一种协作机器人工作空间灵活度的求解方法

传统机器人工作空间灵活度主要采用逆运动学方法(IK)进行求解,而偏置的存在导致协作机器人的逆运动学求解困难,无法求解其工作空间灵活度.为此,提出了一种不需要进行逆运动学求解的改进方法.首先,对机器人偏置进行定义,并分析IK方法的不足.然后,借助服务球的概念得到满足服务点条件的几何约束,通过该几何约束得到求解灵活度的误差模型,并提出影响灵活度求解的误差参数E及工作空间灵活度指标λ.接着,分析改进方法中的参数n、n_0、n_1对E、λ的影响,并确定该参数的取值.最后,对比改进方法与IK方法可知,在保证求解准确性的前提下,改进方法比IK方法的求解时间短、计算效率高.通过求解具有偏置的协作机器人工作空间灵活度,证明了改进方法具有适应性强的特点.     

Stewart并联机器人力敏感性分析及实验验证

研究了Stewart并联机器人的人机交互安全性问题．首先建立机器人的静力学方程,提取关节力敏感度和关节力敏感方向指标,度量关节力对操作力的感知敏感性．采用解析法和数值法结合的方法求算关节全局力敏感度．接着分析关节力敏感度在笛卡儿工作空间和位姿工作空间中的分布,以及构型参数对关节全局和局部力敏感度的影响．然后通过限制工作空间和调节末端执行器在工作过程中的位姿,在设计阶段合理选取构型参数,改善关节力敏感度的方法提高人机交互安全性．最后通过实验测试证明了,关节力敏感度能有效度量关节对交互力的敏感性,末端执行器的位置和姿态能直接改变关节力敏感度．     

基于计算的工业喷涂机器人基本参数设计方法

设计与确定机器人参数需要在各项性能之间进行折衷,常常是一个耗时的迭代过程。本文提出了一种工业喷涂机器人基本参数确定的一般方法。通过喷涂机器人的设计与开发过程,基于机器人建模方法,归纳出机器人基本参数对各项性能尤其是工作空间特性的影响因素与规律,并在此过程中上分析了其结构参数对机器人工作空间和性能的影响,从而得出了机器人工作空间特性与结构参数之间的内在联系,为工业机器人的设计提供依据。     

六自由度模块化机械臂工作空间量化对比分析*

针对六自由度模块化机械臂的两种不同构型,对其工作空间进行了量化对比分析。首先采用DH法进行了手臂结构建模,得到正运动学模型;然后基于MATLAB机器人工具箱搭建了两种构型手臂的仿真平台,运用蒙特卡洛法求解两种构型手臂的工作空间并采用可视化方法得到其工作空间的点云图,结合计算机辅助设计软件绘制两种手臂构型的3D工作空间,采用SLI指标对两种手臂构型的工作空间进行量化处理分析;最后通过对比两种手臂构型的工作空间点云图、3D工作空间实体和SLI指标性能分析了两种构型手臂的优劣,为后续的模块化机械臂的结构参数优化和空间灵活性研究奠定了基础。     

机器人灵活工作空间的边界分析

机器人灵活工作空间的分析是机器人运动学至今没有解决的一个问题.由于机器人在灵活工作空间中工作不会受到本身机构对它的限制.所以,机器人灵活工作空间的大小对于提高机器人的操作性能就显得格外重要.本文旨在解决机器人灵活工作空间边界的计算问题.首先.它分析了灵活工作空间边界的性质;其次,用一种新的方法——网络跟踪法确定了灵活工作空间在横截面内的边界;最后.提出了灵活工作空间端边界的求解方法.     

砂带磨削机器人的灵活性分析与优化

总结了磨削机器人的当前发展和阻碍砂带磨削机器人广泛应用的难点．根据复杂曲面磨削任务对机器 人的实际要求,提出了一种磨削机器人构型．这种机器人属于PPPRRR 构型,具有很高的定位精度和结构刚度．利 用旋量理论中的指数积公式推导了该机器人的运动学正反解．引入了模拟退火算法,分析获得了相对于末端坐标系 描述的砂带磨削机器人的灵活磨削空间,并绘制了灵活磨削空间的横截面图谱．进一步,采用模式搜索法,优化了 磨削机接触轮相对于机器人基坐标系的位移偏移量,获得了最大的灵活磨削空间体积,提高了机器人砂带磨削系统 的灵活性．     

基于仿真的外科手术机器人术前引导优化

给出一种保证术中较高灵巧度、可达性和可视化指标的手术机器人布置方法,建立一个能够辅助医生完成手术机器人术前布置的虚拟现实系统.基于粒子群优化算法提出了引导手术切口布置和机器人摆位的方法,该方法不仅能够有效完成针对某一手术空间的摆位优化,还通过手术空间划分并赋予权值的方法来反映手术空间内部差异,在空间分割的基础上提出加权平均的全域各向同性和多臂协同性两个目标函数,分别反映机器人系统的单臂性能和三臂协作能力.该方法可以在兼顾手术机器人性能和手术空间内部差异的前提下直观地引导医生完成复杂的术前设置工作.实验证明,3只臂的灵巧度优化结果均高于不加权方法,三臂协作能力指标相对不加权方法提高25%~30%,而且优化结果能够优先满足手术空间内的重要区域.     

