一种六输入三自由度并联平台机构分析

提出一种六输入、动平台自由度为3的并联平台机构.对于动平台,输入是冗余的.引入协调构件,使机构的自由度为6,所以对于整个机构,输入是确定的,避免了超确定输入协调控制的问题,同时使机构具有冗余驱动机构的优点.将动平台和协调构件的运动作为机构的广义输出,对机构进行了运动学分析,建立了输入和广义输出的映射关系,得到了机构的1阶、2阶影响系数矩阵.应用虚功原理和达朗贝尔原理对机构进行了动力学分析,得到了动力学模型.仿真结果表明,该并联平台机构具有承载能力高等特点,是设计重载并联机构的一种新的解决方案.     

六自由度并联机器人动力学方程

本文研究了6自由度并联机器人机构的显式动力学方程的建立。文中首先导出了构件6维惯性力矢关于主动副速度、加速度的显表达式,引入了仅与机构位形和质量分布有关的一、二阶惯性影响系数,进而应用达朗伯原理方便地建立起6自由度并联机器人的显式动力学方程。最后进行了实例计算。     

并联6—SPS机器人的影响系数及其应用

本文根据并联机构的特点,对位置反解直接求导,建立了并联6-SPS 机器人的一、二阶影响系数矩阵,解决了速度分析和加速度分析问题.为机器人的误差分析和动力学分析奠定了基础.所得的一、二阶影响系数矩阵的形式简单统一,特别实用于计算机计算.最后给出了实例计算.     

3-RPS并联机构弹性动力学建模方法

运用子结构综合和模态缩聚技术,提出了一种全柔性3自由度并联动力头(3-RPS)的弹性动力学建模方法.在建模过程中,将机构划分为动平台子结构和3条RPS伸缩支链子结构.模型中考虑了所有铰链和支链柔度对整机动态特性的影响.将球铰和转动副处理为具有等效刚度的虚拟弹簧;通过有限元软件和模态缩聚技术对伸缩支链进行处理,进而建立支链的弹性动力学方程;通过引入变形协调条件,对系统整体刚度矩阵进行组装,建立了3-RPS并联动力头的整体动力学方程.研究结果表明,整机的各阶固有频率随着机构位姿的变化而变化,并且呈三对称形式分布.通过模态实验验证了该方法所得的固有频率和振型.     

高速运动下并联机器人主动支链的动力学耦合特性

为研究并联机器人主动支链间在关节空间内的动力学耦合特性,首先,建立了一般并联机器人基于关节空间的动力学模型,进行了动力学耦合力矩分析,定义了动力学耦合强度系数,该系数适用于一般并联机器人动力学耦合特性描述,且具有统一标度.然后,以一种2(3HUS+S)并联机器人为例,基于动力学耦合强度系数进行了动力学耦合特性分析,得到了动力学耦合特性在所需运动轨迹内的变化规律,并设计实验测得了主动支链的实际耦合力矩,通过对比分析验证了理论研究的正确性.最后,针对2(3HUS+S)并联机器人,得到了其动力学耦合特性随结构参数的变化规律,通过适当减小连接杆长度及动平台半径与底面基座半径的比值,可在一定程度上降低主动支链间的动力学耦合程度.     

基于边界搜索法的一种四自由度并联机器人工作空间分析

本文设计了一种新型四自由度并联机构,以动平台中心点为参考点进行了运动学逆解分析,采用边界搜索法分析并联机构定姿态时的工作空间,获得工作空间的三维图形.研究该并联机构的支链长度、动静平台半径和运动副转角等结构参数和运动参数对其工作空间大小的影响,为机构的参数优化提供理论依据.     

用6-RUS型并联机构实现海上补给自动对接的关键技术

提出了用6-RUS型并联机构来实时调整对接喇叭口的位姿状态以实现海上补给中的自动对接.首先,对该机构支链的相对位置关系及约束进行了讨论,建立了该机构的逆运动学模型;其次,对该机构支链的受力情况进行了理论分析,基于凯恩方程建立了该机构的逆动力学模型;最后,对该机构在运动过程中电机输出转角及输出扭矩进行了数值仿真.仿真结果...     

