Algorithm And System Development Of In-situ Measurement Planning For Large And Complex Structural Parts

Large and complex structural parts are widely used in aerospace,transportation and national defense industries.Such parts include many holes,bosses and other features.They are usually interspersed with various measurement tasks during processing.In the task of precision testing of structural parts,large and complex structural parts have a large number of surfaces to be measured,and each surface to be measured has its own set of sampling points.This poses a challenge to the planning of in-situ measurement trajectories.At present,the research is mainly focused on the measurement trajectory planning of a certain surface to be measured.Most of the empty trajectories between the surfaces to be measured are manually completed by technicians.problem.Therefore,it is of great significance to solve the in-situ measurement trajectory planning problem of large and complex structural parts.Aiming at this problem,this paper proposes a new measurement trajectory planning method that comprehensively considers the sampling points of the entire part.The main research contents are as follows:(1)The measurement trajectory of a single surface to be measured is planned.First,according to the analysis of the characteristics of the surface to be measured,the sampling point set is obtained using methods such as curvature adaptive sampling and uniform sampling.Then,according to a selection method based on bounding box proposed in this paper,a variety of starting point and end point combinations of the sampling point set are obtained.Finally,this paper uses genetic algorithm to plan the sampling point set to obtain multiple measurement trajectories for a single surface to be measured.(2)The sequence between the measurement planes is planned.In this paper,a trajectory planning algorithm based on heuristic algorithm is proposed.First,the measurement trajectory of the surface to be measured was genotyped to obtain the data structure of the measurement trajectory of each surface to be measured,and the data structures of features such as holes and bosses were optimized.Then,create the crossover operator,mutation operator,and fitness objective function suitable for the data structure,and obtain the measurement sequence of the surface to be measured through multiple optimization iterations.(3)Collision detection and collision avoidance processing is performed on the global trajectory.Traverse the distance matrix of the heuristic algorithm,use the swept volume method for collision detection for each feasible trajectory,and find the trajectory where the collision occurs,and use the extended bounding box method to create the avoidance point to obtain the collision-free trajectory.(4)Developed an in-situ measurement trajectory planning system.The system is based on Visual C++,calls the three-dimensional data processing kernel ACIS,the three-dimensional model display framework VTK,and the graphical user interface application development framework QT.Finally,the operation demonstration and simulation verification are carried out,which proves that the method proposed in this paper can effectively complete the measurement trajectory planning and significantly improve the measurement efficiency.