摘要
大型平移式喷灌机虚拟试验研究是“十一五”国家科技支撑计划课题——农业装备虚拟试验技术研究(2006BAD11A1706)的研究内容之一。传统的大型喷灌机试验,不仅需要符合试验要求的场地、水源和电源,而且需要安装、调试喷灌设备,经过重复多次喷洒、测量,最后计算试验数据,存在费时、费水、费力、费钱等问题。本文研发的基于Multigen Creator和Vega的大型平移式喷灌机虚拟试验系统,通过建立和优化喷灌数学模型,利用虚拟现实技术,在计算机上进行大型平移式喷灌机喷灌仿真试验,不仅克服了传统喷灌试验的不足,而且减少资源的浪费,降低成本,提高效率,节水环保。
本文的主要工作如下:
1.概述了大型平移式喷灌机的喷灌试验技术的国内外研究现状和发展趋势,确定了基于Multigen Creator和Vega的大型平移式喷灌机虚拟试验系统的研发总体方案和技术路线。
2.研究了虚拟现实的建模和渲染方法,建立了大型平移式喷灌机的三维立体模型;创建了LOD地形细节层次,利用Polymesh算法对地形模型进行优化处理,通过纹理贴建立逼真的喷灌机虚拟试验场景。
3.在研究分析大型平移式喷灌机的工作原理、结构参数、运动参数等与喷灌均匀度相关的参数的基础上,建立了一种计算大型平移式喷灌机的单个喷头喷灌强度的数学模型。
4.喷灌均匀度是衡量喷灌质量好坏的关键指标之一,本文提出了一种基于虚拟试验技术的大型平移式喷灌机喷灌均匀度的计算方法,开发了喷灌机喷灌均匀度的参数化模型接口。
5.基于粒子系统的相关理论,定义了喷灌机水滴的数据结构体,设置了喷灌机喷头水滴的产生、生长和消失的条件,通过调用OpenGL的图形库函数和回调函数在虚拟环境中展现喷灌机的喷灌效果,用户可以通过计算机与虚拟环境中的个体进行自然交互,逼真的观察、体验虚拟试验的过程。
6.通过分析大型平移式喷灌机的喷洒过程,建立了大型平移式喷灌机在无风条件下的水量分布模型。以Microsoft Visual C++6.0为平台开发了大型平移式喷灌机虚拟试验系统,并以PY10型喷头为例,对该虚拟试验系统进行了多次仿真验证。
本文的主要创新点如下:
1.提出基于虚拟试验系统的大型平移式喷灌机的喷灌均匀度计算机辅助系统,用该计算机辅助系统可以计算出不同喷头间距,不同喷嘴直径下的大型平移式喷灌机的喷灌均匀度。
2.进一步改进了大型平移式喷灌机喷灌强度的计算模型,对开发喷灌均匀度的参数化模型接口具有重要意义。
This project was supported by“11th Five-Year”National Science andTechnology Support Programme project“agriculture equipment virtual testtechnology (Project’s number:2006BAD11A1706). Traditional LargeIrrigation System Test need not only site,water, and power fitting for tesrequirements but also installating, debugging the irrigation equipment. The tesdata is finally calculated through measuring the spraying depth repeatedly. Thismethod is difficult,water-wasting and time-consuming etc.Lateral movesprinkler irrigation’s virtual experiment system based on Multigen Creator andVega,which is simulated in computer by virtual reality technology, has createdand optimized mathematical model.This simulating experiment not onlyovercame the deficiency of traditional irrigation test and save resources, reducethe cost, improve efficiency and protect water environment.
The main work of this paper is as follows:
1. The present research progress of lateral move sprinkler irrigation’ssprinkler test technology is reviewed and overall planning and technologyroute of virtual test system about Lateral move sprinkler irrigation based onMultigen Creator and Vega is created in this paper.
2. The method of establishing and rendering the models in the virtuareality system is researched. The 3D model of lateral move sprinkler irrigationis established. The terrain model is created and optimized using the LODterrain hierarchy and polymesh algorithm.The virtual realistic scene about thesprinkler irrigation is set up by texture maps.
3. Based on analyzing the lateral move sprinkler irrigation’s workingprinciple, structural parameters, motion parameters and so on related toirrigation uniformity, a mathematical model for calculating the sprinklerintensity of a single sprayer is established.
4. Sprinkler uniformity(Cu) is an important indicator to evaluate thequality of sprinkler irrigation.A algorithm of sprinkler uniformity based onvirtual experiment technology is brought out and the interface of sprinkler uniformity machine parametric model is developed.
5. Data structure of water droplets is defined and the conditions of the sprinkler water droplets’produce, growth and disappearance is installed based on the theory of particle system in this paper. Irrigation of sprinkling machine is shown in the virtual environment by calling the OpenGL graphics library functions and the callback function. Users can observe and know the process of virtual test.What’s more,users can interact with virtual prototyping by computer.
6. The water distribution model of lateral move sprinkler irrigation in no wind conditions is established through the analysis of irrigation’s working process. With the use of Microsoft Visual C++ 6.0, virtual sprinkler irrigation test system is developed in this paper.For the example of PY10-type nozz -le,many simulating test is done.
The main innovation of this paper is as follows:
1. It is the first time to develop a computer-aided system of sprinkler irrigation aiming at uniformity, This system used to calculate the sprinkler irrigation uniformity under conditions of different nozzle distance and different nozzle diameter.
2. the calculation model of sprinkler irrigation’s sprinkler intensity is more improved in this paper which plays an important in exploiting parametric model interfaces of sprinkler uniformity.
引文
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