基于MSC Adams的3-UPS并联机床动态特性仿真

以3-UPS并联机床为研究对象,应用虚拟样机技术建立机构参数化仿真模型,给出并联机床虚拟样机联合仿真设计方案. 通过对样机模型动力学分析,确定影响整机动态性能的关键部件,采用MSC Adams完成这些部件的弹性体建模. 通过动态仿真分析给出弹性并联机构的动态响应、固有频率等动态特性参数,为并联机床整机的优化设计奠定基础.     

基础激励下6-UHP并联平台的动力学建模与仿真

面向隔振指向技术的研制需求,开展了基础激励下6-UHP(universal-Hooke-prismatic)并联平台的动力学建模与仿真研究.首先,介绍了6-UHP并联平台的结构特点;接着,利用Kane方法对并联平台进行理论建模,得到完整动力学方程;最后,利用联合仿真技术对并联平台的理论模型进行验证.结果表明,仿真得到的6维加速度曲线与输入加速度曲线吻合度良好,最大误差为5.40%,最小误差为0.25%,充分验证了动力学模型的准确性.     

一类球面机器人动力学建模与无源控制

针对一类作为拟人肩的球面3-RRR并联机器人的轨迹跟踪问题,在分析该机器人机构特性的基础上,通过计算各构件的动、势能,采用拉格朗日方法建立了其动力学模型,并给出了模型参数矩阵的基本性质.针对模型利用Backstepping方 法,结合其参数矩阵基本性质,设计了一种无源控制器.控制器作用下,系统严格输出无源,其广义变量能够很好地跟踪给定信号,进而使得系统动平台能够跟踪给定位姿变化.严格证明和仿真验证了控制器的有效性及该机器人能够满足作为拟人肩必需的跟踪特性.     

直升机升力系统数字化装配设备设计

针对直升机升力系统手工装配质量不稳定、效率低等问题,提出基于6-PUS并联机构的数字化装配设备方案,进行机构构型分析、运动学建模与分析、误差映射分析等,设计用于直升机升力系统装配的6-PUS并联机构。面向装配精度需求,研究关键零部件的加工、装配精度设计及分析技术。分析结果表明该机构可用于直升机升力系统的数字化装配,代替人工操作,提高装配质量。     

并联机器人曲面汉字雕刻刀路规划算法研究

解决了并联机器人在空间曲面上雕刻汉字时所遇到的相关问题,包括平面刀路向曲面刀路的映射方法、曲线插补计算及刀具姿态实时规划算法等,给出了算例并以6-PUS并联机器人为模型进行了实验,实验结果验证了所提方法的有效性和可行性,这些方法理论上适用于任意种类的文字及空间曲面,也适用于雕刻之外的其它加工领域.     

五轴并联机床的尺度综合

基于逆向思维提出了一种满足工作空间要求的五轴并联机床的尺度综合方法．首先用极坐标来描述并联机床的姿态空间；然后基于工作空间的要求得到运动平台上铰链点与固定平台上铰链点的距离极值表达式；最后考虑到杆件的力传递性能，得到一组性能较优的参数．该方法对类似的并联机构的尺度综合具有较高的参考价值．     

Optimal design of a 3-PUPU parallel robot with compliant hinges for micromanipulation in a cubic workspace

In recent years, nanotechnology has been developing rapidly due to its potential applications in various fields that new materials and products are produced. In this paper, a novel macro/micro 3-DOF parallel platform is proposed for micro positioning applications. The kinematics model of the dual parallel mechanism system is established by the stiffness model with individual wide-range flexure hinge and the vector-loop equation. The inverse solutions and parasitic rotations of the moving platform are obtained and analyzed, which are based on a parallel mechanism with real parameters. The reachable and usable workspace of the macro motion and micro motion of the mechanism are plotted and analyzed. Finally, based on the analysis of parasitic rotations and usable workspace of micro motion, an optimization for the parallel manipulator is presented. The investigations of this paper will provide suggestions to improve the structure and control algorithm optimization for the dual parallel mechanism in order to achieve the features of both larger workspace and higher motion precision.     

