绳牵引并联机构的研究概况与发展趋势

总结了近20年来关于绳牵引并联机构的研究概况和研究内容；论述了绳牵引并联机构的构型、工作空间、刚度和冗余性等方面的研究；分析了绳牵引并联机构的应用前景与发展趋势，指出了绳牵引并联机构在建筑机器人、虚拟现实的力反馈装置和触觉装置、大型运动仿真器、大型射电望远镜、超高速机器人、超大工作空间的轻型机器人和风洞试验等领域的应用前景，展望了绳牵引并联机构的预期研究内容。     

一种可用于微创手术的并联机构运动学分析与性能优化

与串联机构相比,并联机构具有刚度好,精度高,响应快等优点,适合用于医疗领域。微创穿刺活检等手术要求机器人机构能够输出远中心运动。提出了一种用于微创手术的新型远中心并联机构,其分支内部包含平行四边形闭环子链。采用螺旋理论对机构自由度进行了分析,证明其能输出两个转动运动和一个移动运动,且所有运动均通过远端固定中心。对机构进行位置分析,建立了驱动参数与末端参数之间的映射。通过速度分析建立了雅可比矩阵,并分析得到了机构的奇异位形,包括逆解奇异、正解奇异和混合奇异。应用搜索法分析了机构的工作空间。采用运动/力传递指标对机构进行了性能分析,绘制工作空间内的性能图谱。以优质空间大小为目标对机构进行了尺度优化。     

中医推拿机器人主体机构的运动学分析

为实现中医推拿技术的机械自动化,提出了利用串并联机器人代替推拿医师完成推拿动作的想法,并设计了该机器人的主体并联机构.该机器人采用三自由度并联机构为主体机构,配合相应的串联机构共同完成推拿动作.该并联机构包含三条相同的混合单开链支路.均为结构.该机构为3T少自由度机构,能实现三个方向的移动.利用转换矩阵对该机构进行运动学正解和反解分析.结果表明该机构可以完成推拿机器人所需的运动.     

解耦的三平移力反馈机构运动学分析

提出了一种新型具有三个移动自由度解耦结构的并联机器人，该并联机器人运动平台和静平台之间由三个正交分布的分支相联系，且所有传动副均为转动副。这三个分支正交分布使得该机构的运动平台只有三个称动自由度，且输入、输出运动——对应。这种机构最突出的优点是：运动副简单，三维移动解耦及运动学分析非常简单。文中讨论了它的自由度，选择了驱动副，给出了其位置、速度正反解。     

混合型三维移动并联机构及其运动学分析

为丰富空间并联机器人机型,提出了两种具有混合分支的三维移动并机器人机构模型。其中一种由两个ＣＲＲ分支,一个ＳＰＳ分支构成;另一种由两个ＣＰＲ分支,一个ＳＰＳ分支构成。在文中,采用螺旋理论分析了它能实现空间三维移动的机构学原理,计算了它的自由度;给出了其位置速度和加速度的正反解,并进行了数值验证。     

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。     

一种三自由度并联机器人的运动学分析

提出了一种具有混合分支的三平移并联机器人机构，采用螺旋理论分析了这种机构实现空间三维移动的机构学原理及其自由度，给出了其位置、速度的正反解和加速度分析的方法；在大型机械动态分析软件ADAMS上建立了仿真模型，验证了自由度分析的正确性。这种机构部分解耦，控制简单，具有较好的应用前景。     

一种无汇交轴线对称三转动并联机构的运动分析

传统的三自由度转动并联机构（又称球面并联机构）一般都有一个转动中心,且这个中心点往往是分支间多个运动副轴线的汇交点,这种严格的几何条件给机构的加工制造带来很大的难度,制约了这类机构的应用。针对此,提出了一种无汇交轴线的对称三转动并联机构,其三个分支对称布置,分支内及分支间均无汇交轴线。对机构进行了位置反解,得到了机构四种对称的装配构型;从分支运动奇异、平台约束奇异和驱动奇异三个方面对机构进行了奇异分析;最后给定了一组尺寸参数,采用数值搜索的方法得到了机构的姿态工作空间。通过结果可以看出,该机构可以实现三维转动,具有较大的姿态工作空间,而且制造装配相对容易,具有很好的应用前景。     

