一种所有转轴均连续的五自由度混联机器人机构

根据两转一移并联机构两转动自由度转轴的分布,提出构造五自由度混联机器人机构构型的新思路,基于2-RPU&UPR并联机构构造一种新型五轴混联机器人机构。建立2-RPU&UPR并联机构的位置正反解模型,由于该并联部分存在两条连续转轴,可将其等效成一个三自由度串联机构RPR,进而将整个混联机器人机构等效为一个四自由度串联机构RPRR和一个移动平台的组合进行分析,根据这两部分位姿之间的解耦性,建立了混联机器人完整的位置正反解模型,并用加工球面轨迹的算例验证了所建运动学模型的正确性。提出的5自由度混联机器人所有转动自由度均具有连续转轴,能够得到解析的位置模型表达式,能够很容易实现轨迹规划与运动控制,具有良好的应用前景。     

RGRR-Ι构造混联6R机器人

新型并联双自由度转动关节(RGRR-Ⅰ)活动构件少、工作空间大,利用RGRR-Ⅰ构造混联6R机器人可以实现高刚度、大工作空间、机构紧凑等。提出混联机构的求解新方法,即建立少自由度并联机构的运动坐标参数与机构运动输入参数之间的关系,把混联机构的求解转化为各少自由度并联机构的求解和运动坐标参数之间的串联求解,降低了求解难度,可以方便地推导出位置的正解和反解。此方法对其他混联机器人的运动学分析有借鉴作用。     

3T-2R五自由度并联机构的型综合

基于单开链单元的并联机构结构组成原理,提出了一些三平移两转动五自由度(3T-2R 5-DOF)的新的单开链。使用拓扑结构的设计原理和方法,全面综合了3T-2R 5-DOF并联机构的机型,得出了一些新机型。所有机型都满足主动副配置在静平台上的要求,便于控制。分析了机型的主动副的配置及其耦合度等基本特征,通过ADAMS软件验证了机型的正确性,并将研究结果列于表中。这些机型具有更强的实用性,它们为三平移两转动机型的优选提供了参考依据。     

五自由度并联驱动机构及其位置分辨能力分析

提出了一种具有三移动和二转动的多分支耦合并联驱动机构,基于方位特征集法分析了机构自由度及机构末端的运动特征.利用齐次变换法建立了机构的运动学逆解模型,求解了并联驱动机构的全雅可比矩阵.基于牛顿迭代法建立了运动学正解模型,并对理论模型进行了仿真验证.利用CAD变分几何法绘制了机构的可达工作空间.定义了机构的全域位置敏感度...     

Spring-joint method for topology optimization of planar passive compliant mechanisms

There is seldom approach developed for the initial topology design of flexure-based compliant mechanisms. The most commonly-used approaches, which start with an existing rigid-body mechanism, do not consider the performances between different topologies. Moreover, they rely heavily on the rigid-body topology, therefore limit the diversity of compliant mechanisms topology. To obtain the optimal initial topology of such mechanisms directly from problem specifications without referencing to the existing mechanism topologies, a spring-joint method is presented for a restricted class of the serial passive flexure-based compliant mechanisms, which are the building blocks of parallel compliant mechanisms. The topology of the compliant mechanisms is represented by a serial spring-joint mechanism（SSJM） that is a traditional rigid-body mechanism with a torsional spring acting on each joint, and is described by position vectors of the spring-joints. A simplified compliance matrix, determined by the position vectors, is used to characterize the tip of the SSJM kinematically, and is optimized to ensure the desired freedoms of the compliant mechanisms during optimization. The topology optimization problem is formulated as finding out the optimal position of the spring-joints in a blank design domain with an objective function derived from the simplified compliance matrix. In design examples, syntheses of the compliant mechanisms with both single freedom and two decoupled freedoms are presented to illustrate the proposed method. The proposed method provides a new way for the initial design of flexure-based compliant mechanisms.     

一种新型运动副及其在并联机床上的应用

提出了一种基于新型运动副——复合球铰的虚拟轴机床,它是由5-SPS分支组成的并联机构,其中3个分支汇交于一个三重球铰,另2个分支汇交于一个二重球铰,两个球铰固接在一起形成一个复合球铰,代替了并联机构的活动平台,而且机床主轴位于复合球铰中心线上。这种基于复合球铰的5个分支新型虚拟轴机床与基于Stewart平台机构的6个分支的虚拟轴机床相比具有同样多的实用自由度,并且机床结构简单、解耦,其正反解计算及控制亦相对简单。探讨了5分支机床的结构形式,尤其对关键结构——复合球铰的结构,机构位置反解,以及一定姿态下的可达工作空间进行了分析和计算。这种新型虚拟轴机床在空间曲面加工领域将有着广泛的应用前景。     

Actuation Spaces Synthesis of Lower-Mobility Parallel Mechanisms Based on Screw Theory

The lower-mobility parallel mechanism has been widely used in the engineering field due to its numerous excellent characteristics.However,little work has been devoted to the actuator selection and placement that best satisfy the system's functional requirements during concept design.In this study,a unified approach for synthesizing the actua-tion spaces of both rigid and flexure parallel mechanisms has been presented,and all possible combinations of inputs could be obtained,laying a theoretical foundation for the subsequent optimization of inputs.According to the linear independence of actuation space and constraint space of the lower-mobility parallel mechanism,a general expres-sion of actuation spaces in the format of screw systems is deduced,a unified synthesis process for the lower-mobility parallel mechanism is derived,and the efficiency of the method is validated with two selective examples based on screw theory.This study presents a theoretical framework for the input selection problems of parallel mechanisms,aiming to help designers select and place actuators in a correct and even optimal way after the configuration design.     

