Papers by Keyword: Kinematic Accuracy

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Authors: Qiang Yang, Zhi Li Sun, Yan Yan Shi, Dan Dan Jia, Yu Tao Yan
Abstract: Five-axis CNC machine tool is the top product of numerically controlled machine tool. Kinmatic accuracy is an important index to evaluate the quality of mechanism. Kinematic accuracy analysis of the Five-axis machine tool in previous study ignores the randomness of each input error component, so the conclusions are imprecise. Using the homogeneous transformation, inverse kinematics of VMC650 Five-axis machine tool is calculated. Based on Multi-body System Theory, error model of the machine tool is presented. Considering the randomness of every input error components, applying the Monte Carlo method, math model of kinematic reliability of the mechanism is deduced. The calculation method of kinematics reliability are put forward applying point evaluation and track evaluation. Kinematic reliability analysis provides some theoretical reference for improving the machining accuracy and operation life of machine tool.
Authors: Jian Guo Zhang, Jian Jun Chen, Jing Li Du
Abstract: By using gray theory model, the problem with less data and poor information is easy to be solved. Thus, the grey theory and the reliability assessment method were connected to analyze the mechanism motion. At first, the concept and model of mechanism’s grey movement reliability were presented. And then, from the limit state equations of a mechanism’s moving function and kinematic accuracy, the gray reliability calculation formulas were deduced. Finally, combined with two examples the method was applied to the actual reliability analysis. The results show that the method is feasible and efficient, so it is practical to apply the grey reliability model in mechanism reliability analysis.
Authors: Bing Li, Li Yang Xie, Yu Lan Wei, Ying Wu, Ming Yang Zhao, Shi Zhe Xu
Abstract: The reliability of kinematic trajectory of manipulators describes the ability that manipulators keep kinematic accurate. It is an important parameter to evaluate the performance of manipulators. The kinematic accuracy of manipulators can be improved when piezoelectricity material are used as a transducer to suppress the vibration of flexible manipulators. First, a 3 degree-of-freedom parallel manipulator system and its dynamic equations are introduced. The theory and experiment of a vibration suppression system are then presented. The calculation method of both error and reliability of kinematic trajectory of manipulator is further implemented. Finally, the reliability of kinematic accuracy are calculated and analyzed for the 3 degree-of-freedom parallel manipulator with or without vibration suppressing control. The results show that the reliability of kinematic accuracy is improved using vibration suppressing control.
Authors: Yang Qiang, Geng Hua Wang, Bian Ji, Luo Hao
Abstract: Considering the flexibility performance of lightweight slender axle in Delta parallel mechanisms, the effects of the elastic deformation on the kinematic accuracy of the mechanism are calculated based on the virtual prototype technology. Firstly, the 3D model of the mechanism is built via ADAMS software. Secondly, the geometric model of the driving rod is imported into ANSYS software to get meshed and generate the modal neutral files. Then, getting back to ADAMS, the original rigid component is replaced with the flexible body which constraint and driving is added to lately. At last, the rigid-flexibility hybrid model of the mechanism is built. Each frequency and vibration mode of the flexible body is calculated, using the simulation capabilities of the software. Furthermore, changes in motion accuracy of the mechanism under the effect of the force-elastic coupling are analyzed comparatively.
Authors: Rui Jun Zhang, Qing Xuan Jia, Liu Meng, Ji Wei Qiu
Abstract: A kind of accuracy sensitivity analysis and numerical simulation method about the mechanism kinematic is proposed for the purpose of getting the reliability sensitivity of the planar mechanism. Combining with the reliability sensitivity analysis method and the computer simulation technology, this method is on the basis of the research of the kinematics equations and the mechanism kinematic accuracy model. Taking the kinematic accuracy sensitivity analysis of the planar four-bar mechanism as an example, the results verify the effectiveness and feasibility of the method.
Authors: Qing Zhong He, Wen Chun Zhao, Jia Wang, Yan Ling Zhang, Ming Chao Wang
Abstract: The new type of pipeline-cleaning robot discussed in this paper is developed to clean pipelines within the diameter range 200mm-250mm, which is propelled by using screw locomotion. With the help of CATIA, the modeling & simulation software, the simulation model of the robot and its vibration analysis has been obtained. From the analysis, dynamic characteristics of pipeline robot vary with the output parameters of control module and the structures of robot joints. Stimulated vibration has very little influences on the whole machine. The stability and reliability of the robot have been proven. According to the experimental study of principle prototype and dynamic simulation study of the virtual prototype, dynamic characteristics can be improved by optimizing the structures of robot and the related output parameters of control module, which contributes to the improvement of its motion stability. Therefore, it is believed that the robot has great value in practical use.
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