【作者】 潘超；

【导师】 左健民；

【作者基本信息】 江苏大学 ， 机械电子工程， 2011， 博士

【摘要】 高速切削技术及多功能复合加工中心的迅猛发展要求数控机床进给系统具有高刚度、高精度、高速度和高响应能力,而传统滚珠丝杆进给系统无法满足这种高性能进给要求。直线电动机可以实现高速直接驱动,避免了滚珠丝杆传动中的反向间隙、惯性、摩擦力和刚度不足等缺点,可获得高速、高精度运行并具有极好的稳定和动态性能,直线电动机直接驱动进给系统是当前国际上公认的最有前途的数控机床高性能进给系统。数控机床直线电驱进给系统的高性能运行完全依赖于高性能的直线伺服控制技术,机械传动结构的简化必然增加直线电驱进给系统电气控制的难度,直线电驱进给系统的“零传动”方式使得各种扰动不经过任何中间环节的衰减而直接作用于直线电动机,影响了进给系统的性能；同时,直线电动机存在端部效应、推力波动、齿槽效应等非线性因素,这也增加了控制的难度。为充分发挥直线电动机在数控机床进给系统中的优势,必须对直线电驱进给系统的动态特性进行深入的理论和试验研究,从控制和补偿的角度提出适合于直线伺服系统实时控制的有效方法。论文围绕数控机床直线电驱进给系统的控制技术及其动态特性展开研究,保证直线电驱进给系统的各种动静态性能指标,提高直线电驱进给系统的动态刚度和抗干扰能力,充分满足高性能数控机床进给系统的要求。论文主要研究内容如下：(1)简要介绍了直线电动机基本结构及工作原理,建立了直线电驱进给系统数学模型和传递函数,对直线电驱进给系统的关键参数进行分析,并与传统滚珠丝杆传动方式进行了比较,指出直线电驱进给系统的优点及控制难点；分析总结了数控机床直线进给伺服系统工作过程中存在的非线性及不确定性扰动因素。(2)构建了直线电驱进给系统的三闭环控制结构,根据工程设计方法设计了电流环、速度环和位置环的PID数字控制,并进行了仿真和试验。重点研究了基于极点配置算法的直线电驱进给系统,详细介绍了极点配置控制器设计的基本原理及设计方法,具体给出了极点配置自适应算法的计算机实现方法,并通过仿真分析验证了控制器的有效性,最后通过试验比较了PID控制和极点配置两种算法的性能特点。(3)针对直线电驱进给系统的非线性、不确定性和动态复杂性的特点,引入具有非线性逼近能力、自适应自学习能力的神经网络智能控制算法,设计出基于神经网络的直线伺服控制系统。设计出具有局部逼近快速反应的CMAC神经网络自适应控制器,控制过程和在线学习过程同时进行,充分满足伺服控制实时性要求；引入具有动态递归特性的Elman神经网络,其“部分递归,全局前馈”的结构兼顾前馈神经网络的优点,具有适应时变特性的能力,充分利用Elman神经网络存储的历史控制信息,提高了直线电驱进给系统的动态抗干扰能力和系统的控制精度；对Elman神经网络的存储方式进行优化,创新性的提出具有稀疏存储功能的改进Elman神经网络,进一步提高网络的泛化能力和响应速度,并通过仿真验证了此算法的可行性和有效性；针对直线电驱进给系统运动过程中存在的各种非线性干扰,提出基于前馈和反馈的神经网络复合补偿的控制系统,不必对扰动力进行辨识和计算,因而无需过分依赖扰动力的精确数学模型,在同一网络结构中不仅对扰动力进行反馈补偿,而且对给定信号进行预测前馈补偿,提高了直线电驱进给系统的控制性能。(4)构建直线伺服系统整体结构；详细介绍了直线伺服控制器的硬件设计,主要包括驱动单元、检测单元和控制单元；根据矢量控制原理设计了伺服控制器的软件结构,对设计中存在的关键问题进行了探讨；并对所设计的具有自主知识产权的直线伺服控制器样机进行了调试试验。(5)构建了数控机床直线电驱进给系统试验平台,详细介绍了试验平台的结构、性能参数和检测方法；通过试验测定了工作台的摩擦系数和电动机推力系数；试验研究了PID控制、极点配置控制下直线电驱进给系统的动态性能,并分析了主要控制参数对系统动态性能的影响；最后,试验研究了直线电驱进给系统位置跟踪性能及动态刚度。更多还原

