Reflective workpiece detection and localization for flexible robotic cells

A smart vision system for industrial robotic cells is presented. It can recognize and localize a reflective workpiece, and allows for automatic adjustments of the robot program. The purpose of the study is to improve industrial robots awareness of the environment and to increase adaptability of the manufacturing processes where full control over environment is not achievable. This approach is particularly relevant to small batch robotic production, often suffering from only partial control of the process parameters, such as the order of jobs, workpiece position, or illumination conditions.A distinguishing aspect of the study is detection of workpieces made of diverse materials, including shiny metals. Reflective surfaces are common in the industrial manufacturing, but are rarely considered in the research on object recognition because they hinder many of the object recognition algorithms. The proposed solution has been qualified and tested on a selected benchmark in a realistic workshop environment with artificial light conditions. The training of the object recognition software is an automatic process and can be executed by non-expert industrial users to allow for recognition of different types of objects.     

An adaptive knowledge evolution strategy for finding near-optimal solutions of specific problems

Most real-world problems cannot be mathematically defined and/or structured modularly for peer researchers in the same community to facilitate their work. This is partially because there are no concrete defined methods that can help researchers clearly describe their problems and partially because one method fits one problem but does not apply to others. In order to apply someone’s research results to new domains and for researchers to collaborate with each other more efficiently, a well-defined architecture with self-adaptive evolution strategies is proposed. It can automatically find the best solutions from existing knowledge and previous research experiences. The proposed architecture is based on object-oriented programming skills that in turn become foundations of the community interaction evolution strategy and knowledge sharing mechanism. They make up an autonomous evolution mechanism using a progressive learning strategy and a common knowledge packaging definition. The architecture defines fourteen highly modular classes that allow users to enhance collaboration with others in the same or similar research community. The presented evolution strategies also integrate the merits of users’ predefined algorithms, group interaction and learning theory to approach the best solutions of specific problems. Finally, resource limitation problems are tackled to verify both the re-usability and flexibility of the proposed work. Our results show that even without using any specific tuning of the problems, optimal or near-optimal solutions are feasible.     

Cloud-based approach for automatic CNC workpiece origin localization based on image analysis

Computer vision applications in the industry have been a constant field of research in academia. Industrial daily challenges such as quality inspection, object detection, and measurement are examples of situations where some automation could be done by using computer vision techniques. In this paper, a cloud-based approach of an automatic system based on stereo vision and image analysis has been developed to automate a daily routine present in machining companies: workpiece referencing. The proposed architecture uses two cameras mounted in the spindle of a machining center. All images are processed in custom software, running on the cloud, to return the position of the Workpiece Coordinate System (WCS) directly to the Computer Numerical Control (CNC) machine controller. Experimental results validate the application of the proposed architecture in a real machining process machine.     

A hybrid procedure strategy for vehicle localization system: Design and prototyping

This work presents an estimation strategy that provides a good localization and a highly accurate measurement of the distance run by a public transportation vehicle. To this aim, the vehicle is equipped with a global positioning system (GPS) sensor, to retrieve the geographical position, a wheel speed sensor, to measure the vehicle velocity, and a gyroscope, to measure the yaw velocity.A model-based hybrid procedure has been proposed, based on the GPS signal reliability, guaranteeing robustness for temporary loss of satellite signal. In particular, the algorithm switches between a Kalman filter strategy, when the GPS is available, and an open-loop model-based estimation, when it is not available. The algorithm has been tested both in simulation and experimentally and the results are analyzed. In particular, a prototype has been realized to test the strategy on urban and extra urban circuits in Benevento (Italy). The experiments are conducted on a Lancia Kappa 2.0 vehicle, by means of a dSpace MicroAutoBox electronic control unit.     

