Simulation Research On Pose Fitting Calculation And Trajectory Planning Of Fuselages Join

The join of fuselages is always considered as a core part in the assembly process of aerospace products,whose efficiency and quality have an important effect on the cycle,cost and quality of manufacturing.However,many problems,such as low efficiency,poor accuracy and uniformity of quality,are existing in the traditional join method,which is hard to meet the fast-growing needs.Therefore,the implementation of automated join is especially important to improve the production efficiency and quality of products.As two key techniques to implement the task of automated fuselages join,the pose fitting algorithm and trajectory planning method of parallel mechanism are researched and simulated in the dissertation.Based on the analysis of join process,an automated system mainly consisting of laser trackers and parallel mechanism is developed for the join of fuselages.The working principle of the system,along with the laser tracking measurement scheme and the method of expression of pose are introduced.Finally,the kinematics and dynamics analysis of parallel mechanism are presented.In order to realize the pose fitting of fuselages and the moving platform,the datum of coordinate system is constructed first.Then a new least square posture fitting algorithm based on key features of fuselage is proposed.The fixed fuselage is taken as an example and its numerical simulation of measurement is carried out.The initial spatial pose of the moving platform is fitted and calculated by the quaternion method,and a numerical simulation analysis is implemented to verify the method.Finally,the target pose of the moving platform is obtained through the analysis and deduction of pose chain.Through the analysis of the boundary conditions and constraints,three optimizing objectives,i.e.the total time of motion,the total energy consumption and maximum absolute value of links' jerk are defined as three performance indexes to evaluate the planned trajectory of parallel mechanism.The trajectory of moving platform is defined by a fifthdegree B-Splines in Cartesian space.Meanwhile,the artificial immune algorithm is applied to solve the multi-objective trajectory optimization problem.Then the pareto optimization solution set are obtained.Finally,an optimal trajectory determined by average optimal solution is obtained and analyzed.Firstly,the trajectory tracking control system of parallel mechanism is developed and implemented with Simulink and Sim Mechanics.A simulation experimental platform,integrated with the function of pose fitting and calculation,trajectory planning and tracking control,has been designed for the automated join of fuselages.Finally,the function verification test is carried out through a simulation experiment.