智能装载机铲取过程动力学建模分析

通过对装载机工作装置的运动和受力分析 ,在广义坐标下 ,运用拉格朗日方程建立起轮式装载机在铲取过程中的动力学模型 ,即机构的运动微分方程 ,从而得到力与运动之间的关系 ,最后对该模型作了必要的分析     

基于ADAMS的轮式装载机运动学及动力学仿真分析

基于虚拟样机技术,利用ADAMS软件对某轮式装载机建模,并对其进行运动学及动力学仿真,检查装载机在运动工作过程中是否出现干涉,同时获得装载机各部件的运动学及动力学相应曲线,分析装载机结构设计及其受力情况是否合理,为装载机设计提供参考.     

机器人动力学分析的等效有限元建模方法

介绍了一种机器人动力学建模的等效有限元法。引入等效单元的概念,通过广义惯量矩阵相等的等效单元准则提出了单元伪质量阵的概念,基于有限元思想规则组装得到等效系统的伪质量阵。基于动力学普遍方程和等效力系的概念推导出了系统的动力学微分方程,该方程表述简单、规范,适于计算机编程,使人工分析量大大减少,提高了建模效率。利用该方法推导了2-DOF平面并联机器人的动力学方程,验证了方法的正确性和有效性,为其他复杂机器人机构的动力学分析提供了一种新的可供利用的手段。     

智能装载机铲取过程动力学建模分析

通过对装载机工作装置的运动和受力分析，在广义坐标下，运用拉格朗日方程建立起轮式装载机在铲取过程中的动力学模型，即机构的运动微分方程，从而得到力与运动之间的关系，最后对该模型作了必要的分析。     

轮式装载机驱动桥壳疲劳失效预测模型研究

针对轮式装载机驱动桥桥壳疲劳失效问题,运用疲劳失效原理,对轮式装载机驱动桥壳工作特征进行理论及有限元建模,研究了轮式装载机疲劳失效规律,提出了一种驱动桥壳疲劳失效预测计算模型。分析结果表明:由于计算模型考虑了随机载荷谱和修正后的应力疲劳曲线,轮式装载机驱动桥壳失效模型贴合实际;轮式装载机驱动桥壳轮边截面剧烈变化位置存在规律性的应力集中;桥壳的前六阶固有频率值皆远离实际工况路面的激振频率;轮式装载机驱动桥壳损伤大部分出现在低应力幅下。     

ZL50轮式装载机工作装置动力学特性

以某型轮式装载机为研究对象,利用Solidworks三维造型设计软件对轮式装载机工作装置建立三维模型,导入动力学仿真软件ADAMS中,添加约束、载荷建立虚拟样机系统。对工作装置进行动力学仿真分析,获得主要铰接点处的载荷受力曲线,为轮式装载机工作装置的设计和改进提供了理论参考依据。     

计及二阶效应的刚柔耦合连杆系统动力学分析

根据虚功原理和达郎伯原理推导了计及二阶效应的柔性单元运动方程,并利用刚化条件得到了刚性梁单元运动方程,给出了刚柔耦合连杆系统动力学建模与分析的方法.对构件刚度相差悬殊的多体系统进行动力学分析时,如若当作多刚体系统分析,会因忽略弹性变形导致结果不准确;当作多柔体系统建模分析求解,则因自由度太多导致方程庞大难求解.可行的方法是:将刚性单元与柔性单元耦合建模,在多柔体系统基础上,引入刚性单元和刚性约束条件,对刚性构件自身的动力学特性进行等效,然后按照一般弹性系统有限元方法集成得到虚拟柔性系统动力学方程,建立过渡坐标与广义坐标关系,消除非独立坐标,得到真实的系统运动方程,降低系统方程维数,提高分析效率.以曲柄滑块机构为例,介绍了计及二阶效应的刚柔耦合系统动力学的建模分析过程.     

