基于视觉标志间相对位姿的可变形臂标定方法

针对家庭服务机器人工作的非结构化环境, 本文设计了一种可以根据任务需求相应地调整连杆形状的可变形操作臂.该操作臂工作空间易于拓展、灵活度较高且成本低廉.但连杆形状的改变给操作臂的建模和控制带来了困难.首先, 可变形臂的运动学参数发生了巨大且无规律的变化, 使得固结在操作臂连杆上的关节坐标系可能脱离操作臂本体, 变得不可测量.其次, 为适应不同任务需求, 可变形臂的连杆形状需要经常改变, 而传统标定方法往往追求更高的标定精度而非标定效率.最后, 可变形臂的标定方法必须低成本且易于在家庭环境中实施, 而基于激光等传感器的标定方法设备价格昂贵, 对实验环境要求严格, 不便于在家庭中实施.因此, 一种廉价、快速、易于实施的标定方法是可变形臂应用的基础.本文分别基于Denavit-Hartenberg(DH)模型和旋量模型提出了基于视觉标志块间相对位姿测量的标定算法, 该算法在标志块处建立虚拟关节, 通过测量不同标志块间的相对位姿可快速、高效地获取可变形臂的运动学参数.实验说明了两种标定方法的有效性, 同时还表明旋量模型更适合可变形臂的建模.最后, 本文给出了利用可变形臂进行点触任务操作的实例, 展示出可变形操作臂在家庭使用中的优势.     

基于距离传感器的双边遥操作

为了改善双边遥操作的力反馈性能,本文根据从端操作臂上的传感器检测的目标距离信息,设计了新 的PD 双边控制器．证明了系统的稳定性条件,并通过单自由度双边遥操作实验系统,对提出的控制方法进行了实 验验证．实验结果表明,当从端操作臂靠近目标时,主端操作臂产生了逐渐增大的反馈力．这种控制策略为操作者 安全实现遥操作任务提供了有效手段．     

主从式胃镜介入机器人系统

针对胃镜操作难度高、医生工作强度大、消化液污染以及X射线辐射等问题,提出了主从式胃镜辅助介入机器人系统.在充分分析医生手动操作胃镜特点的基础上,将机器人分为镜体输送机械臂与镜体操作机械臂两部分.镜体输送机械臂调整镜体相对于病人口部的位姿,并完成插镜动作;对镜体输送被动臂进行逆运动学分析,确定各关节参数与基座位置;对输送器与镜体间作用力进行分析以确定输送电动机输出力矩.镜体操作机械臂控制操作部完成镜体旋转、操作部跟随、末端弯曲以及送气送水和抽吸功能.采用手柄实现对胃镜介入操作的主从控制,完成手柄与镜体在动作上的直观映射.在体外测试实验之后,进行活体动物实验发现机器人系统可完成对镜体的各项操作且未发现对组织造成损伤.实验结果表明,本文提出的胃镜辅助介入机器人系统可直观有效地完成胃镜介入,降低了操作难度,符合人类工程学设计.     

机器人臂的模型参数识别及其仿真

本文提出了一种识别机器人臂动力学方程的模型参数的方法.通过重组机器人臂的拉氏函数,使得臂的动力学方程中的模型参数个数最少;进一步形成了上三角块形式的机器人臂的模型参数识别公式.通过使用最小二乘法和龙格-库塔方法,对一个两连杆操作臂的模型参数的识别进行了仿真,得到了高的仿真精度.本方法有助于机器人的控制算式中有关操作臂的参数的确定和机器人的机械设计.     