两平移两转动并联机器人机构运动学分析

分析了一种两平移两转动并联机器人机构,求出其运动学正解和反解封闭解,讨论了该机构的控制解耦性。与其它类似机构相比,该机构结构简单、位置分析求解容易。同时,设计了一种利用本并联机构的中医推拿串并联机器人,该机器人具有工作空间大,动平台动力性能好等特点。该并联机构还可应用于工业装配机器人、微动机器人、虚拟轴并联机床、多维减振平台等领域。     

Orientation-singularity representation and orientation-capability computation of a special class of the Gough-Stewart parallel mechanisms using unit quaternion

Singular configuration seriously affects the performance of the Gough-Stewart parallel mechanism and has attracted many researchers’ attentions. However, most of existing topics often focus on the position-singularity of the mechanism for a constant-orientation, but few reports research the orientation-singularity for a given position. In order to investigate the orientation-singularity of the Gough-Stewart parallel mechanisms with two dissimilar semi-regular hexagonal platforms for a given position, after constructing the discrimination matrix of the singular configuration of the mechanism and computing the determinant of this matrix by using unit quaternion as the orientation parameters which can avoid the singularities in parameterization, a general symbolic expression representing the three-dimensional orientation-singularity locus for a given position is obtained and the three-dimensional view of the orientation-singularity locus is further described. The orientation-singularity-free void exists inside the orientation-singularity locus, but the shape of the orientation-singularity-free void is irregular and inconvenient for the design of the mechanism. The minimal inscribed sphere of the three-dimensional orientation-singularity locus namely the orientation-singularity-free ball is described. The radius of the ball orientation-capability is used as the measurement for the orientation-singularity-free void size. A new efficient algorithm is proposed for the computation of the orientation-capability. Finally, the influences of the geometry parameters and the different positions of the mechanism on the orientation-capability are discussed. A new method of the singularity analysis of the Gough-Stewart parallel mechanism is advanced based on the unit quaternion, and the research finds have important referential value for the configuration parameters optimization of this class of the parallel mechanisms with the goal of having the maximal singularity-free zone.     

Gait Analysis of a Radial Symmetrical Hexapod Robot Based on Parallel Mechanisms

Most gait studies of multi-legged robots in past neglected the dexterity of robot body and the relationship between stride length and body height.This paper investigates the performance of a radial symmetrical hexapod robot based on the dexterity of parallel mechanism.Assuming the constraints between the supporting feet and the ground with hinges,the supporting legs and the hexapod body are taken as a parallel mechanism,and each swing leg is regarded as a serial manipulator.The hexapod robot can be considered as a series of hybrid serial-parallel mechanisms while walking on the ground.Locomotion performance can be got by analyzing these equivalent mechanisms.The kinematics of the whole robotic system is established,and the influence of foothold position on the workspace of robot body is analyzed.A new method to calculate the stride length of multi-legged robots is proposed by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle.Referring to service region and service sphere,weight service sphere and weight service region are put forward to evaluate the dexterity of robot body.The dexterity of single point in workspace and the dexterity distribution in vertical and horizontal projection plane are demonstrated.Simulation shows when the foothold offset goes up to 174 mm,the dexterity of robot body achieves its maximum value 0.164 4 in mixed gait.The proposed methods based on parallel mechanisms can be used to calculate the stride length and the dexterity of multi-legged robot,and provide new approach to determine the stride length,body height,footholds in gait planning of multi-legged robot.     

新型两平移一转动并联机器人机构位置分析

分析了一种新型两平移一转动并联机器人机构．求出其运动学正解和反解封闭解．讨论了该机构的控制解耦性。与其它类似机构相比。该机构不仅结构简单、位置分析求解容易，而且正解具有完全控制解耦关系。该机构可广泛应用于工业装配机器人、微动机器人、虚拟轴并联机床、多维减振平台和推拿机器人等领域。     

新型串并联中医推拿机器人研究

研究了中医推拿中常用的滚法、按法、揉法、推法等手法的运动学及动力学特征,获得完成各推拿手法的运动输出矩阵和施力方向。提出一种能满足推拿要求的基于三自由度并联机构新型串并联中医推拿机器人机型。对该机型中的三自由度并联机构进行了分析,求出其运动学正反解的解析解。系统讨论了该并联机构的推拿范围及转动能力,为扩大该机器人的推拿范围提供依据。该串并联机器人机构综合了串并联机构的优点,不仅能模拟中医推拿常用的几种手法,而且结构简单、位置分析求解容易、解耦性强,易于实时控制。     