新型6-HTRT并联机器人工作空间和参数研究

本文介绍了新型6-HTRT并联机器人的机构型式和工作原理，给出了考虑到约束条件的 位置逆解算法和存在多组解时的逆解选取准则．利用逆解算法和三维搜索，得到了确定该类 型机器人工作空间的方法和工作空间体积的计算公式．分析了6-HTRT并联机器人工作空间 的形态特点以及机器人结构参数和运动参数对工作空间体积的影响．     

多个地面移动机器人建立构型空间

研究多机器人系统运动规划问题,经典的构型空间(C-space)通常用于静态障碍物并且机器人有环境全局知识的假设下.有局部传感能力的多机器人系统(MRS)不具备全局规划性能.针对上述问题,要求MRS建立C-space功能,采用环境和机器人的模型建立多边形集合,每个机器人都是自主地面移动机器人.机器人的传感范围是有限的,并能互相通讯.一种分散式的算法被提出来解决两个机器人探索环境并建立构型空间障碍的任务,两个机器人定期的交换和合并对方产生的部分构型空间障碍,直到整个构型空间障碍建立.算法类似于同时绘图与定位(CML),采用产生和合并C-space的算法进行仿真,结果表明了算法的有效性.     

Kinect动作捕捉到Gazebo人体模型数据转换的研究与开发

人机协作中人与机器人之间没有物理防护栅,存在碰撞风险,研究通过Kinect采集人体运动,在仿真软件Gazebo中分析工作空间中人与机器人之间的关系来防止碰撞。由于Kinect人体模型与Gazebo人体模型存在差异,将Kinect采集的人体运动数据以四元数形式存储在CSV文件中,通过编制转换软件,从而能够正确驱动Gazebo中人体模型运动,为将来实现人机协作的仿真研究奠定基础。     

A Formal-Numerical Approach for Robust In-Workspace Singularity Detection

Singularity is a major problem for parallel robots as in these configurations the robot cannot be controlled, and there may be infinite forces/torques in its joints, possibly leading to its breakdown. Hence, such a configuration must usually be avoided, and certifying the absence of singularity within a prescribed workspace or on a given trajectory is essential for a practical use of this type of robots. Singularity conditions are usually quite complex, and therefore a purely analytical analysis is difficult. We present here an algorithm that combines formal and numerical calculations for detecting singularity or closeness to a singularity within an arbitrary workspace or trajectory. This algorithm has the very important advantage of being able to deal with any robot mechanical structure and to manage uncertainties in the robot control and in the robot modeling.     

Real-Time Collision-Free Path Planning for Robots in Configuration Space

Collision-free path planning for an industrial robot in configuration space requires mapping obstacles from robot‘s workspace into its configuration space.In this paper,an approach to real-time collision-free path planning for robots in configuration space is presented.Obstacle mapping is carried out by fundamental obstacles defined in the workspace and their images in the configuration space.In order to avoid dealing with unimportant parts of the configuration space that do not affect searching a collision-free path between starting and goal configurations,we construct a free subspace by slice configuration obstacles.In this free subspace,the collision-free path is determined by the A^* algorithm.Finally,graphical simulations show the effectiveness of the proposed approach.     

基于性能驱动的船载稳定平台尺度参数优化设计

为提升船载稳定平台的运动学性能,针对■并联机构的尺度参数优化问题,以机构的工作空间体积和全域力传递率为综合评价指标,采用小生境遗传算法优化得到稳定平台的最佳几何构形。具体地,采用数值法与解析法相结合的方式判断支链长度、关节转角、奇异位形等约束条件的生效情况,求解出并联稳定平台的工作空间;基于力雅可比矩阵逆矩阵的最小奇异值定义机构的局部力传递性能,以工作空间内局部力传递率的平均值作为全域力传递性能评价指标;以工作空间体积和全域力传递率的加权和为优化目标,采用小生境自适应遗传算法完成优化求解,获得最优尺度参数。与初始构形的性能对比分析表明,优化构形在力传递性能方面有35%的提升,具有更好的综合运动学性能。制作试验样机并完成相关实验,验证了所提尺度参数优化方法的有效性。最后探讨了多目标优化过程中不同的权重系数取值对优化结果的作用规律,发现选用均衡的权重可获得更佳的综合性能。     

Near-minimum time control of flexible manipulators with a payload

In this paper near-minimum time controllers for coordinating flexible two-link robots carrying an object in a workspace are developed. Bang-bang control theory in conjunction with synchronization of execution time for each joint is used to derive the near-minimum lime controller. The near-minimum time control law is implemented for two distinct cases. One is for a single flexible robot grasping a payload white the other is for a master/slave configuration for the motion of two flexible robots and their load. Simulation results indicate the feasibility of the proposed schemes.     

