Research On Structure Optimization And Control Of Automatic Hole-making End Effector

Robotic hole-making systems are widely used in aircraft manufacturing due to their high flexibility,large workspace,and high drilling efficiency.The hole-making end effector is the core component of the robot hole-making system,and its performance directly affects the machining quality of the workpiece.In this thesis,the mechanical structure optimization and countersink depth control of hole-making end effector were thoroughly studied by means of theoretical analysis,computer simulation and experimental verification.The purposes of this research are to realize the lightweight and high precision hole making process of the end effector.The main research content of this thesis is as follows:(1)A chassis structure optimization method combining topology optimization and size optimization was proposed to realize the structural optimization design of the hole-making end effector.According to the workflow of the robot hole-making system and the functional requirements of the hole-making end effector,the structure composition and overall design of the hole-making end effector were determined.Aiming at the problem of large weight of the chassis of the hole-making end effector,the topological optimization of the chassis was carried out by variable density method.Then,the improved harris eagle algorithm was used to optimize the initial weight threshold of the BP neural network algorithm,and the chassis sizes were optimized based on the improved BP neural network algorithm,and the optimal sizes of the chassis were obtained.The modal analysis of the optimized hole-making end effector as a whole shows that its dynamic characteristics fully meet the functional requirements.(2)A mathematical model of the feed unit of hole-making end effector was established,and research on the compensation control method for countersink depth error was carried.On the basis of analyzing the source of countersink depth error,an error compensation control strategy was developed and a fuzzy PID controller was designed.In order to further improve the control performance of the fuzzy PID controller,a universe regulator was introduced to improve its control accuracy and adaptive ability by adjusting the universe of the fuzzy PID controller in real-time.The simulation and comparison experiments prove that the variable universe fuzzy PID has better control effect.(3)In order to verify the effectiveness of error compensation control strategy in improving the accuracy of countersink depth,an experimental platform of hole-making end effector was built,and hole-making comparative experiments were conducted on countersink depth error compensation.The aperture and countersink depth were measured by image measuring instrument and the countersink depth precision of before and after error compensation was compared.Through the comparison of experimental results,it is found that the accuracy of countersink depth after the error compensation is significantly improved,and the accuracy of the hole diameter also meets the requirement of hole making accuracy.