基于闭环矢量法的五杆合作机器人运动学建模及仿真

利用闭环矢量法对五杆机构进行正运动学建模,给出了五杆并联机器人的闭环矢量方程,推导了其运动学方程,并用MATLAB软件编写MATLAB函数来求解运动学方程.利用Simulink仿真工具建立了五杆合作机器人的运动学仿真模型,仿真分析得到了运动学仿真曲线.研究过程表明,采用闭环矢量法对五杆并联机器人进行运动学分析既简便又快捷.这种方法对其他复杂平面并联机构的运动学分析具有一定的参考价值.     

一种类球面并联腕部机构及其运动学分析

采用构型演变法将2自由度球面并联机构Omni-Wrist V演变为一种3自由度2R1T(2转动1移动)的类球面并联机构,并对其运动学特性进行了系统的分析.首先,采用基于约束理论的图谱法对该机构的自由度进行了分析;其次,建立了其等效运动学模型,推导了解析形式的正、逆运动学方程,并讨论了其奇异性;最后,采用蒙特卡洛法求得机构的工作空间,并提出一种3维切片法分析其特性.在工作空间分析中,选择水平切片的面积和形状来衡量机构的旋转性能,采用定偏转角切片形成的扇形片径向位移量来表征其平移性能.该并联机构可作为腕部串接于SCARA(选择顺应性装配机械手)或Delta机器人末端,组成混联机器人,应用于需要同时大转角改变姿态和位置的电子或轻工生产等场合.     

2RPU_RPS并联机构运动学分析及仿真

从并联机构在实际应用中的运动控制出发,对2RPU_RPS构型的并联机构进行运动学分析及仿真。通过分析其结构约束条件,求解出机构的关节变量与末端姿态变量的关系,进而完成其逆运动学求解。在逆解的基础上,构建其正运动学模型。基于建立的运动学模型,分析其工作空间,并进行运动学仿真加以验证,为并联机构的实际应用提供理论指导。     

3-PRC并联机构运动学分析及结构参数优化

根据3-PRC并联机构的结构特点,分析了并联机构的运动学逆解,通过牛顿迭代法得到并联机构的运动学正解。使用SolidWorks、MATLAB和Adams软件对并联机构进行三维建模和运动学仿真,并验证了并联机构运动学正反解的正确性。为了限制整体结构尺寸并获得较大的工作空间,对相关结构参数进行了优化,最终通过三维搜索法得到机构的工作空间。     

基于Beckhoff平台Delta并联机构轨迹规划的实现

本研究基于Beckhoff的自动化平台,实现Delta并联机构轨迹规划的程序开发。首先对Delta并联机构进行分析和结构简化,求解了运动学逆解。针对并联机构运动学逆问题求解容易的特性及运动方面高速、平稳的需求,提出了在笛卡尔坐标空间采用正弦规律函数进行轨迹规划。然后借助Beckhoff工业自动化控制平台自带的电子凸轮和时间虚轴工具,将已确定的轨迹规划的在程序内部的进行实现。最后将开发的Delta并联机构轨迹规划的程序在公司自主研发的并联机器人上进行实机的应用测试,测试的数据结果表明轨迹规划在Beckhoff平台上实现方法的正确性及其性能满足Delta并联机构高速平稳的指标。     

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.     

基于并联原理的调姿机构位置分析

并联机器人已成为机器人研究与应用的一个热点，并联机构与串联机构在结构和性能上都存在对偶关系^[1-2]，而且并联机构的逆运动学问题比较容易，这有利于轨迹规划，本文对一对基于并联原理的新型调姿机构建立了数学模型，给出了它的位置方程，并分析了它的输入输出关系。     

并联机床数控系统运动学变换的研究

并联机床由于完全摒弃了传统机床固定导轨的刀具导向方式,其数控系统中必然需要添加运动学变换模块,以实现加工代码中的直角坐标与其可控制的关节空间坐标之间的转换.本文介绍了3-TPS并联机床数控系统中运动学变换方程组的建立和求解,详细分析了五坐标加工时运动学变换的实现,并在实际平台中仿真测试了运动学模块的性能.     

