3-RRR平面并联微动机器人的运动学分析

运动学分析是并联机器人机构分析中的首要问题,是进行机构动力学分析、精度分析的基础,而全柔性微动机器人机构的首要目标就是精确实现所需的运动。因此对其运动学的研究在机构学领域占有重要的地位。本文对平面并联微动机器人进行了建立伪刚性模型,采用闭环矢量原理建立理论运动学线性模型,得到理论Jacobian矩阵,其次对该机构进行实验分析,得到工作平台的实验输出位移和方位角(Jacobian矩阵);然后用ANSYS软件对其进行有限元分析,得到有限元运动学模型(Jacobian矩阵值),最后通过分析比较该机构的理论运动学方程、实验运动学方程和有限元运动学方程,得到输出平台适用的运动学方程。     

三自由度平面并联微动机器人运动学模型及工作空间分析

运动学分析是并联机器人机构分析中的首要问题,是进行机构动力学分析、精度分析的基础,而全柔性微动机器人机构的首要目标就是精确实现所需的运动。介绍了平面并联微动机器人伪刚性模型的建立方法,并采用闭环矢量原理建立理论运动学线性模型,得到理论Jacobian矩阵,其次对该机构进行实验分析,得到工作平台的实验输出位移和方位角(Jacobian矩阵);然后用ANSYS软件对其进行有限元分析,得到有限元运动学模型(Jacobian矩阵值),最后通过MATLAB7.1软件对该机构的三种运动学模型进行工作空间分析,并进行误差分析,得到输出平台适用的运动学方程。     

新型三转动并联机构的动力学分析

提出一种基于Stewart机构的新型三转动并联机构,该机构有三个驱动缸和三个拉杆,能实现三自由度的转动.建立该机构的运动学方程,推导其运动学反解的封闭解和运动学正解的数值解,然后建立系统的动力学方程,最后对其动力学特性进行仿真分析.该新型并联机构在运动模拟领域具有广阔的应用前景.     

7自由度拟人臂仿人运动的逆运动学解析解

为了求解末端位姿已知时拟人臂的仿人臂姿,以人臂运动特性为依据,针对7自由度拟人臂提出了一种新的逆运动学求解方法。该方法将人臂的末端运动转化为腕部的达点运动,利用肘部的自运动理论解耦了人臂的冗余度,并结合最小势能指标确定了自运动角。在利用末端位姿确定腕部位置的基础上,依据自运动角求解肘部位置,进而推导出拟人臂仿人运动的逆运动学解析表达式。试验和仿真结果证明了该方法解的仿人性和连续性。最后,从拟人臂的运动灵活性的角度分析了方法的失稳现象,结果表明自运动角发生突变时拟人臂奇异。该方法属于解析方法,有利于对拟人臂进行实时的仿人运动控制。     

冗余度柔性杆机器人自运动中的混沌

研究了杆件全柔冗余度机器人自运动中的混沌现象.通过有限元方法和拉格朗日方程建立动力学模型.运用混沌数值分析方法中的相图法、Poincare映射法、最大李雅普诺夫(Lyapunov)指数法,发现了该类机器人自运动中存在混沌现象.对一平面3R柔性机器人研究表明,基于雅可比矩阵的伪逆求解运动学逆解,采用典型的PD控制器控制其末端重复跟踪工作空间内的封闭路径,其自运动中存在混沌现象.     

Properties and structure of dynamic robot models for control engineering applicationsStructure et proprietes des modeles dynamiques robotiques a appliquer au controle automatique

Controller design for robotic manipulators requires a fundamental physical understanding of the properties and structure of dynamic robot models. This paper focuses on the Lagrangian formulation which is attractive from both the dynamic modeling and control engineering points-of-view. Physical and mathematical properties and structural characteristics of the complete dynamic robot model are demonstrated. Implications of the model for control system analysis and design are then indicated. Physical interpretation leads naturally to the decomposition of the model into the positioning arm and end-effector subsystems and motivates the application of decentralized control to robotic manipulators. The authors then propose the application of control the positioning arm and artificial intelligence and intelligent sensors to control the end-effector.     

Generalized Jacobian analysis of lower mobility manipulators

Exploring screw theory through the formalities of linear algebra, this paper presents a general approach for Jacobian analysis of lower mobility manipulators. Given the definitions of twist/wrench spaces and their subspaces of the end-effector, the underlying relationships amongst these subspaces are identified using the virtual work principle. Using the orthogonal and dual properties of these subspaces and variational representations to account for the permitted and restricted instantaneous motions of the end-effector, a rigorous general and systematic procedure for the formulation of a generalized Jacobian is proposed. The merit of the generalized Jacobian is that it allows the first order kinematic and static modeling (velocity, accuracy, force and stiffness) to be integrated into a unified mathematical framework, so standardizing the modeling procedure and improving the efficiency of design and analysis. The generalized Jacobians for the three well-known parallel manipulators are derived as examples to illustrate the generality and effectiveness of this approach.     

