多轴冗余振动台的模态与自由度复合控制策略研究

发布时间：2018-10-24 16:31

【摘要】：我国是一个地震频发的国家,振动台作为测试建筑物抗震性的设备,在防灾减灾中起这至关重要的作用。为避免缩尺实验所带来的问题,冗余多轴振动台是一个发展趋势。对于多输入多输出系统,不可避免各自由度之间存在耦合,耦合不仅使得振动台的实际振动产生了不必要的耦合输出,同时也影响了各自由度的性能的调节。考虑到解耦是属于基础性工作,只有耦合性降低才能更好提高系统的各性能,本文着重研究振动台的解耦控制。本文针对多轴冗余振动台,建立其运动学动力学方程,进而对振动台各自由度的耦合进行了相关分析,结果表明:各自由度的耦合比较严重,并且各自由度的动态特性存在多个谐振峰,在此基础上再进行相关控制,比较困难,因此在此基础上引入模态控制。本文对模态理论进行了相关分析,建立了物理空间与模态空间的映射关系。考虑到引入模态控制控制的根本原因是:模态空间中各自由度无耦合,各阶振型独立。故而本文着重分析,建模存在误差时对模态控制的影响,结果表明:不考虑液压支腿质量时,模态空间中各自由度的耦合仍然非常严重,故不能忽略液压支腿质量。本文对模态空间中固有频率、阻尼比以及谐振峰进行了相关分析,结果表明:随着6阶模态固有频率的增加,其对应的阻尼越来越小,谐振峰值越来越大,同时模态空间中各自由度间的耦合谐振峰取决于耦合输出模态自由度的动态特性。考虑到实际系统质量阵和刚度阵的不确定性,本文提出了基于实验的模态阵求取,将6×6的模态阵简化为仅受两个参数影响。针对无耦合的模态空间映射至物理空间之后,物理空间中耦合仍然比较严重,本文提出了基于模态控制联合自由度控制,前馈控制,三状态反馈控制,内力控制策略,实现了在理论上物理空间中各自由度的完全解耦,仿真结果表明:解耦效果十分明显,近似于全解耦,而实验解耦效果有3-8d B,表明算法可行。同时结果表明:模态前馈通过调节使得各模态自由度幅频特性一致化,映射至物理空间后,各自由度仍然无耦合。而自由度前馈对物理空间的耦合没有丝毫影响。
[Abstract]:China is a country with frequent earthquakes. As an equipment for testing the earthquake resistance of buildings, vibration table plays an important role in disaster prevention and mitigation. In order to avoid the problem caused by scale experiment, redundant multi-axis vibration table is a developing trend. For multi-input multi-output systems, coupling between degrees of freedom is inevitable. Coupling not only causes unnecessary coupling output of vibration table, but also affects the regulation of performance of each degree of freedom. Considering that decoupling is a basic work, only when the coupling property is reduced, the performance of the system can be improved better. In this paper, the decoupling control of vibration table is studied emphatically. In this paper, the kinematics and dynamics equations of multi-axis redundant vibration table are established, and the coupling of various degrees of freedom of vibration table is analyzed. The results show that the coupling of each degree of freedom is serious. And there are many resonance peaks in the dynamic characteristics of each degree of freedom, so it is difficult to carry out correlation control on this basis, so modal control is introduced on this basis. This paper analyzes the modal theory and establishes the mapping relationship between physical space and modal space. It is considered that the fundamental reason for the introduction of modal control is that each degree of freedom in the modal space is not coupled and the vibration modes of each order are independent. Therefore, the effect of modeling error on modal control is analyzed. The results show that the coupling of various degrees of freedom in modal space is still very serious, so the mass of hydraulic leg can not be ignored. In this paper, the natural frequency, damping ratio and resonance peak in modal space are analyzed. The results show that with the increase of the natural frequency of the sixth mode, the corresponding damping becomes smaller and the resonance peak becomes larger and larger. At the same time, the coupling resonance peak between the various degrees of freedom in the modal space depends on the dynamic characteristics of the coupled output modal freedom. Considering the uncertainty of mass matrix and stiffness matrix of real system, an experimental modal matrix is proposed in this paper. The 6 脳 6 modal matrix is simplified to be affected by only two parameters. The coupling is still serious in the physical space after the uncoupled modal space is mapped to the physical space. In this paper, the joint freedom control, feedforward control, three-state feedback control and internal force control strategy based on modal control are proposed. The complete decoupling of each degree of freedom in the physical space is realized theoretically. The simulation results show that the decoupling effect is very obvious and approximate to the full decoupling effect, while the experimental decoupling effect is 3-8 dB, which shows that the algorithm is feasible. At the same time, the results show that the modal feedforward can make the amplitude and frequency characteristics of each mode of freedom uniform by adjusting, and after mapping to physical space, each degree of freedom still has no coupling. The degree of freedom feedforward has no effect on the coupling of physical space.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB534.2

【相似文献】