环形桁架式可展开天线机构设计及展开动力学研究

发布时间：2018-05-09 11:48

本文选题：可折展机构 + 活动度　；参考：《哈尔滨工业大学》2016年博士论文

【摘要】：随着通信技术、空间科学以及地球观测技术的快速发展,对大口径天线的应用需求变得愈加迫切。由于受运载工具储藏空间的限制,天线必须具备折叠展开性能,因此大口径展开天线成为空间天线的最佳选择,而网面展开天线具有质量轻,口径大,精度高等优点,越来越受到科研工作者的重视。本文以环形桁架式展开天线机构为研究对象,对机构活动度分析方法、折展机构设计、天线索网找形与精度调整、机构展开动力学建模以及地面模拟实验等关键技术进行了深入研究。大尺度空间可折展机构归根到底是由多个简单的单闭环机构组成,因此以单闭环机构环路方程的分析为基础,提出针对多闭环机构活动度分析的方法。将单闭环机构的运动等效为一个变参数运动链,然后将多环机构化简为简单的单环机构进行活动度分析。在此基础上,利用D-H方法推导出5R Myard机构和面对称Bricard机构的运动环路方程,并以它们为基本模块单元进行大尺度空间折展机构组网研究,分析这些多闭环机构保持连续运动的几何协调条件,获得多种新型空间折展机构网络构型。为了构建大尺度空间展开天线,提出一种以平面六杆机构为基本组成模块的大型环形展开机构,该机构具有很好的折展性能,可以用来作为空间展开天线的支撑机构。通过采用闭环同步绳索系统和双曲柄滑块机构,实现了环形展开机构多模块联动,同时提出了两种展开驱动方式:绳索驱动方法和扭簧驱动方法,并设计完成一种适用于空间天线机构的高刚度扭簧驱动关节。建立了环形展开机构的整体运动学模型,并进行了速度和加速度分析,通过案例仿真验证了模型。天线索网结构的设计直接关系到展开天线的精度,因此本文以三向网格索网为研究对象,研究天线索网找形和精度调整问题。提出考虑垂跨比的网格几何划分方法,确定了抛物面索网反射面各索段的理想长度。建立了基于力密度法的索网双目标找形优化数学模型,该模型以索网形面精度和力均匀性为目标,获得索网平衡状态下的最优预应力分布,在此基础之上提出考虑周边桁架变形影响的索网找形优化方法,获得了更加精确的找形结果。针对索网精度调整的问题,建立了基于节点调整法的索网精度调整优化数学模型,提出了两种用于索网精度调整的求解算法:多维进退法和最小步长逼近法,实现了索网精度的快速调整。为了预测机构展开过程中动力学特性的变化,必须建立空间展开机构的动力学模型并进行仿真实验。本文基于多体动力学基本理论,选取机构的展开角度为广义坐标变量,利用拉格朗日动力学分析方法建立含索网环形展开天线系统的展开过程动力学模型,该模型综合考虑了柔性索网、关节阻尼、扭簧驱动力以及控制绳索对环形机构展开运动的影响。提出了一种基于展开速度控制的机构运动规划方法,推导出控制绳索的运动方程。通过天线机构的正、逆动力学仿真实验,分析了机构在展开过程中系统能量的变化规律以及阻尼对机构展开的影响,获得了绳索的力控曲线,并提出了绳索布置的改进方案。为了验证本文所提天线方案的可行性,设计研制一套环形桁架式展开天线地面原理试验样机及相关的地面实验系统。对原理样机进行了多次展开收拢实验、精度测试实验、刚度实验以及绳索张力测试实验,实验结果表明机构有良好的展收性能,非常高的重复定位精度,绳索张力实验结果验证了本文所建动力学模型的正确性,为电机控制参数的设计提供了参考。
[Abstract]:With the rapid development of communication technology, space science and earth observation technology, the demand for large aperture antenna has become more and more urgent. Due to the limitation of the storage space of the carrier, the antenna must have the folding expansion performance. Therefore, the antenna with large aperture is the best choice for the space sky line, and the network surface deployable antenna has the quality. With the advantages of light, large caliber and high precision, the researchers pay more and more attention. This paper takes the ring truss deployable antenna mechanism as the research object, and deeply studies the key technologies such as the analysis method of the mechanism activity, the design of the folding mechanism, the shape finding and precision adjustment of the antenna cable network, the dynamic modeling of the mechanism and the ground simulation experiment. In the final analysis, a large scale space folding mechanism is composed of a number of simple closed loop mechanisms. Therefore, based on the analysis of the loop equation of a single closed loop mechanism, a method for analyzing the activity of a multiple closed loop mechanism is proposed. The motion of a single closed loop mechanism is equivalent to a variable parameter transport chain, and then the multi loop mechanism is simplified to a simple single single. On the basis of this, the D-H method is used to derive the motion loop equation of the 5R Myard mechanism and the Bricard mechanism, and a large scale space folding mechanism is used as the basic module unit to analyze the geometric coordination conditions of the multiple closed loop mechanism to maintain continuous motion, and a variety of new type of empty space is obtained. In order to construct a large scale space deployable antenna, a large circular unfolding mechanism with a planar six bar mechanism as the basic module is proposed. The mechanism has good folding performance and can be used as a supporting mechanism for the space deployable antenna. The closed loop synchronous rope system and the double crank slider