空间4R冗余度机器人的混沌自运动研究

通过数值仿真及分析混沌的相图法、Poincare映射法和最大Lyapunov指数法对一个空间4R刚性冗余度机器人采用PD调节器控制其末端重复跟踪工作空间内的一条封闭路径时的杆件自运动状态进行了研究。研究首次发现,基于Jacobian矩阵的伪逆法求解该机器人运动学逆解时其自运动是混沌的。     

Kinematics and optimization of a 2-DOF parallel manipulator with a passive constraining leg and linear actuators

This paper presents a two degree-of-freedom (DOF) planar parallel manipulator with two linear actuators, whose degree of freedom is dependent on a passive constraining leg connecting the base and the platform. The kinematics of the presented manipulator is first studied: the inverse and forward kinematics problems are solved in the closed form, the practical workspace is described symbolically, the Jacobian matrix is derived, and several singular conditions are discussed. Then, in order to determine the geometric parameters and the operating range of the actuators, the optimization of the mechanism is performed considering its dexterity and stiffness.     

Derivation of dual forces in robot manipulators

According to the principle of transference, a compact three-dimensional representation of a rigid body kinematics is obtained by substituting dual for real numbers. This representation has recently been applied to robotics where in addition to its compactness, it allows to constitute the Jacobian matrix explicitly from the product of the dual transformation matrices with no additional computation.This paper introduces the generalized Jacobian matrix. This matrix consists of the complete dual transformation matrices as opposed to the regular Jacobian matrix which consists of specific columns only. The generalized Jacobian matrix relates force and moment at the end-effector to force and moment in all directions, at the joints. It is therefore possible to use the dual transformation matrices to derive, with no additional computation, the full force and moment vector at the robot's joints. Furthermore, the generalized Jacobian matrix also relates motion in all directions at the joints to the motion of the end-effector, an essential relation required at the design stage of robot manipulators (in particular, flexible ones). An extension of these kinematics and statics schemes into dynamics is possible by applying the dual inertia operator as is shown by an example of a three degrees-of-freedom robot.     

柔性冗余度机器人自运动中的混沌

研究了柔性冗余度机器人的自运动状态，通过将其中的柔性连杆简化为Euler—Bernoulli梁建立了柔性冗余度机器人的运动学模型。运用混沌数值分析法中的相图法、Poincare映射法和最大Lyapunov指数法发现了该类机器人自运动中的混沌现象。对一个未杆是柔性连杆的平面3R柔性冗余度机器人的自运动状态的研究结果表明，基于Jacobian矩阵的伪逆法求解该柔性冗余度机器人采用PD调节器控制其末端重复跟踪工作空间内的一条封闭路径时的运动学逆解，其自运动是混沌的。     

Method for six-legged robot stepping on obstacles by indirect force estimation

Adaptive gaits for legged robots often requires force sensors installed on foot-tips, however impact, temperature or humidity can affect or even damage those sensors. Efforts have been made to realize indirect force estimation on the legged robots using leg structures based on planar mechanisms. Robot Octopus III is a six-legged robot using spatial parallel mechanism(UP-2UPS) legs. This paper proposed a novel method to realize indirect force estimation on walking robot based on a spatial parallel mechanism. The direct kinematics model and the inverse kinematics model are established. The force Jacobian matrix is derived based on the kinematics model. Thus, the indirect force estimation model is established. Then, the relation between the output torques of the three motors installed on one leg to the external force exerted on the foot tip is described. Furthermore, an adaptive tripod static gait is designed. The robot alters its leg trajectory to step on obstacles by using the proposed adaptive gait. Both the indirect force estimation model and the adaptive gait are implemented and optimized in a real time control system. An experiment is carried out to validate the indirect force estimation model. The adaptive gait is tested in another experiment. Experiment results show that the robot can successfully step on a 0.2 m-high obstacle. This paper proposes a novel method to overcome obstacles for the six-legged robot using spatial parallel mechanism legs and to avoid installing the electric force sensors in harsh environment of the robot’s foot tips.     

