Design and motion analysis of vibration-driven small robot Rizeh

Vibration mechanism is good candidates to be used as actuation system in small robots. However, mini fabrication of small electrical and mechanical drives is a challenging issue. Moreover, no analytical model for motion analysis of vibration driven robots is devised. In this paper, a small robot is developed. To setup a low-cost robot, cell phone vibrators are employed as actuation mechanism. Motion principle of the robot is analytically obtained and appropriate mechanical and electronic derives are designed. Some technical tips are employed to reduce the size of the robot. The obtained model was evaluated by simulations in MSC.ADAMS as well as some standard experiments on a real robot named Rizeh. Moreover, the robot is tested in a line following task, as a typical task for mobile robots.     

Reaching for redundant arms with human-like motion and compliance properties

This work proposes a redundant arm torque controller for reaching, guaranteeing desired completion time and accuracy requirements without the need for trajectory planning and prior knowledge of robot dynamics. The proposed controller is designed based on the prescribed performance control methodology and it is a reaching regulator in which the target pose for the hand acts as an attractor for the arm. It provides configuration consistency in return motions and hand and joint velocity smoothness. Its use in an admittance control scheme given measurements or estimates of external forces is also proposed providing active compliance capabilities in robot–environment interactions. Simulation studies for a 5dof human arm-like robot and experiments with a 7dof arm are performed to verify the approach and demonstrate the proposed controller’s performance.     

分子蒸馏技术与日用化工(Ⅰ)——分子蒸馏技术的原理及特点

介绍了分子蒸馏技术发展简况，并从分子运动平均自由程的定义出发，介绍了分子蒸馏技术的基本原理、特点以及与常规蒸馏、超临界萃取与层析分离等方法的不同。分子蒸馏操作温度低、受热时间短及分离效率高，特别适用于热敏性物质的提纯，有广阔的应用前景。     

遥感器像移与图像参数的分析建模研究

卫星平台运动会产生恶化像质的像移,像移是影响遥感图像质量的重要因素.针对这种情况,建立了像移和图像参数的关系模型,可通过卫星生成图像的内在特征定量研究卫星成像过程中产生的像移,而不必通过产生像移的卫星平台等因素建立物理模型来研究像移.首先模拟了遥感器在轨成像过程,通过人工制造出影响因素的干扰获得了仿真图像数据,然后定量分析了像移与图像参数之间的相关性,选出了相关性较强且适合建模的图像参数,最后通过对这些图像参数构成的向量的降维得到了反映图像质量的综合参数,并建立了综合参数与像移的关系模型,以通过图像综合参数来计算像移.实验结果表明,这种模型能够很好地反映图像综合指标与像移之间的关系.该研究通过图像参数定量研究像移,为在轨运行卫星的遥感器像移与外景条件下的遥感图像要素的相关建模研究提供了部分技术支持.     

WATER MIST FLOW IN A SUPERCONDUCTING MAGNET INCLINED AT VARIOUS ANGLES

Water mist (diamagnetic) flow in a superconducting magnet of 10 T at various angles is studied experimentally and numerically. Water mist is produced by ultrasonic atomizers and fed into a cylindrical Plexiglas pipe (inner diameter, 90 mm) placed in a bore space of an inclined superconducting magnet. The water mist is found to stop at some locations in the magnet at inclined angles ψ ≤ π/6. At ψ ≥ π/4, the amount of mist flowing out of the other opening of the pipe increases with an increase in inclined angle. In the computation of this phenomenon, water mist is simulated with 1000 water droplets of 3 μm diameter. Brownian motion is considered and the Langevin equation is solved. The numerical results show that at ψ ≤ π/6, most of the water droplets accumulate above the magnetic coil. However, at ψ ≥ π/4, with an increase in inclined angle, the number of water droplets passing through the magnetic coil increases.     