具有冗余自由度的移动操作臂逆运动学分析

针对一类具有冗余自由度的移动操作臂,提出了一种逆运动学求解策略,它将操作臂末端的自由度在移动机器人与操作臂各关节间进行了合理分配,并根据该自由度分配方案对移动操作臂系统引入了两个约束条件,在尽量保障了操作臂末端工作空间完整性的同时,极大地方便了逆运动学的求解。最后对加入约束前后的移动操作臂工作空间大小进行了对比分析,并通过实验对所得到的逆运动学求解结果进行了验证。在实验中,利用固定在移动机器人上的CCD摄像机对目标物体进行定位,然后根据目标物体的位姿信息,通过逆运动学分析的结果控制移动操作臂实现了对目标物体的抓取操作。     

基于QR分解的冗余度机械臂雅可比矩阵求逆方法

针对冗余度机械臂在轨操作实时性的需求,提出一种基于QR分解的冗余度机械臂雅克比矩阵求逆方法。根据具体的冗余度机械臂的构型特点,将运动学逆解过程划分为多个模块,采用修正施密特QR分解方法计算机械臂雅可比矩阵的伪逆,利用硬件描述语言在FPGA上对各个模块进行了实现。以机械臂直线运动为例,通过仿真实验与利用Matlab解算的方法进行了对比,并研究了定点数长度对硬件资源和误差的影响。实验结果验证了所提出雅克比矩阵求逆方法的可行性及有效性。     

面向非完全姿态约束问题的旋转矩阵群中的垂线理论

在很多机器人领域,有很多给定任务要求并不需要3维空间的完整姿态约束,而是只限定了目标姿态某一轴的方向．这类问题称为非完全姿态约束问题．针对该问题,定义了旋转矩阵群中测地线的垂足和垂线,并给出了其解析表达式．基于垂线理论,提出了沿垂线规划的点到点轨迹生成算法．最后通过仿真实验求解操作臂的轨迹规划问题,仿真以6自由度的PUMA 560为平台,并依次固定第6关节、第4关节得到5自由度和4自由度的操作臂．提出的算法不仅适用于具有功能冗余的6自由度操作臂,也可应用于不具有冗余特性的5自由度和4自由度操作臂．实验结果验证了提出的理论和算法在解决非完全姿态约束问题上的通用性．同时,该算法还能避免参数表示方法中的奇异性问题．     

基于柔性关节机械臂振动的空间非合作目标质量辨识

针对空间在轨服务任务中捕获的非合作目标的质量辨识问题,提出了一种基于柔性关节机械臂振动频率的质量辨识方法.在该方法中,首先利用操作航天器上的柔性关节机械臂捕获空间非合作目标;然后对操作航天器、柔性关节机械臂与空间非合作目标形成的组合体进行动力学建模;最后通过分析柔性关节机械臂的振动频率来辨识空间非合作目标的质量.数值仿真结果证实了该方法的有效性.     

智能柔性机械臂的建模和振动主动控制研究

针对伺服电动机、谐波齿轮减速器、柔性臂及压电致动器组成的智能柔性机械臂系统,基于假设模态法和Hamilton原理建立系统动力学方程.为了实现系统较高精度的位置控制,同时快速抑制柔性臂的弹性振动,提出了对伺服电动机采用PD(proportional derivative)控制、对压电致动器采用模糊(fuzzy)控制的复合控制策略.在数值仿真分析的基础上,搭建了智能柔性机械臂系统测控平台.数值仿真和实验结果表明所提出的控制策略是可行的:PD控制算法控制伺服电动机以较高的位置精度完成了系统运动控制,模糊控制算法控制压电致动器较快地抑制了柔性臂的弹性振动.实验中柔性臂的振动衰减时间由6.5s缩短为3.5s,提高了柔性臂末端的定位控制精度,改善了系统的操作效率.     

基于运动预测和阻抗控制的未知受限机构操作

针对服务机械臂操作各种未知受限运动机构的需要,提出了一种基于运动预测和阻抗控制的控制方法,本方法采用试探一预测一修正的滚动操作策略,通过阻抗控制保证机械臂与未知受限机构交互的柔性.首先试探受限机构的运动能力,根据已有操作臂运动轨迹估计受限机构的运动模型,然后预测受限机构的运动方向,进而修正机械臂的运动轨迹,并根据交互作...     

