【作者】 李长林；

【导师】 毛恩荣；

【作者基本信息】 中国农业大学 ， 车辆工程， 2014， 博士

【摘要】 针对我国农业机械研发多采用传统设计模式、设计周期长,效率低及产品性能差等现状,本文以农机专业底盘总体设计为研究对象,以联合收割机底盘为例构建了基于知识工程的农机专业底盘快速设计体系；系统研究了农机专业底盘设计知识表示、设计知识获取和存储等关键技术；研究了农机专业底盘快速设计推理机制；集成知识工程与底盘零部件CAD参数化模型构建了农机专业底盘数字化快速设计平台。该设计平台可用于自走式农业机械底盘的快速设计,有助于缩短产品的开发周期,提高产品的开发质量,从而提升我国农机底盘的设计水平。本文的研究工作主要包括以下方面：首先,从农机专业底盘的设计需求出发,研究提出了基于知识的农机专业底盘快速设计TFBS过程模型；在采用农机专业底盘TFBS过程模型实现产品功能结构层次展开的基础上,利用IDEFO功能描述建模方法建立了产品的功能模型；基于TFBS过程模型和IDEFO功能模型构建了农机专业底盘快速设计体系框架。其次,在研究专家经验、设计标准规范的基础上,收集整理了市场现有大量的成熟联合收割机设计案例参数,并综合运用粗糙集和回归分析对现有数据进行挖掘、知识发现,为构建联合收割机底盘快速设计知识库做准备。然后,从分析设计过程知识、启发性知识和经验性知识特点入手,结合当前知识表示技术发展,建立了案例知识的框架表示、启发性知识的规则表示、经验性知识的产生式表示,对总体方案应用面向对象的知识表示方法,对模型知识、经验知识和设计结果进行了封装,建立了总体设计案例类和各系统案例类；基于SQL Server2008关系型数据库,构建了农机专业底盘快速设计系统知识库及其管理系统,主要包括实例库、规则库和资料库。接着,研究了农机专业底盘快速设计推理流程模块；研究了CBR推理中基于面向对象技术的案例表示形式；研究了CBR推理中案例相似度的最近邻算法；研究提出了基于CBR和RBR的农机专业底盘集成推理技术。最后,在上述理论与方法研究的基础上,进行了快速设计平台搭建关键技术的研究。研究了农机专业底盘快速设计模型参数化技术；在此基础上建立了农机专业底盘快速设计参数化模型库；对农机专业底盘快速设计参数化模型库的管理进行了研究；确立了基于知识的农机专业底盘快速设计系统工作流程；基于Visual Studio2008开发平台,集成SQL Server知识库、推理机、Pro/E二次开发,搭建了农机专业底盘快速设计系统平台,并对平台进行了应用实践。基于该平台可以实现农机专业底盘设计过程的快速化。更多还原

【Abstract】 The research and development of agricultural machinery in China mostly adopts the traditional design patterns which have many shortcomings, such as long design cycle, low efficiency, poor product performance and so on. In order to solve these problems, this paper takes the overall design of agricultural machinery chassis as the research objiect. Based on knowledge engineering, a rapid design system of agricultural machinery universal chassis is constructed using the combine harvestser chassis as an example. At the same time, the key technologies of knowledge acquisition, representation, and storage about agricultural machinery chassis design are researched. Then, the inference mechanism of agricultural machinery chassis rapid design is analyzed. By integrating knowledge engineering and the paramatic CAD models of chassis parts and components, the digital rapid design platform of agricultural machinery chassis is built. The platform can be applied for the rapid design of self-propelled agricultural machinery chassis, shorten the development cycle of new product, and improve product quality, thereby enhance the design level of China’s agricultural machinery chassis design. The main research work of this paper includes the following aspects.Firstly, based on the design needs of agricultural machinery chassis, a knowledge-based process model TFBS is presented. The TFBS model is used to realize the functional structure level of agricultural machinery chassis product and on this basis, the functional model of products is formed by using the modeling method of IDEFO functional description. Then a frame of the rapid design system of agricultural professional chassis is built by using the process model TFBS and the functional model IDEFO.Secondly, based on the study of expert experience and design standards, a large number of design parameters of combine harvesters on existing market are collected. Meanwhile, the integrated application of rough set and regression analysis is used to implement data mining and knowledge discovery, which is to prepare for the construction of knowledge base about the combine harvester chassis’ rapid design.Thirdly, from the analysis of characters of design process knowledge, heuristic knowledge and experiential knowledge, combining with the development of the current knowledge representation technology, the article establishes the framework for cases knowledge representation, the heuristic representation for rules knowledge and the production of empirical knowledge. Then the knowledge of models, experience and design results is packed up by using object-oriented knowledge representation for the general scheme, also the overall design case class and the sub-system case calss are formed. Based on relational database SQL Server2008, the knowleege base and it’s corresponding management system are established, including case base, rule base and data base.Next, the module of reasoning process on rapid design of agricultural machinery chassis is studied. In the process of CBR, the object-oriented case representation method and the nearest neighbor algorithm of case similarity are researched. Also, on the basis of CBR and RBR, the integrated resoning technology of the rapid design of combine harvester chassis is put forward. Finally, based on the above theories and research methods, the key technologies of constructing the rapid design platform of knowledge-based agricultural professional chassis are analyzed. The parametric technology of design models is studied and based on this the parametric model base of agricultural machinery chassis rapid design is established. Then, the managing approaches of the parametric model base are researched. Meanwhile, the working process of the knowledge-based rapid design system of agricultural professional chassis is formed. Based on the development platform of Visual Studio2008, integrated SQL Server knowledge base, reasoning machine and Pro/E secondary development, the rapid design platform of agricultural professional chassis is built and practiced. It’s concluded that the platform can achieve the rapid design of agricultural machinery chassis.更多还原