【作者】 杜滨；

【导师】 赵京；

【作者基本信息】 北京工业大学 ， 机械工程， 2013， 博士

【摘要】 全方位移动机械臂相对一般的移动机械臂具有了全方位移动能力，可在较狭窄或拥挤的工作场所中自如地操作和能更好地控制机械臂的操作姿态与操作精度。因此，研究这类系统的规划与控制问题具有十分重要的理论价值和实践意义。论文的主要研究内容如下：（1）全方位移动机械臂实验平台的搭建。在分析全方位移动机械臂特点的基础上，研制全方位移动机械臂的移动平台，并采用全方位轮为驱动轮。对该轮的旋转机构和转向机构进行设计。在分析全方位移动机器人的运动特点及负载等情况下，对驱动电机进行选型。根据全方位移动机器人设计的具体参数对其进行运动学建模。采用Pmac多轴运动控制器对全方位移动机器人进行运动控制。采用Plus超宽频即时定位系统对全方位移动机器人的运动进行定位及导航。（2）机器人雅可比矩阵量纲统一研究。对全方位移动机械臂进行运动评价，需要考虑子系统不同自由度类型引起的雅可比矩阵量纲差异。针对机器人的雅可比矩阵量纲不统一而不能对其进行灵活性评价这一问题，提出了一种新的雅可比矩阵量纲统一及评价方法。首先基于倍四元数，将三维空间的旋转和平移统一为四维空间的纯转动，推导了基于倍四元数的连杆坐标系变换通式。然后利用该方法对机器人进行了运动学建模，得到了具有统一量纲的雅可比矩阵。（3）机械臂子系统最优运动研究。移动机械臂的基座位置对机械臂能否完成任务有较大的影响。目前对移动机械臂基座位置的研究中，大多数只考虑可行基座区域中，对候选基座位置进行评估，而没有考虑完成任务的质量。首先，对机械臂的工作空间进行分析。利用机械臂关节自运动，采用可操作度指标向关节梯度方向进行投影，使机械臂的操作能力最大化。其次，根据得到的工作空间中操作能力分布，定义了相对可操作度指标，并绘制了全局操作能力图。再次，对机械臂基座安装位置的可行区域进行了分析。为了评价机械臂的运动性能，定义了依赖于机械臂关节运动的指标。对RRT算法、RRT*算法进行了简要的分析，并将上述定义的指标作为RRT*算法的耗费函数。对提出的机械臂基座位置优化方法，进行数值仿真研究，并对仿真结果进行分析，得到研究结论。（4）全方位移动机械臂整体协调运动研究。针对全方位移动机械臂整体建模会导致雅可比矩阵量纲不统一这一问题，采用基于倍四元数的建模方法，对全方位移动机械臂进行整体运动学建模，得到一个量纲统一的雅可比矩阵，解决传统方法对混合关节建模雅可比矩阵量纲不统一的问题。基于方向可操作度提出了方向可操作度传递率指标用来评价OWMM对末端速度方向变化的敏感程度。为了验证评价方法的有效性，对同一个任务，让OWMM进行两种类型的仿真实验：即移动平台固定而机械臂运动和OWMM整体运动，结果表明该评价方法不仅适用于相同类型关节的机器人，同时适用于混合关节类型的机器人。（5）全方位移动机械臂实验验证。在现有的硬件平台基础上，通过调用相关软件的接口函数，开发全方位移动机械臂虚拟及样机实验平台。该平台具有环境建模、机器人运动规划、运动控制、定位与导航等功能，能够实施一系列的全方位移动机械臂的运动控制实验。通过对全方位移动机器人的典型轨迹运动实验、运动规划、避障导航实验研究，验证机器人的综合性能。通过对全方位移动机械臂的子系统最优运动规划实验、协调运动规划实验验证本文中提出的算法的有效性。通过以上研究，形成了一套全方位移动机械臂整体运动学建模、协调规划、运动评价、仿真及实验的理论和方法，为全方位移动机械臂系统的结构优化设计和协调运动控制提供理论依据和方法支持。更多还原

