面向冗余机器人实时控制的逆运动学求解有效方法

针对7自由度冗余机器人实时运动控制,对机器人逆运动学提出了一种新的求解方法.采用位姿分解方式,使7自由度冗余机器人逆运动学简化为4自由度位置逆运动学求解.在梯度投影法得到位置优化解的基础上,利用机器人封闭解公式求得一组优化解.通过对7自由度机器人仿真分析,表明了该方法的有效性.     

基于神经网络的机器人的逆运动学分析

文章提出了基于BP神经网络算法的机器人逆运动学的求解方法,给出了基于神经网络的机器人逆运动学求解的具体步骤和设计神经网络的相关注意事项.通过时KLD-600六自由度机器人仿真表明该算法简单可靠.     

仿人机器人7DOF腿部的运动分析与仿真

传统的6自由度腿部逆运动学求解可以得到唯一解,仿人机器人7自由度腿部由于冗余自由度的存在,其逆运动学求解比6自由度腿部更难.本文采用D-H方法对现有的仿人机器人7自由度的下肢进行运动学建模与分析,用位姿分离法求解步行运动中的逆运动学解,在LMS Virtual.Lab仿真平台上仿真,为解决机器人的动力学问题做必要的准备.     

面向冗余机器人实时控制的逆运动学求解有效方法

针对-自由度冗余机器人实时运动控制,对机器人逆运动学提出了一种新的求解方法.采用位姿分解方式,使-自由度冗余机器人逆运动学简化为,自由度位置逆运动学求解.在梯度投影法得到位置优化解的基础上,利用机器人封闭解公式求得一组优化解.通过对-自由度机器人仿真分析,表明了该方法的有效性.

     

仿人机器人手臂抓取运动规划广义逆RRT算法

针对高维空间冗余仿人机器人手臂抓取对象运动规划时所面临的目标位形未知、抓取空间受限、位形空间存在大量障碍物等难题,提出了一种广义逆快速探索随机树法(RRT)避碰运动方法.首先,提出分层子维空间运动规划概念模型,建立了仿人机器人上肢手臂运动学和逆运动学模型;其次,提出一种加权最小范数广义逆RRT规划算法;最后,通过计算机三维仿真,采用基于有向包围盒法开发的碰撞检测算法,验证了该算法的有效性.     

七自由度带电作业机器人逆运动学求解方法研究

本文以七自由度双臂带电作业机器人为研究对象,针对七自由度逆运动学求解计算复杂,实时控制困难的问题,在分析机器人的机械结构及建立正向运动学模型的基础上,采用位姿分解法与代数迭代法相结合的方式求解运动学逆解,将七自由度逆运动学求解转化为四自由度位置冗余问题,并设计了具体的程序流程图,经过仿真验证,该算法减小了逆运动学求解的计算量,提高了机器人控制的实时性。     

冗余自由度超声检测机器人的逆运动学分析

针对一类冗余自由度超声检测机器人的传统逆运动学求解算法耗时长且准确度低的问题,提出了一种基于集合划分和解析解法相结合的逆运动学求解算法。首先采用De-navit-Hartenberg方法建立检测机器人的运动学方程;其次,利用解析解法求出机器人逆解的解析表达式,并提出三种自由度分配方案;最后,选择合适的自由度分配方案,据此对超声波探头位姿集合作划分,结合逆解解析式求出运动学逆解。实际应用中,借助十一轴超声波检测机器人,利用该算法对具有复杂外形的飞机螺旋桨叶片进行检测。结果表明,与传统的纯数值解法相比,该算法能够快速得到精确的运动学逆解。     

基于MATLAB的模块化机器人手臂运动学算法验证及运动仿真

针对由模块化关节构成的六自由度串联机器人手臂, 采用DH法对手臂的操作空间进行了描述, 得到了正运动学模型; 采用欧拉角表示手臂姿态, 得到了包含六个参数的用于表示手臂位姿的完备广义坐标, 并对欧拉角的几何关系进行了分析。针对SolidWorks虽然实体建模简洁方便但计算并非其强项的缺点, 编写相应接口程序, 将建立的手臂三维实体模型保留几何约束关系简化后导入MATLAB软件。基于MATLAB编写正逆运动学算法验证程序以及连杆驱动程序, 实现了手臂的仿真运动。通过仿真, 不仅更进一步验证了手臂正逆运动学解算的正确性, 而且非常直观地看出手臂末端在空间中运行的路径以及各关节的动作情况。机器人手臂正逆运动学算法正确性的验证及运动仿真为手臂的精确定位及其路径规划提供了必要的保证。     

EMR系统机器人运动学和工作空间的分析

本文研究了EMR系统机器人的运动学和工作空间。首先对机器人的工作空间进行了分析,并提出了求解机器人末端灵活性的方法;接着解决了机器人位姿正运动学描述和逆运动学求解的问题;最后针对欠自由度的机器人结构,提出采用一组变量来描述机器人的速度运动学,避免了采用伪逆求逆速度运动学。     

高精度解耦六自由度机械臂逆运动学解法

根据6自由度机械臂正交解耦的结构特点,采用位姿分解方式,将6自由度逆运动学降为3自由度位置逆运动学、3自由度方向逆运动学;利用欧儿里德范数导出机械臂定位、定向的逆运动学解析解,使机械臂高速、准确运动.在定向控制方面,提出一种以单位四元数为目标输入的控制形式,只需计算两个角度逆解,既简化计算,又利于实际操作;利用逆运动学计算机械臂的工作空间和奇异点空间,借助移动机器人车体自由度弥补因计算以及关节长度不够引起的奇异位形,极大扩展了机械手臂的有效运动区域.     

