交替方向的扩散方程精细积分并行算法

给出了交替方向的二维扩散方程的精细积分算法，将一个时间步积分分为两个方向，使大规模矩阵的计算转化为一些小矩阵的计算，减小了每一步求解的计算量．对于方形区域的齐次方程，计算结果与全城精细积分完全相同，而计算量和存储量都要小得多．算例表明了算法具有较高的并行计算加速比和计算效率．     

模糊逻辑在机器人逆运动学求解中的应用

冗余机器人逆运动学求解的方法很多，多数都不能很好的满足实时控制的要求，本文运用模糊逻辑的思想，构造了一种逆运动学求解方法，其计算量较其它方法大大减小，且满足实时控制的要求，仿真结果也证明了该方法的可行性。     

模糊逻辑在机器人逆动动学求解中的应用

冗余机器人逆运动学求解的方法很多，多数都不能很好的满足实时控制的要求，本文运用模糊逻辑的思想，构造了一种逆运动学求解方法，其计算量较其它方法大大减小，且满足实时控制的要求，仿真结果也证明了该方法的可行性。     

用随机规划方法寻求线性回归模型小样本L_1－估计量的分布

为了使Ｌ１－估计能在ｉ导手械玫接τ这里我们给出求线性回归模型小样本Ｌ１－估计量的概率分布的方法．根据Ｌ１－估计量的特殊结构和使用随机规划的方法可以省去不少计算量，从而使这一方法更加有效．     

基于旋量理论的开链机器人动力学Kane方程研究

首先介绍了旋量的基本理论、指数积及雅可比矩阵．在此基础上定义了基于旋量理论的主动力旋量、惯性力旋量、偏速度旋量、广义主动力及广义惯性力等概念,之后推导出了基于旋量理论的开链机器人动力学Kane方程,再者阐明了偏速度旋量几何计算,最后以示例验证结论的正确性．     

保险费中安全加成量的一种计算方法

杜瑞芝，齐治平．保险费中安全加成量的一种计算方法．数理统计与管理，１９９８，１７（２），３０～３２．由于未来经济状况的不确定性，保险人所收取的保险费很可能不足以补偿实际发生成本。为了避免和减少风险，本文给出一种计算安全加成量的方法     

简化解析几何计算的若干途径

在解析几何中，面对同样一个问题往往可有多种解题方法，但是各种解法的计算量常常有很大的差异．因此，恰当地选择解题途径，尽可能简化解题计算过程就显得尤为重要．一般地．欲简化解析几何问题解题的计算过程．我们可以从以下几条途径予以考虑：一是选择合适的坐标系及点的坐标；二是充分注意对称性，尽量使问题简化；三是适当利用几何知识。     

可逆整数阵的一种标准形及其应用

消元法是线性代数最基本的计算方法，特别在解方程、矩阵求逆、求秩、向量组相关分析中都是不可或缺的，教材中的例题和习题都是整数，消元法解题时多出现分数，使计算量增大而得不出结果，给教和学都带来困难。针对这个问题，给出可逆整数阵的一种标准形，并用之给出整数阵求逆和伴随阵的方法，可避免分数运算，使消元法的运用变得简单可行．     

巧构妙用简化解几运算

在解决圆锥曲线的问题中，大部分学生觉得“计算量太大，太复杂，没信心继续算下去”．其实，学好圆锥曲线的关键是过好两个关：方法关与运算关．而计算量大往往与选择的方法有很大关系．笔者就如何构建函数、方程等手段，巧妙利用好韦达定理，把繁复的计算变得简洁流畅，进行探究．、1构造函数，运用韦达定理     

“物理意义”下积分问题的解决

数学是物理的基础与工具，物理为数学提供背景和应用。借助物理意义去构建和理解数学知识十分必要．特别地，我们在积分问题中讨论物理意义的应用，比如在“质量”意义下进一步把握三重积分的定限，在“质量”与“质心”意义下处理重积分、线面积分的计算问题；还可以进一步挖掘或转移数学知识本身的物理意义。以利于问题的进一步解决．     

Using PSO for a walk of a biped robot

This paper is a presentation of a work that consists to model a biped robot walk in simulation. The specific objective is to develop a strategy based on an evolutionary method. The chosen architecture to represent the biped includes ten degrees of freedom on ten articulations between seven links. This evolutionary method is a generation of articulation angles using a particle swarm optimization (PSO). This work invokes also the direct kinematic principle. The PSO guarantees the stability of the biped by using a constraint on the center of mass (CoM) and the polygon of support. Results show that this method is tempting for a high level development.     

