复杂机电系统多维频谱特征建模与集成设计方法

Multi-axis high speed machine tool, one of the typical complex electromechanical systems, consists of mechanical parts, servo driver and control unit. It is featured as multi-axis motion, multi-source energy inputs and united control aiming to reach a wide range of working velocity and acceleration, and high transient and steady accuracies. Earlier research found that these two accuracies, to a great extent, depend on the correlation between force spectrum from servo system and mechanical system's spectrum at low, intermediate and high frequencies., Furthermore, the force spectrum varies with the control strategy and parameters, and the mechanical systems' dynamic characteristics are also frequently variable during the working state...In this project, the multidimensional spectrum theory is developed. The research agenda is divided into four primary tasks. The goal of Task 1 is multidimensional spectrum solution of mechanical system in space, velocity and acceleration dimensions. Important considerations include: 1) component's flexibility, 2) joint's nonlinearity, and 3) structural coupling. Task 2 aims to obtain multidimensional spectrum of servo driving system and its variation due to different control and measuring methods. Task 3 is the description and calculation for spectrum coupling and its intensity between force/moment from servo system and mechanical systems. Task 4 is integrated design theory development for complex electromechanical systems including mechanical, servo, and control parts as well as its global optimization. This project will provide a new design technique for complex electromechanical systems.

复杂机电系统的典型代表多轴高速机床由机械、伺服驱动和控制三部分构成，具有多轴运动、多源能量输入、集中控制的特点，且工作速度、加速度范围宽，要求高的瞬态及稳态运动精度。研究发现，机床在工作过程中的伺服驱动力/力矩频谱与机械执行系统的低、中、高阶固有频率及其分布的相关程度决定了系统的稳态与瞬态精度，并且不同控制方式下伺服驱动力/力矩频谱会产生变异；而机械系统动态特性也具有复杂的演变特性。.本项目提出多维频谱理论，研究各运动轴在考虑构件柔性、结合部非线性、结构耦合下，在空间、速度及加速度维的频谱特征及变异；伺服驱动力/力矩频谱表征以及不同控制方式和反馈信息对力/力矩频谱特征的变异作用；伺服驱动力/力矩频谱与机械系统频谱特征之间的耦合特性、强弱的表征与计算；高速机床结构设计、伺服驱动设计、控制设计局部以及全局优化设计方法。本研究旨在揭示复杂机电系统的耦合本质和规律，建立集成设计理论与方法。

高档数控机床是一个典型的复杂机电系统，在高速高加速度运动过程中，机械、伺服和控制各部分特性随不同运动参数表现出多维演变规律，而且各部分之间存在着复杂的机电耦合关系，对机床的瞬态和稳态精度具有重要的影响。本项目提出多维频谱特征建模方法，揭示内部机电耦合的本质机理，形成综合数控—伺服—机械系统—切削工艺的机电集成设计优化方法，为实现高档数控机床的高速高精运动提供理论依据和技术指导。. 提出了一种多维频谱特征建模方法，利用变系数动力学方程，解析表征了各轴动态特性随运动位置、速度、加速度变化的多维演变规律；提出多子系统经单自由度耦合的动力学建模方法，揭示了滚珠丝杠传动机构中多个振动子系统在螺母处耦合的动力学响应特性；发现结构耦合轴之间的惯性力影响刀尖点的位移响应，表征了位移响应随进给轴运动位置及运动状态的变化规律；综合考虑伺服驱动电路和电机结构非线性，解析表征了伺服输出推力/力矩的频谱特性以及多维演变规律；. 发现旋转电机力矩谐波对滚珠丝杠传动系统具有自激励作用，提出了一种进给方向位移波动的计算方法，解析表征了这种单向机电耦合过程；针对直线电机进给系统，建立了不同耦合方式下的机电耦合方程，揭示了耦合关系的本质机理，解析表达了耦合强度。针对耦合问题，提出了考虑非同位和变动态特性的智能控制策略和力矩/力谐波抑制补偿策略，有效改善了谐波造成的稳态位移波动和不同工况下系统运动精度的一致性。. 针对多轴联动加工过程，提出了进给轴运动控制（数控-伺服-机械系统）与铣削过程的动力学集成建模方法，分析了机床多轴联动误差、铣削过程误差以及零件加工误差之间的传递、耦合叠加关系与精度控制规律。揭示了切削过程对机床联动运动精度的影响规律，实现了柔性工艺系统多轴联动加工过程的物理仿真，可进行加工误差的准确预测与溯源。