A near-optimal Algorithm for H 8 identification of fixed order rational models

This paper presents a near-optimal algorithm for H     

A comparison of human and near-optimal task management behavior

OBJECTIVE: The primary contribution of this work is the development of an abstract framework to which a variety of multitasking scenarios can be mapped. The metaphor of a juggler spinning plates was introduced to represent an operator performing multiple concurrent tasks. BACKGROUND: This allowed seeking a quantitative model for management of multiple continuous tasks instead of a model for completing multiple discrete tasks, which was considered in previous studies. METHODS: The multitasking performance of 10 participants in five scenarios was measured in a low-fidelity simulator (named Tardast), which was developed based on the concept of the juggler metaphor. This performance was then compared with a normative model, which was a near-optimal solution to a mathematical programming problem found by tabu search heuristics. RESULTS: Tabu outperformed the participants overall, although the best individual performance nearly equaled that of tabu. It was also observed that participants initially tended to manage numerous tasks poorly but that they gradually learned to handle fewer tasks and excel in them. CONCLUSION: This suggests that they initially overreacted to the penalization associated with poor performance in the software. Participants' strategic task management (e.g., what tasks to handle) was more significant in obtaining a good score than their tactical task management (e.g., how often to switch between two tasks). APPLICATION: Potential applications include better design of equipment, procedures, and training of operators of complex systems.     

Bioreactor control using a probing feeding strategy and mid-ranging control

The paper presents a fed-batch fermentation technique for bioreactors operating close to their maximum oxygen transfer capacity. The method combines the advantages of the probing feeding strategy and the temperature limited fed-batch technique. When the maximum oxygen transfer capacity of the reactor is reached, the temperature is decreased to lower the oxygen demand. To achieve a good control of the dissolved oxygen a mid-ranging controller manipulating the stirrer speed and the temperature is used. The feeding strategy is analysed and it is also illustrated by simulations and an experiment.     

协同定位中的坐标配准策略研究

坐标配准是协同定位的重要组成部分,一个合理的坐标配准体系可以体现协同定位算法的性能,否则可能会放大定位算法的误差。本文详细比较了基于最小二乘 (least square, LS)与基于普氏分析(Procrustes analysis, PA)的配准方法的设计思想、适用条件,并给出了基于普氏分析的坐标配准算法的详细步骤。利用协同定位算法(经典MDS和Levenberg–Marquardt算法)得到的实验数据,详细分析了锚节点数量、测距误差、网络节点平均连通度对配准精度的影响。实验表明,在2D和3D环境中,基于普氏分析的配准算法,其配准精度和稳定性都优于最小二乘法,配准误差降低约为20%。     

A revisit to stochastic near-optimal controls: The critical case

This paper revisits the stochastic near-optimal control problem considered in Zhou (1998), where the stochastic system is given by a controlled stochastic differential equation with the control variable taking values in a general control space and entering both the drift and diffusion coefficients. A necessary condition of near-optimality is derived using Ekeland’s variational principle, spike variation techniques, and some delicate estimates for the state and the adjoint processes. We improve the error bound of order from “almost” ${\epsilon }^{\frac{1}{3}}$ in Zhou (1998) to “exactly” ${\epsilon }^{\frac{1}{3}}$.     

An automated tactile sensing strategy for planar object recognitionand localization

The planning problem associated with tactile exploration for object recognition and localization is addressed. Given that an object has been sensed and is one of a number of modeled objects, and given that the data obtained so far are insufficient for recognition and/or localization, the methods developed determin the paths along which a point contact sensor must be directed in order to obtain further highly diagnostic measurements. Three families of sensor paths are found. The first is the family of paths for which recognition and localization are guaranteed. The second guarantees only that something will be learned. The third represents paths to avoid because nothing new will be learned. The methods are based on a small but powerful set of geometric ideas and are developed for two-dimensional, planar-faced objects. They are conceptually easily generalized to handle three-dimensional objects, including objects with through holes     

A near-optimal database allocation for reducing the average waiting time in the grid computing environment

In a grid computing environment, a great many users may access the same database simultaneously. To reduce the average waiting time for all users, a grid designer usually replicates the frequently accessed database among nodes based on the load balance heuristic. On the other hand, users may raise identical queries regarding an issue of interest, e.g., stock information, on a database and each of the queries will be directed to any node having a replica of that database. That is, the same answer will be determined by multiple nodes. Consequently, there exist two shortcomings of poor data sharing and duplicate calculations if the database is not replicated and allocated adequately. In this paper, we aim to minimize average waiting time and try to overcome the two shortcomings by performing database allocation over multiple nodes without any replication. The main idea behind the proposed method is to map the original problem to the Euclidean space Rⁿ and to solve the mapped problem in Rⁿ by a gradient-based optimization technique. The theoretical analyses ensure that the proposed method can converge linearly and achieve near-optimal results.     