三分支非均匀分布球面并联机器人的工作空间分析

通过分析球面三转动副并联机构中三个分支的布局对工作空间大小及分布的影响,把一般球面并联机构的三个分支由均匀分部改为非均匀分布,提出了一种三分支非均匀分布球面并联机器人,介绍了其结构布局特点,建立了结构约束条件,绘制出了工作空间的α截面边界图,定量分析了机构参数和工作空间大小及分布形状的关系,设计了一种三分支非均匀分布球面并联机器人样机.     

完全各向同性3自由度平面并联机构的型综合

提出了完全各向同性3自由度平面并联机构型综合的系统方法.首先,根据螺旋理论讨论了完全各向同性平面并联机构的运动学必要条件.然后,基于机构各分支对动平台控制功能的不同,通过互易螺旋理论推导出各分支的驱动螺旋、主动螺旋和可动非主动螺旋,并按照分支连接度的不同列举出所有可行的分支运动链.最后,按照机构各分支相应的装配条件,选取所综合出的3条分支运动链将动平台和静平台连接起来得到预期的机构,共得到新型机构3 167种.由于综合出的并联机器人机构的运动雅可比矩阵均为单位阵,即条件数恒为1,因此这类机构具有良好的运动学和力传递性能,在工业机器人、微操作机器人和医用机器人等领域具有潜在的应用前景.     

一种新型完全解耦移动并联机构的运动和奇异性分析

提出一种新型三自由度完全解耦移动并联机构,机构的三条分支中各包含一个平行四边形结构,推导出该机构运动位置和速度的正、逆解析解,讨论了机构主动副的移动范围,并根据机构正、逆雅可比矩阵的奇异性对机构奇异位形进行了系统地分析。由于在整个运动过程中机构雅可比矩阵为三角阵,因此机构为完全解耦并联机构,这使得机构在控制和轨迹规划等方面较为简单。此外,分支中平行四边形结构增加了机构的刚度。该机构在坐标测量机和虚轴机床等方面具有广阔的应用前景。     

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。     

Workspace Analysis of a Six-Degrees of Freedom, Three-Prismatic- Prismatic-Spheric-Revolute Parallel Manipulator

This paper studies the workspace of a six-degrees-of-freedom parallel manipulator of the general three-PPSR (prismatic-prismatic- spheric-revolute) type. It is known that a drawback of parallel manipulators is their limited workspace. To develop parallel mechanisms with a larger workspace is of use to potential applications. The mechanism of a three-PPSR manipulator and its variations are briefly analysed. The workspace is then investigated and the effects of joint limit and limb interference on the workspace shape and size are numerically studied. The constituent regions of the workspace corresponding to different classes of manipulator poses are discussed. It is shown that the workspace of this parallel manipulator is larger than that of a comparable Stewart platform, especially in the vertical direction.     

Kinematic analysis of a hybrid serial-parallel manipulator

The kinematic analysis of a new type hybrid serial-parallel manipulator is presented. This manipulator is based on two kinds of 3-UPU parallel mechanisms (PM). Each 3-UPU possesses one platform, one base and three limbs, and hence has 3 degrees of freedom (DOF). Each limb comprises of universal (U), prismatic (P), and universal (U) joints in series. Therefore the hybrid manipulator has totally 6 degrees of freedom and has also an elegant structure. The moving platform (mid platform) of the first PM moves with pure translation with respect to the fixed base and the moving platform (end platform) in the second PM only changes its orientation with respect to the mid platform. In this paper, closed-form kinematic solutions are obtained for this type of mechanism and related theoretical results have been verified numerically.     

