| The macro-micro dual-drive precision positioning mechanism,which can achieve the nano-positioning in large travel range has become a hot research topic all over the world due to its wide applications in the fields of manufacturing and testing of Micro-electromechanical system,large-scale integrated circuit production,biomedical engineering,precision optical engineering,and ultra-precision machining.Under this background,this thesis focuses on the research on the control method of a planar 3-RRR Parallel Mechanism and the coupling characteristics of Macro-Micro dual-drive Precision Positioning Mechanism.Firstly,a macro-micro dual-driven precision positioning system based on 3-RRR parallel mechanism is proposed.According to the load effect generated from micro positioning mechanism mounted on the macro positioning mechanism,a theoretical dynamics model of the macro-micro precision positioning system is established,relying on which we can discuss the influence of micro positioning mechanisms with various mass to the macro positioning system and the influence to the driving joints while the end of macro-micro system is at different speeds.Secondly,an intelligent control algorithm for the macro 3-RRR parallel mechanism is proposed in order to ensure the positioning accuracy of the mechanism under different interference factors.Considering that the motion control system of the macro 3-RRR parallel mechanism is based on the kinematic inverse solution,and that the changes in time-varying joint clearance,load and other factors can largely affect the 3-RRR's absolute positioning accuracy during the use of it,two kinds of control algorithms based on neural network adjusting PI control parameters were designed.Lastly,the experimental research is designed to evaluate the performance of the macromicro dual-drive positioning system.First of all,the macro-micro precision positioning systems are integrated and displayed.Each part's hardware and software system are briefly introduced.Afterwards,by setting up two kinds of mechanism end measurement systems,the 3-RRR macro positioning mechanism's control loop is fully closed.At the same time,the human-computer interaction control system is combined with the measurement module designed using C# language to ensure that the system is efficiently operated.Then the two measurement systems' measuring accuracy are evaluated by using a laser interferometer.In the section of system control,the full-closed-loop precision positioning experiment based on two neural network tuning PI control parameters was performed on the 3-RRR macro parallel mechanism,which verified the validity of the theory of intelligent control algorithm.Then,the macro-micro coupling characteristics of the macro-micro dual-drive precision positioning system are conducted through several sets of experiments,which the coupling phenomena of the macromicro coupling part are described and analyzed. |
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