Clearances in the joints of real mechanisms are unavoidable due to assemblage, manufacturing errors, and wear. The dual-axis driving and positioning mechanism is one kind of space actuating mechanism for satellite antenna to implement precise guidance and positioning. However, in dynamics analysis and control of the satellite antenna system, it is usually assumed that the revolute joint in the satellite antenna system is perfect without clearances or imperfect with planar radial clearance. However, the axial clearance in an imperfect revolute joint is always ignored. In this work, the revolute joint is considered as a 3D spatial clearance joint with both the radial and axial clearances. A methodology for modeling the 3D revolute joint with clearances and its application in satellite antenna system is presented. The dynamics modeling and analysis of the satellite antenna system are investigated considering the 3D revolute clearance joint. Firstly, the mathematical model of the 3D revolute clearance joint is established, and the definitions of the radial and axial clearance are presented. Then, the potential contact modes, contact conditions, and contact detection of the 3D revolute clearance joint are analyzed. Further, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in the 3D revolute clearance joint. Finally, a satellite antenna system considering the 3D revolute clearance joint with spatial motion is presented as the application example. Different case studies are presented to discuss the effects of the 3D revolute clearance joint. The results indicate that the 3D revolute clearance joint will lead to more severe effects on the dynamic characteristics of the satellite antenna system. Therefore, the effects of axial clearance on the satellite antenna system cannot be ignored in dynamics analysis and design of the satellite antenna system.

中文翻译：

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考虑3D旋转间隙联合的卫星天线系统动态特性研究

由于装配，制造错误和磨损，不可避免地要在真实机构的接头处留出间隙。双轴驱动和定位机构是一种用于卫星天线的空间致动机构，以实现精确的引导和定位。然而，在卫星天线系统的动力学分析和控制中，通常假设卫星天线系统中的旋转接头是完美的，没有间隙，也没有完美的平面径向间隙。但是，不完善的旋转接头中的轴向间隙始终被忽略。在这项工作中，旋转关节被视为具有径向和轴向间隙的3D空间间隙关节。提出了一种带有间隙的3D旋转关节建模方法，并将其应用于卫星天线系统。考虑了3D旋转间隙接头，研究了卫星天线系统的动力学建模和分析。首先，建立了3D旋转间隙关节的数学模型，并给出了径向间隙和轴向间隙的定义。然后，分析3D旋转间隙接头的潜在接触方式，接触条件和接触检测。此外，建立法向和切向接触力模型来描述接触现象并确定3D旋转间隙接头中的接触力。最后，提出了一种考虑了3D旋转间隙关节和空间运动的卫星天线系统作为应用示例。提出了不同的案例研究来讨论3D旋转间隙清除关节的效果。结果表明，3D旋转间隙接头将对卫星天线系统的动态特性产生更严重的影响。因此，在卫星天线系统的动力学分析和设计中，不能忽略轴向间隙对卫星天线系统的影响。