平面五连杆高速高精度机械手

针对微电子器件封装作业对高速高精度的自动设备的需求，提出了一种具有平面五连杆结构的机械手，机械手采用集成了高分辨率角位移反馈元件的旋转直接驱动电机作为驱动元件。并给出其运动学、动力学模型及雅克比矩阵。结合并联机构和直接驱动的优点，实现了高速高精度运动。     

6—SPS正交机构的运动学传递性分布研究

并联机器人的运动学传递性能是随其位姿变化而变化的,研究运动学传递性能在工作空间内的分布规律,对并联机器人驱动器的选择与控制有重要意义。本文介绍一种6自由度正交三维平台机器人新机型结构特点,定义其运动学传递性能评价指标,并给出了这些指标在定位姿工作空间内的分布情况。     

3-RRRT并联机器人位置正解的快速解法

研究3-RRRT型并联机器人的运动学及正向求解方法.根据3-RRRT型并联机器人机构特点以及关节运动的取值范围,提出了以并联机器人支链中支杆的方向余弦和动平台绝对位置坐标为系统的广义坐标的方法,并详细地推导了3-RRRT型并联机器人运动学模型.提出了一种位置正解的数值求解方法,推导了位置正解迭代格式,并利用MATLAB进行了位置正解数值仿真,结果表明求解程序稳定、快速、有效.     

基于输入组的六自由度解耦并联机器人

串联机器人具有很好的运动解耦性,多数并联机器人各支链间是耦合的。本文基于输入分组的思想,研究了在给定主动输入关节时机器人的输入组解耦问题,使得传统意义上耦合的一类机器人具有了解耦的特征,极大地简化了控制系统设计。最后给出了基于速度雅可比矩阵的判别方法,并将该方法用于分析一种六自由度输入组解耦的并联机器人,表明该矩阵判别法简便而有效。     

Kinematic analysis of the wire parallel mechanism for full coordinate measuring of industrial robot

This paper presents a wire parallel mechanism for full coordinate measuring of industrial robot. The mechanism is constructed with six parallel wires that act as links. The position and orientation of a robot end-effector are obtained from the wire lengths. The equations of the forward kinematics are solved by a Newton-Raphson method, and the unique solution is determined from the geometric configuration of the mechanism. A method to estimate the workspace is presented. Through simulations, it is verified that the proposed mechanism can measure a robot pose over a large workspace, and can be used effectively for full coordinate measuring of a robot with little cost and effort.     

Orientation planning of robot end-effector using augmented reality

This paper presents a methodology for planning the orientation of the end-effector for an industrial robot based on the application of augmented reality. The targeted applications are those where the end-effector is constrained to follow a visible path, which position and model are unknown, at suitable inclination angles with respect to the path. The proposed approach enables the users to create a list of control points interactively on a parameterized curve model, define the orientation of the end-effector associated with each control point, and generate a ruled surface representing the path to be planned. An approximated time-optimal trajectory, which is a determined subject to robot actuators and joint velocity constraints using convex optimization techniques, is implemented to simulate a virtual robot, allowing the users to visually evaluate the trajectory planning process. A case study is presented and discussed.     

Force transmission analyses with dimensionally homogeneous Jacobian matrices for parallel manipulators

To avoid the unit inconsistency problem in the conventional Jacobian matrix, new formulation of a dimensionally homogeneous inverse Jacobian matrix for parallel manipulators with a planar mobile platform by using three end-effector points was presented (Kim and Ryu, 2003). This paper presents force relationships between joint forces and Cartesian forces at the three End-Effector points. The derived force relationships can then be used for analyses of the input/output force transmission. These analyses, forward and inverse force transmission analyses, depend on the singular values of the derived unit consistent Jacobian matrix. Using the proposed force relationship, a numerical example is presented for actuator size design of a 3-RRR planar parallel manipulator.     

基于人工生命算法的并联机器人最优轨迹规划

基于机器人直纹面概念和人工生命算法,提出一种并联机器人位姿轨迹最优规划方法.应用计算几何中的三维直纹面生成原理,对机器人末端执行器的位置和姿态进行统一描述.考虑到机器人姿态直纹面面积及其变化率能够反映和评价机器人的运动学和动力学性能,通过求解等效角位移矢量在空间的运动轨迹形成的三维直纹曲面面积及其变化率,并将其作为泛函的泛函极值,同时考虑运动时机器人的灵活度,建立机器人位置和姿态轨迹优化的数学模型.采用人工生命优化算法对代表并联机器人位姿轨迹的高阶参数化空间曲线的参数进行优选,通过优化轨迹直纹曲面面积及其变化率和机器人的灵巧度,使并联机器人具有良好的运动学和动力学性能.最后以一三自由度球面并联机器人轨迹规划实例,验证所提出方法的可行性.