【Abstract】 Compared to mobile manipulators, the omni-directional wheeled mobilemanipulator has omni-directional mobility to achieve free operation and better controlof the operating property and precision of manipulators in more narrow and crowdedspace. Consequently, there is very important theoretical value and practicalsignificance to study the planning and control problems of this kind of systems. Theprincipal research contents are as follows:(1) The construction of an experimental platform for omni-directional wheeledmobile manipulator. Develop a mobile platform on the analytical basis of thecharacteristics of omni-directional wheeled mobile manipulator and useomni-directional wheel as the driving wheel. We design the rotating and steeringmechanism of the wheel. Select the driving motor on the analysis of motioncharacteristics and load. Build motion model according to the specific parameter ofthe omni-directional wheeled mobile manipulator. Use Pmac multi-axis motioncontroller to take control of movement of the omni-directional wheeled mobilemanipulator. Adopt Plus location system based on ultra wideband to locate and guidethe movement of the omni-directional wheeled mobile manipulator.(2) Study on the dimension unity of robot Jacobian matrix. The dimensiondifference of Jacobian matrix coursed by various freedom types of subsystem needs tobe considered in the kinematic performance evaluation of omni-directional wheeledmobile manipulator. In view of the fact that the dexterity evaluation on robots cannotbe made due to the dimensional inhomogeneity of Jacobian, a new approach toformulate the dimensional homogeneous Jacobian and kinematic dexterity measurefor the robot with mixed joints is proposed. According to the double quaternion, therotation and translation in three-dimensional Euclidean spaces converts to the purerotation in four-dimensional Euclidean spaces. The universal transformationalexpression of the link coordinate system is derived based on double quaternion. Thenthe kinematics model of the robot is developed and the non-dimensional Jacobian isobtained by this approach.(3) Study on the optimal motion of the subsystem. A mobile manipulatortypically consists of a mobile platform and a robotic manipulator mounted on the platform. The base placement of the platform has a great influence on whether themanipulator can perform a given task. In the current study of base placement ofmobile manipulators, most only evaluate the candidate base placement in the feasiblearea of base (FAB), regardless of the quality of the implementing task. Firstly, theworkspace of a redundant manipulator is investigated. The manipulation capability ofthe redundant manipulator is maximized based on the manipulability index throughthe joint self-motion of the redundant manipulator. Next, the relative manipulabilityindex (RMI) is defined for analyzing manipulation capability of the manipulator in itsworkspace, and the global manipulability map (GMM) is presented based on theabove measure. Moreover, the feasible area for the installation of the manipulatorbase is analysed. Indices are defined dependent on the joint movements to evaluatethe kinematic performance of manipulators. RRT and RRT*algorithm is analyzedbriefly while indices mentioned in the last section are regarded as the cost function ofthe latter. Finally we study the optimization method of manipulator base placementproposed in this dissertation by means of simulation research based on severalkinematic performance criteria. At last, conclusions are obtained through the analysisof the simulation results.(4) Study on the overall coordinated motion of omni-directional wheeled mobilemanipulator. The unified analysis of omni-directional wheeled mobile manipulator(OWMM) through the dimensionally nonhomogeneous Jacobian matrix may lead tounreliable results. We present a new approach to formulate the dimensionallyhomogeneous Jacobian matrix and a new index for OWMM. The integrated modelingof OWMM is established based on double quaternion, and the non-dimensionalJacobian matrix is obtained from the above matrix. Next, by examining the concept ofdirectional manipulability, we propose a new index to evaluate the directionalmanipulability of OWMM along the specified task direction. Furthermore, thekinematic performance of the fixed base operation of manipulator and the operation ofOWMM are analyzed by numerical simulation. The results suggest that the proposedapproach is equivalent to the method of traditional kinematic modeling, and the newindex is more effective to reflect the variation of the task direction.(5) Experimental study on omni-directional wheeled mobile manipulator. Avirtual and prototype experimental platform of omni-directional wheeled mobilemanipulator has been developed by means of calling interface function of relatedsoftware on the basis of existing hardware platform. This platform has functions including environment modeling, robot motion planning, motion control, location andguidance, which enables the implementation of series motion control experiments ofomni-directional wheeled mobile manipulator. To study experiments of typical trackmovement, motion planning and obstacles avoidance navigation is a way to test thecomprehensive properties of robots. And the experiments of optimal motion planningof subsystem and coordinated motion planning of omni-directional wheeled mobilemanipulator provide evidence of the algorithm effectiveness mentioned.The study above has developed a set of theory and method of global motionmodeling, coordinated planning, motion evaluation, simulation and experiment, tooffer theoretical basis and method support for the structural optimization design andcoordination motion control of omni-directional wheeled mobile manipulator.更多还原