多路况下轮式装载机行驶动力学研究

为了研究多路况下轮式装载机的行驶动力学特性,提出轮式装载机行驶动力学评价方法,建立轮式装载机与路面耦合的动力学模型,仿真模拟得到了轮式装载机在F级对称和非对称路面上空载低速、空载高速、满载低速、满载高速行驶工况下轮心和铲斗处的横向、行驶方向和垂直方向上的加速度值。结果表明：轮式装载机在多路况下垂直方向上的振动是行驶动力学性能最大的影响因素。这种基于ADAMS软件的装载机行驶动力学仿真模拟试验,为轮式装载机行驶动力学的优化与改进提供了一种新颖、有效的方法。     

基于虚拟样机的装载机反转六杆工作机构设计

利用Pro/E对装载机反转六杆工作机构进行三维数字化建模、仿真,并将Pro/E中的三维实体模型导入ADAMS中,应用ADAMS/View模块提供OPTDES-SQP优化算法,以动臂举升时转斗平动性为优化目标函数,对装载机的工作机构进行优化设计,获得了符合要求的机构优化设计参数。虚拟样机技术提升了轮式装载机开发效率,提高了装载机工作机构设计水平和工作性能。     

基于广义坐标形式牛顿－欧拉方法的空间并联机构动力学正问题分析

基于具有广义坐标形式的牛顿－欧拉方法建立一般空间并联机构动力学正问题建模与仿真的通用方法。在动力学建模时,选取空间并联机构动平台的工作空间变量作为系统广义坐标,从各构件的牛顿－欧拉方程出发,结合运动学逆解和虚功原理,得到与广义坐标相对应的系统动力学方程－运动微分方程和系统理想铰约束力方程。对6-UPS型空间并联机构进行动力学建模,计算外力作用下的动态响应,验证了该方法的有效性。理论分析和仿真案例表明,该方法可以简化并联机构动力学正问题的建模步骤,提高计算效率。     

TRACTIVE PERFORMANCE ANALYSIS ON RADIALLY DEPLOYABLE WHEEL CONFIGURATION OF LUNAR ROVER VEHICLE BY DISCRETE ELEMENT METHOD

With the consideration of volume constraint of launch vehicle and trafficability of rover vehicle on lunar regolith terrain, a new design of radially deployable wheel is presented. For the purpose of achieving the meso-mechanics and dynamical behavior of lunar soil particles as well as macro-parameters of tractive performance for radially deployable wheel, the interaction between two types of wheel configurations and lunar soil particles is analyzed by means of discrete element method. The network of contact forces, the displacement vector chart, and the deformation of lunar soil beneath wheels are plotted. The equations of soil thrust, motion resistance, drawbar pull and driven torque are derived in granular scale based on the coordinates transformation and algebraic summation. The calculated results show that there is sufficient traction for both 6-split and 12-split radially deployable wheels with 304 mm outspread diameter to negotiate lunar regolith terrain specified here; the value of drawbar pull enhances with the increase of split number of radially deployable wheel, however, the required driven torque increases simultaneously, therefore, the tractive efficiency decreases.     

谐波齿轮传动柔轮的应力和疲劳强度分析

柔轮的工作应力和寿命决定了整个谐波减速机的传动性能,对柔轮的应力和疲劳强度的研究,有利于提高谐波传动精度和柔轮使用寿命.从理论的角度计算了某型号谐波齿轮减速机的杯型柔轮空载下的应力峰值和负载时柔轮的疲劳安全系数,利用Inventor建模和ANSYS Worbench仿真软件验证了计算结果的可靠性,得到了柔轮最大等效应力...     

Identification of the nonlinear excitation force acting on a bowed string using the dynamical responses at remote locations

For achieving realistic numerical simulations of bowed string instruments, based on physical modeling, a good understanding of the actual friction interaction phenomena is of great importance. Most work published in the field including our own has assumed that bow/string frictional forces behave according to the classical Coulomb stick-slip model, with an empirical velocity-dependent sliding friction coefficient. Indeed, the basic self-excited string motions (such as the Helmholtz regime) are well captured using such friction model. However, recent work has shown that the tribological behavior of the bow/string rosin interface is rather complex, therefore the basic velocity-dependent Coulomb model may be an over-simplistic representation of the friction force. More specifically, it was suggested that a more accurate model of the interaction force can be achieved by coupling the system dynamical equations with a thermal model which encapsulates the complex interface phenomena. In spite of the interesting work performed by Askenfelt [32], a direct measurement of the actual dynamical friction forces without disturbing the string motion is quite difficult. Therefore, in this work we develop a modal-based identification technique making use of inverse methods and optimization techniques, which enables the identification of the interface force, as well as the string self-excited motion, from the dynamical reactions measured at the string end supports. The method gives convincing results using simulated data originated from nonlinear computations of a bowed string. Furthermore, in cases where the force identifications are very sensitive to errors in the transfer function modal parameters, we suggest a method to improve the modal frequencies used for the identifications. Preliminary experimental results obtained using a basic bowing device, by which the string is excited with the stick of the bow, are then presented. Our identifications, from the two dynamical string reactions, are consistent as attested by the comparison of the two available versions of the string dynamical motion and of the friction force. Furthermore, the method seems adequate to investigate the interface force for the bowed string.     

