机械系统典型运动过程单片机控制与数字仿真

以锻造机械手典型机械运动水平直线运动为例,建立该运动过程的动态数学模型,通过变参数仿真研究各种参数对系统动态特性的影响,分析系统响应特性对控制系统及控制精度的影响.采用AT89C51单片机对步进电机进行控制,通过I/O口输出的脉冲信号作为步进电机的控制信号,对于提高大型复杂机械系统的控制精度具有参考价值.     

航空遥感惯性稳定平台LuGre摩擦参数的分步辨识

由于航空遥感惯性稳定平台框架角运动受限,本文提出了基于LuGre摩擦模型进行参数初步和精确辨识的方法以进一步提高其控制精度。从数字控制系统出发,构建了摩擦参数辨识系统,把摩擦参数辨识问题转化为曲线拟合问题。通过限定输入信号幅值和频率,解决了框架角运动受限导致摩擦参数辨识困难的问题。结合数字控制系统特性,优先辨识摩擦线性项参数;根据摩擦静态和动态特性,提出分步夹逼和分步搜索法依次辨识剩余参数,完成初步辨识。然后代入初步辨识结果,用遗传算法完成摩擦参数的精确辨识。仿真结果表明:摩擦参数初步辨识误差小于5%,精确辨识误差小于0.7%;用辨识出的摩擦参数构建摩擦补偿器,系统对基座低频角运动干扰的抑制能力提高了4倍。最后,基于某原理样机开展了摩擦参数辨识和补偿实验,结果表明控制精度提高了1倍,证实了提出的辨识方法的有效性和工程实用意义。     

基于PWM的开关阀控电液位置伺服系统负载特性仿真研究

针对开关阀控电液位置伺服系统在负载条件下上行和下行运动特性不一致,对液压回路中平衡阀模块加以改进,使得平衡阀两端压差不受负载变化影响,从而使液压缸上下行运动特性保持一致。通过分别研究空载和加载条件下系统静、动态性能,对系统进行AMESim仿真分析和优化,以提升系统运动过程平稳性。研究结果表明,结构优化后的系统动态响应速度快、跟随响应误差小、控制精度高,且加载后液压缸运动特性仍能保持一致,有效地提高了系统性能,为下一步系统样机研制奠定基础。     

参数自调整模糊控制器在空调控制系统中的应用

针对空调温度控制的大惯性、大滞后、非线性特点，提出一种基于参数自调整模糊控制器，阐述了参数自调整的原则，仿真实验结果表明：空调温度控制系统具有较高的控制精度、良好的动态特性和鲁棒性，超调小、系统响应快、调节时间短，达到了良好的控制效果。     

机构运动非线性参数预测的动态神经网络模型

研究目的是建立考虑摩擦影响的复杂机构非线性运动参数辨识模型。复杂机构的动态响应为高度非线性，考虑摩擦的影响使机构运动的不确定性增大，机构控制的难度较大。应用动态神经网络技术，建立机构运动参数动态参数辨识模型，对柔性机构的运动参数进行辨识和预测。通过机构实例的验证，该方法计算速度较快，精度较高，为实现复杂大系统的辨识提供了一种有效可行的方法。     

二次调节加载系统的预测控制研究

分析了二次调节加载系统的特性。针对系统的特点，提出一种动态矩阵预测控制（DMC）和PID相结合的方法。通过内环来克服随机干扰，外环采用预测控制来获得优良的跟踪性能和鲁棒性，实现目标和控制的分层，对有关设计参数的选择进行了讨论。仿真试验结果表明：动态矩阵预测控制和PDI相结合的方法有效地克服了系统时变、干扰等未知影响，有较高的控制精度和较强的鲁棒性，可获得满意的控制效果。     

磨削动态特性对光学材料亚表面损伤机理研究

本文在面向光学元件的加工需求背景下,对其磨削加工做了基础设计,并根据课题组研究基础设定了不同的磨粒尺寸。研究动态特性对光学材料磨削亚表面损伤的影响,以断裂力学中的裂纹扩展模型为基础,建立运动副动态特性指标以及磨削参数与亚表面损伤深度和分布的量值传递模型,通过对不同支承形式运动副磨削系统的建模仿真对量值传递模型进行检验和修正,并采用磨削工艺试验、动态特性参数监测和亚表面损伤检测方法对所建立的模型进行验证,形成以光学材料磨削亚表面损伤确定性控制为目标的运动副动态特性指标设计和磨削工艺参数优化方法。     

