机器人运动灵活性问题的研究

对各类现有机器人的运动灵活性指标进行了分析比较,并且提出了一个新指标。同时,定义了指标灵敏度的概念,用来评价机器人灵活性的稳定性。基于这些运动灵活性指标,对平面机器人和空间机器人的运动灵活性进行了数值仿真研究,并对各指标优化结果进行了比较。结果表明,采用该指标对机器人的运动灵活性进行优化,机器人的综合灵活性更好。     

Effective manipulation for industrial robot manipulators based on tablet PC

Along with the progress in robot technologies, industrial robot manipulators nowadays have applied for more diverse and complex tasks. Consequently, the conventional manipulative devices, such as the teaching pendant and keyboard, become less suitable for task governing and teaching. Motivated by it, in this paper, we propose a novel manipulation system for industrial robot manipulators based on a tablet PC. With wireless communication, the proposed system provides flexibility for remote manipulation. Furthermore, a graphical interface and several assistive tools are developed, allowing the operator to conduct tasks in a more intuitive way. Experiments are executed to demonstrate the effectiveness of the proposed manipulation system, with its performance compared to conventional manipulative devices.     

Uncertainty analysis and allocation of joint tolerances in robot manipulators based on interval analysis

Many uncertain factors influence the accuracy and repeatability of robots. These factors include manufacturing and assembly tolerances and deviations in actuators and controllers. The effects of these uncertain factors must be carefully analyzed to obtain a clear insight into the manipulator performance. In order to ensure the position and orientation accuracy of a robot end effector as well as to reduce the manufacturing cost of the robot, it is necessary to quantify the influence of the uncertain factors and optimally allocate the tolerances. This involves a study of the direct and inverse kinematics of robot end effectors in the presence of uncertain factors. This paper focuses on the optimal allocation of joint tolerances with consideration of the positional and directional errors of the robot end effector and the manufacturing cost. The interval analysis is used for predicting errors in the performance of robot manipulators. The Stanford manipulator is considered for illustration. The unknown joint variables are modeled as interval parameters due to the inherent uncertainty. The cost-tolerance model is assumed to be of an exponential form during optimization. The effects of the upper bounds on the minimum cost and relative deviations of the directional and positional errors of the end effector are also studied.     

基于凸规划的机械臂轨迹规划方法

研究了快速求解具有时间约束的机械臂轨迹规划问题,提出了一种基于凸规划的轨迹规划方法。该方法针对机械臂轨迹规划中动力学约束非线性强、时间约束不易处理的问题,首先通过变量替换,将非线性约束转化为线性约束,然后添加新的约束,将原始非凸优化问题转化为凸规划问题,在此基础上,将其写作二阶锥规划（SOCP）形式,使用SeDuMi等优化工具包近似实时求解。该方法具有以下优点：计算高效,凸规划问题能够在多项式时间内得到求解;算法全局稳定,能收敛到全局最优解,不需要提供优化初值;可扩展性强,工业机器人的多种约束以及性能指标如加速度平滑约束、功率等均可扩充。仿真实验表明,与现有方法相比,该方法能够有效提高轨迹规划的效率,机器人的轨迹规划可以近似实时求解。     

基于结构特征的柔性机器人动态性能优化研究

以改善柔性机器人的动态性能为目的,提出了对机器人的拓扑结构进行改进以优化其动态性能的想法.利用支杆引入一种局部运动,通过动力学耦合的方式改善机器人的动态性能.利用模态理论,将机器人的振动控制转换到模态空间中.通过规划支杆的局部运动构造合适的模态控制力,起到消减激振力、获得期望阻尼特性的作用,以此对柔性机器人的低阶振动进行控制.最后,通过仿真算例验证了这种方法的有效性.     

基于微分几何的非完整移动操作臂解耦控制

针对在非完整移动操作臂(NMM)系统协调控制中传统解耦线性化方法所带来的局部线性化及近似线性化等问题,采用微分几何方法,通过适当的微分同胚和非线性反馈实现NMM系统多输入多输出非线性解耦控制,将多变量、强耦合、非线性的复杂系统精确转换为线性解耦系统.由NMM系统的状态方程建立其仿射非线性系统模型,并进行解耦条件验证,通...     

改进FMECA的工业机器人失效风险分析

针对传统失效模式、影响及危害性分析(FMECA)方法利用风险优先数(RPN)对失效风险进行量化排序存在RPN量化取值不连续,指标自身无明确物理意义、受主观影响较大,指标设计未考虑权重因子等缺陷,该文提出一种基于风险度量和风险排序的改进FMECA模糊综合评判法,设计重复偏差率P、维修费用W和发生概率O的全新评估指标集,利用模糊综合评判,引入层次分析法进行权重赋值。结果表明:该方法可以有效改善FMECA方法量化排序不合理、重复现象,实现指标评价的客观化、意义化和风险评价指标的量化连续性、权重化,提高工业机器人失效风险分析结果可信性。     

基于阻抗控制的幕墙安装机器人柔顺操作研究

为了提高幕墙安装机器人操作的柔顺性,从而真正解决建筑幕墙自动安装中人机协调的问题,采用自适应阻抗控制方法作为柔顺操作策略.依据建筑机器人物理模型建立了较为准确的阻抗控制模型,在机器人末端未接触运动空间和环境接触空间进行了自适应阻抗控制的研究,提出了通过减小力峰值防止幕墙破坏的控制参数的调整方法,借助MATLAB对控制系统进行了仿真,并对基于该算法的幕墙安装机器人进行了柔顺性操作实验.经过仿真和实验得到了适用于幕墙安装机器人的力控制算法,验证了自适应阻抗控制算法能够满足幕墙安装机器人柔顺性操作的要求.     

