Research On Motion Trajectory Planning Of A Hybrid Automatic Drilling And Riveting Machine

The automatic drilling and riveting system(ADRS)is widely used in aircraft automation assembly because of its high precision and high efficiency.In the process of automatic drilling and riveting,the ADRS needs to guarantee the smoothness of the movement during positioning as well as the good processing performance during the drilling and riveting.Taking a hybrid-ADRS with redundant degrees of freedom as the research object,its kinematic trajectory planning problem was researched.The main research contents are as follows:Firstly,the kinematic forward and inverse solutions of the hybrid-ADRS were analyzed based on D-H method.The kinematical models of the hybrid-ADRS's serial upper and lower end-effectors were established by D-H method.The kinematical model of the asymmetric limited-DOF parallel bracket was established based on the dummy mechanism method and the D-H method.Then the kinematical forward analytical solution of the hybrid-ADRS can be obtained.For the hybrid-ADRS with redundant degree of freedom,a decoupling strategy of the kinematical inverse solution was proposed.Finally,the correctness of the kinematic forward and reverse solutions of the hybrid-ADRS were verified by an experiment.Secondly,the velocity and acceleration of the hybrid-ADRS were analyzed based on loop route equations method.According to the parallel bracket with redundant actuation of the hybrid-ADRS,the combination of the virtual mechanism method and the loop equation method were used to analyze its velocity and acceleration.Additionally,the influence coefficient method was used to analyze the velocity and acceleration of the serial upper and lower end-effectors.After that,the velocity model and acceleration model of the hybrid-ADRS were obtained.At last through a simulation example,the correctness of the kinematical velocity and acceleration equations for the hybrid-ADRS were verified.Thirdly,the algorithm of optimizing the hybrid-ADRS's posture based on the optimal drilling and riveting stiffness and trajectory planning of the hybrid-ADRS were proposed.Considering the effects of redundant actuation and restraining force on stiffness,the complete stiffness model of the parallel bracket was established.Besides,the simplified serial upper and lower end-effectors' stiffness models were established,then the joint stiffness of the serial mechanisms were identified.Moreover,drilling-and-riveting-direction stiffness was used as an index to evaluate the overall stiffness performance of the hybrid-ADRS during drilling and riveting.Taking the index as the optimization goal,an optimization algorithm about the position and posture of the hybrid-ADRS was proposed.A quantic polynomial trajectory planning algorithm for the hybrid-ADRS was proposed as well.The above algorithms were verified by an example for a certain aircraft panel component assembly.The results showed that the optimization algorithm of the drilling and riveting posture can effectively reduce the deformation of the automatic drilling and riveting machine,improve the precision of drilling and riveting,optimize the position and normal direction of the riveting point as well.The trajectory optimization for a given drilling and riveting path can effectively improve the processing efficiency of the hybrid-ADRS.