mechanism are used. At the same time, the multi module linkage of the ring expansion mechanism is realized. At the same time, two kinds of expansion drive methods, the rope driving method and the torsion spring drive method, are put forward, and a high stiffness torsion spring drive joint suitable for the space antenna mechanism is designed and completed. The overall kinematic model of the ring expansion mechanism is established, and the velocity and acceleration analysis is carried out, and the analysis of the speed and acceleration is carried out. The design of the antenna cable net structure is directly related to the accuracy of the unfolded antenna. Therefore, the three direction grid cable network is taken as the research object to study the problem of shape finding and precision adjustment of the antenna cable network. The mesh geometry division method considering the vertical span ratio is proposed, and the ideal length of each segment of the reflector surface of the parabolic surface cable net is determined. Based on the force density method, the mathematical model of the cable net double target shape finding optimization is established. The model takes the cable net shape surface precision and the force uniformity as the objective, and obtains the optimal prestress distribution under the cable net balance state. On this basis, the cable net shape finding optimization method considering the influence of the surrounding truss deformation is proposed, and the more accurate shape finding results are obtained. In order to adjust the precision of cable network, the mathematical model of cable net precision adjustment and Optimization Based on the node adjustment method is set up, and two kinds of solving algorithms are proposed, which are used to adjust the precision of cable network: multidimensional return method and minimum step length approximation method, which can realize the rapid adjustment of cable net precision. Based on the basic theory of multi-body dynamics, this paper selects the expansion angle of the mechanism as a generalized coordinate variable, and uses the Lagrange dynamic analysis method to establish the dynamic model of the expansion process of a cable network unfolded antenna system with a cable net. The influence of the damping, the torsion spring driving force and the control of the rope on the movement of the ring mechanism is introduced. A motion planning method based on the expansion velocity control is proposed, and the motion equation of the control rope is derived. The variation of the system energy is analyzed by the positive and inverse dynamics simulation experiments of the antenna mechanism. And the influence of damping on the mechanism, the force control curve of the rope is obtained, and the improvement scheme of the rope arrangement is put forward. In order to verify the feasibility of the antenna scheme proposed in this paper, a prototype prototype of the ring truss deployable antenna ground principle and the related ground experiment system are designed and developed. The test results, the precision test experiment, the stiffness experiment and the rope tension test experiment. The experimental results show that the mechanism has good performance and high repetition precision. The results of rope tension test verify the correctness of the dynamic model built in this paper, and provide reference for the design of motor control parameters.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN820

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