基于粒子群算法的6自由度机械臂动力学模型参数辨识

提出了基于粒子群优化(PSO)算法的工业机器人动力学参数辨识方法。首先利用改进的牛顿-欧拉方法,建立考虑关节摩擦的机械臂线性动力学模型,然后引入PSO算法,建立基于PSO算法的估计未知动力学参数的算法,最后以UR工业机器人为实验对象,通过设计激励轨迹,激励工业机器人关节运动,并对关节运动参数进行采样,实现UR工业机器人的动力学参数估计,并根据力矩预测精度验证动力学模型。实验证明了所提出算法辨识工业机器人动力学模型参数的准确性和有效性。     

Path planning in multiple obstacle areas for omni-directional mobile manipulators based on the APFIGA

为解决机器人在多障碍区的路径规划问题,提出了一种基于由遗传算法改进的人工势场法(APFIGA)的全方位移动操作机器人路径规划方法.该规划方法通过在可穿越的障碍区添加障碍物穿越系数来鼓励机器人走捷径,进而提高其路径优化能力;利用当前点邻域内势场强度信息,结合遗传算法确定全方位移动操作机器人的运动方向及速度,并引入机器人速度及移动障碍物速度的影响,得出势场强度下降最快的路径,提高方法的动态环境规划能力.该方法能克服机器人在障碍物附近易于抖动的现象,通过在斥力势中添加与目标距离成正比的系数项解决目标不可达问题,并利用填平势场跳出局部极小.仿真与实物实验结果验证了所提出路径规划方法的正确性和有效性.     

Kinematic measures for assessing gait stability in elderly individuals: a systematic review

Falls not only present a considerable health threat, but the resulting treatment and loss of working days also place a heavy economic burden on society. Gait instability is a major fall risk factor, particularly in geriatric patients, and walking is one of the most frequent dynamic activities of daily living. To allow preventive strategies to become effective, it is therefore imperative to identify individuals with an unstable gait. Assessment of dynamic stability and gait variability via biomechanical measures of foot kinematics provides a viable option for quantitative evaluation of gait stability, but the ability of these methods to predict falls has generally not been assessed. Although various methods for assessing gait stability exist, their sensitivity and applicability in a clinical setting, as well as their cost-effectiveness, need verification. The objective of this systematic review was therefore to evaluate the sensitivity of biomechanical measures that quantify gait stability among elderly individuals and to evaluate the cost of measurement instrumentation required for application in a clinical setting. To assess gait stability, a comparative effect size (Cohen''s d) analysis of variability and dynamic stability of foot trajectories during level walking was performed on 29 of an initial yield of 9889 articles from four electronic databases. The results of this survey demonstrate that linear variability of temporal measures of swing and stance was most capable of distinguishing between fallers and non-fallers, whereas step width and stride velocity prove more capable of discriminating between old versus young (OY) adults. In addition, while orbital stability measures (Floquet multipliers) applied to gait have been shown to distinguish between both elderly fallers and non-fallers as well as between young and old adults, local stability measures (λs) have been able to distinguish between young and old adults. Both linear and nonlinear measures of foot time series during gait seem to hold predictive ability in distinguishing healthy from fall-prone elderly adults. In conclusion, biomechanical measurements offer promise for identifying individuals at risk of falling and can be obtained with relatively low-cost tools. Incorporation of the most promising measures in combined retrospective and prospective studies for understanding fall risk and designing preventive strategies is warranted.     

基于路径规划的迷宫移动机器人

基于路径规划的迷宫移动机器人的设计目的是开发一种在迷宫的未知行进环境中,以恰当的搜索策略进行路径搜索来选择正确路线,最终走出迷宫到达预定目标的轮式移动机器人。设计中采用红外传感器实现简单而有效的迷宫路径搜索和路口类型识别。软件分为三个层次来完成不同的功能,并应用了遇到路口“左转优先”的简单优化决策法则。开发的成果为优化、快捷走出更为复杂的路径规划的迷宫提供了可行的方法。     

基于VRML的空间并联机器人运动仿真优化

虚拟现实技术(VRML)经常被运用于机器人仿真,针对传统的并联机器人运动学反解运算量大所引发的仿真系统效率问题,采用VRML的IndexedLineSet节点,通过负载平台的运动学参数动态更新IndexedLineSet节点,并以该节点为基础解出导杆的位姿.通过JavaScript与VRML交互编程实现了6自由度机器人的运动仿真.结果证明,优化后的系统仿真效率相比于传统的方法有很大的提升.     