Design and kinetostatic analysis of a new parallel manipulator

This paper proposes an innovative design for a parallel manipulator that can be applied to a machine tool. The proposed parallel manipulator has three degrees of freedom (DOFs), including the rotations of a moving platform about the x and y axes and a translation of this platform along the z-axis. A passive link is introduced into this new parallel manipulator in order to increase the stiffness of the system and eliminate any unexpected motion. Both direct and inverse kinematic problems are investigated, and a dynamic model using a Newton–Euler approach is implemented. The global system stiffness of the proposed parallel manipulator, which considers the compliance of links and joints, is formulated and the kinetostatic analysis is conducted. Finally, a case study is presented to demonstrate the applications of the kinematic and dynamic models and to verify the concept of the new design.     

Performance Analysis and Application of a Redundantly Actuated Parallel Manipulator for Milling

This paper deals with the performance analysis of a 3-degree-of-freedom (3-DOF) planar parallel manipulator with actuation redundancy. Closed-form solutions are developed for both the inverse and direct kinematics about the redundant parallel manipulator. In performance analysis phase, the dexterity is analyzed, three kinds of singularities are investigated, and the stiffness is estimated. Compared with the corresponding non-redundant parallel manipulator with the redundant link removed, the redundantly actuated one has better dexterity, litter singular configurations and higher stiffness. The redundantly actuated parallel manipulator was applied to the design of a 4-DOF hybrid machine tool which also includes a feed worktable to demonstrate its applicability.     

Kinematic analysis and optimal design of a novel 1T3R parallel manipulator with an articulated travelling plate

Driven by the requirements of the large-scale component assemblage for the docking platform, this paper proposes a novel one-translational-three-rotational (1T3R) parallel manipulator with an articulated travelling plate, which can provide high stiffness and good accuracy performances in the assemblage. The underlying architecture of this manipulator is briefly addressed with emphasis on the practical realization of the articulated travelling plate. On the basis of the kinematic analysis of the 1T3R parallel manipulator, its optimal design considering the force and motion transmissibility is carried out, in which the generalized virtual power transmissibility of this manipulator is defined. This paper aims at laying a solid theoretical and technical foundation for the prototype design and manufacture of the 1T3R parallel manipulator.     

TriM: An Ultra-Accurate High-Speed Six Degree-of-Freedom Manipulator Using Planar Stepper Motors

In this paper, we propose a novel six degree-of-freedom positioning system. This mechanism is a tripod structure with inextensible limbs actuated at the base by two-dimensional linear stepper motors (other types of actuators may also be utilized). This manipulator has a closed-chain kinematic structure. Both the direct and the inverse kinematics of the manipulator are presented in detail. While the inverse kinematics are obtained in closed form, the direct kinematics can not be solved in closed form and an algorithm is provided for numerically computing the direct kinematic solution. A detailed dynamic model of the positioning system is also provided. The dynamics of the actuators (Sawyer motors) are also included in the dynamic modeling. The design of the tripod manipulator (TriM) included a kinematic optimization of the system parameters to maximize the manipulator workspace. The proposed manipulator achieves large range of motion in all the 6 degrees of freedom. Furthermore, high resolution and high speed motion may be achieved in all axes due to the actuators used and the direct-drive nature of the manipulator. This work was supported in part by NSF under grants ECS-9977693 and ECS-0501539. An earlier version of this paper was presented at the 2003 IEEE/RSJ International Conference on Intelligent Robots and Systems, Las Vegas, NV, Oct. 2003.     

Intelligent spherical joints based tri-actuated spatial parallel manipulator for precision applications

This paper contributes to the design of a new table top size tri-actuated spatial parallel manipulator. The manipulator configuration is considered for its ability to provide a maximum achievable workspace freedom. A minimum of three legs with all the spherical joints is selected to make three SPS (Spherical-prismatic-spherical) kinematic chain configuration. The complexity of building a minimum constraint manipulator lies in the fact that it cannot stand on its own on three ball joints. To transform this into a workable mechanism, spherical joints are designed with internal stiffness and braking system such that the manipulator can withstand even external loads. A detailed design analysis is conducted for the customized ball joint with different inside actuation mechanisms. Manipulator working in the workspace is found smooth under a pre-loaded condition whereas magnetic actuation locks the joints at the destination point, thereby achieving both capabilities. The manipulator overall stiffness is then evaluated to make its use in micro‑meso scale applications.     

