In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the ...In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.展开更多
Redundantly actuated parallel manipulators have the advantage of enhancing load-carrying capability over their non-redundant ones, however they also cause the problem of uneven load distribution and need a high requir...Redundantly actuated parallel manipulators have the advantage of enhancing load-carrying capability over their non-redundant ones, however they also cause the problem of uneven load distribution and need a high requirement for the control system. This paper presents a 2-RPR/RP planar redundantly actuated parallel manipulator which can self-coordinate the distribution of external loads. This capability is realized by an appropriate design of the moving platform to make the manipulator stable at equilibrium position. The stability is proved by the theorem of direct Lyapunov method in classical mechanics. The numerical simulations are conducted to validate the stable capability by means of the observation of potential energies and phase planes. This paper offers an alternative way to design a redundantly actuated manipulator with the capability of self-coordinating the load distribution to actuations, such that parts of the controlling work are assigned to the manipulator itself by its own structure and only a little work remains to the control system.展开更多
Saturation of peripheral oxygen （SpO2） is one of the most important parameters of vital signs. Pulse oximeter based on near-infrared spectroscopy is commonly used as a non-invasive method to measure SpO2 yl. Current...Saturation of peripheral oxygen （SpO2） is one of the most important parameters of vital signs. Pulse oximeter based on near-infrared spectroscopy is commonly used as a non-invasive method to measure SpO2 yl. Currently, medical device manufacturers as well as metrology measurement agencies in China usually use pulse oximeter simulator as the commonly accepted functional calibration equipment for pulse oximeters. So far, no experimental protocol or devices can be used to test the accuracy and reliability of a pulse oximeter simulator. Therefore, a set of new metrology apparatus with the name of calibration device for pulse oximeter simulator have been designed in order to make a traceable system for the calibration or verification of pulse oximeter simulators. The principles and some research methods of this calibration device for pulse oximeter simulator will be discussed in this paper. Besides that, many experiments have been applied in order to guarantee the accuracy as well as traceability of this set of device.展开更多
基金supported by National Basic Research Program of China(973 Program, Grant No. 2006CB705400)
文摘In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2014CB046600)National Natural Science Foundation of China(Grant No.11472172)+1 种基金National Science Foundation for the Youth(Grant No.51305256)Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20130073110039)
文摘Redundantly actuated parallel manipulators have the advantage of enhancing load-carrying capability over their non-redundant ones, however they also cause the problem of uneven load distribution and need a high requirement for the control system. This paper presents a 2-RPR/RP planar redundantly actuated parallel manipulator which can self-coordinate the distribution of external loads. This capability is realized by an appropriate design of the moving platform to make the manipulator stable at equilibrium position. The stability is proved by the theorem of direct Lyapunov method in classical mechanics. The numerical simulations are conducted to validate the stable capability by means of the observation of potential energies and phase planes. This paper offers an alternative way to design a redundantly actuated manipulator with the capability of self-coordinating the load distribution to actuations, such that parts of the controlling work are assigned to the manipulator itself by its own structure and only a little work remains to the control system.
文摘Saturation of peripheral oxygen （SpO2） is one of the most important parameters of vital signs. Pulse oximeter based on near-infrared spectroscopy is commonly used as a non-invasive method to measure SpO2 yl. Currently, medical device manufacturers as well as metrology measurement agencies in China usually use pulse oximeter simulator as the commonly accepted functional calibration equipment for pulse oximeters. So far, no experimental protocol or devices can be used to test the accuracy and reliability of a pulse oximeter simulator. Therefore, a set of new metrology apparatus with the name of calibration device for pulse oximeter simulator have been designed in order to make a traceable system for the calibration or verification of pulse oximeter simulators. The principles and some research methods of this calibration device for pulse oximeter simulator will be discussed in this paper. Besides that, many experiments have been applied in order to guarantee the accuracy as well as traceability of this set of device.