基于自由运动一维标定物的多摄像机参数标定方法与实验

一维标定方法易于实现且标定效率高,为了克服现有一维标定方法的一些不足,本文提出一种用一维标定物标定多摄像机内外参数的方法,首先进行两两标定,在此过程中,假定主点坐标近似已知而仅考虑畸变、焦距、旋转和平移等参数,接着利用基本矩阵及一维标定物上特征点之间的几何约束,估计两摄像机的内外参数,两两标定完成后,采用Dijkstra最短路径法和捆绑调整对多摄像机系统进行全局标定(含主点坐标),仿真和真实实验表明本文的方法是切实有效的.     

六自由度机械臂约束预测控制系统的设计

本文提出了一种基于约束预测控制的机械臂实时运动控制方法.该控制方法分为两层,分别设计了约束预测控制器和跟踪控制器.其中,约束预测控制器在考虑系统物理约束的条件下,在线为跟踪控制器生成参考轨迹;跟踪控制器采用最优反馈控制律,使机械臂沿参考轨迹运动.为了简化控制器的设计和在线求解,本文采用输入输出线性化的方式简化机械臂动力学模型.同时,为了克服扰动,在约束预测控制器中引入前馈策略,提出了带前馈一反馈控制结构的预测控制设计.因此,本文设计的控制器可以使机械臂在满足物理约束的条件下快速稳定地跟踪到目标位置.通过在PUMA560机理模型上进行仿真实验,验证了预测控制算法的可行性和有效性.     

基于Hamiltonian马氏链蒙特卡罗方法的突变运动跟踪

在计算机视觉领域,由镜头切换、目标动力学突变、低帧率视频等引起的突变运动存在极大的不确定性,使得突变运动跟踪成为该领域的挑战性课题.以贝叶斯滤波框架为基础,提出一种基于有序超松弛Hamiltonian马氏链蒙特卡罗方法的突变运动跟踪算法.该算法将Hamiltonian动力学融入MCMC（Markov chain Monte Carlo）算法,目标状态被扩张为原始目标状态变量与一个动量项的组合.在提议阶段,为抑制由Gibbs采样带来的随机游动行为,提出采用有序超松弛迭代方法来抽取目标动量项.同时,提出自适应步长的Hamiltonian动力学实现方法,在跟踪过程中自适应地调整步长,以减少模拟误差.提出的跟踪算法可以避免传统的基于随机游动的MCMC跟踪算法所存在的局部最优问题,提高了跟踪的准确性而不需要额外的计算时间.实验结果表明,该算法在处理多种类型的突变运动时表现出出色的处理能力.     

Estimation of Concentration of Particles in Polymerizing Fluid during Centrifugal Casting of Functionally Graded Polymer Composites

The concentration of uniformly distributed particles in a fluid changes with time in the direction of gravitational or centrifugal force to form a concentration gradient. The change in the concentration is an outcome of velocity variation of particles in a fluid. A modified equation for terminal velocity, v _m of particles in polymerizing-fluid under centrifugal force is proposed to estimate the changes in the volume fraction of particles in the graded composites. The proposed equation introduces the effect of cure kinetics of polymer and its effect on particle movement in the model that was based on the modified Stoke’s law, considering the parameters related to particle hindrance, centrifugal force, particle dimensions, viscosity variation etc. The model predictions of concentration changes at the different locations of samples were compared with calcium carbonate filled polysulphide-modified-epoxy graded composites prepared by centrifugal casting.. The effect of particle size, delayed curing rate of matrix were explored. The simulated results are in good agreement with those of experiments.     

基于一致性的小型四旋翼机群自主编队分布式运动规划

设计一种小型四旋翼无人机群起飞后自主形成正多边形编队的分布式运动规划方法.在四旋翼无人机的串级控制系统框架下,分布式编队控制器以简化agent模型为基础,同时采用平均一致性算法和有领导一致性算法,共同产生各无人机位置与偏航角的期望轨迹.讨论了达成最终协调目标队形的拓扑条件,并给出一种基于有向Hamilton环的通信拓扑设计方案.最后通过数值仿真验证了所提出算法的有效性.