Research On The Key Technology Of Intelligent Flexible Assembly Line

The intelligent flexible assembly line puts higher requirements on the assembly precision of the assembly workstation,the controllability of the conveyor system and the optimization degree of the flexible assembly system.In response to these requirements,this paper studies the key technology of intelligent flexible assembly line.A flexible assembly line based on machine vision is designed.Actuator visual online calibration and error compensation method,distributed transport system and its control method and assembly line multi-objective dynamic optimization method are mainly researched.In order to realize the assembly precision and real-time requirements of the intelligent flexible assembly line,the high-precision positioning and capture of the actuator of the assembly workstation,the online hand-eye calibration method of the robot based on the nonlinear optimization model and the automatic compensation method of the actuator error are put forward.In order to avoid the error transmission of the linear hand-eye calibration method,the robot nonlinear hand-eye calibration model is established based on the re-projection coordinate transformation relationship.For various processing and installation errors that are difficult to quantify,various errors of the robot end actuators are combined,and an actuator error model is established based on the difference between the actual and the theoretical offset.Aiming at the assembly precision and real-time requirements of assembly workstations,an online hand-eye calibration and actuator error compensation method is proposed.The quasi-Newton iteration algorithm is adopted as the nonlinear parameter optimization strategy and experimental verification is carried out.For the non-uniform assembly process of process rework,aiming at the flexible assembly intelligence and the requirements of assembly logistics flexibility and intelligence,a distributed transportation system is designed based on the analysis of the shortcomings of the existing material delivery system,Its core control logic is discussed,including power-on initialization control logic,work area reset control logic,and work control logic.And an embedded control system is developed which implements the above control logic.Aiming at the multi-objective dynamic optimization problem of flexible assembly line with workstation revisiting,and combine with flexible assembly intelligence for the intelligent requirements of assembly design optimization and online resource planning.A dynamic multi-objective optimization model is proposed with the goals of maximum capacity of assembly line,minimum manufacturing cost and assembly speed.Considering the workflow constraints,equipment cost constraints and assembly speed constraint,the workstation layout,buffer setting and assembly speed are taken as variables by the model.Genetic algorithm based on population iterative partition is designed to solved the model.Applying the above research results,a flexible transformer assembly line based on machine vision was developed with small and medium-sized transformers as the assembly object.Based on this,the assembly line optimization experiment and the online adjustment experiment to cope with the change of working conditions were carried out.The fast convergence and practicability of the algorithm and the robustness of the system are verified by the analysis of the fitness iterative curve obtained by the experiment,the calculation of the optimized assembly line utilization rate and the calculation of the maximum buffer time of the assembly line after the change of working conditions.