基于运动学正解的三转动并联机构迭代补偿控制

首先建立三转动并联机构的运动学方程,研究该并联机构的运动学反解和运动学正解,然后建立该机 构的动力学方程并分析其动力学特性．基于该机构研制了能复现自行武器行进时的车体姿态变化过程的动态模拟器 试验台．该试验台利用运动学反解算法进行闭环控制,并采用基于运动学正解的开环迭代补偿控制算法修正姿态驱 动信号,使试验台的响应逐渐逼近期望的姿态指令．测试表明该系统时域波形复现精度优于95%,验证了迭代补偿 控制的有效性．     

平面全柔性3-DOF过驱动并联机构的最优综合

以设计全柔性多自由度过驱动并联机构为目标,研究了平面3-DOF 4RRR过驱动并联机构的最优综合问题．从一般四分支3-DOF平面并联机构出发,建立了机构的运动学模型;给出了机构的4种可能拓扑结构分类,对不同拓扑结构类型机构的运动学和力学性能进行了分析比较．建立了并联机构全工作空间操作性改善优化模型,采用遗传算法进行优化设计并给出了实例,根据优化实例的结果设计制造了平面全柔性三自由度过驱动并联机构．以上方法对其它全柔性并联机构的优化设计具有参考价值．     

Structural synthesis of 5 DoFs 3T2R parallel manipulators with prismatic actuators on the base

A method is presented to synthesize 5 degrees of freedom (DoFs) of 3 translational and 2 rotational (3T2R) parallel kinematic structures. This method is based on the theory of linear transformation and geometrical analysis. Central to this method is a set of novel 5 DoFs 3T2R parallel mechanisms (PMs). Based on the legs configuration, the generated mechanisms are classified. Moreover, the promising mechanisms of each class are introduced with respect to some criteria, i.e.: (a) degree of coupling between the actuators and degrees of freedom; (b) easy kinematics and control command; (c) easy construction (or low cost construction); and, (d) manufacturability. With reference to these criteria, some discussions are given on the promising mechanisms. Finally, to demonstrate the role of legs configuration in relation to the characteristics of a manipulator, the kinematic analysis of two of the introduced mechanisms is compared.     

The optimum design of robotic manipulators using dexterity indices

This paper presents new dexterity indices that can be applied to planar and spatial manipulators. These indices are based on the condition number of the Jacobian matrix of the manipulators which is known to be a measure of their kinematic accuracy. Dexterity indices based on that same criterion have been presented elsewhere. However, due to the formulation of the kinematic equations, the existing indices are affected by a scaling of the manipulator when both the position and the orientation of the end effector are included in the kinematic equations. A new formulation of these equations is proposed here to avoid this problem of dimensional dependence. Two dexterity indices are presented for planar manipulators: the first one is based on a redundant formulation of the velocity equations whereas the second one is based on the mininum number of parameters. The corresponding indices are also derived for spatial manipulators. Finally, an example is included to illustrate the use of these indices in the context of design and optimization of manipulators.     

并联机构不同正解间无奇异转换问题探讨

并联机构的正解具有多解性,以一种平面三自由度并联机构为例,研究了不同正解之间的无奇异连接路径问题．结合Innocenti发现的第一条无奇异路径,采用基于奇异曲面的图形化方法分析了正解构型在工作空间中的分布．发现了两个正解间的多条类似路径,这些路径形成了连接两个正解位形的近似于螺旋状的管道空间．首次发现了在其它的正解之间也存在着这样的非奇异路径．这些结果表明并联机构的奇异曲面及正解分布异常复杂,如果两个正解对应的雅可比矩阵行列式值异号,则一定不存在无奇异路径;如果同号,则还要根据奇异曲面来定．两个正解构型间无奇异路径的判定还最终依赖于对奇异曲面更为清楚的描述．     

Optimal design of a parallel mechanism with three rotational degrees of freedom

This paper presents the concept design of a pose-adjustment system applied in the large fuselage or wing assembly of aircraft manufacturing which including a 3-degree-of-freedom rotational parallel mechanism (3-DoFs RPM), pogo columns and three tracks. The optimal design of the 3-DoFs RPM with its topology a 3-PUS&S mechanism is detailed, which is designed as a rigid yet compact module that can act as a pose-adjustment mechanism moving along three long tracks for large aircraft structural component assembly, a middle fuselage for example. Inverse kinematics of the 3-DoFs RPM with the exponential product method is achieved to lay the foundation for its kinematic synthesis. Next, with the commercial mathematical software, one can get the reachable workspace and define the prescribed workspace, respectively. Then, dimensional synthesis of the 3-DoFs RPM is executed to achieve a relatively good kinematic performance within its workspace. With the commercial CAE software, stiffness analysis is carried out for performance evaluation of the 3-DoFs RPM virtual prototype.     