铸件切割打磨机器人工作臂关键部件有限元分析

为保证铸件切割打磨机器人工作臂关键部件强度和零件材料选择的合理性,运用ANSYS Workbench软件对铸件切割打磨机器人工作臂关键部件进行静力学分析,有限元分析结果表明:砂轮切削打磨装置进行曲面切削打磨,承受左三向力极限载荷时,最大位移变形量为0.29332mm,发生在打磨头;最大等效应力为85.45MPa,发生在打磨头与打磨头固定位置左上侧,即结构强度和刚度满足砂轮切削打磨装置工作要求,为铸件切割打磨机器人结构设计和强度校核提供了参考。     

多个物体直线位移传动机构设计

针对多物体直线位移传动、且对同一个供货位连续供货的设计要求，我们采用螺旋机构，通过在螺旋导程上合理放置货物，将多个物体的单个离散传动变为连续的供货传动。解决了多物体直线位移的有序传动问题。其关键构件有动力减速机构、螺旋导向机构和弹簧卡环拨轮机构。     

月球探测车的运动学建模

给出了六轮摇臂-转向架式月球探测车的运动学建模方法。该模型共有6个自由度，包括沿x、y、z方向的移动和绕x、y、z方向的转动。为了获得月球探测车的位置和姿态，正运动学方程由车轮的雅可比(Jacobian)矩阵推导，并对矩阵方程进行了求解；逆运动学方程为已知探测车本体的运动速度，确定单个车轮的驱动速度，以达到期望的探测车位姿。该运动学模型为月球探测车的运行、运动控制系统的设计及自主导航提供了理论基础。     

内,外啮合斜齿轮三维接触应力有限元分析

本文针对建立斜齿轮接触应力有限元模型所涉及的若干问题进行了分析,在此基础上编制了包含内、外啮合并计及轮体结构的斜齿轮接触应力分析有限元建模程序;针对７个考题的有限元结果与ＩＳＯ、ＡＧＭＡ４１１．０２、ＡＧＭＡ２００１齿轮标准的计算结果进行了对比验证分析。     

基于遗传算法的轮式挖掘机折叠动臂轻量化设计

以某型轮式挖掘机折叠动臂工作装置为研究对象,针对其工作要求和工况特点对动臂结构进行分析,以质量最小为目标函数,依据强度、刚度等性能要求构建优化数学模型。考虑约束非线性规划问题的特点,采用遗传算法进行参数优化,以所得参数建模导入ANSYS软件进行应力分析。所得结果表明,此方法能有效的减轻前动臂质量,达到轻量化设计的预期目标。     

Comparative study of tracking control for a mobile manipulator: Nonholonomic and dynamic cases

This paper gives an in-depth treatment of the modeling and control of a mobile manipulator which consists of a robotic manipulator mounted upon a mobile robot. By neglecting slip of the platform's tires, nonholonomic constraints are introduced into the equations of motion. By considering wheel slip, the assumption of nonholonomic motion is violated. Nonholonomic and dynamic models of a mobile manipulator are developed and compared using the Lagrange-d'Alembert formulation and the Newton-Euler method, respectively. The dynamic model which considers wheel slip incorporates a nonlinear tire friction model. The tracking problem is investigated by using imput-output linearization for the nonholonomic model. For the dynamic model, a robust control method based on a matching condition is developed to eliminate the harmful effects of wheel slip, which acts as a disturbance to the system. Then, the effect of wheel slip on the tracking of commanded motion is identified via simulation. The effectiveness of the proposed control algorithm is demonstrated through computer simulation.