Multirobot coordination in pick-and-place tasks on a moving conveyor

This paper considers the problem of multirobot coordination in pick-and-place tasks on a conveyor band. The robot team is composed of identical robots with mutually exclusive, but neighboring workspaces. The products are fed in at one end of the band, move through each workspace sequentially until being picked up and are collected at the other end—if not picked up interim. Each robot has the same task—that is picking up and packaging as many products as possible. We propose an approach based on noncooperative game theory where each robot uses local observations of the conveyor band and their neighbors' actions in order to decide on its actions. The developed algorithm has been implemented and tested in a simulated manufacturing environment using Webots. Results obtained from the simulations are analyzed using a variety of statistical performance measures.     

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Abstract

Industrial robots often operate at high speed, with unpredictable motion patterns and erratic idle times. Serious injuries and deaths have occurred due to operator misperception of these robot design and performance characteristics. The main objective of the research project was to study human perceptual aspects of hazardous robotics workstations. Two laboratory experiments were designed to investigate workers' perceptions of two industrial robots with different physical configurations and performance capabilities. Twenty-four subjects participated in the study. All subjects were chosen from local industries, and had had considerable exposure to robots and other automated equipment in their working experience. Experiment 1 investigated the maximum speed of robot arm motions that workers, who were experienced with operation of industrial robots, judged to be ‘safe’ for monitoring tasks. It was found that the selection of safe speed depends on the size of the robot and the speed with which the robot begins its operation. Speeds of less than 51 cm/s and 63cm/s for large and small robots, respectively, were perceived as safe, i.e., ones that did not result in workers feeling uneasy or endangered when working in close proximity to the robot and monitoring its actions. Experiment 2 investigated the minimum value of robot idle time (inactivity) perceived by industrial workers as system malfunction, and an indication of the ‘safe-to-approach’ condition. It was found that idle times of 41 s and 28 s or less for the small and large robots, respectively, were perceived by workers to be a result of system malfunction. About 20% of the workers waited only 10 s or less before deciding that the robot had stopped because of system malfunction. The idle times were affected by the subjects' prior exposure to a simulated robot accident. Further interpretations of the results and suggestions for operational limitations of robot systems are discussed.     

实施流域水功能区限制纳污制度细部工作

文章就当前如何深入落实和有效实施流域水功能区限制纳污制度,在流域执行层面怎样做好谋划整体、做实载体和求真具体3个重要环节的细部工作,进行了深度分析思考,切合实际地提出了有针对性的思路对策和具体做法,有助于实践中的借鉴和运用。     

Operator strategies in a dynamic environment in relation to an operator model

Results of an analysis of the cognitive activity of operators in controlling incidents in a Steam Generating Heavy Water Reactor in relation to a computer-based model of an operator (COSIMO, Cacciabue et al. 1992) are presented. The analysis focuses on information checking and actions to be taken in five incidents of varying levels of specification. Two experienced and two less-experienced operators participated in the experiments. Techniques of video and protocol analysis have been employed. Results indicate that operators use strategies in order to overcome the dynamic feature of incidents; in particular they break down problems into elementary problems, and they aim at maintaining a stable situation. A central characteristic is the importance of actions in terms of their timing and their results. Actions are carried out incrementally, and their effects then used as pointers to guide the course of future problem-solving and future actions. Problems may be postponed when they are not urgent, or when system latency does not allow an effect to be obtained following an action. Finally the paper discusses some elements that should be modified in order to increase the predictive capability of the COSIMO model.     

The influence of low frequency vibration on pilot performance (as measured in a fixed base simulator)

This report describes a study on the effects of low frequency vibration on pilot performance. Army pilots acted as subjects and flew simulated helicopter missions in a realistic fixed base simulator environment. While flying the two-hour missions pilots were exposed to vibration stimuli varying in frequency from 6 to 12 Hz and in amplitude from ±0·1 to ±0·3g (measured at the floor). Measurements were taken of the vibration tramsmissibility of the pilot's seat so that the vibration actually felt by the subject could be determined.

Missions involved transporting external loads in a simulated logistics environment. Performance was evaluated by measuring flight path deviations from prescribed en route, approach, and hover parameters.

The vibration stimuli used did not degrade performance. In fact, performance tended to improve with increased stress. It is hypothesized that this trend was due to motivation, i.e. as subjects felt the onset of fatigue they compensated by working harder and thus tended to improve their performance.

On about 6% of their scores pilots exhibited sudden lapses in their ability to respond to display indications. This resulted in poor scores in the midst of otherwise normal data. These lapses are probably of very short duration (seconds in length) and seem to occur randomly. This same effect was also observed in a previous study by the author. It may be possible that lapses of this type are related to so called ‘pilot error’ accidents. Further research is needed to verify this.     

漓江风景名胜区沿岸乡镇污水处理与排放方案

在综合考虑漓江风景名胜区沿岸乡镇污水特性、污水排放要求、受纳水体景观影响和经济技术因素的基础上,从污水收集方式、处理规模、处理工艺、出水标准等方面,构建景区沿岸乡镇污水处理方案,并提出乡镇小片区和大片区污水处理方案的主要工艺流程及技术指标。研究表明：乡镇小片区污水处理宜采用高效地埋无动力生物反应器处理系统,乡镇大片区污水处理宜采用一体化A/O生物反应器处理系统,并根据乡镇环境特征和景观要求设计景观塘排放和污水扩散器排放等排放方式。     

地图投影的拓扑学原理

根据拓扑映射的定义,指出了“刺孔球面”（S2-｛z｝）与二维平面R2的同胚性质。从有限闭区间及其彼此等势的拓扑学原理,推出f（A）为非空集。f（A）的边界是二维平面上的约当闭曲线,约当闭曲线的任意性,使得f（A）可以在拓扑变换下变形为任意的形状,构造多种多样的投影网格。以若干实例说明了拓扑映射ff1、f2的实现方法。     

控制性详细规划创新研究

本文在创新的控制性详细规划编制中,引入＂区域分析法＂进行深入分析,从指导思想和规划理念上保证规划编制准确的方向.创新的控制性详细规划控制体系,实行通则、控制单元图则和地块详细控制图则三位一体控制模式：通过科学细致的分析研究,制定当地的规划通则,并作为控制单元图则与地块详细控制图则编制的主要依据;运用＂分区平衡方法＂对控制单元进行总量控制,运用＂二元控制方法＂控制城市规划布局建设;划定＂六线＂、标明禁止开口路段与主要出入口、确定各项控制指标,并对用地性质兼容与土地开发强度进行弹性控制.     

流域初始水权分配方法与模型

针对初始水权的分配问题,分析了目前两种主要分配机制———计划与市场的原理和模型及其不足,将拍卖方式引入初始水权配置,建立初始水权的拍卖模型;以玛纳斯河流域为例,分析了流域初始水权配置的现状及存在的问题,最后给出流域初始水权配置新的思路,为干旱内陆河流域初始水权配置提供理论基础.     

平顶山市河滨公园总体规划说明

依据平顶山市河滨公园现状,将公园划分为文化娱乐区、体育活动区、儿童活动区、动物展览区、游览休息区五个区,并以园内地理状况将公园规划为孤山景区、平湖区、花苑景区、柏林景区、游乐景区五个景区。