Research On Assembly Path Planning Of Marine Diesel Engine Pipes

As an important part of the marine diesel engine assembly process,the quality of the pipe assembly directly affects the overall performance of the marine diesel engine.Assembly path planning can realize pipe assembly performance prediction and optimization decision,which is of great significance for improving pipe assembly quality and assembly efficiency.In view of the compact internal space of marine diesel engines and the complicated assembly environment,the pipe assembly path planning faces many difficulties and challenges.This article studies the assembly path planning of marine diesel engine pipes in complex and narrow spaces.The specific research contents are as follows:According to the MBD data structure of the product and the data information requirements in the pipe assembly process,an MBD information model for pipe assembly was established;the characteristics of four CATIA secondary development tools were analyzed,and CAA was determined through a comparison of advantages and disadvantages As a way of developing a path planning system.Through the integration of the existing general pipe modeling standard and the pipe modeling rules built in CATIA system,the modeling specification for marine diesel engine pipe is established;the pipe standard component library module for CATIA system was established With simple structure and limited number of standard parts,a standard parts library for marine diesel engine piping and its accessories used for product assembly was established as the basic module of the marine diesel engine path planning system.The assembly path planning technology is studied by using CAA tool,and the assembly information extraction of marine diesel engine pipe is realized.CAA was used to transform the CATIA’s default pose matrix,and the pipeline’s pose matrix was transformed.Aiming at the characteristics of the marine diesel engine with many parts and the complicated and narrow internal space,an automatic constraint identification function was established,and the function verification was performed by taking the flange as an example.By comparing the performance of several enclosures,the AABB enclosure was selected as the basic unit for the planning of the diesel pipe assembly path.For the complex and narrow assembly environment of marine diesel engines,a double-tree RRT algorithm based on target bias is proposed.Based on the double-tree RRT algorithm,this algorithm introduces a target biased expansion strategy,increases the directionality of the expansion,and enables the random tree to be expanded in multiple steps toward the sampling point.In order to ensure the balance of double-tree expansion,this algorithm improves the traditional double-hibernation alternate expansion method,and selects a tree with a small number of nodes in the exchange order to expand.Aiming at the problem of too many valid path nodes searched by the algorithm and the phenomenon of “foldback”,the piecewise linear fitting method was used to optimize the algorithm.Simulation results show that the algorithm can significantly improve path planning efficiency and path quality in complex and narrow spaces.The assembly path planning system of marine diesel engine pipe and its accessories is developed under CATIA platform based on the above research.Functional modules were built by using CAA secondary development technology,such as the pipe and its accessories standard parts library,assembly path planning,etc.And the improved RRT algorithm was integrated into the CATIA environment.Taking marine diesel engine pipe as an example,an example application of assembly path planning was carried out.