空间机器人组装超大型结构的动力学分析北大核心CSCD

超大型航天结构具有超大柔性、超低固有频率的特点,空间机器人在轨组装时应尽可能避免激起超大型结构的柔性振动.空间机器人组装超大型结构模块的过程分成抓捕阶段、位姿调整与稳定阶段、安装阶段和爬行阶段.通过对安装阶段的动力学与控制研究,提出共线安装的轨迹规划方法,有效避免了柔性结构振动.首先,采用自然坐标法和绝对节点坐标法建立主结构-空间机器人-待组装结构的在轨组装系统动力学模型.然后,将共线安装的要求转化为空间机器人的轨迹规划约束,要求空间机器人质心到主结构/待组装结构的距离保持不变,实现共线安装的轨迹规划.数值仿真表明:提出的组装方法在组装过程中可有效避免超大型结构的横向运动,降低夹持力矩.最后,分析了系统参数对组装过程动力学响应的影响,为超大型航天器的在轨组装提供了参考.     

一种基于Dijkstra算法的机器人避障问题路径规划

移动机器人的避障问题是移动机器人控制领域的研究热点.针对给定的移动机器人避障问题,探讨了最短路径及最短时间路径的路径规划问题.对于最短路径问题,建立了简化的路径网格模型,将其抽象为由节点及边构成的两维图,再使用经典的Dijkstra算法获得可行的最短路径.对于最短时间路径问题,通过分析移动机器人弯道运行的速度曲线,基于几何方法得出了移动时间与过渡圆弧圆心之间严格的数学关系,此后借助MATLAB优化函数获得最佳的移动路径.算法可为类似机器人避障问题的解决提供借鉴.     

Minimal distance calculation between the industrial robot and its workspace based on circle/polygon-slices representation

The real-time and reliable collision detection is the vital basis for the robotic motion control in real applications. In this work, the minimal distance calculation between the industrial robot and its workspace is presented. This method first uses circular/polygonal slices to represent robotic sub-structures with curved edges more accurately, and uses polygonal planes to construct its workspace. Being the basis of the distance calculation, the shortest distance between the spatial circle/polygon and the polygonal plane, as well as that between the circular/polygonal plane and the polygonal plane are first modelled through spatial relation analysis. The simulation validation indicates that the proposed algorithm is more efficient and reliable than both the point-clouds-based and bounding-volume-hierarchies-based algorithms. And the influence of the refinement size on the performance of the proposed model is revealed. Finally, the application example shows that this work is a significant contribution for the collision-free motion control of the industrial robot. The proposed algorithm can also be applied to the distance calculation of other complex objects because of the generality of the proposed slices representation way.     

Dynamic Modeling and Force Control of a Redundant Robot for Polishing Applications

For many robotic applications with tasks such as cutting, assembly or polishing, it is necessary to get in contact with the surrounding. In this paper a redundant robot with seven degrees of freedom in a metal polishing task is considered. For simulation as well as for the controller design a dynamic model of the robot and a contact model are required. The equations of motion of the robot are calculated with the Projection Equation in subsystem representation and the contact model contains linear tool elasticities and work piece elasticities. In the case of a polishing task, a constant contact force during the process is required even if the robot moves along a trajectory. Thus some degrees of freedom of the robot tool center point have to be position controlled while the other ones have to be force controlled. The redundant robot offers the possibility to avoid singular positions or to maximize the available end-effector forces within the inverse kinematics and is therefore best suited for polishing large objects. The actual process forces are measured with a six axis force-torque-sensor mounted at the tool center point. These forces are used in a parallel force/position control law to achieve the desired behavior. Results from measurements of a test arrangement are presented. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Computation of program controls performed nonstop by gyrodynes

A new method for calculating space vehicle (SV) attitude controls ensuring their effective implementation by a system of collinear pairs of single-gimbal forced unrestrained gyros (gyrodynes) has been proposed. The novelty of the method consists in a virtual kinematic configuration of the gyro system, i.e., the precession of gyro units in the collinear pairs of gyrodynes is coupled in a nonmechanical manner. In addition, the angular momentum of the system as a state variable for describing the dynamics of the SV permanent rotation was used for the first time at the stage of computing controls performed nonstop by gyrodynes. In the general formulation, when the desired final state of the SV is arbitrary, the SV attitude control problem can be reduced to a sequence of permanent rotations. The performance of the method is demonstrated as applied to the calculation of program gyrodyne controls with a permanent reduction in the SV angular velocity around its center of mass with a nonzero SV angular momentum after its discharge.

