编写轮胎属性文件与路面激励文件,构建拖拉机-座椅-路面系统的虚拟样机。针对不同的行驶速度与路面激励,对拖拉机的行驶平顺性进行仿真分析,探究行驶速度与路面激励对拖拉机平顺性的影响。结果表明,行驶速度与路面激励不平度对拖拉机行驶平顺性具有重要影响,以较高车速行驶时,驾驶员垂直方向振动强度明显高于较低车速的振动强度;在粗糙路面上行驶时,驾驶员的主观振动感明显强于平坦路面的振动感。增设座椅悬架系统改进拖拉机座椅结构,探究增设座椅悬架系统对行驶平顺性的影响,结果表明,增设座椅悬架系统可以明显降低其垂直方向的振动幅度,避开人体内脏器官和脊椎系统振动敏感频率区域,提高拖拉机行驶的平顺性。     

手扶拖拉机组制动性能的试验研究

通过对手扶拖拉机组制动初速度、载重量、制动力矩和道路等因子的试验和分析，得出影响机组制动性能的各因子定量数学表达式．     

基于滑转率的拖拉机驱动防滑模糊PID控制算法仿真分析

对基于滑转率的拖拉机驱动防滑模糊PID控制算法进行了仿真分析。首先建立系统的数学模型,并用Matlab/simulink建立计算机仿真模型,然后设计系统的模糊PID控制器,并进行了仿真分析,观察控制效果,同时用PID控制算法、模糊控制算法进行仿真研究,分别进行响应性、抗干扰性、适应性的对比分析,对比发现,模糊PID控制算法较为合适。     

设施番茄果实生长及产量形成模拟模型

为探明番茄果实生长与温度、光照的关系以及建立番茄产量预测的新方法,该研究对不同播期、品种、氮素水平及茬口的试验数据进行处理,构建了反映果实生长与温度、光照关系的果实横、纵径生长模型,以及果实干物质机理性模型和果实鲜重与横、纵径关系的线性模型,并建立了以上述模型为基础的番茄产量预测模型。运用独立数据对产量模型进行验证,结果显示:在不同氮素水平下,当利用干物质机理性模型模拟番茄产量时,模拟值与实测值的RMSE和ADe都小于30 g(每株);当用果实横径经验性模型模拟番茄产量时,RMSE和ADe都小于35 g(每株);当用果实纵径经验性模型模拟番茄产量时,RMSE和ADe都小于40 g(每株)。表明番茄产量模型均具有较高的预测精度,能够很好地模拟番茄产量,可为设施番茄生产提供理论依据和决策支持,其中利用果实横、纵径的线性关系模型来预测番茄产量,具有参数少、不破坏果实活体、实用性强等特点。     

利用作物模拟模型辅助决策小麦新品种推广初探

在田间试验和前人研究的基础上,以比较成熟的CERES—WHEAT模型为研究工具,以我国的主要作物小麦为研究材料,探讨了作物模型在区域试验和良种评价方面的潜在应用。目的在于应用作物模型的动态性和预测性功能,利用品种已有生理和遗传参数以及各地的气象、土壤资料,对冬小麦不同品种同一地点和同一品种不同地点的生育期、物候期、产量和产量构成因素进行预测,并与实测值进行比较,最后对品种的生态适应性进行综合评价,并在品种产量表现和生态适应性等方面为品种区域试验和良种推广提供决策的依据。辅助指导和决策河北省小麦新品种引进、试验和推广,提出了作物模拟模型辅助决策小麦新品种推广的应用模式。     

拖拉机性能自动检测车的研制

研究了一种拖拉机性能自动检测车，该检测车采用机，电，液，电子和计算机等综合技术，具有操作简单，测试项多，测试精度高等特点，能对拖拉机的左右制动性能，轴重，车速，烟度，灯光，噪声进行自动测试，实际应用表明，该新型测车可作为农机管理部门，拖拉机检测和维修部门开展拖拉机年检审工作和技术状态检测的设备。     

