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No-wait task assignment in flexible manufacturing cells
Abstracts minimum (x~st or maximum production rate. The system then computes the m a ~ i a l removal rate, machining time and power consumlXion, and recommends a statable processing .mach~.e based on the op~xized qperating parameten, tne result or tins research is based on geoerative process planning, accessing the best knowledge obtainable using the rule set ann mathematical model for cutting parameters selection. 100
Unified Modelling of Manufacturing Process, Prodoction Flows and Control System in Mnnufocturing Workshops J.L. Part.& G. Vallet, J.P. Bonrri~res, F. Lhote, pp 329-334
Starting from assembly process modelling by means of Petri nets, this paper describes the corresponding tasks at different levels of detail. By considering flow requirements, production unhs are then associated with these tasks. Then, new tasks relative to the decisional systems are defined, in order to capture the state of the operative system and to send the control orders to it. Finally, an example of dynamic routing policy is proposed, using the concepts exposed in this paper. 101
Product Modeling: From Geometrical Modeling to z.L~ical Modeling ong, R. Tang, Y, Sun, pp 335-340
This paper investigates the linguistic characteristics of a scheme for product modeling, and formalizes the scheme with formal lan.gnage theory. The rationality and effectiveness of the three major types of product modeling--gnometrical modeling, feature modeling and logical modelins-are analyzed and compared from the integration of CAD/CAM. 102
In-Cycle Minimum Variance Control of Extrusion Blow Moulding R.W. DIRnddo, A. Garcia-Rejon, pp 341-345
207 (programming language -- S1), as well as data display and documentation, ensures high-quality and efficient contnd.
10S
This paper proposes a new path-planning method for obstacle avoidance by mobile robots. The free space of the envirommmt is represented by a skeleton consisting of ~ and nodes, where the number of nodes is a measure of compmtiomd
complexly.
103
Real Tlme Quality Optimization in Flexible Manufacturing Systems S. Jacqmart, D. Glen, pp 347-352
In this paper a quality-oriented model is proposed for product and process as a whole. A hierarchical structural description allows both model consistency and integration of detailed information. Material and data flows are thus perfectly clef'reed. Inaccurate or uncertain data are modelled by means of fuzzy quantities. Associated operators and relations permit information propagation in the model. That strict but flexible approach shows advantages above standard statistical methods. Product quality and process operation are evaluated in order to build a goal-cost function, used to define the optimal control strategy. A distributed computation process reduces information exchanges and contributes greatly to safe on-line quality management.
104
Computer System of Thermal Imaging Quality Control of Complex Objects V.G. Ivanov, pp 353.354
Given in the paper are the results of investigations on the development of.an interactive computer system of thermal unagmg processmg, based on the home-made "Raduga-MT' thermal imager and DBK-4 personal computer (functional analogue of DECs VAX). The system, provided with a userfriendly format, is intended for use in technical and medical diagnostics where there is a need to estimate the quality of an object under comrol according to the thermal field character. The developed applied system of mathematical software
A path graph, introduced to ~
the
connecti~ty between nodes and wires, facilitates the determination of feasible paths, on which a path improvement process is performed in order that a robot may follow the path smoothly. Compared with the visibility graph (V-graph) method, the prepmed method is optimized in terms of searching time. The effectiveness of the proposed method is verified by a series of simulation studies.
106 A Rule-Breed Selection of C-Space Repres~ltatlon for Rapid 3D Robot Path Planning C. Balnguer, F.J. Rodrique% J.M. Pastor, E. Gambne, R. Araell, A. Barrlentex, pp 361-365 This work presents a rule-based algorithm for selection of adequate free space representation, in order to calculate In a rapid way the collision-free 3D paths of up to 6DOF robots. These representations are based on the C-space techniques. Each of them generates different path planning algorithms which are: a)cell (cube) mapping, b)octrecs and c)slice. The selection depends on several parameters, like the distance between start and goal positions and orientations, number of obstacles in the environment, number of robot movements in the environment, etc. The results of the real implementation are presented. 107
Disturbances occurring during the blow moulding process can be of a high-frequency or a low-frequency nature. Traditional blow moulding practice has involved the correction of process deviations in a cycle-to-cycle time frame, allowing for the correction of low-frequency disturbances, such as material property changes and temperature drifts. This paper studies the process correcuon of high-frequency disturbances that occur during the product formation cycle. These include die gap fluctuations and pressure surges. In-cycle control entails as a first step, the study of process dynamics to changes input during the cycle. Once the identification procedure is complete, the appropriate control algorithm is introduced
Path Planning for Mobile Robot Using Skeleton of Free Space H.R. Beom, H.S. Clio, pp 355-359
production Scheduling Using Genetic Algorithms J.W. Schulte, B.-D. Becker, pp 367-372
Genetic algorithms (GAs) have proved to be robust and reasonably fast in finding good solutions, but are still regarded as an academic toy. The work presented here prepares for a broad application of GAs in industrial settings by providing a user-oriented modelling environment. After stating the problem in a functiou-oriented way, any scheduling-related problem can be transformed into the GA-amenable form and solved. Key issues with GAs are coding and speed of evaluation. Three basic GA problem types are identified and the coding is explained. Results on evaluation speed obtained so far are presented. 108
No-Wait Task Assignment in Flexible Manufacturing Cells A. Agnefls, F. Nicolo', M. Lucertini, pp 373.377
The problem of task assignment for a class of flexible manufacturing ceils is considered. The cell is designed for cyclic production of one product, characterized by a sequence of operations of given length and each requiring a robot: the problem is therefore to allocate the o~eratious to the robots in order to maximize the throughput` The problem of f'mding a task assignment such that the parts are never in a waiting state is discussed. If such an assignment exists, the maximum theoretical throughput is achieved. The complexity of the problem for some structures of the system is illustrated by means of graph-theoretical modes.