Kinematic analysis and optimal design of 3-PPR planar parallel manipulator

This paper proposes a 3-PPR planar parallel manipulator, which consists of three active prismatic joints, three passive prismatic joints, and three passive rotational joints. The analysis of the kinematics and the optimal design of the manipulator are also discussed. The proposed manipulator has the advantages of the closed type of direct kinematics and a void-free workspace with a convex type of borderline. For the kinematic analysis of the proposed manipulator, the direct kinematics, the inverse kinematics, and the inverse Jacobian of the manipulator are derived. After the rotational limits and the workspaces of the manipulator are investigated, the workspace of the manipulator is simulated. In addition, for the optimal design of the manipulator, the performance indices of the manipulator are investigated, and then an optimal design procedure is carried out using Min-Max theory. Finally, one example using the optimal design is presented.     

Motion capability analysis of a quadruped robot as a parallel manipulator

This paper presents the forward and inverse displacement analysis of a quadruped robot MANA as a parallel manipulator in quadruple stance phase, which is used to obtain the workspace and control the motion of the body. The robot MANA designed on the basis of the structure of quadruped mammal is able to not only walk and turn in the uneven terrain, but also accomplish various manipulating tasks as a parallel manipulator in quadruple stance phase. The latter will be the focus of this paper, however. For this purpose, the leg kinematics is primarily analyzed, which lays the foundation on the gait planning in terms of locomotion and body kinematics analysis as a parallel manipulator. When all four feet of the robot contact on the ground, by assuming there is no slipping at the feet, each contacting point is treated as a passive spherical joint and the kinematic model of parallel manipulator is established. The method for choosing six non-redundant actuated joints for the parallel manipulator from all twelve optional joints is elaborated. The inverse and forward displacement analysis of the parallel manipulator is carried out using the method of coordinate transformation. Finally, based on the inverse and forward kinematic model, two issues on obtaining the reachable workspace of parallel manipulator and planning the motion of the body are implemented and verified by ADAMS simulation.     

仿人机器人SJTU-HR1及其运动分析

SJTU-HR1是由并联关节的组成的34个自由度新型仿人形机器人,根据人体生理结构设计了其各个关节。把各个并联机构关节作为一个模块,定义了关节的输出角度和输入角度,建立仿人形机器人整体坐标系,建立手臂和腿末端的位置正反解模型。为仿人机器人运动规划,动作设计以及控制系统建立奠定基础。     

Enhanced stiffness modeling of manipulators with passive joints

The paper presents a methodology to enhance the stiffness analysis of serial and parallel manipulators with passive joints. It directly takes into account the influence of external and internal loadings on the manipulator configuration and, consequently, on its Jacobians and Hessians. The main contributions of this paper are the introduction of a non-linear stiffness model for the manipulators with passive joints, a relevant numerical technique for computing the Cartesian stiffness and stability criteria for configurations of the kinematic chains. Within the developed technique, the manipulator elements are presented as pseudo-rigid bodies separated by multidimensional virtual springs and perfect passive joints. Simulation examples are presented that deal with parallel manipulators of the Ortholide family and demonstrate the ability of the developed methodology to describe non-linear behavior of the manipulator structure such as a sudden change of the elastic instability properties (buckling).     

Design of a planar 3-DOF parallel micromanipulator

A planar three degree-of-freedom (DOF) parallel manipulator is proposed to be applied for alignment during assembly of microcomponents. It adopts a PRR (prismatic-revolute-revolute) mechanism to meet the requirements of high precision for assembly and robustness against disturbance. The mechanism was designed to have a large workspace and good dexterity because parallel mechanisms usually have a narrow range and singularity of motion compared to serial mechanisms. Inverse kinematics and a simple closed-loop algorithm of the parallel manipulator are presented to control it. Experimental tests have been carried out with high-resolution capacitance sensors to verify the performance of the mechanism. The results of experiments show that the manipulator has a large workspace of ±1.0 mm, ±1.0 mm, and ±10 mrad in the X-, Y-, and θ-directions, respectively. This is a large workspace when considering it adopts a parallel mechanism and has a small size, 100 × 100 × 100 mm³. It also has a good precision of 2 μm, 3 μm, and 0.2 mrad, in the X-, Y-, and θ-axes, respectively. These are high resolutions considering the manipulator adopts conventional joints. The manipulator is expected to have good dexterity.