Dynamics analysis for a novel 6-DoF parallel manipulator I with three planar limbs

A novel 6-DoF parallel manipulator I with three planar limbs is proposed and its dynamics is analyzed systematically. First, its characteristics and DoF are analyzed and calculated. Second, the formulae for solving kinematics of the moving platform and the planar limbs are derived. Third, the formulae for solving the inertial wrench applied on the planar limbs and the moving platform are derived, and dynamics formula is derived for solving dynamic active forces applied onto the planar limbs. Fourth, a singularity of the proposed parallel manipulator is determined and analyzed. Fifth, an analytic example is given for solving the kinetostatics and dynamics of the proposed parallel manipulator, and the solved results are analyzed and verified by the simulation mechanism. Finally, a workspace is constructed and analyzed by comparing with an existing 6-DoF parallel manipulator.     

Trajectory control of incompletely restrained parallel-wire-suspended mechanism based on inverse dynamics

This paper discusses parallel wire mechanisms where an end-effector of the mechanism is suspended by multiple wires. The mechanisms enable not only three-dimensional (3-D) positioning but also 3-D orienting of the end-effector, unlike typical wire suspension-type mechanisms such as overhead crane. To discuss the parallel-wire-suspended mechanisms generally, two forms of basic dynamic equations are presented. Then the parallel wire mechanisms are classified into two types based on the basic equations. Dynamical properties of the two types of wire-suspended positioning mechanism are discussed. In this paper, one of the wire-suspended mechanism, incompletely restrained-type parallel wire mechanism, is mainly discussed on its inverse dynamics problem and its trajectory control problem. The inverse dynamics problem for the incompletely restrained-type mechanism plays an important role on its control problem, because the mechanism has low stiffness based on incomplete constraints on the suspended object which is governed by its dynamics. The paper proposes an antisway control method for the suspended object. In the method, the inverse dynamics calculation is used for nonlinear dynamics compensation to control the suspended object of the incompletely restrained parallel wire mechanism.     

Dynamic modeling and redundant force optimization of a 2-DOF parallel kinematic machine with kinematic redundancy

High precision is still one of the challenges when parallel kinematic machines are applied to advanced equipment. In this paper, a novel planar 2-DOF parallel kinematic machine with kinematic redundancy is proposed and a method for redundant force optimization is presented to improve the precision of the machine. The inverse kinematics is derived, and the dynamic model is modeled with the Newton–Euler method. The deformations of the kinematic chains are calculated and their relationship with kinematic error of the machine is established. Then the size and direction of the redundant force acting on the platform are optimized to minimize the position error of the machine. The dynamic performance of the kinematically redundant machine is simulated and compared with its two corresponding counterparts, one is redundantly actuated and the other is non-redundant. The proposed kinematically redundant machine possesses the highest position precision during the motion process and is applied to develop a precision planar mobile platform as an application example. The method is general and suitable for the dynamic modeling and redundant force optimization of other redundant parallel kinematic machines.     

Contact Stiffness Identification with Delay and Structural Compensation for Hardware-in-the-Loop Contact Simulator

The hardware-in-the-loop (HIL) simulation is necessary to test the contact dynamics of spacecraft in space. The stiffness parameter is important for the state recording and compliant control. A contact stiffness estimation method is proposed, where the force measurement delay and structural dynamics of the upper platform are compensated to guarantee the estimation accuracy. The force measurement delay and structural deformation of the upper platform lead to the delayed force signal and the position error respectively, and then the contact stiffness identification error. A phase lead based delay compensation is used to reconstruct the true contact force from the measured force. The structural deformation of the upper platform is compensated by a structural dynamics model to obtain the true contact position. Based on the compensated force and position signals, the stiffness identification is performed using the real time recursive least squares (RLS) method. The effectiveness of the proposed method is verified by simulations and experiments. In the experiments, the stiffness identification error is about ± 5 %, which is satisfactory for monitoring and control applications.     

基于IP传感和网络接口的环境测控平台设计

论述基于IP通信技术的测控平台的特点及优势,介绍了一种基于IP传感器和网络接口设备的环境测控平台的设计方法、构成机制、各组成部分的作用和整个平台的运作过程,同时介绍在环境测控平台中的应用虚拟仪表技术的情况。