     

Heuristic fuzzy-neuro network and its application to reactive navigation of a mobile robot

A novel pattern recognition approach to reactive navigation of a mobile robot is presented in this paper. A heuristic fuzzy-neuro network is developed for pattern-mapping between quantized ultrasonic sensory data and velocity commands to the robot. The design goal was to enable an autonomous mobile robot to navigate safely and efficiently to a target position in a previously unknown environment. Useful heuristic rules were combined with the fuzzy Kohonen clustering network (FKCN) to build the desired mapping between perception and motion. This method provides much faster response to unexpected events and is less sensitive to sensor misreading than conventional approaches. It allows continuous, fast motion of the mobile robot without any need to stop for obstacles. The effectiveness of the proposed method is demonstrated in a series of practical tests on our experimental mobile robot.     

Computed torque control of an under-actuated service robot platform modeled by natural coordinates

The paper investigates the motion planning of a suspended service robot platform equipped with ducted fan actuators. The platform consists of an RRT robot and a cable suspended swinging actuator that form a subsequent parallel kinematic chain and it is equipped with ducted fan actuators. In spite of the complementary ducted fan actuators, the system is under-actuated. The method of computed torques is applied to control the motion of the robot.The under-actuated systems have less control inputs than degrees of freedom. We assume that the investigated under-actuated system has desired outputs of the same number as inputs. In spite of the fact that the inverse dynamical calculation leads to the solution of a system of differential–algebraic equations (DAE), the desired control inputs can be determined uniquely by the method of computed torques.We use natural (Cartesian) coordinates to describe the configuration of the robot, while a set of algebraic equations represents the geometric constraints. In this modeling approach the mathematical model of the dynamical system itself is also a DAE.The paper discusses the inverse dynamics problem of the complex hybrid robotic system. The results include the desired actuator forces as well as the nominal coordinates corresponding to the desired motion of the carried payload. The method of computed torque control with a PD controller is applied to under-actuated systems described by natural coordinates, while the inverse dynamics is solved via the backward Euler discretization of the DAE system for which a general formalism is proposed. The results are compared with the closed form results obtained by simplified models of the system. Numerical simulation and experiments demonstrate the applicability of the presented concepts.     

Numerical analysis of a rigid rotor supported by aerodynamic four-lobe journal bearing system with mass unbalance

This paper presents the effect of rotor mass on the nonlinear dynamic behavior of a rigid rotor-bearing system excited by mass unbalance. Aerodynamic four-lobe journal bearing is used to support a rigid rotor. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directions under different operating conditions, the dynamic trajectory, the power spectra, the Poincare maps and the bifurcation diagrams are used. From this study, results show how the complex dynamic behavior of this type of system comprising periodic, KT-periodic and quasi-periodic responses of the rotor center varies with changes in rotor mass values by considering two bearing aspect ratios. Results of this study contribute a better understanding of the nonlinear dynamics of an aerodynamic four-lobe journal bearing system.     

Mathematical modelling and dynamic response of a multi-straight-line path tracing flexible robot manipulator with rotating-prismatic joint

In this study, mathematical modelling and dynamic response of a flexible robot manipulator with rotating-prismatic joint are investigated. The tip end of the flexible robot manipulator traces a multi-straight-line path under the action of an external driving torque and an axial force. Considered robot manipulator consists of a rotating prismatic joint and a sliding flexible arm with a tip mass. Flexible arm is assumed to be an Euler–Bernoulli beam carrying an end-mass. Equations of motion of the flexible manipulator are obtained by using Lagrange’s equation of motion. Effect of rotary inertia, axial shortening and gravitation is considered in the analysis. Equations of motion are solved by using fourth order Runge–Kutta method. Numerical simulations obtained by using a developed computer program are presented and physical trend of the results are discussed.