【Abstract】 With the rapid development of high-speed cutting technology and multifunctional CNC machine center, feed system with high rigidity, high accuracy, high speed and high responsiveness was required. While the traditional ball-screw feed system can not satisfy the high-performance requirements. In comparison with the ball-screw drive, the direct drive feed system by linear motor has the advantages of less friction, no backlash, less mechanical limitations on acceleration and velocity, higher accuracy and speed, higher reliability and dynamic performance. The direct drive feed system by linear motor is regarded as the most promising high-performance feed system of CNC machine tools.The performance of Linear motor direct drive feed system is largely determined by linear servo control technology. The more simplify of mechanical transmission structure, the more difficulty of electrical control. Disturbance variations, without any attenuation of the transmission mechanism, directly impose on the motor shaft, leading to significant effect on the linear servo system performance. Meanwhile, the end effect, force ripple, cogging and other nonlinear factors have increased the difficulty of control. In order to satisfy the requirements of speed tracking performance and eliminate the influence of disturbance, an appropriate controller and research on dynamic performance are necessary and important for linear servo system of CNC machine tools. This paper focuses on the control technology and dynamic characteristics of Linear motor direct drive feed system, to improve disturbance rejection abilities and dynamic stiffness of Linear motor direct drive feed system, ensure all kinds of dynamic and static performance index, meet the requirements of high-performance CNC machine tools.The research works were as follows:(1) The basic structure and working principle of linear motor were introduced. The mathematics model and transfer function were established. The key parameters of Linear motor direct drive feed system were analyzed. In comparison with the ball-screw drive, It is realized the advantages and control difficult of linear servo system. The nonlinear and uncertain factors of Linear motor direct drive feed system were summarized.(2) Digital control technology of Linear motor direct drive feed system was introduced and the cascaded-loop structure of servo system, which contains current, velocity and position loops, was constructed according to the engineering design method. The pole placement controller was researched in detail including the basic principle, specific design process and digital realization method. The effectiveness of the proposed schemes was verified by simulation and experiment. The performance of two algorithms was compared finally.(3) According to characteristics of nonlinear, uncertainty and dynamic complexity in Linear motor direct drive feed system, the linear servo system based on neural network with the abilities of non-linear approximation, learning and adaptive were designed. CMAC adaptive neural network controller with the characteristic of rapid response and partial approximation was designed to meet the requirement of real-time. The tracking performance and disturbance resistance abilitie of the Linear motor direct drive feed system were improved by dynamic recurrent Elman neural network. An improved Elman neural network with spares memory was proposed and rapid associate theory based on table-look up was introduced to enhance learning speed and generalization capability of neural network. The information of neural network was classified, stored and selected to use. Compound controller with feedforward and feedback comprehensive compensation was proposed. The disturbances were compensated by feedback component and reference speed input signal was preview controlled by feedforward component. The tracking performance and respect speed of linear server system were improved.(4) The structure of linear servo system was constructed. The hardware of system including driver, detection and controller and so on was introduced in detail. The software was designed according to the principle of space-vector control and the important problems were discussed. The debugging test of servo controller was carried out.(5) The linear servo system test platform, the performance parameters and measure method were introduced. The parameters of friction and thrust coefficients were obtained and the dynamic performances of Linear motor direct drive feed system based on PID and pole placemen controller were researched by experiment. The key parameters which influence the performance of system in controller were analyzed. The position tracking performance and dynamic stiffness of Linear motor direct drive feed system were studied.更多还原