基于3-UPS/RRR的并联踝关节康复机构及其性能分析

基于踝关节的生理解剖结构和运动特性分析,提出了一种适用于踝关节康复的3自由度3-UPS/RRR并联机构.该机构采用三个主动支链倾斜布置避开了机构的奇异位形,能满足踝关节康复运动需要,同时约束支链和动平台的设计使机构的转动中心与患者的踝关节转动中心重合.应用解析法得到了机构的位置反解,建立了速度雅可比矩阵和静力雅可比矩阵,求解了机构的工作空间.基于雅可比矩阵,仿真分析了机构的运动学性能和静力学性能.结果表明在规定的工作空间内机构具有良好的可操作性、运动灵活性、刚度特性和力矩传递性能.最后运用牛顿-欧拉法建立了机构的逆动力学方程,得到了驱动力、约束力与运动参数的关系,并给出了仿真实例.     

Kinematic Analysis of a Macro–Micro Redundantly Actuated Parallel Manipulator

In this paper the kinematic and Jacobian analysis of a macro–micro parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of the Large Adaptive Reflector (LAR), the Canadian design of the next generation of giant radio telescopes. This structure is composed of two parallel and redundantly actuated manipulators at the macro and micro level, which both are cable-driven. Inverse and forward kinematic analysis of this structure is presented in this paper. Furthermore, the Jacobian matrices of the manipulator at the macro and micro level are derived, and a thorough singularity and sensitivity analysis of the system is presented. The kinematic and Jacobian analysis of the macro–micro structure is extremely important to optimally design the geometry and characteristics of the LAR structure. The optimal location of the base and moving platform attachment points in both macro and micro manipulators, singularity avoidance of the system in nominal and extreme maneuvers, and geometries that result in high dexterity measures in the design are among the few characteristics that can be further investigated from the results reported in this paper. Furthermore, the availability of the extra degrees of freedom in a macro–micro structure can result in higher dexterity provided that this redundancy is properly utilized. In this paper, this redundancy is used to generate an optimal trajectory for the macro–micro manipulator, in which the Jacobian matrices derived in this analysis are used in a quadratic programming approach to minimize performance indices like minimal micro manipulator motion or singularity avoidance criterion.     

Dimensional synthesis of a robotized cell of support fixture

In this paper, an optimal designed 8-SPU parallel mechanism, acting as a cell of the self-configurable fixture which is used to support and clamp the thin-walled, large-scale plate and shell workpiece in automotive, aircraft and ship manufacturing industries, is proposed. In order to locate the maximum workspace with the global dexterity and conformity dexterity, single and multiple objective optimizations are performed under conditions of geometric constraints and kinematic performance indices by particle swarm optimization. The structural comprehensive parameters of parallel mechanism, such as the layout of joint points on the upper platform, the angle between two limbs of leg, and the ratio of radii of fixed to moving platforms, are optimized to obtain the optimal design dimensions. Furthermore, the effect of the optimized variables on kinematic performance indices is also intensively investigated. The compared results of the two optimization approaches indicate the feasibility of the proposed procedures.     

A comparison study on the dynamics of planar 3-DOF 4-RRR, 3-RRR and 2-RRR parallel manipulators

This paper presents a comparison study on the dynamics of three planar 3-DOF parallel manipulators, one with 3-RRR structure, and the other two with 2-RRR and 4-RRR structures. The inverse kinematics and Jacobian matrix of these mechanisms are analyzed. The dynamic formulations in the linear form are derived and a dynamic performance index is given to compare their dynamic performances. The results show that the 2-RRR parallel manipulator has the worst dynamic performance.     

Kinematics analysis of a hybrid manipulator for computer controlled ultra-precision freeform polishing

As one of the final processing steps of precision machining, polishing process is a very key decision for surface quality. This paper presents a novel hybrid manipulator for computer controlled ultra-precision (CCUP) freeform polishing. The hybrid manipulator is composed of a three degree-of-freedom (DOF) parallel module, a two DOF serial module and a turntable providing a redundant DOF. The parallel module gives the workpiece three translations without rotations. The serial module holds the polishing tool and gives it no translations on the polishing contact area due to its particular mechanical design. A detailed kinematics model is established for analyzing the kinematics of the parallel module and the serial module, respectively. For the parallel module, the inverse kinematics, the forward kinematics, the Jacobian matrix, the workspace and the dexterity distribution are analyzed systematically. Workspaces are also investigated for varying structural parameters. For the serial module, the inverse kinematics, the forward kinematics, the workspace and the precession motion analysis are carried out. An example of saddle surface finishing with this manipulator is given and the movement of actuators with respect to this shape is analyzed theoretically. These analysis results illustrate that the proposed hybrid manipulator is a very suitable machine structure for CCUP freeform polishing.