Dragging motion of a two-link mobile manipulator with large pull force through singular configuration: theoretical analysis and experimental verification

This paper reveals the advantageous feature of singular configuration for a two-link mobile manipulator by theoretical analysis, numerical simulations and experiments. When a mobile manipulator drags a heavy object on a flat floor, a large pull force is required to overcome the friction force between the object and the floor. In the motion obtained by numerical optimization, unlike humans, a two-link mobile manipulator pulls the object with a large force by passing through singular configuration. We analyze theoretically the force applied to the object by the manipulator under several assumptions, and show that a large pull force can be generated near singular configuration from the energy stored in the manipulator. The feasibility of the motion obtained by numerical optimization is also shown by experimental results.     

Hoof pathologies influence kinematic measures of dairy cow gait

To explore how hoof pathologies affect the gait of dairy cattle, we studied gait profiles of cows with no visible injuries (n = 17), sole lesions (n = 14), and sole ulcers (n = 7). Video recordings of dairy cows were digitized using motion analysis software to calculate 6 stride variables for each hoof. Compared with cows with sole ulcers, healthy cows walked faster (1.11 ± 0.03 vs. 0.90 ± 0.05 m/s, mean ± SEM), had shorter stride durations (1.26 ± 0.03 vs. 1.48 ± 0.05 s), and longer strides (139.5 ± 2.1 vs. 130.0 ± 3.2 cm). Percentage of triple support in the gait cycle (time when cattle were supported by 3 legs) more than doubled for cows with sole ulcers compared with healthy cows (42 vs. 18%). Gait differences were likely due to cows reducing the load on an affected leg. Few differences were detected between healthy cows and those with sole lesions, perhaps because of variation in number, severity, and location of injuries. Kinematic gait analysis is a promising approach in understanding how hoof pathologies affect dairy cow gait.     

基于OpenGL的六自由度机械臂三维建模与仿真

针对六自由度机器臂,为了解决运动学分析结果不易验证以及在实体机械臂上演示成本较高的问题,设计了一套六自由度机械臂三维仿真软件.该软件以VS2008为开发平台,基于OpenGL函数库和Qt框架类,采用模块化的方法进行三维模型的创建,具有灵活性大、易于扩展的优点.结果表明,该仿真软件能够良好地仿真出机械臂的运动过程,对机械臂的研究和教学起到了促进作用.     

一种解析的反向运动学方法*

针对多关节的反向运动学（IK）提出一种解析的求解方法,直接给出公式来求解关节链中所有待求关节的位置和旋转变量。同传统的迭代方法相比,该方法省却了繁琐的迭代计算,具有更高的求解效率,可以应用于角色动作、运动轨迹的设计、编辑及优化等交互性强和实时性要求高的应用中。     

应用基于运动螺旋的机器人正解映射求解搬运机器人的逆运动学问题

应用基于旋量理论的指数积公式建立了搬运机器人的正解映射,并基于矩阵变换了求解该机器人逆运动学问题的方法,该方法为求解一般机器人的逆运动学问题提供了参考.     

Exact Solution of a Cylinder Tube Made of Metallic Foam Under Inner Pressure

Exact solution of the stress and velocity fields of a cylinder tube of metallic foams under inner pressure is given in which the Triantafillou and Gibson constitutive law （TG model） for the material is taken as a basis of the calculation. The nonlinear equation is turned linear equation by introducing a kinematics parameter. The differences between the full condensed materials and the effect of the relative density are also discussed.     

VB环境下的双曲柄滑块机构运动分析

为研究平面多杆机构的运动分析解析法,以双曲柄滑块机构为例,根据机构组成原理将其分解为一个双曲柄机构和一个曲柄摇杆机构的串联,后级机构的运动输入来自前级机构的输出。分别建立这两个机构的运动分析解析模型,在VB环境中逐级求解出整个机构的运动结果,采用计算机动画和线图输出。由此说明机构的运动分析应以结构分析为基础,并且充分发挥电子计算机的计算能力和图形处理能力。     

三肢体机器人运动分析及规划

针对一种腿臂机构功能融合设计的三肢体机器人,将其肢体操作模式作为移动模式下的特殊状态进行分析,将机器人整体的运动学分析分解为各肢体分别作为站立腿和摆动腿的运动学组合问题,实现了机器人2种工作模式运动学模型的统一,并分别进行了规划. 通过机器人步态运动仿真验证了理论分析的正确性,为机器人控制器的设计提供了理论基础.     

Coordination control for bilateral teleoperation with kinematics and dynamics uncertainties

The coordination control design problem for the master–slave system is addressed in this paper. In order to meet the actual work condition, we assume that the master works in a laboratory, the slave works in remote side where the environment is very complex, and the master and slave are in different sizes. Three problems are needed to be solved: system dynamics uncertainties, system kinematics uncertainties, and the asymmetric time-varying delays. The new task-space based Proporation plus damping (P+d) controller and adaptive fuzzy P+d controller are proposed for the master and the slave, respectively. By choosing proper Lyapunov functions, we have proved that the synchronization errors converge to zero asymptotically with the new controllers. The delay-dependent stability criterion is derived. With the given parameters, the proposed allowable maximal transmission delay can be computed. Finally, the simulations are performed to show the effectiveness of the proposed method.