Research On Rapid Design Method Of Combine Harvester Cleaning Device

Aiming at the problems of complex design knowledge and low efficiency of reasoning model in rapid design of cleaning device of rice-wheat combine harvester,a graphical knowledge representation method and inference engine that can intuitively reflect the relationship among design knowledge were studied,and the inference engine of cleaning device was established to realize the reasoning of design parameters of cleaning device.The parametric model library of key parts of cleaning device was established,and the automatic assembly technology of the model was studied to realize the automatic assembly of the parts model of cleaning device.This paper realises an intelligent design process from the calculation and reasoning of design parameters by inference engine to the establishment of parametric model according to design parameters,and finally to the automatic assembly,which helps to shorten the development cycle of cleaning device and improved the design efficiency.The research can be divided into the following four parts :(1)The arrangement,representation and storage of cleaning device design knowledgeThe design knowledge of cleaning device was sorted out,and the representation method of design knowledge was studied.The IF-THEN production expression method was used to express the design knowledge of cleaning device as the production rule.According to the relationship between the parameter transmission of design knowledge of cleaning device,the production rule was further expressed as a graphical model,so that the independent rules were integrated into a whole knowledge model,which directly reflected the relationship between design knowledge.The storage method of design knowledge of cleaning device was studied.SQL Server database was used as the storage tool,and the design knowledge of cleaning device was stored in the database in the form of production rules.The rule base of cleaning device was established,which provided a knowledge basis for the establishment of reasoning machine of cleaning device.(2)The establishment of reasoning machine based on Petri netThe knowledge representation and reasoning mechanism of cleaning device based on Petri net were studied.The corresponding relationship between production rules and Petri net elements was studied,and the design knowledge of the key components of the cleaning device was further expressed as the form of Petri net model according to the interrelation between the design knowledge of the cleaning device and the design processed of the cleaning device,which made the connection between the design knowledge more clear and the design process more clear,and provided the basis for the establishment of the inference engine.Using CPN Tools software as Petri net modeling tool and CPN ML programming language,the parameters and rules of design knowledge needed in the reasoning process were defined.Combined with Petri net representation model of cleaning device design knowledge,a cleaning device reasoning machine based on Petri net was established.Through the simulation of the inference engine,the inference from design requirements to size parameters in the key components of the cleaning device was realized.(3)Research on parametric design and automatic assembly method of cleaning deviceUsing Visual Studio as the development platform,the secondary development of UG NX was carried out.According to the structural characteristics of the key components of the cleaning device of the rice-wheat combine harvester,the interactive dialog box of the cleaning device model design was created by using the NX / OPEN UIstyle tool.Using UG / Open API function,the parameterized model of cleaning device was programmed,and the model library of cleaning device was established.The parametric design was deeply explored,and the automatic assembly method of assembly parts was studied.According to the assembly relationship between the key parts of the cleaning device,the automatic assembly method based on coordinate position and constraint relationship was used.The automatic assembly program was written by calling UG / Open API function,and the assembly model of the cleaning device was constructed to realize the automatic assembly of the parametric model of the key parts of the cleaning device.(4)Reasoning example of cleaning deviceBy using the inference engine,parametric design and automatic assembly technology,the rapid design of cleaning device and the output of parametric assembly model of rice-wheat combine harvester were realized.Firstly,the design requirements of the cleaning device were input into the inference engine based on Petri net,and the design parameters of the cleaning device were output after the calculation and inference by the inference engine.Then the model library of cleaning device generated the parameterized model of cleaning fan,cleaning screen and driving device according to the size parameters.After automatic assembly,the parametric model of each part was assembled into the cleaning device.Finally,the model was simulated to verify the feasibility of reasoning design based on Petri net.