基于Matlab的打击气压对液气锤动态特性影响的研究

打击气压是液压锤打击参量中影响动态特性的关键因素,为了提高设备的控制精度,以液气锤为研究对象,分别建立液气锤打击过程在未发生塑性变形阶段和塑性变形阶段的拉格朗日动力学模型,利用Matlab/Simulink数值计算方法研究液气锤打击过程的运动规律,深入分析打击气压变化对锻打系统动态特性的影响,为后期设备调试提供理论依据,以达到精确控制的目的。经现场试验研究表明,控制系统可以满足液气锤精确打击工艺的要求。     

压电微动工作台动态迟滞模型研究

为实现压电微动工作台的快速准确运动定位,研究了其运动定位模型。压电工作台的运动定位精度主要受到工作台动态特性和迟滞特性的影响。在介绍这两类典型特性模型及其适用范围的基础上,提出了能够同时体现压电工作台动态特性和迟滞特性的动态迟滞模型,并给出了采用Prandtl-Ishlinskii (PI)迟滞算子的动态迟滞模型参数辨识方法。实验研究表明,动态迟滞模型的模型精度在压电工作台大行程、快速运动定位时较以往线性动态模型和迟滞模型有较大提高,其平均误差为0.16μm,最大误差为0.38μm,为下一步高性能运动定位工作台控制系统的设计提供了必要的模型基础。     

压电驱动器的非线性模型及其精密定位控制研究

压电驱动器的非线性特性和迟滞特性是影响微动平台定位控制精度的主要因素。采用改进的Preisach模型对压电驱动器的迟滞特性进行建模，利用建立的Preisach模型进行开环精密定位控制和作为PID反馈控制的前馈环节的研究。实验结果表明，该模型能够有效地降低非线性迟滞特性对压电驱动器位移输出精度的影响，提高驱动器的动态响应特性。     

液压同步运动系统变结构控制设计

该文以一执行器的实际运动轨迹作为另一执行器的理想跟踪目标，针对实际液压系统非线性时变特点，对两执行器的同步误差采用变结构控制策略。研究和仿真表明：采用变结构控制的液压同步运动系统，不仅具有较强的鲁棒性，而且有良好的动态品质和同步精度。     

Comprehensive analysis of the influence of structural and dynamic parameters on the accuracy of nano-precision positioning stages

Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine.     

BP网络在进给系统定位误差预测中的运用

针对机床进给伺服系统定位精度预测的难点,分析了进给伺服系统机械传动系统定位误差增长的原因,提出了一种定位误差预测的方法。在Adams中建立进给伺服系统动力学仿真模型,得到不同初始状态下的定位误差值,基于BP神经网络建立工作台与螺母座间隙、滚珠丝杠倾斜度、工件负载与定位误差之间的映射模型,根据映射模型提出对定位误差预测的方法。利用所建立的精密运动可靠性试验平台进行验证,证明了该方法的正确性和有效性。     

APPROACH TO IMPROVEMENT OF ROBOT TRAJECTORY ACCURACY BY DYNAMIC COMPENSATION

Some dynamic factors, such as inertial forces and friction, may affect the robot trajectory accuracy. But these effects are not taken into account in robot motion control schemes. Dynamic control methods, on the other hand, require the dynamic model of robot and the implementation of new type controller. A method to improve robot trajectory accuracy by dynamic compensation in robot motion control system is proposed. The dynamic compensation is applied as an additional velocity feedforward and a multilayer neural network is employed to realize the robot inverse dynamics. The complicated dynamic parameter identification problem becomes a learning process of neural network connecting weights under supervision. The finite Fourier series is used to activate each actuator of robot joints for obtaining training samples. Robot control system, consisting of an industrial computer and a digital motion controller, is implemented. The system is of open architecture with velocity feedforward function. The proposed m     

基于干扰观测器的龙门机床双驱系统的同步控制

根据动梁式龙门机床双驱动系统的结构特点及运动特性,基于拉格朗日方程,建立了龙门机床两轴之间的机械耦合模型,结合传动系统动态模型和伺服系统三闭环控制结构,得到了龙门机床双驱动系统模型;为了降低非对称结构和偏心负载等干扰对同步性能的影响,提高系统的抗干扰性,提出了一种基于干扰观测器（DOB）的双驱动系统同步控制方法;最后进行了仿真分析,仿真结果表明,通过干扰观测器对干扰进行补偿后,龙门机床双驱动系统的同步性能得到了明显的提高。     

