Search results for "Manufacturing systems"
showing 8 items of 28 documents
A hierarchic approach to production planning and scheduling of a flexible manufacturing system
1999
Abstract The paper deals with the problem of improving the machine utilization of a flexible manufacturing cell. Limited tool magazine space of the machines turns out to be a relevant bottleneck. A hierarchic approach for this problem is proposed. At the upper level, sets of parts that can be concurrently processed (batches) are determined. At the lower levels, batches are sequenced, linked, and scheduled. Methods taken from the literature are used for the solution of the latter subproblems, and an original mixed integer programming model is formulated to determine batches. The proposed methods are discussed on the basis of computational experience carried out on real instances.
Robust control of uncertain multi-inventory systems via linear matrix inequality
2008
We consider a continuous time linear multi inventory system with unknown demands bounded within ellipsoids and controls bounded within ellipsoids or polytopes. We address the problem of "-stabilizing the inventory since this implies some reduction of the inventory costs. The main results are certain conditions under which "-stabilizability is possible through a saturated linear state feedback control. All the results are based on a Linear Matrix Inequalities (LMIs) approach and on some recent techniques for the modeling and analysis of polytopic systems with saturations.
Average flow constraints and stabilizability in uncertain production-distribution systems
2009
We consider a multi-inventory system with controlled flows and uncertain demands (disturbances) bounded within assigned compact sets. The system is modelled as a first-order one integrating the discrepancy between controlled flows and demands at different sites/nodes. Thus, the buffer levels at the nodes represent the system state. Given a long-term average demand, we are interested in a control strategy that satisfies just one of two requirements: (i) meeting any possible demand at each time (worst case stability) or (ii) achieving a predefined flow in the average (average flow constraints). Necessary and sufficient conditions for the achievement of both goals have been proposed by the aut…
Minimizing the cycle time in serial manufacturing systems with multiple dual-gripper robots
2006
Robots are being used more and more extensively as material-handling systems for automated manufacturing systems. This is especially true for dual-gripper robots whose in-process buffer (the robot's second gripper) constitutes a further element of flexibility. When the number of stations to be served is high and the set of activities the robot must execute is great, the system throughput may depend on robot capability rather than on process times. In such conditions, the use of several robots leads to an increase in system productivity. Obviously, the design and the management of such a handling system becomes more complex: the minimum number of robots required, the work stations to be serv…
An ADOxx Based Environment for Problem Based Learning in Manufacturing Systems Design
2019
The Problem Based Learning (PBL) as student centred approach and learning-by-doing method is suited for the modern higher education. However, the first contact with the method can be overwhelming for the students, in the absence of prior domain knowledge. The preparation of the learning material can be time and resource consuming for the teacher. The goal of the research was the implementation of an environment that should enhance the learning experience for the student and reduce the implementation burden for the teacher. The environment is based on the ADOxx platform and allows the collaboration of the learner teams and the teacher-learner interaction on three levels. The Metamodeling lev…
Low-cost solutions for manipulation tasks in manufacturing systems: balancing costs and performances
2010
Abstract Industrial robots are distinguished from other types of machinery mainly on the basis of their programmability and adaptability to different tasks. However, the cost s of the state of the art solutions for every system within their structure became very high compared with some applications. This work presents two proposed solutions of so called robotic manipulators, which may fulfil some of the manipulating tasks specific to industrial robots while using low-cost solutions of transmission, actuation and automation systems.
Speed control of double-sided linear induction motors for automated manufacturing systems
2014
The double-sided linear induction motor (DLIM) is acquiring a significant relevance in the application of automated manufacturing systems. For this purpose, the modeling, simulation and determination of the parameters of a double-sided linear induction motor is presented in this paper. Furthermore, the DLIM constant voltage/frequency speed control system for this application is here described. In order to verify the performance of the proposed system, a suitable test bench for the DLIM motor is set-up. From the good agreement shown by the comparison between measured and simulated results, it can be stated that the DLIM model and the speed control system is successfully validated. © 2014 IEE…
Globalization and its impact on operational decisions
2009
PurposeThis paper aims to analyse the impact of globalization on the manufacturing operations of industries and industrial districts and how it influences the specialization and diversification of manufacturing decisions.Design/methodology/approachThe sample includes 9,684 Spanish manufacturing textile firms and the analysis is both cross‐sectional and longitudinal.FindingsThe results show that globalization tends to diminish the district and subsector effects over time, but they also show the positive impact of specialization on productivity and of diversification on business growth.Originality/valueThe paper indicates to managers that the production function in textile firms has viability…