末端有未知扰动的分布参数柔性机械臂的鲁棒边界控

本文研究在柔性机械臂的末端具有未知扰动的边界控制,以降低机械臂的振动.柔性机械臂的动态特性由偏微分方程表示的分布参数模型描述.在机械臂的末端边界基于Lyapunov直接法进行控制,以调节机械臂的振动.应用本文所提出的边界控制方法,可达到外界干扰下的指数稳定性.所提出的控制方法与系统参数无关,可确保在参数变化下系统具有鲁棒性.最后对所提控制方法的有效性进行了数值模拟.     

Kinematic Design and Analysis of a 7 Degree-of-Freedom Dual-Stage Inspection Manipulator for Dexterous Subsea Applications

This paper describes the design of a 7 degree-of-freedom (d.o.f) manipulator for underwater inspection applications. The functional requirements of an underwater manipulator for subsea inspection are discussed and the desired performance requirements identified. The inspection process of a weld joint using a manipulator is described and the desirable attributes of a 5 d.o.f manipulator for the inspection process established. A novel kinematic structure, for Underwater Robotic Vehicle (URV) operation, having a 2 d.o.f launching stages and a 5 d.o.f inspection stage is proposed for the manipulator. This configuration increases the dexterity, without compromising on the total reach of the manipulator. The kinematic structure of the 7 d.o.f, 2 stage, manipulator is presented. A hybrid power actuation is proposed for the manipulator to exploit the benefits of both hydraulic as well as electric actuators. Kinematic analysis of the manipulator is presented. The link dimensions of the inspection stage manipulator is done on the basis of kinematic performance indices of the manipulator. The novel kinematic structure and the hybrid power actuation strategy results in a power efficient, dexterous manipulator for underwater applications.     

Visual motor control of a 7 DOF robot manipulator using a fuzzy SOM network

A fuzzy self-organizing map (SOM) network is proposed in this paper for visual motor control of a 7 degrees of freedom (DOF) robot manipulator. The inverse kinematic map from the image plane to joint angle space of a redundant manipulator is highly nonlinear and ill-posed in the sense that a typical end-effector position is associated with several joint angle vectors. In the proposed approach, the robot workspace in image plane is discretized into a number of fuzzy regions whose center locations and fuzzy membership values are determined using a Fuzzy C-Mean (FCM) clustering algorithm. SOM network then learns the inverse kinematics by on-line by associating a local linear map for each cluster. A novel learning algorithm has been proposed to make the robot manipulator to reach a target position. Any arbitrary level of accuracy can be achieved with a number of fine movements of the manipulator tip. These fine movements depend on the error between the target position and the current manipulator position. In particular, the fuzzy model is found to be better as compared to Kohonen self-organizing map (KSOM) based learning scheme proposed for visual motor control. Like existing KSOM learning schemes, the proposed scheme leads to a unique inverse kinematic solution even for a redundant manipulator. The proposed algorithms have been successfully implemented in real-time on a 7 DOF PowerCube robot manipulator, and results are found to concur with the theoretical findings.     

Master-slave intelligent robot telepresence system

In this paper, the analysis and design of master-slave intelligent robot telepresence system are discussed. When the operator acts on the master manipulator, the position and attitude information of the master manipulator are gathered by the computer. After calculating and coordinate transforming, the data are send to the computer of the slave manipulator. Then the slave manipulator-PUMA562 robot follows the master manipulator's movement precisely. Six-dimension force/toque sensor(lord cell) is mounted on the slave manipulator. As the master manipulator and the toque on the slave manipulator are different in structure, the force and the slave manipulator should be send to the master manipulator computer and dissociated by the master manipulator computer. Proper ratio of the force on the master manipulator and the force on the slave manipulator is selected, and distribute to the master manipulator joints. So that the operator could feel the force from the master manipulator, which is obtained by the motors of the joints. The proposed control scheme is introduced to a prototype master-slave system and the experimental results show the validity of the proposed scheme.     

