Time-optimal extension and retraction of robots: Numerical analysis of the switching structure

The problem of the time-optimal control of robot manipulators is of importance because of its potential for increasing the productivity of assembly lines. This work is part of a series of papers by the authors on this topic using direct and indirect methods of optimization. A cylindrical robot or a spherical polar robot constrained to the horizontal plane is considered, and optimal solutions for radial maneuvers are generated. Indirect methods are employed in order to establish the switching structure of the solutions. The results show that even such apparently simple maneuvers as extension or retraction of a robot with a prismatic joint can produce very complex optimal solutions. Time-optimal retraction can exhibit ten different switching structures with eight switching points and two singular arcs.This research was supported by the Deutsche Forschungsgemeinschaft. The results reported in this paper first appeared in the thesis of the first author and were presented at the 1989 AIAA Guidance, Navigation and Control Conference (Refs. 1 and 2).     

An application of the neural network energy function to machine sequencing

We apply a neural network approach for solving a one-machine sequencing problem to minimize either single- or multi-objectives, namely the total tardiness, total flowtime, maximimum tardiness, maximum flowtime, and number of tardy jobs. We formulate correspondingly nonlinear integer models, for each of which we derive a quadratic energy function, a neural network, and a system of differential equations. Simulation results based on solving the nonlinear differential equations demonstrate that our approach can effectively solve the sequencing problems to optimality in most cases and near optimality in a few cases. The neural network approach can also be implemented on a parallel computing network, resulting in significant runtime savings over the optimization approach. This paper should not be disseminated without written permission of the authors.     

智能科学在频率规划中的应用

文章针对目前频率规划中存在的问题，提出了利用专家系统及遗传算法解决手工频率规划和电子地图要求极高的障碍。在电子地图缺少的情况下，借助专家的经验和知识同时利用优化算法亦能给出较准确的频率规划方案。     

发展ISDN促进电信新业务的应用与普及

本文从ＩＳＤＮ的业务能力入手，讨论其在开发新业务方面的应用，并对我国电信网开放ＩＳＤＮ业务的装备条件和在我国推进ＩＳＤＮ的策略做了分析的探讨。     

An Attractor-Repeller approach to floorplanning

The floorplanning (or facility layout) problem consists in finding the optimal positions for a given set of modules of fixed area (but perhaps varying height and width) within a facility such that the distances between pairs of modules that have a positive connection cost are minimized. This is a hard combinatorial optimization problem; even the restricted version where the shapes of the modules are fixed and the optimization is taken over a fixed finite set of possible module locations is NP-hard. In this paper, we extend the concept of target distance introduced by Etawil and Vannelli and apply it to derive the AR (Attractor-Repeller) model which is designed to improve upon the NLT method of van Camp et al. This new model is designed to find a good initial point for the Stage-3 NLT solver and has the advantage that it can be solved very efficiently using a suitable optimization algorithm. Because the AR model is not a convex optimization problem, we also derive a convex version of the model and explore the generalized target distances that arise in this derivation. Computational results demonstrating the potential of our approach are presented.     

Controlled Markov Chains with Weak and Strong Interactions: Asymptotic Optimality and Applications to Manufacturing

This paper deals with the asymptotic optimality of a stochastic dynamic system driven by a singularly perturbed Markov chain with finite state space. The states of the Markov chain belong to several groups such that transitions among the states within each group occur much more frequently than transitions among the states in different groups. Aggregating the states of the Markov chain leads to a limit control problem, which is obtained by replacing the states in each group by the corresponding average distribution. The limit control problem is simpler to solve as compared with the original one. A nearly-optimal solution for the original problem is constructed by using the optimal solution to the limit problem. To demonstrate, the suggested approach of asymptotic optimal control is applied to examples of manufacturing systems of production planning.     

Uncertainty and Option Value in Land Allocation Problems

In intensity-modulated radiation therapy (IMRT) not only is the shape of the beam controlled, but combinations of open and closed multileaf collimators modulate the intensity as well. In this paper, we offer a mixed integer programming approach which allows optimization over beamlet fluence weights as well as beam and couch angles. Computational strategies, including a constraint and column generator, a specialized set-based branching scheme, a geometric heuristic procedure, and the use of disjunctive cuts, are described. Our algorithmic design thus far has been motivated by clinical cases. Numerical tests on real patient cases reveal that good treatment plans are returned within 30 minutes. The MIP plans consistently provide superior tumor coverage and conformity, as well as dose homogeneity within the tumor region while maintaining a low irradiation to important critical and normal tissues.     

基于地理信息技术的移动通信网络规划和优化

首先简要介绍了地理信息技术在移动通信网络规划和优化中的应用范畴，继而总结归纳了移动通信网络规划和优化工作中所采用的数字地图的数据类型及生产控制，最后给出了基于地理信息技术的移动通信网络规划和优化的具体应用实例。     

Free-floating closed-chain planar robots: Kinematics and path planning

The study of free-floating manipulators is important for the success of robotics program in space and in the design of innovative robot systems which can operate over a large workspace. In order to study the fundamental theoretical and experimental issues encountered in space robotics, a closed-chain planar manipulator was built at Ohio University (OU) which floats on a flat table using air bearings. Due to the absence of external forces in the plane of the table and couples normal to this plane, the linear momentum in the plane and the angular momentum normal to this plane are conserved. It is well known that the linear momentum equations are holonomic while the angular momentum equation is nonholonomic. Due to this nonholonomic behavior, the path-planning schemes commonly used for fixed-base manipulators do not directly apply to free-floating manipulators. In this paper, we present an algorithm for motion planning of planar free-floating manipulators based on the inverse position kinematics of the mechanism. It is demonstrated that the inverse position kinematics algorithms, commonly used for fixed-base manipulators, can be successfully applied to free-floating manipulators using an iterative search procedure to satisfy the nonholonomic angular momentum constraints. This procedure results in paths identical to those predicted by inverse rate kinematics. The inverse position kinematics algorithm is then used to avoid singularities during motion to result in successful paths. The results of the simulation of this algorithm using parameter estimates of the OU free-floating robot are presented.     

网络管理系统规划问题的研究

本文通过对网络管理系统概念的定义，分析了制约网络管理系统建设的因素，以指导电信运营公司对网络管理系统建设的合理规划。