The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wal...The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.展开更多
The mass production of plastic parts containing micro structures in optical quality requires molds with corresponding surface quality. These micro structured molds can be produced by UPC （ultra precision cutting）. T...The mass production of plastic parts containing micro structures in optical quality requires molds with corresponding surface quality. These micro structured molds can be produced by UPC （ultra precision cutting）. To produce a high surface quality the ultra precision machine spindles must be well balanced. It is not sufficient to balance the tools and the spindle separately. They have to be balanced while assembled to ensure the required balance quality grade better than G0.4. One possibility to decrease setup times and increase the quality of the spindle balancing is to enhance the unbalance induced vibrations and thus allowing better unbalance detection. In this paper a coupling system between the spindle and machine frame based on flexure joints is presented. The experimental setup provides two states： operational and setup. The operational state provides a high stiffness, whereas the setup state allows the spindle to vibrate along one degree of freedom, enhancing the vibrations created by the unbalance. The system is analyzed concerning its ability to restore the defined conditions in the operational state as well as its capability to enhance the detection of unbalances in the setup state.展开更多
This paper proposes an ontology-driven discovering model for the geographical information services to improve their recall ratio and precision ratio. This model uses the geographical information service ontology. In t...This paper proposes an ontology-driven discovering model for the geographical information services to improve their recall ratio and precision ratio. This model uses the geographical information service ontology. In this paper, first we study the multilevel matching arithmetic of geographical information services. This arithmetic is used for filtering and matching the services in the service register center according to the similarity between services selected and services requested from the definition of the function similarity and credit standing similarity. The matching arithmetic, geographical information service ontology and semantic description constitute the discovering model. Finally, we test and analyze the model from the recall ratio, precision ratio, responsivity and load balance. The result indicates that the ontology-driven discovering model is excellent in recall ratio and precision ratio, and can maintain the dynamic load balance of service copy.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51005239)
文摘The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.
文摘The mass production of plastic parts containing micro structures in optical quality requires molds with corresponding surface quality. These micro structured molds can be produced by UPC （ultra precision cutting）. To produce a high surface quality the ultra precision machine spindles must be well balanced. It is not sufficient to balance the tools and the spindle separately. They have to be balanced while assembled to ensure the required balance quality grade better than G0.4. One possibility to decrease setup times and increase the quality of the spindle balancing is to enhance the unbalance induced vibrations and thus allowing better unbalance detection. In this paper a coupling system between the spindle and machine frame based on flexure joints is presented. The experimental setup provides two states： operational and setup. The operational state provides a high stiffness, whereas the setup state allows the spindle to vibrate along one degree of freedom, enhancing the vibrations created by the unbalance. The system is analyzed concerning its ability to restore the defined conditions in the operational state as well as its capability to enhance the detection of unbalances in the setup state.
基金Supported by the Degree Dissertation of Doctor Natural Science Innovation Foundation of Information Engineering University(2007)
文摘This paper proposes an ontology-driven discovering model for the geographical information services to improve their recall ratio and precision ratio. This model uses the geographical information service ontology. In this paper, first we study the multilevel matching arithmetic of geographical information services. This arithmetic is used for filtering and matching the services in the service register center according to the similarity between services selected and services requested from the definition of the function similarity and credit standing similarity. The matching arithmetic, geographical information service ontology and semantic description constitute the discovering model. Finally, we test and analyze the model from the recall ratio, precision ratio, responsivity and load balance. The result indicates that the ontology-driven discovering model is excellent in recall ratio and precision ratio, and can maintain the dynamic load balance of service copy.
