非对称式6/6-SPS型Stewart并联机构位置正解的研究

建立了一类具有非对称式结构的6/6-SPS型Stewart并联机构位置正解的数学模型,构造了一个关于该并联机构动平台位置参数及姿态参数的多元多项式方程组.基于该方程组并采用Mathematica符号计算软件编制了基于Mathematica语言的非对称式结构的6/6-SPS型Stewart并联机构位置正解的求解程序.研究结果表明,对于任意给定的该类并联机构的结构参数及6个驱动杆杆长,该类6/6-SPS型Stewart并联机构的位置正解在复数域内最多有28组解析解,并且其位置正解实数解的个数必定为偶数.并联机构位置正解的研究为该类并联机构的工作空间分析、轨迹规划及控制奠定了重要的理论基础.     

Position analysis of a 3-DOF parallel manipulator

The forward and inverse kinematics of a 3-DOF parallel mechanism for beam aiming applications is derived in closed form. The mechanism has three actuated arms attached to a base via revolute joints. Another three arms are also attached to an upper platform via passive revolute joints. Each of the three base arms is connected to its respective opposing passive arm via a spherical joint. The platform has three degrees of freedom with respect to the base, two rotational and one radial motion.     

Singularity analysis with respect to the workspace of a double parallel manipulator

Singularity analysis is an important issue in the design of parallel manipulators, since they become uncontrollable at singular configurations due to the rank deficiency of the Jacobian. This paper analyzes the singularity of a double parallel manipulator with respect to its workspace. The workspace is decoupled into a positional workspace generated by the first parallel mechanism, and an orientational workspace by the second mechanism. The singularities occurring outside each workspace are analytically found by a Jacobian matrix derived for the velocity transformation from the end-effecfor to the linear actuators. The singularity loci are presented and their geometric properties are examined to prove that the double parallel manipulator is free from the singularity problem.     

新型三自由度并联机构工作空间分析

随着并联机构技术的发展,少自由度并联机构由于具有结构相对简单,控制容易等优点,逐步成为机构学领域新的研究热点,在工业领域有着广阔的应用前景。针对并联机构工作空间较小的特点,对一种新型三自由度并联机构进行研究。该机构的工作空间对称分布于定平台的两侧。在分析其结构特点的基础上,推导出其位置反解方程。根据约束条件,采用数值方法绘制出工作空间的三维立体图和Z截面上的边界图。并定量分析了机构设计参数对工作空间大小的影响。     

Optimum design of the reconfiguration system for a 6-degree-of-freedom parallel manipulator via motion/force transmission analysis

Journal of Mechanical Science and Technology - This research introduces a 6-degree-of-freedom parallel manipulator with a reconfigurable fixed base; the manipulator performance has been evaluated...     

2-UPU-RRC并联机构及奇异位形分析

提出一种新型三平移三自由度空间并联机器人机构,进行机构运动输出特性分析及自由度计算,并建立2-UPU-RRC并联机器人机构的位置正、反解方程。得到该机构的奇异位形。该机构解耦性好,为系统控制提供了方便。     

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.     

Singularity analysis of a novel 4-dof parallel manipulator H4

Recently, it has been shown that a novel parallel manipulator called H4 can be employed to perform high speed motion for semiconductor applications. In this new family of parallel manipulator, singularities are associated with either loss or gain of degrees of freedom (DOF). This paper deals with singularity analysis of H4 utilizing line geometry tools and screw theory. Firstly, the static equilibrium condition of the end effector is derived to obtain the full 6×6 matrix, which is set of governing lines of the manipulator. Based on linear dependency of these lines, the singular configurations of the manipulator can be identified. Moreover, in order to deal with singularities associated with loss of DOFs (serial singularity), the static equilibrium of the actuators is also defined. Secondly, architecture and constraint singularities associated with gain of DOFs (parallel singularity) are defined and analyzed using linear complex approximation algorithm (LCAA), which is employed to obtain the closest linear complex, presented by its screw coordinates, to the set of governing lines. The linear complex axis and pitch provide additional information and a better physical understanding of the manipulator’s self-motion when in or closed to a singular configuration. Lastly, various singularities of an example H4 manipulator are presented and analyzed using the proposed methods.     

Singularity analysis of a 3-RPS parallel manipulator using geometric algebra

Singular configurations must be avoided in path planning and control of a parallel manipulator. However, most studies rarely focus on an overall singularity loci distribution of lower-mobility parallel mechanisms. Geometric algebra is employed in analysis of singularity of a 3-RPS parallel manipulator. Twist and wrench in screw theory are represented in geometric algebra. Linear dependency of twists and wrenches are described by outer product in geometric algebra. Reciprocity between twists and constraint wrenches are reflected by duality. To compute the positions of the three spherical joints of the 3-RPS parallel manipulator, Tilt-and-Torsion angles are used to describe the orientation of the moving platform. The outer product of twists and constraint wrenches is used as an index for closeness to singularity(ICS) of the 3-RPS parallel manipulator. An overall and thorough perspective of the singularity loci distribution of the 3-RPS parallel manipulator is disclosed, which is helpful to design, trajectory planning and control of this kind of parallel manipulator.     

