Search results

Outlines current research into multiple co‐operative robots and discusses the practicality of a set of experiments developed to study robot applications better and to verify different solution methodologies. Looks at the design criteria for co‐operating robot systems and describes the laboratory set up to study them.

This article presents a study on assembly automation in small subcontracting enterprises. In this scenario the evaluated production volumes of each product limit the competitiveness of flexible assembly systems. At the same time the uncertainty of the economic life of the product causes high risk factors in the use of assembly transfer lines. The proposed solution is characterized by the employment of an asynchronous line with single‐purpose automatic stations and manual stations.

Looks at studies into the definition of design and management criteria for assembly cells with co‐operating robots. Examines task typologies into which the assembly process can be divided and discusses co‐ordination levels and control‐communication architectures. Also looks at the various phases of application development and how it covers many of the same areas of the manual assembly process. Concludes with a consideration of the three main classes of constraints between the actions which different robots have to carry out and states the co‐ordination level that robots have to maintain during constraint‐affected operations depends on these classes.

Reports on a comparison by computer simulation between conventional periodic loading (PL) and job‐group loading (JGL). When conventional PL is used, the search of the best part input sequence must be performed in order to optimize performance of a flexible manufacturing system (FMS). JGL works, instead, as a dynamic rule for real time scheduling of FMS, defining a part releasing policy able to guarantee the reaching of a periodic steady state without non‐productive times on the bottleneck workstation. However, JGL does not assure, in some cases, the same performance arising from the optimal part input sequence of conventional PL, in terms of non‐productive times in FMS filling and emptying phases, work in progress and throughput time. The paper demonstrates that using any JGL rule or the best PL part input sequence gives rise to negligible differences in FMS performance. Furthermore, the dynamic capabilities of the JGL also allow for spontaneously restoring the FMS periodic steady state without non‐productive times after any transient, for instance when production mix changes occur.

The principal results of a study concerning the industrial transfer in MOS memory wafer fabrication, of an intrabay material handling system based on a track‐robot are presented. A prototype system, installed in L'Aquila University Operations Laboratory, was used in order to verify the congruence of the track‐robot performance within the productive tasks to be carried out. Particular attention was given to the safety systems and the vibrational behaviour of the track‐robot, that strictly influence the aspects that can create risks for a person's safety or the wafer's integrity.

A methodology for introducing computer integrated manufacturing (CIM) technology in small companies has been developed. With the aim to assess the capabilities in real applications of the proposed approach, a case study is presented in this paper. The case study refers to a small Italian company (Italpneumatica Sud) producing pneumatic components under one of the leading trademarks in the world (SMC). Results of first experimental tests demonstrate ability of the developed methodology in improving overall company performances, maintaining at the same time low implementation costs.

FMS real time scheduling requires the concurrent solution of both loading and despatching problems. The loading strategy is the most critical and important scheduling decision in an FMS. Presents an effective loading rule (job‐group loading rule), based on experimental observations: a group of jobs, reflecting the ratios of the production mix, is loaded on the input warehouse every time that it is completely empty; all the jobs loaded on the input warehouse have to be accessible for the material handling system. Demonstrates how this job‐group loading works as a dynamic rule for real time scheduling of manufacturing systems, defining a part releasing policy able to guarantee reaching a periodic, steady state production. The capability of the job‐group loading rule has been verified when the FMS characteristics are closest to a real situation. Analyses the effects of the interferences on transport operations, the variability of machining times, the finite capacity of interoperational storage and the stops for preventive maintenance or breakdown. Research results show the capability in FMS management of real time scheduling based on the job‐group loading rule.

The purpose of this paper is to focus on the accurate and steady control on trajectory tracking for wafer transfer robot, suppress the vibration and reduce the contour error.

The wafer transfer robot dynamic model is modeled. Through analyzing the characteristics of wafer transfer robot, cross‐coupled synchronized control is proposed based on the contour error model in task space to improve synchronization of the joints; the shaping for the joints by input shaper in task space is applied to suppress the vibration of the end effector during trajectory tracking. Then combining the cross‐coupled synchronized control with input shaping is proposed to improve accuracy and suppress the vibration.

The combination of cross‐coupled synchronized control and input shaping control method can improve the contour accuracy and reduce the vibration simultaneously during trajectory tracking. And the control method can be used to control the trajectory of wafer transfer robot.

The transfer station is in the center of the robot body. When the transfer station may deviate from the center of the robot body, the synchronizing performance of three axes on the same plane must be considered.

The proposed method can be used to solve the vibration and synchronizing performance problems on similar SCARA robots in semi‐conductor and liquid crystal display industry.

The proposed control method takes advantage of the cross‐coupled synchronized control and input shaping control method. This combination has improved contour accuracy and reduced vibration than applying other methods, and it has achieved better performance than using single one control method only.

The purpose of this paper is to examine the dynamic dependence structure in credit risk between the money market and the derivatives market during 2004-2009. The authors use the TED spread to measure credit risk in the money market and CDS index spread for the derivatives market.

The dependence structure is measured by a time-varying Gaussian copula. A copula is a function that joins one-dimensional distribution functions together to form multivariate distribution functions. The copula contains all the information on the dependence structure of the random variables while also removing the linear correlation restriction. Therefore, provides a straightforward way of modelling non-linear and non-normal joint distributions.

The results show that the correlation between these two markets while fluctuating with a general upward trend prior to 2007 exhibited a noticeably higher correlation after 2007. This points to the evidence of credit contagion during the crisis. Three different phases are identified for the crisis period which sheds light on the nature of contagion mechanisms in financial markets. The correlation of the two spreads fell in early 2009, although remained higher than the pre-crisis level. This is partly due to policy intervention that lowered the TED spread while the CDS spread remained higher due to the Eurozone sovereign debt crisis.

The paper examines the relationship between the TED and CDS spreads which measure credit risk in an economy. This paper contributes to the literature on dynamic co-movement, contagion effects and risk linkages.

A bay configuration arranged along a central spine and served by an automated monorail material‐handling system are common designs for the layout and material‐handling system in new semiconductor wafer fabrication facilities. Investigates the facility design problem in semiconductor fabrication facilities and proposes a procedure to determine the optimal spine layout design, given a design of the material‐handling system. Explains and tests the procedure to demonstrate the use of the model for solving semiconductor facility design problems. The procedure is applicable for the important semicondutor industry as well as in other facilities that use a central spine layout configuration.