全柔性机构在并联微动机器人中的应用

柔性机构,特别是全柔性机构以其特殊的性能在微位移、微操作、微装配等领域得到广泛应用。通过对柔性机构的特点、全柔性微动机器人与普通平面机构、平面并联机构、空间并联机构结合的例子等的介绍,对柔性机构,特别是全柔性机构在微动并联机器人领域的国内外发展现状作了较全面的介绍。指出了目前存在的若干主要问题。     

Direct kinematics of a double parallel robot arm for real time velocity control

The determination of the direct kinematics of a parallel mechanism is a difficult problem but must be solved for practical application. This paper presents the efficient formulation of the direct kinematics and the Jacobian of a double parallel robot arm for velocity control. The robot arm consists of two parallel mechanisms, and a central axis that generates positional and orientational motions independently. Given a set of lengths for the linear actuators, the direct kinematics computes the position and orientation of the end-effector, and the Jacobian transforms the velocities of the end-effector to those of the linear actuators. The developed formulation is implemented in a real-time control setting and its efficiency is demonstrated. Department of Control and Instrumentation Engr.     

Design and control of a 3DOFs parallel actuated mechanism for biped application

In this paper, a novel approach to carry out the design of a three degrees of freedom (3DOF) actuated mechanisms for humanoid robots joints is presented. Instead of common serial mechanism, a more robust parallel mechanism was developed. This kind of structure gives the terminal body the ability to move within a cone from the nominal position and permits unlimited rotation about the cone pointing axis. Kinematic analysis are presented in this paper. A biped robot ROBIAN with parallel hip and ankle mechanisms was developed and experimental tests were carried out to evaluate the performances of the adopted structure.     

一种新型并联机床的位置正反解

提出一种基于新型的运动副——复合球铰的虚拟轴机床,它是由5-SPS分支组成的并联机构,其中3个分支交于一个三重球铰,另2个分支交于一个二重球铰,两个球铰固接在一起形成一个复合球铰,代替了并联机构的活动平台,而且机床主轴位于复合球铰中心线上。该机床的特点是结构简单、解耦。针对机构模型建立了约束方程,利用解析法求解机构的位置正反解,并绘制出机构装配简图。     

基于螺旋理论的单闭环多自由度过约束机构综合

以螺旋理论为基础,分析构成单闭环过约束机构的约束数目、运动副数目和自由度数目之间的关系,给出针对单闭环过约束机构的自由度计算公式。按照约束螺旋的性质将过约束螺旋分为具有不同阶数的力约束和力偶约束两类,总结所有可能形式的独立过约束性质和数目及其组合。在给出特定过约束组合的条件下,应用虚功原理,以反螺旋理论为计算手段,得到多自由度单闭环机构的综合条件。应用解析的方法,得到满足机构为非瞬时运动的条件,给出机构的运动副轴线布置、运动副数目、运动副排列和空间几何条件。全面系统地解决了单闭环多自由度过约束机构的构型综合问题,群举所有可能的单闭环过约束并联机构。给出机构综合步骤以及部分典型机构的设计范例。     

3-RUU微动并联机构的尺寸型模型及性能图谱

基于伪刚体模型及运动学参数的量纲一化,建立了3-RUU微动并联机构的尺寸型模型,该模型在有限区间内给出了3-RUU微动并联机构所有可能的尺寸参数组合,模型空间内的任意一点代表具有相同或相似运动性能的同一族机构。结合对微操作运动性质的分析,提出了作业空间体积值、作业空间形状值及常值雅克比矩阵条件数等三种描述微动机构运动学性能的评价指标,并根据尺寸型模型及定义的性能指标绘制了反映机构性能与尺寸参数关系的性能图谱。     

两平移一转动并联机构位置分析及运动学仿真

设计提出了一种两平移一转动并联机构,进行了结构学分析,包括其自由度计算及输出运动类型分析;给出了位置分析的正、逆解。通过SolidWorks及与其无缝集成的运动学分析模块—Cos-mosMotion,开发了该机构的三维实体模型并进行了运动学仿真。分析表明,该机构的位置分析求解容易,易于实时控制,可广泛应用于工业装配机器人、微动机器人、虚拟轴并联机床和多维减振平台等领域,同时验证了该机构的正确性。     

基于PMAC运动控制卡的混联码垛机器人研制

根据串联机构和并联机构的特点,以及搬运机器人的性能要求,设计了一种4自由度混联码垛机器人,分析了该机器人的运动学特性,求出其位置正反解析解,给出了机器人码垛的路径规划.控制系统采用工业PC(IPC)作为主计算机,利用分布式二级控制结构实现系统的监控和作业管理,协调各关节的运动,准确地跟踪轨迹规划.最后针对普通示教再现作业方式,提出了码垛机器人离线编程方法,重点对搬运机器人离线码垛过程进行了研究,自主开发了机器人控制软件.实际使用结果表明,所研制的机器人已能满足物流自动化系统中的码垛需求.