基于避障区域的足球机器人路径规划方法

提出了一种基于避障区域的机器人运动路径的规划方法,并通过仿真实验验证了这种方法的有效性。仿真结果表明,该方法很好地实现了机器人避障,而且与其他方法相比有如下优点：（1）通过划分避障区域,极大地减少了计算量;（2）采用解三角形的方法判断机器人是否处于避障区内,方法简单有效;（3）通过定义两个集合和在其上的两种运算来构造网格,方法简单可行。     

Dynamics of spatial beams in quaternion description based on the Newmark integration scheme

The rotational quaternions represent a unique four dimensional parametrization of rotations in the three dimensional Euclidean space. In the present paper they are used as the basic rotational parameters in formulating the finite-element approach of geometrically exact beam-like structures. The classical concept of parameterizing the rotation matrix by the rotational vector is completely abandoned so that the only rotational parameters are the rotational quaternions representing both rotations and rotational strains in the beam. The space discretization based on the collocation method is used and the adjustment of the Newmark time-integration algorithm to the quaternion parameterizations of rotation is presented.     

Industrial robot layout based on operation sequence optimisation

The robot layout is one of the primary problems in the robot work cell design. An optimal layout not only makes the robotic end-effector reach the desired position with the desired orientation, but also minimises the robot cycle time for completing a given task with collision avoidance. There may be many feasible robot operation sequences for a given task. The optimisation of operation sequence for a robot placed in a fixed location is NP-complete. There may be different optimal operation sequences as the robot is placed in the different locations. Hence the problem of robot layout is quite complex. This paper presents a method of industrial robot layout based on operation sequence optimisation. The robot motion control model with velocity, acceleration and jerk is established. The feasible space of robot base is calculated and then divided into discrete grids before the optimisations. Then the ant colony algorithm is applied to optimise the operation sequence for each grid. The adjacent grids are merged or divided enough times to form the bigger grids. The pattern search algorithm is adopted to solve the local optimal position and orientation of the robot base in each big grid, and the global optimal layout is found through the comparison of the local solutions. The industrial robot layout method has been applied to the work cell design for car door welding.     

基于视觉的微机器人结肠镜运动导航

设计出一种用形状记忆合金驱动的头部转动机构和一种基于视觉的控制算法,用其进行了微机器人结肠镜在肠道内的自主导航研究.建立了转动机构模型,推导出记忆合金弹簧位移和偏转角度之间的关系.针对人体腔道内图像特点,使用腐蚀生长法找到腔道中心,反推出头舱的偏转角度和记忆合金弹簧位移.基于Preisach模型,提出了记忆合金驱动的前馈控制算法,进行了数字仿真和猪大肠内离体试验.结果表明,控制算法偏转误差小于2.6°,具有良好的实时性.该系统灵活可靠、控制方便,为主动式无创诊疗内窥镜的临床应用奠定了基础.     

基于UKF的室内移动机器人定位技术研究

为提高室内轮式机器人定位精度,采用多传感器信息融合的机器人自主定位方法,根据室内轮式移动机器人的运动模型,建立了定位系统的状态方程;基于传感器的工作原理和数学模型,建立了各自的观测方程。鉴于二者的非线性,利用无味卡尔曼滤波算法对传感器信息进行融合。实验中开发了基于FPGA的主控平台,降低了数据处理系统的冗余度,提高了系统的稳定性。另外,设计了多传感器并行采集与快速处理的算法,提高了传感器信息融合的实时性和有效性。通过进行的机器人行走实验,结果表明该算法明显减小了定位误差,有效地提高了定位精度。     

基于残余动量时频特征和SVM的机械臂故障分类

针对两连杆三自由度机械臂的电机故障和碰撞故障的分类,将残余动量信号时域中的均值、方差、相关系数与频域中的小波包能量谱组合成高维特征向量;搭建ADAMS机械臂虚拟样机,分析故障引起的残余动量特征值变化情况;虚拟样机与Matlab/Simulink进行联合仿真和支持向量机故障分类器训练,测试表明采用时频特征向量得到的故障分类准确率为98%;在工业机械臂上开展了碰撞故障实验,得到的故障分类结果表明,基于残余动量时频特征和支持向量机分类器的故障检测算法能有效检测出碰撞故障.     

挖掘机器人轨迹的模糊CMAC神经网络控制

在对挖掘机器人工作装置动力学分析的基础上,为克服多变量、强耦合及负载扰动对轨迹控制系统的影响,提出了模糊CMAC神经网络与常规控制相结合的控制方法,使神经网络逼近挖掘机器人工作装置逆动力学模型,很好地解决了轨迹控制的问题.利用MATLAB进行仿真研究,结果表明该控制方法具有较高的控制精度和鲁棒性,满足挖掘机器人轨迹控制的要求.