【作者】 路英杰；

【导师】 任革学；

【作者基本信息】 清华大学 ， 力学， 2007， 博士

【摘要】 本文以国家天文台500米口径球面射电望远镜FAST项目为应用背景,针对其关键技术移动小车式无平台馈源支撑系统,进行动力学与反馈控制一体化仿真研究和测量控制方案研究。论文主要进行了如下三项研究工作:针对移动小车式无平台馈源支撑系统中大尺度时变索系和Stewart平台机构耦合动力学仿真的需要,本文实现了一种大范围运动一阶连续长索单元,利用它模拟了卷扬钢索和钢索过定滑轮的动力学,并在多体动力学框架下实现了时变索系与多刚体组合系统的建模和数值求解。为实现射电望远镜馈源在大范围运动中高精度定位和指向的目标,本文提出了直接测量受控平台位姿的末端反馈控制策略。在驱动索系定位控制的同时,耦合索系张力分配的非线性控制,有效地避免了钢索虚牵。通过模型实验和仿真实验,对大范围运动驱动索系、指向机构和Stewart平台三级耦合机械结构的测量控制方案进行了验证。针对测量数据的噪声问题,本文提出了一种基于频率分析的实时滤波器。该滤波器在传统多项式拟合滤波器的基础上,采用动态频率分析和预测技术,使得滤波时滞只有采样周期的三分之一左右,适合高实时性要求的应用。在柔性悬挂Stewart平台振动控制实验中,该滤波器的应用提高了控制效果。本文构建了一套基于多体动力学的反馈控制仿真系统。对密云50米尺度时变索系驱动馈源小车运动控制实验,和柔性悬挂Stewart平台振动控制实验,进行动力学与反馈控制一体化仿真。仿真结果与物理实验相符合。利用基于多体动力学的反馈控制仿真系统,对500米尺度原型移动小车式无平台馈源支撑系统进行仿真研究。在大范围运动时变机械结构和测量控制耦合仿真模型上进行虚拟实验,优化机械结构、控制算法和控制参数,考察风荷载作用下馈源长时间跟踪观测的定位和指向控制效果。通过对大量的系统的虚拟反馈控制实验的结果进行对比和整理,本文工作为FAST馈源支撑系统的方案设计提供了建议和参考。更多还原

【Abstract】 As part of the Five-hundred-meter Aperture Spherical Telescope (FAST) project from the National Astronomical Observatory, this work carries out dynamics and control all-in-one simulation research and feedback control scheme study on the moving-car platformless feed support system, which is one of the key technologies of FAST.In order to simulate dynamics of the large-scale time varying cable network combined with a Stewart parallel mechanism, which arises from the moving-car platformless feed support system, this paper implements a large-displacement first order continuous long cable element, uses it as the base to simulate dynamics of winding cable and sliding cable through fixed pulley, and numerically solves the time varying cable network and rigid bodies combined system under the framework of flexible multibody dynamics.To achieve high precision positioning and orientating control in large-range tracing of the radio telescope feed, this paper proposes a terminal feedback control scheme by directly measuring the position and orientation of the platform to be controlled. Nonlinear control for distributing tension among cable network is applied simultaneously with positioning control of the cable drive architecture and effectively avoids runtime cable over-sagging. Feedback control scheme for the feed support mechanism consisting of a large scale cable drive architecture, an orientating platform and a Stewart platform is verified through field and virtual control tests. For the measurement noise problem, this paper proposes a real time filter based on frequency analysis. Derived from traditional least square polynomial fit filter, the new filter employs dynamic frequency analysis and prediction technique, making the filter-introduced-delay only one third of the sampling period and particularly suits applications where real time is heavily demanded. Application of the proposed filter improves control effect remarkably in the flexible-supported Stewart platform vibration control experiments. This paper constructs a set of feedback control simulation system based on flexible multibody dynamics. Dynamics and control all-in-one simulation is made on tracing control experiments of the 50-meter-scale cable driven trolley and vibration control experiments of the flexibly supported Stewart platform, results of which generally agree with the corresponding physical experiments. This paper then conducts simulation research on the 500-meter-scale moving-car platformless feed support system employing the feedback control simulation system based on multibody dynamics. Simulation experiments on the virtual digital model coupling large-displacement time varying mechanism and feedback control components are carried out on PC to optimize the mechanical structure,control algorithms and parameters and to investigate positioning and orientating precision of the feed in long term tracing under wind load. Quite a lot of result data from systematic virtual feedback control experiments are processed and provide design advices and reference for construction of the feed support system for FAST.更多还原