超精密机床的变增益交叉耦合控制研究

超精密加工的轮廓精度控制直接影响到工件的加工精度,交叉耦合控制算法通过对２轴进行协调而影响轮廓控制精度。在分析超精密数控机床误差模型的基础上,将变增益交叉耦合控制算法引入超精密数控机床的伺服控制。实验结果表明：变增益交叉耦合控制算法可以在不改变位置环的情况下,有效提高系统的轮廓精度。     

基于积分分离数字PID控制的超精密定位系统的设计

作为精密加工工业的基础，超精密定位技术已经成为高精度加工的关键环节之一。本文设计了集位移数据采集、处理、控制于一体的超精密定位系统。在阐述了PID控制算法的一般原理基础上，采用了一种基于积分分离数字PID的控制算法，实现了对超精密定位系统的闭环控制。     

基于轮廓最优圆逼近方法的轮廓误差控制

设计并实现了基于轮廓最优圆逼近方法的轮廓误差估计模型,该模型克服了常规方法对于任意加工曲线,廓误差计算过程复杂、计算量大、难以应用到实时任务的缺点,通过实时读取数控机床的位置反馈值和插补器的指令数据估算出轮廓误差值,结合双模糊变论域自适应控制算法,应用于两轴数控系统并实时补偿各单轴控制器,实现对复杂加工过程轮廓误差实时估算并补偿。在实验数控机床上加工两种典型轮廓,对比实验表明,所提出的基于轮廓最优圆逼近方法的双模糊变论域轮廓误差控制方法能有效减小加工轮廓误差,有更高的轮廓精度。     

提高加工精度的有关技术探讨

数控技术和数控机床的诞生开创了控制和生产领域的新时代,给机械制造业带来了一次新的技术革命.数控机床技术的迅速进步大大推进了精密、超精密加工技术的发展,使加工精度提高到了一个新的台阶,提高数控机床精度的研究也得到了极大的重视.     

基于设定值前向补偿的XY平台直线电机控制

数控机床优化精度控制系统中,XY平台伺服系统存在扰动、系统参数不确定性、机械延迟以及两轴驱动系统参数不匹配等原因,影响了平台的定位精度.为此对轮廓误差分配模型的交叉耦合控制方法进行了改进,对于设定值前向补偿的交叉耦合控制,估算出两轴间的轮廓误差,直接反馈予各轴的设定值输入,进行补偿.上述方法具有预先修正偏差的能力,及时修正了偏差,加快了误差修正速度,有效提高了系统的控制精度.仿真结果表明,所提出的两轴运动平台直线电机控制方法有效地减小了平台的轮廓误差和位置误差,提高了平台的定位精度.     

多线切割机的无模型自适应交叉耦合控制

为提高硅材料切割加工的精度,在分析多线切割机钢丝线张力波动的基础上,将无模型自适应控制和交叉耦合控制相结合,提出了一种多轴同步的间接张力控制策略。无模型自适应控制提高了系统动态响应的快速性,增强了系统的鲁棒性,减小了跟踪误差,实现了准确跟踪;交叉耦合控制用于消除各轴之间的增益参数和动态参数不匹配的影响,减小了同步误差,实现了多轴同步。实验结果表明所提出的控制方案十分有效,可提高多轴同步的运动精度,减小钢丝线张力波动。     

全自动化学发光免疫分析仪取样平台运动控制器设计

本文设计了全自动化学发光免疫分析仪取样平台的运动控制器。单轴控制器采用速度内环、位置外环的双闭环结构。其中位置控制环采用模糊控制,并进行前馈补偿,构成复合控制。同时考虑两轴联动的动态配合,设计了变增益交叉耦合控制器,补偿轮廓误差。实验结果表明,采用此控制策略不仅有效的提高了系统的单轴跟踪性能,而且轮廓误差明显降低。     

挖掘机器人精细作业的综合轨迹控制策略研究

挖掘机在国民经济建设领域发挥着重要作用,挖掘机器人是一种对传统挖掘机经过机器人化改造后的智能装备。针对挖掘机控制系统非线性强、数学模型难以建立、精细作业轨迹精度要求高的问题,提出了一种基于变论域模糊PID控制与交叉耦合控制的综合轨迹控制策略。采用带死区补偿的变论域模糊PID控制进行单执行器跟踪控制,利用交叉耦合控制提高执行器末端轮廓精度。通过联合仿真模型对控制策略进行验证分析。仿真结果表明：对比PID、变论域模糊PID两种控制策略,所设计的控制策略在响应性和准确性方面均优于其他两种算法,验证了方法的有效性。     

