Research On Flexible Positioning Mechanism Based On Parallel Configurations For Aircraft Assembly

With the continuous development of the aviation industry and constantly being produced of new generation aircraft,a higher demand for aircraft service time is represented by aircraft industry.Service-life for aircraft is conditional on assembly quality,but high-quality and accurate assembly has to depend on flexible positioning.The assemblies on the plane is thin-walled structure with large size and complicated shape,deformation will be caused easily under stress.At this time,the flexible positioning tools are necessary to ensure the quality of hole and riveting.In recent years,Applications of parallel mechanisms with fast response,high precision and strong bearing capacity on aircraft assembly show remarkable technical superiority.Aiming at the requirements of the positioning for aircraft panel parts,a flexible positioning mechanism based on parallel configuration is designed by modular organization,a further study on actuating configuration and positioning precision about 3-RPS parallel mechanism is carried out.The main contents of this paper are as following:(1)In order to meet the positioning requirements for aircraft fuselage panel parts with different curvature radius,a flexible positioning mechanism based on parallel configuration with 5 degrees of freedom is proposed,which can achieve all-wave position and posture alignment of the panel parts.(2)Actuating configuration of 3-RPS parallel mechanism is studied.Firstly,based on the dihedral group and screw theory,the rationality of actuating input scheme is analyzed.Then the manipulability as an evaluation index is established and the optimum scheme of three prismatic pairs as 3-RPS mechanism actuating configuration is obtained by MATLAB programs.Finally,the effectiveness and practicability of actuating configuration are identified by the simulation of ADAMS.(3)Kinematics precision of 3-RPS parallel mechanism is studied.A compensation strategy for the pose error caused by joint clearance is imposed by optimizing the parameters to displacement compensation of the drive rods.According to the forward kinematics,the system error model is established.Fuzzy set theory and Non-dominated sorting genetic algorithm-?are used to optimize actuated volume,which improved the posture and position precision of the mechanism.Actuating configuration and Error analysis of 3-RPS parallel mechanism are studied in this paper,which provides technical support for the development of flexible positioning mechanism based on parallel configurations for the assembly of airplanes.