Visual servoing of redundant manipulator with Jacobian matrix estimation using self-organizing map

Vision based redundant manipulator control with a neural network based learning strategy is discussed in this paper. The manipulator is visually controlled with stereo vision in an eye-to-hand configuration. A novel Kohonen’s self-organizing map (KSOM) based visual servoing scheme has been proposed for a redundant manipulator with 7 degrees of freedom (DOF). The inverse kinematic relationship of the manipulator is learned using a Kohonen’s self-organizing map. This learned map is shown to be an approximate estimate of the inverse Jacobian, which can then be used in conjunction with the proportional controller to achieve closed loop servoing in real-time. It is shown through Lyapunov stability analysis that the proposed learning based servoing scheme ensures global stability. A generalized weight update law is proposed for KSOM based inverse kinematic control, to resolve the redundancy during the learning phase. Unlike the existing visual servoing schemes, the proposed KSOM based scheme eliminates the computation of the pseudo-inverse of the Jacobian matrix in real-time. This makes the proposed algorithm computationally more efficient. The proposed scheme has been implemented on a 7 DOF PowerCube? robot manipulator with visual feedback from two cameras.     

Design philosophy of an isotropic six-axis serial manipulator

Presented in this paper is the design philosophy employed for the constructtion of DIESTRO, an isotropic, six-axis, serial manipulator. The kinematic criteria applied so far in manipulator design have been based largely on kinematic solvability, in the sense of allowing for closed-form inverse kinematic solutions. As opposed to this rather limiting criterion, DIESTRO was designed kinematically so as to having a set of configurations in which its Jacobian matrix allows its inversion without roundoff error amplification. Although the basic kinematic chain is of the serial type, this design criterion led to an architecture not admitting closed-form inverse kinematic solutions. The central task was to produce an accurate robot under the prescribed specifications. It is believed that, under similar workspace and load specifications, the particularly challenging design of many other serial manipulators with complex architectures can benefit from the design guidelines given here.     

Simulation and computer-aided kinematic design of three-degree-of-freedom spherical parallel manipulators

Parallel robotic manipulators are complex mechanical systems that lead to involved kinematic and dynamic equations. Hence, the design of such systems is in general not intuitive, and advanced simulation and design tools specialized for this type of architecture are highly desirable. This article discusses the kinematic simulation and computer-aided design of three-degree-of-freedom spherical parallel manipulators with either prismatic or revolute actuators. The kinematic analysis of spherical parallel manipulators is first reviewed. Solutions for the direct and inverse kinematic problems are given, and the expressions for the singularity loci are then introduced. The determination of the workspace of this type of manipulator is also addressed. Finally, a computer package developed specifically for the CAD of spherical parallel manipulators is presented. This package allows the interactive analysis of manipulators of arbitrary architecture including the representation of the workspace, the representation of singularities, and the graphic animation of trajectories specified either by the direct or the inverse kinematic module. It can be used for the design of any spherical parallel three-degree-of-freedom actuated mechanism, which can find many applications in high-performance robotic systems. © 3995 John Wiley & Sons, Inc.     

线驱动模块化七自由度机器人轨迹跟踪控制

阐述了一种线驱动与常规串联驱动相结合的混合设计方法．这种设计方法融合了线驱动并联机构和模块化串联机构的优点，而且混合驱动机器人的工作空间大于完全线驱动机器人的工作空间．文章首先介绍了混合驱动机器人的机构设计，也就是机器人的肩关节采用模块化串联结构，而肘、腕关节采用线驱动结构．然后利用几何分析的方法来解机器人前向运动学问题．在分析驱动线长与关节角之间变换关系的基础上，分别利用速度法和关节角增量法来计算机器人逆向运动学解．最后，使用VC++实现混合驱动机器人对直线运动轨迹进行跟踪的仿真，从而证明了文章所描述的设计方法的正确性．     

Extended Jacobian inverse kinematics algorithms for mobile manipulators

We consider the inverse kinematic problem for mobile manipulators consisting of a nonholonomic mobile platform and a holonomic manipulator on board the platform. The kinematics of a mobile manipulator are represented by a driftless control system with outputs together with the associated variational control system. The output reachability map of the driftless control system determines the instantaneous kinematics, while the output reachability map of the variational system plays the role of the analytic Jacobian of the mobile manipulator. Relying on a formal analogy between the kinematics of stationary and mobile manipulators we exploit the extended Jacobian construction in order to design a collection of extended Jacobian inverse kinematics algorithms for mobile manipulators. It has been proved mathematically and confirmed in computer simulations that these algorithms are capable of efficiently solving the inverse kinematic problem. Moreover, a choice of the Jacobian extension may lay down some guidelines for the platform‐manipulator motion coordination. © 2002 Wiley Periodicals, Inc.