二维直线电机的多入多出无模型自适应轮廓控制

针对传统的单入单出控制器无法解决二维直线电机存在的非线性,不确定性以及强耦合作用等问题,依据无模型自适应控制不依赖于被控系统精确数学模型,仅需受控系统输入输出数据便能实现自适应控制这一特点,采用多入多出的紧格式动态线性化无模型自适应控制算法对二维直线电机XY轴进行整体控制器设计.同时,针对二维直线电机这种含有纯二阶积分环节的非自平衡系统,提出了多入多出无模型自适应控制改良方法,并进行严格的稳定性和收敛性证明.为了提高二维直线电机的轮廓精度,在多入多出无模型自适应控制改良方法的基础上,加入交叉耦合控制器,与传统的交叉耦合控制方法相比较,提高了跟踪精度和轮廓精度.最后通过仿真和实物实验证明了所提方案的有效性.     

双轴联动系统广义预测交叉耦合位置控制

在双轴联动系统中,减小轮廓误差和提高轨迹跟踪的能力是位置控制的主要目标.为提高轨迹跟踪的稳态精度和动态性能,本文提出了双轴广义预测交叉耦合控制策略(generalized predictive cross-coupling control,GPCCC).首先将广义预测算法应用于双轴联动控制中,根据已知轨迹进行多步预测、滚动优化和反馈校正来提高双轴控制性能,其次采用交叉耦合结构将轮廓误差作为反馈量来修正广义预测控制的给定轨迹.最后,通过两台永磁同步电机驱动的双轴联动系统完成实验,实验效果证明了所提出的控制策略在保证轨迹跟踪精度的同时,可以有效提高动态响应速度,尤其在轨迹转折点处,相比于传统PID交叉耦合结构,可以明显减小轮廓误差.     

Iterative learning control for integrated system of robot and machine tool

This study is concerned with the integrated system of a robot and a machine tool. The major task of robot is loading the workpiece to the machine tool for contour cutting. An iterative learning control (ILC) algorithm is proposed to improve the accuracy of the finished product. The proposed ILC is to modify the input command of the next machining cycle for both robot and machine tool to iteratively enhance the output accuracy of the robot and machine tool. The modified command is computed based on the current tracking/contour error. For the ILC of the robot, tracking error is considered as the control objective to reduce the tracking error of motion path, in particular, the error at the endpoint. Meanwhile, for the ILC of the machine tool, contour error is considered as the control objective to improve the contouring accuracy, which determines the quality of machining. In view of the complicated contour error model, the equivalent contour error instead of the actual contour error is taken as the control objective in this study. One challenge for the integrated system is that there exists an initial state error for the machine tool dynamics, violating the basic assumption of ILC. It will be shown in this study that the effects of initial state error can be significantly reduced by the ILC of the robot. The proposed ILC algorithm is verified experimentally on an integrated system of commercial robot and machine tool. The experimental results show that the proposed ILC can achieve more than 90% of reduction on both the RMS tracking error of the robot and the RMS contour error of the machine tool within six learning iterations. The results clearly validate the effectiveness of the proposed ILC for the integrated system.     

Contouring controller design based on iterative contour error estimation for three-dimensional machining

Recently, there has been a growth of interest in high precision machining in multi-axis feed drive systems, subjected to problems such as friction, cutting force and incompatibility of individual driving axis dynamics. To guarantee high precision machining in modern computer numerical controlled (CNC) machines, CNC's controllers do its control efforts to reduce contour error. One of the common approaches is to design a controller based on the estimation of contour error in real time. However, for complex contours with severe curvatures, there is a lack of effective algorithms to calculate contour errors accurately. To address this problem, this paper proposes an accurate contour error estimation procedure for three-dimensional machining tasks. The proposed method is based on an iterative estimation of the instantaneous curvature of the reference trajectory and coordinates transformation approach, and hence, it is effective for complex reference trajectories with high curvatures. In addition, contour error controller is presented to reduce the estimated contour error. The feasibility and superiority of the proposed model as well as contour error controller are demonstrated through experimental system using a desk-top three-axis CNC machine.     