基于压力反馈控制的车间机械手智能防碰撞监测系统设计

针对目前提出的车间机械手智能防碰撞监测系统监测精准度低,防碰撞效果较差的问题,提出基于压力反馈控制的车间机械手智能防碰撞监测系统。硬件系统引入自动调心装置,在机械手内部加入两个避碰开关,将避碰开关与报警器相连接,如果出现碰撞,则发出警报,引用JCQ1工作监测器与机械手串联,确定机械手的工作状态和动作次数。软件部分依据机械臂运动的特点,设置机械手双动式液压缸和臂架单活塞杆双动式液压缸,通过压力反馈计算活塞直径得到液压缸直径,判断最大流量,将判断结果与阈值进行对比,完成防碰撞软件监测。实验结果表明,基于压力反馈控制的车间机械手智能防碰撞监测系统能够更加精准地控制机械手智能防碰撞监测数据,防碰撞控制精度较高,说明所设计系统能够有效实现间机械手智能防碰撞。     

基于人机交互的重载机械臂控制方法

针对目前重载机械臂控制系统存在的人机交互性不足问题及重载带来的刚柔耦合问题,设计了一种基于动力学模型的人机交互闭环力!/!位控制算法,并依据该算法设计了7自由度重载机械臂控制系统.首先分析了国内外重载机械臂的工作特点和存在的问题,提出基于力!/!视觉反馈的人机交互方式来增强系统的人机交互性;然后为抑制刚柔耦合带来的控制问题,建立了重载机械臂刚柔耦合动力学模型,提出基于人机交互的重载机械臂力!/!位闭环控制算法.最后搭建重载机械臂控制系统,搭建的控制系统包括人机交互子系统、环境感知子系统、驱动子系统、信息处理子系统及通信子系统.在此基础上,进行重载机械臂控制系统作业试验.试验结果表明,该控制系统能够完成人机交互作业功能,相对于传统重载机械臂作业手段,有效提高了作业效率70%,保障了作业人员安全,验证了所提出控制系统的人机友好性、可行性和实用性.     

Collision-Free Trajectory Planning for Two Cooperative Redundant Manipulators Using the Minimum-Time Criterion

An approach is proposed to generate collision-free, near time-optimal trajectories for two cooperative redundant manipulators between two sets of end-points. The time-optimal trajectory of one manipulator is found first. Then by considering this manipulator as a moving obstacle, the collision-free trajectory for the other manipulator is found. After obtaining the trajectories of both manipulators, an iterative approach is proposed to scale the time profile of the trajectories to minimize the traveling time. A simulation example is included to illustrate the validity of the proposed approach.     

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.     

Control of a flexible manipulator with noncollocated feedback: time-domain passivity approach

A new method to control a flexible manipulator with noncollocated feedback is proposed. We introduce a method to implement the time-domain passivity-control approach to a flexible manipulator with noncollocated feedback, which could not be treated with the previous time-domain passivity-control framework due to a possible active transfer function from the input to the noncollocated output. The proposed method is simulated with a single-link flexible manipulator, and a good control performance is obtained.     

基于专家PID的带臂四旋翼无人机控制方法

相较于未带臂的无人机,带臂无人机（UAV）的飞行轨迹会出现较大偏差,更难以稳定控制。为了解决带臂UAV的精确轨迹控制问题,提出基于专家PID的带臂四旋翼无人机控制方法。首先,将机械臂搭载于UAV上把它们作为整体,并通过拉格朗日方程建立了带臂UAV的运动学和动力学系统模型;其次,设计专家PID控制器用于对系统的稳定控制;然后利用五次多项式对带臂UAV的机械臂进行轨迹规划;最后,通过仿真验证专家PID控制方法对带臂UAV稳定控制的有效性。实验结果表明,相较于常规PID控制,所提基于专家PID的控制方法提高了系统的响应速度,且能够有效地抑制外部扰动;该方法对于动作情况下的机械臂能够稳定地跟踪其轨迹,且具有很好的抗扰性和鲁棒性。