Evaluation of Dynamic Capabilities of Machines and Robots

The paper deals with the formulation and thesolution of the global dynamic problem for multibody systemsgenerally described by redundant coordinates (DAE equations) andwith a redundant number of actuators.Within the dynamics of multibody systems two basic well-known problems have been investigated: the solution of direct dynamicsand the solution of inverse dynamics. Both of these problems enableus to solve in each time instant the relation between the motiondescribed by positions, velocities, accelerations and the actingforces. However, such solutions obtained in isolated timeinstants do not provide us with the global overview about thedynamic capabilities of a mechanical system, i.e. about theaccessible motion described by accessible positions, accessiblevelocities, accessible accelerations and the required (given)forces. Thus, besides the two basic dynamical problems there isa third one: the global dynamic problem.The formulation of the global dynamic problem, the generalmethods for its solution and the specific methods for itssolution for robots and manipulators are included.     

翻滚目标逼近的虚拟域逆动力学轨迹规划

针对追踪星自主逼近和跟踪翻滚目标特定部位的最优规划问题,提出了一种基于虚拟域逆动力学的多约束最优逼近轨迹规划方法.首先,在翻滚目标本体系下建立追踪星相对于翻滚目标特定部位的相对轨道动力学方程,并建立追踪星本体系相对于翻滚目标期望固连坐标系的相对姿态动力学方程;其次,考虑目标星外形、敏感器视场和执行机构控制能力等约束条件,建立时间/能量最优规划模型;然后,采用序列二次规划(sequential quadratic programming,SQP)方法求解时间/能量最优规划问题;最后,数值仿真验证了该方法在满足多约束条件下,可实现对翻滚目标自主逼近与跟踪的最优轨迹规划,同时与高斯伪谱法进行了对比,验证了本方法在计算效率方面的优势.     

Multiple-criterion shortest path algorithms for global path planning of unmanned combat vehicles

We consider a multiple-criterion shortest path problem with resource constraints, in which one needs to find paths between two points in a terrain for the movement of an unmanned combat vehicle (UCV). In the path planning problem considered here, cumulative traverse time of the UCV, risk level, and (communication) jamming level associated with the paths are limited to be less than or equal to given limits. We propose a modified label-correcting algorithm with a new label-selection strategy to find Pareto-optimal solutions for the multiple objectives of minimizing the traverse time, risk level, and jamming level related to the paths. In addition, we develop a path planning algorithm based on the label-correcting method to solve problems with a single objective within a reasonably short time. For evaluation of the performance of the proposed algorithms, computational experiments are performed on a number of instances, and results show that the proposed algorithms perform better than existing methods in terms of a computation time.     

UML与B结合的软件开发研究与应用

B方法主要是用抽象机来描述软件系统的规范说明,且有大量工具支持。UML已广泛用于面向对象技术的建模,许多工程项目和研究成果用UML图例给出。文中将B方法与UML结合用于软件的开发过程,结合工程实际和文献资料分析了从UML的类图、时序图和状态图转换到B的抽象机的技术要点,通过实例展示了具体的转换形式。     

阻尼运动的动力学逆问题和变分法逆问题

以阻尼运动为例,研究动力学逆问题和变分法逆问题的特征,以及两者之间的关联.首先,从该运动的运动规律导出几种对应的运动微分方程,即得到几种不同的作用于质点上的力,并讨论了这几种情况之间的联系和区别;其次,从其中两种运动微分方程出发,直接构造出相应的Lagrange函数和函数族;最后,指出了两种逆问题相组合产生的新结果.     

Simulation-based evolutionary algorithm approach for deriving the operational planning of global supply chains from the systematic risk management

One of the most critical issues facing supply chain managers in today’s globalized and highly-uncertain business environment is how to proactively deal with risks that might cause serious severances and distortions of material flows in a supply chain. This paper proposes a simulation-based evolutionary algorithm approach for deriving the operational planning of global supply chains from the systematic risk management, which proactively deals with the negative consequences of random and hazardous risk events in sourcing, production, distribution, and transportation in an integrated way. The proposed approach incorporates the production lot size of the plant, order quantity and reorder point of DC, and five response coefficients as decision variables to potential risks. The proposed approach is successfully applied to an industrial example of a consumer electronics manufacturing company. The results of the computational study show that the systematic risk management of global supply chains using the proposed approach increases the profit by 20% and 16.1% in the industrial example in comparison with passive and active risk management, respectively. In addition, a mixed strategy for the inventory management of distribution centers is suggested to improve the profits of global supply chains subject to substantial risks.     

Analytical approach for the evaluation of the torques using inverse multibody dynamics

A mathematical model for the analysis of human motion is presented in this paper. This model is based on linkage dynamics in order to understand trajectory and internal moment of force coordination. Mobility at the base of the supporting limb is a critical factor in the freedom to fall forward. The approach used to state a coupled system of differential equations of motion consists in introducing the displacement of the center of mass together with the displacement of each segment of the body and to evaluate the final system as a whole. The resultant methodology is task independent. The main goal of this study is to assist the work of health care professionals in the determination of the torques at the joints generated to maintain the movement. The evaluation of a weighted average of all the forces has served as a basis for other authors to obtain the center of pressure. In this work, the resultant ground reaction force passes through the center of mass of the body system enabling the calculation of the location of this force.     

Algorithmic Foundations of Creation of an Intelligent Software Tool for Investigation and Solution of Cauchy Problems for Systems of Ordinary Differential Equations

Methods are proposed for computer investigation of properties of systems of ordinary differential equations. Based on these methods, algorithms are created for computation of the value of the integration step that provides the stability of a numerical method and obtaining its results with a preassigned accuracy. The components and modes of operation of an intelligent software tool supporting the proposed methods are presented.     

A contribution to the modelling and control of manipulators

The paper discusses manipulator modelling and control through a nonstandard parametrization of rotation motions. The advantage of the method is the computational facilities arising at the kinematical level, not from efficient presentation, but from fundamental topological considerations of the configurational manifold provided with a Lie group structure.