Computationally efficient near-optimal combined antenna selection algorithms for V-BLAST systems

The Vertical Bell Laboratories Layer Space–Time (V-BLAST) system using ordered successive interference cancellation (OSIC) detection is a popular system architecture featuring high data rate and moderate computational complexity. The performance of the V-BLAST system can be further improved by exploiting the diversity and closed-loop gain provided by the technique of combined antenna selection (CAS). In this paper, we investigate the design of CAS algorithms with a goal to minimize the system?s error rate. As the error rate of a system varies dramatically with the transceiver architecture, the proposed CAS algorithms explicitly take the VBLAST detection structure into account. Despite the optimal CAS can be achieved by exhaustively searching all the transmit and receive antenna subsets, the applicability of this brute-force approach is excessively limited due to its huge computational complexity. To this end, we propose two computationally efficient CAS algorithms by implementing a greedy strategy incrementally or decrementally to fully exploit the recursive structure of mean-square-error matrices between consecutive V-BLAST detection stages. Near optimal error rate performance can therefore be obtained with significantly lower complexity as verified by the extensive computer simulations.     

New results for near-optimal control of linear multiparameter singularly perturbed systems

In this paper, we consider the linear quadratic optimal control problem for multiparameter singularly perturbed systems in which N lower-level fast subsystems are interconnected through a higher-level slow subsystem. Different from the existing methods, a new method is developed to design a near-optimal controller which does not depend on the unknown small parameters. It is shown that the resulting controller in fact achieves an O(||μ||²) approximation to the optimal cost of the original optimal control problem.     

依赖方位角测量的多智能体系统事件触发协同定位

论文提出了一种基于事件的方案来实现三维空间多智能体系统的方位定位. 依赖方位角刚度设计了一种事件 触发的定位方法, 该方法在少数个体方位角已知的前提下, 可以对集群网络中所有个体进行定位. 为了保障方法的有效 性, 利用输入到状态的稳定原理, 得到了上述闭环控制系统的稳定性条件, 并且理论保证Zeno行为不发生. 最后, 通过二 维和三维的数值仿真验证了所提出的多智能体系统事件触发定位控制方案的有效性.     

基于WIFI指纹的无人机室内定位策略

针对无人机室内定位问题,提出一种WIFI指纹定位与多传感器融合的定位方法.分析三维空间的WIFI指纹定位方法应用于无人机定位的难点,利用超声波传感器测量的无人机高度信息将定位匹配范围缩减至邻近的两个层面,提升WIFI定位的速度;设计卡尔曼滤波器,将WIFI定位结果作为卡尔曼滤波器预测阶段的输入,通过融合惯性传感器信息得到更准确的无人机位置估计,采用数据拟合的方法对定位结果进一步优化.仿真结果表明,该定位方法可实现无人机室内定位,有良好的定位速度和精度.     

Computing near-optimal solutions for the dominating subset with minimal weight problem

In this work, we consider a combinatorial “dominating subset with minimal weight” problem, which is an associative problem for solving global optimization problem. This problem can be expressed as a kind of assignment problem. The mathematical model and the economical interpretations of the problem are given and its properties are described. Then, we propose a new algorithm which has a ratio bound in polynomial time, by using above properties for solving the problem and present the results of numerical experiments.     

A strategy for vectorization

The community of people using vector processors is growing rapidly. First, within the United States, the National Science Foundation has established several vector supercomputer centers, and a large number of scientists in academe will be using these resources. Second, IBM has added a vector capability to its high-end mainframe system, and the widespread use of these systems will dramatically increase the community of people using vector processors. Finally, host of minicomputer manufacturers have added vector capability to their latest systems. So, as a result, there will likely be a reveal of interest in vectorization and some exciting additions to the associated technology. The intent of this paper is to provide many of these new users of vector processors with a high-level discussion of some of the fundamental aspects of vector processing.