基于柔性铰链的位移放大机构及三自由度调姿平台研究

发布时间：2018-01-01 07:11

本文关键词：基于柔性铰链的位移放大机构及三自由度调姿平台研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：人类对外太空探索的渴求促进了卫星技术的迅猛发展。当前,人造卫星已深入到定位导航、军事侦查、农业气象和对地观测等各个领域,为信息化社会建设作出卓越贡献。由于受到非球形引力场等诸多客观环境因素的影响,卫星在轨期间会发生周期性漂移,调姿平台作为卫星位姿调节控制系统的执行机构,其调节精度将直接影响到卫星的最终姿态。并联机构和微驱动技术作为目前工程应用领域的研究热点,两者的有机结合使精密位姿调节并联机构应用在航天领域成为可能。本文展开了对柔性位移放大机构及三自由度柔性并联平台一系列力学特性的研究,为最后研制卫星调姿平台原理样机提供理论基础与技术支撑。柔性位移放大机构作为柔性平台的核心部件,其力学性能是分析的重点。本文针对柔性位移放大机构普遍存在的结构对称性和过约束性,以机构1/2模型为研究对象,将柔性铰链视为变截面梁,从结构力学的角度,提出了基于力法思想的非正则力法方程用于建立柔性位移放大机构力学计算模型,进而得到机构位移放大比和系统刚度的理论计算公式。以柔性位移放大机构中常见的杠杆式和桥式柔性位移放大机构为算例,分别建立理论模型并与仿真结果进行对比,验证了理论模型的正确性,并分析了结构设计参数对柔性机构力学特性的影响。基于有限元思想,将柔性铰链视为变截面梁单元,在广义坐标系下根据作用在梁单元上力的平衡关系推导了变截面梁单元刚度矩阵,通过坐标系变换及位移公式建立了变截面梁单元在单元坐标系下的单元刚度矩阵、形函数和质量矩阵。根据柔性位移放大机构的结构特点,基于有限单元法哈密顿原理建立了含多点约束方程的系统动力学方程,对柔性机构进行了固有特性分析,得到了机构的固有频率,分析了结构设计参数对柔性机构一阶固有频率的影响,通过有限元仿真结果与理论模型计算结果的对比,验证了理论模型的正确性。在此基础上,基于柔性位移放大机构的静力学计算模型和动态力学计算模型,对柔性位移放大机构进行以机构位移放大倍数、结构系统刚度、一阶固有频率、质量和应力为目标的多目标优化设计,得到最优设计参数。设计了基于柔性位移放大机构和柔性球铰的三自由度柔性并联机构,基于旋量理论讨论了不同构型机构的自由度。利益柔性铰链伪刚体模型法对柔性并联机构进行了运动学建模,给出了其运动学逆解,并对其可达工作空间进行了仿真。此外在建立了柔性球铰末端刚度矩阵的基础上,根据结构力学的柔度矩阵叠加法,建立了柔性并联机构的静刚度解析模型,并系统的分析了结构设计参数对机构各向刚度的影响。搭建了柔性位移放大机构试验系统,在压电陶瓷驱动器处于闭环控制模式下测量了柔性位移放大机构的位移放大比和固有频率。根据机构设计方案,研制出三自由度卫星调姿平台原理样机,并搭建系统实验系统。对于系统静力学性能指标,分别测量了原理样机的运动范围和重复定位精度,对于系统动态性能指标则测量了运动分辨率和系统固有频率,并讨论了温度载荷对平台的影响。实验结果进一步表明原理样机设计和理论分析的合理性。
[Abstract]:The human thirst for foreign space exploration to promote the rapid development of satellite technology. At present, the satellite has been deep into the navigation, military reconnaissance, agricultural meteorology and in various areas of earth observation, made outstanding contribution for the construction of the information society. Due to the impact of non spherical gravitational field and other objective factors, periodically drift the satellite in orbit during the attitude adjusting platform as satellite pose actuator control system, the control precision will directly affect the final attitude. Parallel mechanism and micro drive technology as the current research focus in the field of engineering application, the combination of the precise position and attitude adjusting parallel mechanism in the field of Aerospace applications become possible. This paper focuses on the flexible displacement amplification mechanism and three degree of freedom flexible parallel platform a series of mechanical properties, for the final development of the satellite attitudeadjustment original platform Physical prototype provides theoretical basis and technical support agencies. As a core component of flexible platform for flexible displacement amplification, its mechanical properties are analyzed. Based on the flexible displacement amplification mechanism widely exists symmetrical structure and constraints, the mechanism of 1/2 model as the research object, the flexible hinge as the variable cross-section beam from the structure the mechanical angle, non regular force method equation of force method based on the idea for establishing a flexible displacement amplification mechanism mechanics calculation model is presented, and then obtain the mechanism displacement amplification ratio and system theory, the stiffness formula. Based on the flexible displacement amplification mechanism in common lever type and bridge type compliant displacement amplifier as an example, the paper establishes theory the model is compared with the simulation results, verify the correctness of the theoretical model, and analyze the influence of design parameters on the mechanical properties of flexible mechanism. Based on finite element Thought, will be regarded as flexible hinge tapered beam element, in the generalized coordinates according to the balance between the force acting on the beam element stiffness matrix was derived with variable cross section beam element stiffness matrix, Dan Yuangang through the transformation and the displacement formula of coordinate system to establish a tapered beam element in the unit coordinates, shape function and quality according to the structural characteristics of matrix. Mechanism of flexible displacement amplification, the finite element method based on the principle of the Hamiltonian system dynamic equations with multi point constraint equations of flexible mechanism of natural characteristics analysis, obtain the inherent frequency of institutions, analyzes the influence of design parameters on the flexible mechanism of first-order natural frequency, comparing the calculated results with the the theoretical model through the finite element simulation results, verify the correctness of the theoretical model. Based on this model, and the dynamic mechanics statics based on flexible displacement amplification mechanism The calculation model of the flexible displacement amplification mechanism to displacement magnification structure, system stiffness, natural frequency, multi objective optimization design quality and stress as the goal, to get the optimal design parameters. The design mechanism and flexible ball joint flexible displacement amplification with three degrees of freedom parallel mechanism based on screw theory discuss the different configuration mechanism freedom. Based on the interests of the flexible hinge pseudo rigid body model method for kinematics modeling of flexible parallel mechanism, given its inverse kinematics, and the reachable workspace is simulated. In addition based on the flexible ball joint end stiffness matrix and flexibility matrix according to the superposition structure mechanics, established the static stiffness analysis of flexible parallel mechanism model, and analyze the effect of design parameters on mechanism stiffness. Build flexible displacement amplifier test In the testing system, a piezoelectric ceramic actuator in the ratio and frequency of displacement closed-loop control mode to measure the flexible displacement amplifier amplification. According to the design scheme, developed a three DOF satellite attitude adjusting platform principle prototype, and the experimental system is established. The system for mechanical performance of static system, measured range of motion principle prototype and repeat positioning accuracy, dynamic performance measurement system for the natural frequency and resolution system, and discusses the influence of temperature load on the platform. The experimental results further show that the principle prototype design rationality analysis and gauge theory.

【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】：2017
【分类号】：V448.22;TH112

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