含有柔性铰链并联机器人的刚度分析及刚度优化配置

以一类含有柔性铰链的并联机器人为研究对象，在位置分析的基础上，导出摄动位移间映射关系，为其建立了刚度分析模型。此外，还探讨了有关刚度性能指标的问题，最后以该性能指标为目标函数对其进行了刚度优化配置。     

Kinematics of a star-triangle planar parallel manipulator

This paper addresses kinematics of a 3 degree-of-freedom (DOF) planar parallel manipulator called Star-Triangle manipulator. The manipulator has good accuracy and a relatively large singularity-free workspace. First, position analysis of the manipulator is implemented indicating that both the inverse and forward position problems of the manipulator have only one solution. Then, velocity and singularity analyses of the manipulator are carried out and its isotropic configurations are identified using two Jacobian matrices. Based on the isotropic conditions, the workspace of manipulator is determined geometrically and it is shown that all points in the workspace are free of singularities. At last, kinematic accuracy of the manipulator is investigated on the workspace through a kinematic conditioning index (KCI).     

采用牛顿-欧拉法的排爆机器人机械手动力学分析

机械手是排爆机器人的关键部分,机器人作业主要依赖于机械手的运动。在机械手运动规划基础上重点描述基于牛顿-欧拉法的机械手动力学建模,并利用MATLAB软件编程对机械手进行动力学分析,为机械手的设计和运动控制实现提供支持。     

Error modeling and sensitivity analysis of a hybrid-driven based cable parallel manipulator

This paper deals with the error modeling and sensitivity analysis of a hybrid-driven based cable parallel manipulator (HDCPM). The HDCPM has the advantages of both cable parallel manipulator and hybrid-driven planar five-bar mechanism. Kinematics analysis and error modeling are performed based on closed loop vector conditions and direct differential method. The error model derived for the proposed HDCPM has the ability to account for the original errors from kinematics parameters. In addition, the sensitivity analysis is also carried out to investigate the effects of 36 error sources of kinematics parameters on the end-effector of the HDCPM. A detailed example of the sensitivity of the end-effector's position coordinates for the HDCPM is presented in order to demonstrate the validity of the error modeling and sensitivity analysis developed.     

3-RSR并联机器人静力学和刚度的研究

运用螺旋理论求得3-RSR并联机器人的雅可比矩阵,利用雅可比矩阵建立了动平台所受外力和外力矩到驱动关节的映射关系,使静力学计算变得十分简单,还可以求得动平台的刚度矩阵,并为动力学研究打下基础。     

Kinematic performance analysis and promotion of a spatial 3-RPaS parallel manipulator with multiple actuation modes

Journal of Mechanical Science and Technology - This paper presents a 3-RPaS (R and S denote the revolute and spherical joint, pa denotes the parallelogram) parallel manipulator with...     

Design and nonlinear analysis of a 6-DOF compliant parallel manipulator with spatial beam flexure hinges

In this paper, a compliant parallel manipulator with six compliant limbs is proposed for micro positioning applications. The load–displacement model of a single compliant limb is established using a nonlinear closed-form spatial beam model. The inverse solution to the compliant parallel manipulator is then implicitly derived by applying load equilibrium to the moving platform. Finally, the compliant model of the limb and the implicit inverse kinematic solution of the manipulator are fully tested by FEA. Discrepancies between results of the presented models and the FEA are analyzed within planned workspaces. The validations demonstrate that accuracies of the proposed models are acceptable and can be improved by shrinking the planned workspace.     

新型6-PSS微操作机器人的加速度性能指标分析

提出一种基于并联６－ＰＳＳ机构的新型微操作机器人,建立其速度、加速度输入输出方程并定义共加速度性能指标,分析其加速度性能指标与机构几何参数关系,为设计和使用该微操作机器人提供理论依据。     

Reciprocal screw theory based singularity analysis of a novel 3-DOF parallel manipulator

Singularity analysis is an essential issue for the development and application of parallel manipulators.Most of the existing researches focus on the singularity of parallel manipulators are carried out based on the study of Jacobian matrices.A 3-DOF parallel manipulator with symmetrical structure is presented.The novel parallel manipulator employs only revolute joints and consists of four closed-loop subchains connecting to both base and platform via revolute joints.The closed-loop subchain in each chain-leg is a spherical 6R linkage.The motion characteristics of the output link in the spherical 6R linkage with symmetrical structure are analyzed based on the interrelationships between screw systems.The constraints that are exerted on the platform by each chain-leg are investigated applying the concept of generalized kinematic pair in terms of equivalent screw system.Considering the geometric characteristics of the parallel manipulator,the singularity criteria of the parallel manipulator corresponding to different configurations are revealed based on the dependency of screw system and line geometry.The existing conditions of certain configuration that a singularity must occur are determined.This paper presents a new way of singularity analysis based on disposition of constraint forces on the geometrically identified constraint plane and the proposed approach is capable of avoiding the complexity in solving the Jacobian matrices.     

Experimental characterization of a binary actuated parallel manipulator

This paper describes the BAPAMAN (Binary Actuated Parallel MANipulator) series of parallel manipulators that has been conceived at Laboratory of Robotics and Mechatronics (LARM). Basic common characteristics of BAPAMAN series are described. In particular, it is outlined the use of a reduced number of active degrees of freedom, the use of design solutions with flexural joints and Shape Memory Alloy (SMA) actuators for achieving miniaturization, cost reduction and easy operation features. Given the peculiarities of BAPAMAN architecture, specific experimental tests have been proposed and carried out with the aim to validate the proposed design and to evaluate the practical operation performance and the characteristics of a built prototype, in particular, in terms of operation and workspace characteristics.