Computer aided contouring operation for traveling wire electric discharge machining (EDM)

This paper develops a computational method for numerical control (NC) of traveling wire electric discharge machining (EDM) operation from geometric representation of a desired cut profile in terms of its contours. Normalized arc length parameterization of the contour curves is used to represent the cut profile and a subdivision algorithm is developed together with kinematic analysis to generate the required motions of the machine tool axes. In generating the tool motions for cutting sections with high curvatures such as corners with small radii, a geometric path lifting method is presented that increases the machining gap and prevents gauging or wire breakage.     

微处理器在超精密数控加工中的应用

本文简述了ＡＤＳＰ２１８１微处理器的特点，介绍了该处理器在超精密数控机床中的应用及数控系统下位机结构组成，给出了实验曲线和结果。     

数控机床RTCP精度的分析

RTCP精度是五轴联动数控机床的重要精度指标.本文是基于西门子840D数控系统,结合航空大型结构件加工企业高档五轴数控加工中心的实际情况,分析并总结出一套数控机床RTCP精度的检验与补偿的方法.     

A reinforced learning control using iterative error compensation for uncertain dynamical systems

This paper investigates a learning control using iterative error compensation for uncertain systems to enhance the precision of a high speed, computer-controlled machining process. It is specially useful in mass-produced parts produced by a high-speed machine tool system. This method uses an iterative learning technique which adopts machine commands and cutting errors experienced from previous manoeuvres as references for compensation actions in the current manoeuvre. Non-repetitive disturbances and nonlinear dynamics of the cutting processes and servo systems of the machine which greatly affect the convergence of the learning control systems were studied in this research. State feedback and output feedback methods were used for controller design. Stability and performance of learning control systems designed via the proposed method were verified by simulations on a single degree of freedom servo positioning system.     

Machining accuracy reliability analysis of multi-axis machine tool based on Monte Carlo simulation

Although machine tool can meet the specifications while it is new, after a long period of cutting operations, the abrasion of contact surfaces and deformation of structures will degrade the accuracy of machine tool due to the increase of the geometric errors in six freedoms. Therefore, how to maintain its accuracy for quality control of products is of crucial importance to machine tool. In this paper, machining accuracy reliability is defined as the ability to perform its specified machining accuracy under the stated conditions for a given period of time, and a new method to analyze the sensitivity of geometric errors to the machining accuracy reliability is proposed. By applying Multi-body system theory, a comprehensive volumetric model explains how individual geometric errors affect the machining accuracy (the coupling relationship) was established. Based on Monte Carlo mathematic simulation method, the models of the machining accuracy reliability and sensitivity analysis of machine tools were developed. By taking the machining accuracy reliability as a measure of the ability of machine tool and reliability sensitivity as a reference of optimizing the basic parameters of machine tools, an illustrative example of a three-axis machine tool was selected to demonstrate the effectiveness of the proposed method.     

马波斯E32R测量仪在大型发动机缸体加工中的应用

为了提高数控镗铣床在加工大型发动机缸体时的关键尺寸的精度,在机床上设计安装了马波斯（Marposs） E32R测量仪,本文重点描述了测量仪与数控系统的接口连接、测量仪的校准、宏程序的编制.通过在线检测进一步提高了工件特殊尺寸的加工精度和产品质量.     

快速刀具伺服系统自抗扰控制的研究与实践

快速刀具伺服系统(fast tool servo, FTS)是实现非圆截面和非轴对称表面零件加工的关键部件. 加工过程中,FTS应克服时变切削力负载和自身参数的非线性, 驱动刀具完成高频高精度跟踪运动. 为了解决FTS的快速精密跟踪控制问题, 根据刀具运动参考轨迹已知的特点, 应用自抗扰控制原理和前馈控制策略, 针对基于剪应力和正应力电磁驱动的两种直线执行机构, 分别设计了采用线性和非线性扩张状态观测器的自抗扰控制器, 并利用传递函数和描述函数方法, 分析了线性控制器的跟踪精度和动态刚度特性, 探讨了非线性控制系统的极限环问题. 两种基于自抗扰控制的快速刀具伺服系统已应用于发动机椭圆截面活塞的精密车削和二维正弦微结构表面的超精密车削,满足了加工需求. 研究与应用结果表明: 自抗扰控制思想独特、算法易于工程实现, 具有很好的工程应用价值.     

氧化铝熟料烧成过程人机协同智能控制系统

介绍了烧结法生产氧化铝的关键设备熟料(回转)窑采用计算机实时检测、控制及管理的设计开发过程,以及熟料烧结过程人机协同智能控制系统的组成。论述各个环节的控制原理和方法