基于运动性能分析的双臂冗余度机器人协调运动研究

为了提高双臂冗余度机器人在其交互工作空间中的协调运动能力,以ABB YuMi为例,提出了一种计算简便并且能够有效反映双臂协调运动灵活性的性能指标。利用D-H法建立了YuMi机器人的运动学模型,分析了双臂可操作度的分布情况,分别研究了两种协调运动方式的运动学约束关系以及相应的运动控制规律,基于灵活性分析构建了双臂协调装配电机转子与轴承以及字母绘制的任务,通过仿真和实验验证了本文双臂可操作度指标的有效性及协调运动规划方法的正确性。     

Kinematic Design of Modular Reconfigurable In-Parallel Robots

This paper describes the kinematic design issues of a modular reconfigurable parallel robot. Two types of robot modules, the fixed-dimension joint modules and the variable dimension link modules that can be custom-designed rapidly, are used to facilitate the complex design effort. Module selection and robot configuration enumeration are discussed. The kinematic analysis of modular parallel robots is based on a local frame representation of the Product-Of-Exponentials (POE) formula. Forward displacement analysis algorithms and a workspace visualization scheme are presented for a class of three-legged modular parallel robots. Two three-legged reconfigurable parallel robot configurations are actually built according to the proposed design procedure.     

Design of an anthropomorphic dual-arm robot with biologically inspired 8-DOF arms

From the perspective of kinematics, dual-arm manipulation in robots differs from single-arm manipulation in that it requires high dexterity in a specific region of the manipulator’s workspace. This feature has motivated research on the specialized design of manipulators for dual-arm robots. These recently introduced robots often utilize a shoulder structure with a tilted angle of some magnitude. The tilted shoulder yields better kinematic performance for dual-arm manipulation, such as a wider common workspace for each arm. However, this method tends to reduce total workspace volume, which results in lower kinematic performance for single-arm tasks in the outer region of the workspace. To overcome this trade-off, the authors of this study propose a design for a dual-arm robot with a biologically inspired four degree-of-freedom shoulder mechanism. This study analyzes the kinematic performance of the proposed design and compares it with that of a conventional dual-arm robot from the perspective of workspace and single-/dual-arm manipulability. The comparative analysis revealed that the proposed structure can significantly enhance single- and dual-arm kinematic performance in comparison with conventional dual-arm structures. This superior kinematic performance was verified through experiments, which showed that the proposed method required shorter settling time and trajectory-following performance than the conventional dual-arm robot.     

Performance Evaluation of Human Detection Systems for Robot Safety

Detecting and tracking people is becoming more important in robotic applications because of the increasing demand for collaborative work in which people interact closely with and in the same workspace as robots. New safety standards allow people to work next to robots, but require that they be protected from harm while they do so. Sensors that detect and track people are a natural way of implementing the necessary safety monitoring, and have the added advantage that the information about where the people are and where they are going can be fed back into the application and used to give the robot greater situational awareness for performing tasks. The results should help users determine if such a system will provide sufficient protection for people to be able to work safely in collaborative applications with industrial robots.     

Evaluation of head-collision safety of a 7-DOF manipulator according to posture variation

As the need for the improvement of the productivity in the manufacturing process grows, industrial robots are brought out of the safety fences and used in the direct collaborative operation with human workers. Consequently, the intended and/or unintended contact between the human and the robot in the collaborative operation is no longer an extraordinary event and is a mundane possibility. The level of the risk of the collision depends on various quantities associated with the collision, for example, inertia, velocity, stiffness, and so on. MSI (manipulator safety index) which is based on HIC (head injury criteria) conventionally used in the automotive industry is one of the practically available measures to estimate the risk of the collision between the human and the manipulator. In this paper MSI is applied to evaluate the collision safety of a 7-DOF articulated human-arm-like manipulator. The risk of the collision could be reduced by choosing different postures without deviating from the given end-effector trajectory using the redundant degree of freedom in the 7-DOF manipulator. The paper shows how the redundant degree of the freedom is utilized to design safer trajectories and/or safer manipulator configurations among many available. A parametric analysis and simulation results for a given trajectory illustrate the usefulness of the concept of the trajectory design for alleviating the risk of the manipulator operation in the human–robot coexisting workspace.