基于冗余并联机构重载大行程混合振动隔振机理及其复合控制策略研究

Redundant parallel mechanism with hydraulic active-passive composite branch is a novel hybrid vibration suppression equipment for structure and equipment used in multidimensional and wider bandwidth vibration environment, and it is one of heavy load and long stroke vibration isolation with free-singularity fault and excellent uniformity of control, but the dynamic coupling and uncertainty parameters and model have seriously affected and restricted the overall control performances. To overcome dynamic coupling and the system uncertainty, meet the requirements of larger work space, wider bandwidth, higher precision and reliability vibration isolation performances, this project carries out the research of dynamic decoupling, the mechanism of vibration attenuation and compound control strategy of mixed vibration isolation system using redundant parallel mechanism. The dynamic coupling and vibration transmission characteristics are investigated based on the theories of dynamics of mechanism, modal analysis and control theory, and by adopting the unite method of theoretical analysis, algorithm research, experimental and simulation verification. The law of the cooperative work of the active and passive isolator is studied and a novel method for performance assessment of vibration isolation is explored which is based on the energy transmission of vibration. The modal space dynamic decoupling control strategy is proposed to get dynamic decoupling deeply and independent degree control of multidimensional hybrid vibration suppression system, and to broaden the system bandwidth, and further great improve the control performance of mixed vibration isolation system. To deal with the uncertainty dynamic model parameters, non-modelling dynamics and the failure of drive chains, the compound control strategy is discussed to realize the robust and fault-tolerant control of the hybrid vibration isolation system, and to enhance the reliability of the control system. This research can supply theoretical and technical basis for the development of high precision, high response and high reliability hybrid vibration isolation equipment.

液压式主被动复合支撑的冗余并联机构是结构设备多维宽频振动抑制的新型装置，它是一种无奇异和控制均匀的重载大行程隔振机构，但动力耦合及系统不确定性的存在严重影响和制约了系统振动控制性能。为解决动力耦合及系统不确定性的影响，以满足大工作空间、宽频段、高精度及可靠性的混合隔振要求，本课题开展了冗余并联机构混合隔振系统动力解耦、振动传递机理及复合控制策略研究。基于机构动力学理论、模态分析理论和控制理论，采用理论分析、算法仿真与实验验证相结合的方法，研究并联机构振动传递机理，揭示主被动隔振器协同工作规律，探讨振动控制性能评价能量方法；提出了基于模态空间的动力耦合解耦控制策略，实现混合隔振系统自由度独立控制，提高并联机构混合隔振系统的精度和带宽；提出复合的鲁棒容错控制策略，实现混合隔振系统复合控制，提高了系统的可靠性，为高精度、宽频带和高可靠性混合隔振装置的研制提供理论基础和技术支撑。

本项目首先针对带有主被动复合隔振支撑的液压冗余六自由度并联隔振平台，利用Newton-Euler方法建立了完整的动力学耦合模型，采用矩阵对角化解耦控制策略和模糊PI控制理论，对隔振平台的被动隔振性能、主被动混合隔振性能进行仿真分析，结果表明基于模糊PI解耦控制明显优于基于矩阵对角化解耦控制，扰动衰减达98%以上。为了验证主被动混合隔振性能及平台解耦效果，搭建了基于虚拟样机的模糊PI解耦控制联合仿真模型，仿真结果表明被动混合隔振率最大误差为0.25%，验证了主被动混合隔振性能的有效性，耦合向加速度衰减率最大误差为1.17%，验证了模糊PI解耦控制策略的有效性。然后采用双闭环控制对液压振动台随机波形复现进行研究，并着重分析无负载干扰力、随机外干扰力和摩擦负载干扰对随机加速度复现精度与迭代次数的影响，试验表明在未迭代的情况下，期望加速度波形与反馈加速度波形的相似度为0.8763，经过迭代四次后相似度为0.9325，证明迭代算法的有效性。其次对于存在模型参数摄动和时变负载的电液控制系统，设计了基于Backstepping滑模控制的级联控制算法，内环通过伺服阀流量非线性补偿和活塞速度干扰补偿，使得内环回路增益在工况改变或换向时能够维持不变，不受外负载力的影响，外环采用滑模控制，用以补偿时变负载对系统性能的影响，仿真结果表明采用基于Backstepping滑模控制时系统响应速度快，初始阶段最大跟踪误差为0.005m，稳态跟踪精度达到1.1%，明显优于传统的PID控制，证明了控制算法的正确性。最后对于双阀控缸同步控制，首先设计模糊PID、确定性鲁棒和自适应鲁棒控制器，以保证单缸高精度轨迹跟踪，接着基于交叉耦合同步控制策略，设计自适应鲁棒同步控制器。仿真结果表明，单缸跟踪采用模糊PID和确定性鲁棒控制时最大稳态误差分别是0.49mm和0.2mm，自适应鲁棒控制起始的瞬态误差为0.45mm，稳态误差为0.14mm，稳态跟踪精度可达0.14%；双缸同步控制时，稳态时单轴跟踪误差均在1mm以内，最大同步误差为0.3mm，验证了基于自适应鲁棒的交叉耦合控制策略的正确性。