拖拉机新型线控液压转向系统的研究与仿真

对拖拉机线控液压转向系统进行了总体设计,详细分析了其结构组成和工作原理,并通过对比分析得出了系统的最优控制算法。采用模糊控制作为系统的控制算法,实现了前轮转角的闭环控制技术;最后采用Matlab/simulink对整个系统进行仿真,得出了油缸位移的响应曲线,验证了系统设计的准确性。     

水稻超高产株型的可视化模拟研究

在概述水稻株型及作物模拟技术发展的基础上，提出了水稻超高产株型可视化模拟的技术路线与技术指标，并对存在的问题进行了探讨。     

A simulation model-assisted study on water and nitrogen dynamics and their effects on crop performance in the wheat-maize system I: The model

Based on data collected from field experiments, a comprehensive model was built on the Ithink (a registered trademark of iSee Systems) platform to simulate the dynamics of water and nitrogen, and crop performance in the winter wheat-summer maize double cropping system of the North China plain. The model, consisting of seven sub models, i.e. weather generator, phenology, biomass, dry matter partitioning, water balance, nitrogen balance, and nitrogen absorption and partitioning, well reflects water and nitrogen use and their relationship with crop yield under field conditions. A vertical water movement equation is employed in the water balance sub model to account for movement between layers. Crop transpiration and soil evaporation are simulated separately according to potential evaporation, crop cover and a soil water deficit coefficient. Soil evaporation is from the surface layer only while crop transpiration comprises the total amount of water absorbed by the root system from all soil layers. The model considers that nitrogen transformations, transfers and uptake are fulfilled by root systems. Transformation of nitrogen as mineralization, fixation and denitrification are responsive to soil moisture and temperature. Nitrogen movement is simulated with a convection-dispersion equation with nitrate as the soil solute. Nitrogen absorption and partitioning sub model includes the effects of water and nitrogen supply, crop nitrogen demand and nitrogen content in various crop organs. The model can be used to simulate crop yield, water-and nitrogen-use efficiencies and water-nitrogen leaching to specific soil layers in different water and nitrogen management practices.     

作物生长模拟模型研究进展

作物生长模拟模型是对作物生长发育过程及其与环境条件、栽培管理技术的动态关系进行的定量描述和预测,模型的研究有利于农业科学成就的综合集成,同时也是作物种植管理决策现代化的基础.为此,较系统阐述了作物生长模拟模型的定义、发展、特点及建模原理.分析了目前国内外取得的成果及存在的问题.在此基础上指出作物生长模拟模型研究应趋于微...     

GIS支持下水质模型模拟的实现研究

通过对水质模型与ＧＩＳ技术下ＤＳＳ模块的数据结构及两者间数据的传输分析,应用动态分段技术,实现了水质模型模拟与ＧＩＳ技术的结合。为完成国家省级环境信息管理系统提供了科学依据,为水质模型模拟的发展提供了一条新途径。     

北京市水资源承载力系统动力学模拟

利用系统动力学(SD)方法建立了北京市水资源承载力SD模型,选取工业、农业总产值和可承载的城镇人口数量作为北京市水资源承载力的衡量指标,在现状延续、节水兼污水再生回用、节水兼境外调水和综合型4种方案下模拟2003—2020年北京市水资源承载能力的动态变化,寻求提高北京市水资源承载力的途径。结果表明:现状延续型用水模式水资源承载能力十分脆弱,难以满足未来北京市社会经济发展的需求,承载的城镇人口自2010年开始递减,城市规模开始萎缩;采用污水回用或境外调水模式,虽然工农业总产值维持快速发展,但仍然承载不了与之对应的城市人口规模。在建设节水型社会的前提下,实施污水回用和境外调水的综合型方案,到2020年可承载的工业、农业总产值和城镇人口分别达10 698.6亿元、679.5亿元和1 778.3万人;综合型方案是提高北京市水资源承载力的满意方案。