Optimal robot positioning using task-dependent and direction-selective performance indexes: General definitions and application to a parallel robot

Performance evaluation is an important issue for optimal robot positioning within workcells. Performance indexes can provide essential contributions to such an evaluation, in particular if they can account for the specific task with respect to which the optimization is carried out.     

Analysis of the indoor GPS system as feedback for the robotic alignment of fuselages using laser radar measurements as comparison

The alignment of aircraft fuselages in the aerospace sector is currently done either manually or by complex, expensive automated systems. The manual process introduces a significant production delay and the automated systems are purpose-built and have limited flexibility, apart from its financial drawback. This work proposes a low-cost, high-flexibility system and, as part of it, evaluates the performance of a Rotary-Laser Automatic Theodolite (R-LAT) as a feedback source for the adaptive robot control of an anthropomorphic manipulator. In the proposed solution the robot carries a fuselage barrel and aligns it with respect to a second barrel. A high accuracy, frequency-modulated laser equipment is used to generate the reference system for the procedure. The measurements of the R-LAT are then verified with the frequency-modulated laser equipment in order to determine the linear and angular alignment tolerances achieved by the robot/R-LAT closed loop in a predefined work envelope. A throughout, step-by-step analysis of the measuring procedure is carried out to allow the recognition of error sources and thus the determination of an optimized method. These results identify the operation boundaries of the R-LAT within the process and yield its best configuration for the intended purpose. Using the EN ISO 9283 robot evaluation standard, the closed loop system was found to attain the nominal position with an average accuracy of 0.38 mm and 0.01°, contrasting with an average accuracy of 4.53 mm and 0.21° when the robot was operating in an open loop configuration.     

The Bulk Production Of Colour Prints

Some indication of the use of Phenidone in PQ developer systems in large scale motion picture laboratory practice is given. Various characteristics, which were examined on a plant scale before MQ systems were abandoned in favour of PQ systems, are discussed; the stabilities and economics of the two systems are compared.     

A robust adaptive fuzzy variable structure tracking control for the wheeled mobile robot: Simulation and experimental results

In this paper an adaptive fuzzy variable structure control (kinematic control) integrated with a proportional plus derivative control (dynamic control) is proposed as a robust solution to the trajectory tracking control problem for a differential wheeled mobile robot. The variable structure controller, based on the sliding mode theory, is a well known, proven control method, fit to deal with uncertainties and disturbances (e.g., structural and parameter uncertainties, external disturbances and operating limitations). To minimize the problems found in practical implementations of the classical variable structure controllers, an adaptive fuzzy logic controller replaces the discontinuous portion of the control signals (avoiding the chattering), causing the loss of invariance, but still ensuring the robustness to uncertainties and disturbances without having any a priori knowledge of their boundaries. Moreover, the adaptive fuzzy logic controller is a feasible tool to approximate any real continuous nonlinear system to arbitrary accuracy, and has a simple structure by using triangular membership functions, a low number of rules that must be evaluated, resulting in a lower computational load for execution, making it feasible for real time implementation. Stability analysis and the convergence of tracking errors as well as the adaptation laws are guaranteed with basis on the Lyapunov theory. Simulation and experimental results are explored to show the verification and validation of the proposed control strategy.     

Evaluation of the Missouri River shallow water habitat using a 2D‐hydrodynamic model

Many of the Upper Missouri River dikes have been notched to create additional shallow water habitat (SWH, operationally defined as areas in the stream with depth < 1.5 m, and velocity < 0.75 m s^?1) for fish populations. The goal of this study was to quantify the additional SWH gained from notching these dikes and to evaluate their performance under different flow conditions. A coupled field and numerical study was performed on a reach of the Missouri River, near Nebraska City, NE, which contains a number of dikes notched in 2004. The numerical simulations showed that the SWH criterion for depth was more difficult to satisfy in the study reach than the SWH criterion for velocity. Notching the dikes resulted in a slight shift of the bankline due to local erosion in the vicinity of the dikes and the formation of scour holes downstream of the notches. Results from the study suggested that notching the dikes had limited impact on the SWH because the area gained from the bankline shift was offset by the area lost from the scour holes formation. The performance of the notched dikes in sustaining the minimum habitat suitability conditions for the Missouri River ecosystem was also investigated. These conditions corresponded to discharges < 709 m³ s^?1 for the period from mid‐July to mid‐August, or equivalently SWH areas > 5225 m² dike^?1 during the same period. Analysis of the Missouri River annual discharge records at the study site showed that the dikes can provide the minimum required SWH for mean annual discharges < 667 m³ s^?1. For mean annual discharges > 667 m³ s^?1, new alternative structures or restoration facilities were needed, in addition to the existing dikes, to sustain the minimum required SWH. The dikes were not effective in providing any SWH for mean annual discharges > 2000 m³ s^?1. Copyright © 2010 John Wiley & Sons, Ltd.     

Telenoid android robot as an embodied perceptual social regulation medium engaging natural human–humanoid interaction

The present paper aims to validate our research on human–humanoid interaction (HHI) using the minimalist humanoid robot Telenoid. We conducted the human–robot interaction test with 142 young people who had no prior interaction experience with this robot. The main goal is the analysis of the two social dimensions (“Perception” and “Believability”) useful for increasing the natural behaviour between users and Telenoid. We administered our custom questionnaire to human subjects in association with a well defined experimental setting (“ordinary and goal-guided task”). A thorough analysis of the questionnaires has been carried out and reliability and internal consistency in correlation between the multiple items has been calculated. Our experimental results show that the perceptual behaviour and believability, as implicit social competences, could improve the meaningfulness and the natural-like sense of human–humanoid interaction in everyday life task-driven activities. Telenoid is perceived as an autonomous cooperative agent for a shared environment by human beings.     

SF_6气体密度继电器校验系统的设计

文章根据电力系统中SF6气体密度继电器现场校验工作的需要,提出了以SM89516A单片机为核心的密度校准系统。系统通过采集SF6气体的压力和温度值,然后依据气体密度状态方程,采用卡丹公式对这些数据进行处理,最终完成SF6密度继电器在标准条件下的报警、闭锁动作压力值的测量。工程实践证明,该系统可以方便、准确地对任意环境下的各种SF6密度继电器进行额定压力、闭锁压力及报警压力的校验。     

An empirical study on the quantitative notion of task difficulty

Most Adaptive and Intelligent Web-based Educational Systems (AIWBES) use tasks in order to collect evidence for inferring knowledge states and adapt the learning process appropriately. To this end, it is important to determine the difficulty of tasks posed to the student. In most situations, difficulty values are directly provided by one or more persons. In this paper we explore the relationship between task difficulty estimations made by two different types of individuals, teachers and students, and compare these values with those estimated from experimental data. We have performed three different experiments with three different real student samples. All these experiments have been done using the SIETTE web-based assessment system. We conclude that heuristic estimation is not always the best solution and claim that automatic estimation should improve the performance of AIWBES.     

VSP技术在缅甸石油勘探区块的应用

缅甸中部曼德勒市以西某石油勘探区块勘探程度低，面临许多急需解决的地质问题。A-1井是中国石化在该区块开钻的第1口探井，2008年油气测试获得了较好的油气显示。在A-1井首次采集了零偏和非零偏VSP资料，进行了初至拾取、三分量旋转、波场分离、反射波成像等处理；综合利用A-1井的测井、钻井、VSP、二维地面地震等资料，标定了该区块A-1井处地震反射波组的地质属性，确定了主断层的断点位置，建立了泊松比参数与主力含气层段、非出气层段等的特征关系。VSP技术的应用在该区块的油气勘探中发挥了积极的作用。