闭链结构冗余直驱运动平台的刚柔耦合特性分析与精密协同控制方法研究

Multi-axis direct-drive motion stages with redundant actuations have the potential to provide high system rigidity, fast responses, and large thrusts. As such, they have become the key components for high-end manufacturing equipment and have been widely used in applications such as aerospace, high-performance CNC machine tools, microelectronics manufacturing, especially when large load-carrying capacity and large span structure are needed. However, unknown electro-mechanic-magnetic coupling nonlinearities and flexible modes of motion mechanism make the static/dynamic characteristic analysis and the high-bandwidth/high precision control of these devices rather difficult. Moreover, high rigidity of the closed-chain mechanisms of the direct drive systems with redundant actuations could easily lead to excessive coupled internal forces among axes and control performance deterioration. Other problems such as input saturation, physical limits and coupled dynamics also need to be addressed. This project is to develop H-type precision multi-axis direct-drive motion stages with sub-micron positioning accuracy and high closed-loop bandwidth. Specifically, the project proposes to (i) study the parametric modeling of rigid-flexible coupled dynamics based on the rigid connecting mechanism and the flexible linear bearing guides, (ii) develop the constrained optimization based model compensation adaptive robust control theory that can take into account the rigid-flexible coupling behaviors and nonlinearities, uncertainties, and disturbances of the direct-drive systems, (iii) synthesize innovative synchronization controllers that achieve optimal motion coordination of axes while avoiding excessive internal forces. It is expected that the results of this project will help direct-drive transmission systems with redundant actuations realize their potential of high-speed/high-precision positioning and trajectory tracking, and high closed-loop bandwidth with strong disturbance rejection capability.

多轴冗余直接驱动运动平台具有高刚性、快响应、大功率的优点，是实现高承载大推力长跨距的高性能高端制造装备的重要功能元件，已在航空航天、高档数控机床、微电子制造等领域得到应用。然而，实际系统的机-电-磁耦合未知非线性、运动机构柔性模态等增加了其动静态分析和高动态高精度控制的难度，并存在驱动饱和、物理状态和刚柔耦合动力学限制，以及冗余驱动的高刚性闭链结构容易造成过度的轴间耦合内力，进而导致控制性能退化等问题。本项目将研制实现亚微米级定位精度和高动态响应的H型多轴直驱精密运动平台, 研究系统基于物理连接刚性和导向轴承柔性的刚柔耦合参数化建模方法及高频柔性动力学约束关系, 创建不确定直驱系统基于刚柔耦合特性和实际约束下获得系统性能最优的受限优化模型补偿自适应鲁棒控制新方法，设计兼顾轴间内力与运动性能协调优化的冗余协同控制器，实现冗余直驱系统的高速高精度定位和轨迹跟踪、高精度同步运动和强抗干扰性能。

在日益增加的高精度、高效率运动需求下，冗余直驱运动平台成为高档数控装备的关键功能部件，其冗余驱动及高刚性物理连接的结构特点具有获得更优运动性能的潜力。然而，在高速、高加速运动下，强机械耦合效应及导轨部件柔性变形容易造成过度的耦合约束内力，成为影响系统的平稳运行和使用寿命的主要因素，并进一步限制运动跟踪控制性能的提升。此外，为满足机电系统运动跟踪任务中的高效率性能要求，此类系统需要在受限于实际中各种运动学和动力学约束的情况下，以尽量快的运动速度完成作业任务。提高运动速度有助于获得高效率的运动跟踪性能，但也可能会违反此类约束，造成控制器饱和，进而导致运动跟踪精度的急剧恶化甚至控制系统失稳。因此，本课题围绕如何实现冗余驱动运动平台的高精度、高效率运动控制这一主题，基于对此类系统的刚柔耦合效应产生的根源和作用机制的深入研究，提出的建模分析方法给出了平台完整运动及多自由度复杂耦合特性的准确描述。随后，为了保证系统的平稳运行，提出了兼顾内力调节与运动跟踪的多变量精密协同控制方法；为了满足高精度轮廓加工的需求，创新的提出了兼顾冗余协同及轴间运动协调的轮廓运动控制理念。同时，本课题系统的开展了时间最优的离线和在线轨迹规划研究，构建了一套了高效可靠的机电系统运动学和动力学约束下的轨迹规划方法，为解决目前工业界面临的同时保证机电系统运动跟踪的高精度和高效率这一难题提供了理论和技术支持，具有重要的学术及现实意义。