柔性工装平台伺服系统误差分析与仿真

在随动控制系统中,其准确性和稳定性取决于控制系统的动静态特性指标。在对某柔性工装平台系统建模的基础上,从理论和仿真角度分别分析了伺服系统的动静态特性,并指出了影响动静态特性的参数。     

无油涡旋压缩机防自转机构的研究

从机构学角度,研究了小曲拐机构的运动,确定了小曲拐数目的合理选取及分布;从运动学角度,分析了小曲拐的受力,建立了小曲拐的运动平衡方程,研究了不同数目小曲拐的动力特性。研究结果表明：小曲拐的防自转机构是按平行四边形原理运动的,采用3个小曲拐的防自转机构有比较好的动力特性,其为整周受力,是一种精度高、性能好的防自转机构。     

Dynamic characteristics of a direct-drive air-bearing slide system with squeeze film damping

Direct-drive air-bearing slides have the inherent advantages of high positioning accuracy and smoothness of motion, but due to low damping in the air bearings, they generally lack dynamic stiffness. The rigidity of the drive, both statically and dynamically, can also be low compared to mechanical equivalents. In this paper, the dynamic response of an air-bearing slide fitted with a novel design of oil-lubricated squeeze film damper and driven by a fast-response, high-resolution control system is reported. The results show that the damper produces a substantial improvement in dynamic stiffness and that sufficient drive stiffness can be obtained to enable the slide to be used in some precision-machining applications.     

Clearance Influence on Dynamic Response of Intermittent Roller Chain Drive

The clearances appear in chain link hinges induced by manufacturing tolerance or wear of components are the most important factor that influences the dynamic performance of the intermittent roller chain drives.Due to the existence of the clearances in chain link hinges,the serious impact vibration phenomenon which influences the stability and the position accuracy of the chain drive system would be caused in the intermittent motion.But,the problem may be that a reasonable modeling on the chain with clearances is difficult due to the large clearance's number in chain system and the fact that the clearance' size are different.Currently,the studies on the dynamics of the intermittent roller chain considering the multi-clearance' joints are rare.Most research works have only focused on the constant moving chains.Taking the intermittent roller chain system as an object,this paper designs and builds the experimental device of this kind of mechanical system.The Longitudinal vibration response of the intermittent chain under the different motion laws was tested.The experimental study shows that the clearances presented in chain link hinges can cause severe impact vibration in the intermittent motion of chain.In subsequent work,the dynamic model of the intermittent roller chain system with the multi-clearance' joints was established.By calculating the dynamic response of this kind of mechanical system under the different motion laws,the effect of the clearances on the dynamic response of the intermittent chain drive system was analyzed.The theoretical simulation shows that the serious impact vibration phenomenon of the chain system can be caused by the clearances at the start accelerating period,and the chain drive system is often accompanied by the severe shock and vibration at the moment that the chain moves from the acceleration period to deceleration period.The research conclusions made by the experimental and theoretical studies indicate that the use of motion laws with small and continuous jerk at conversion point can effectively suppress the impact vibration at this point caused by clearances' effect.Additionally,the use of nonsymmetrical motion laws with small jerk approaching the end of the indexing period can obtain a smaller residual vibration.The presented motion law can provide an important reference for the improvement of the dynamic performance of the intermittent chain drive systems.     

Modeling,validation and energy flow analysis of a wheel loader

This paper presents a wheel loader simulation model, validation results and energy flow analysis. The developed simulation model will facilitate the performance evaluation and optimization process in the development stage of a prototype wheel loader. The wheel loader simulation model consists of mechanical and hydraulic powertrain model, multi-body dynamic model and working part dynamic model. The multi-body dynamic model is simplified since the effect of pitch and roll motion of the wheel loader on the energy flow of the powertrain and hydraulic actuator systems is insignificant, a simplified planar model for the dynamic vehicle is good enough for the objective of this study. Every component is modeled and integrated in a simulation package developed using Matlab/Simulink. The simulation model has been validated using experiment data and the validation results show that it effectively represents the actual dynamic characteristic of the target wheel loader. The verified simulation model will be used as a virtual platform to evaluate the performance of alternative powertrain models such as a dual-clutch transmission and hydrostatic transmission. An advanced control system can also be implemented and evaluated using the virtual platform.