109 Computer Meddling in Die Casting Applications C.A. Leonfo D. Frayce, Y. Lauze, pp 379-382 In .~e context of die casting, computer modelling facifitates the design and manufacturing of complex pans. It can help to reduce production costs through design and process fo~timization, and s.horten. product development time. This paper ocuses on moneumg me two roam aspects of die casting-turbulent metal flow and nonisothermal solidification-undertaken by means of the finite element method (FEM). Flow and sofidification patterns are generated and can then be used to evaluate and optimize cavity design, predict potential defects, and formulate manufacturing requirements. Theoretical aspects related to the CASTFILL filling model and CASTSOL
Unified Modelling of Manufacturing Process, Prodoction Flows and Control System in Mnnufocturing Workshops J.L. Part.& G. Vallet, J.P. Bonrri~res, F. Lhote, pp 329-334
Starting from assembly process modelling by means of Petri nets, this paper describes the corresponding tasks at different levels of detail. By considering flow requirements, production unhs are then associated with these tasks. Then, new tasks relative to the decisional systems are defined, in order to capture the state of the operative system and to send the control orders to it. Finally, an example of dynamic routing policy is proposed, using the concepts exposed in this paper. 101
Product Modeling: From Geometrical Modeling to z.L~ical Modeling ong, R. Tang, Y, Sun, pp 335-340
This paper investigates the linguistic characteristics of a scheme for product modeling, and formalizes the scheme with formal lan.gnage theory. The rationality and effectiveness of the three major types of product modeling--gnometrical modeling, feature modeling and logical modelins-are analyzed and compared from the integration of CAD/CAM. 102
In-Cycle Minimum Variance Control of Extrusion Blow Moulding R.W. DIRnddo, A. Garcia-Rejon, pp 341-345
207 (programming language -- S1), as well as data display and documentation, ensures high-quality and efficient contnd.
10S
This paper proposes a new path-planning method for obstacle avoidance by mobile robots. The free space of the envirommmt is represented by a skeleton consisting of ~ and nodes, where the number of nodes is a measure of compmtiomd
complexly.
103
Real Tlme Quality Optimization in Flexible Manufacturing Systems S. Jacqmart, D. Glen, pp 347-352
In this paper a quality-oriented model is proposed for product and process as a whole. A hierarchical structural description allows both model consistency and integration of detailed information. Material and data flows are thus perfectly clef'reed. Inaccurate or uncertain data are modelled by means of fuzzy quantities. Associated operators and relations permit information propagation in the model. That strict but flexible approach shows advantages above standard statistical methods. Product quality and process operation are evaluated in order to build a goal-cost function, used to define the optimal control strategy. A distributed computation process reduces information exchanges and contributes greatly to safe on-line quality management.
104
Computer System of Thermal Imaging Quality Control of Complex Objects V.G. Ivanov, pp 353.354
Given in the paper are the results of investigations on the development of.an interactive computer system of thermal unagmg processmg, based on the home-made "Raduga-MT' thermal imager and DBK-4 personal computer (functional analogue of DECs VAX). The system, provided with a userfriendly format, is intended for use in technical and medical diagnostics where there is a need to estimate the quality of an object under comrol according to the thermal field character. The developed applied system of mathematical software
A path graph, introduced to ~
the
connecti~ty between nodes and wires, facilitates the determination of feasible paths, on which a path improvement process is performed in order that a robot may follow the path smoothly. Compared with the visibility graph (V-graph) method, the prepmed method is optimized in terms of searching time. The effectiveness of the proposed method is verified by a series of simulation studies.
106 A Rule-Breed Selection of C-Space Repres~ltatlon for Rapid 3D Robot Path Planning C. Balnguer, F.J. Rodrique% J.M. Pastor, E. Gambne, R. Araell, A. Barrlentex, pp 361-365 This work presents a rule-based algorithm for selection of adequate free space representation, in order to calculate In a rapid way the collision-free 3D paths of up to 6DOF robots. These representations are based on the C-space techniques. Each of them generates different path planning algorithms which are: a)cell (cube) mapping, b)octrecs and c)slice. The selection depends on several parameters, like the distance between start and goal positions and orientations, number of obstacles in the environment, number of robot movements in the environment, etc. The results of the real implementation are presented. 107
Disturbances occurring during the blow moulding process can be of a high-frequency or a low-frequency nature. Traditional blow moulding practice has involved the correction of process deviations in a cycle-to-cycle time frame, allowing for the correction of low-frequency disturbances, such as material property changes and temperature drifts. This paper studies the process correcuon of high-frequency disturbances that occur during the product formation cycle. These include die gap fluctuations and pressure surges. In-cycle control entails as a first step, the study of process dynamics to changes input during the cycle. Once the identification procedure is complete, the appropriate control algorithm is introduced
Path Planning for Mobile Robot Using Skeleton of Free Space H.R. Beom, H.S. Clio, pp 355-359
production Scheduling Using Genetic Algorithms J.W. Schulte, B.-D. Becker, pp 367-372
Genetic algorithms (GAs) have proved to be robust and reasonably fast in finding good solutions, but are still regarded as an academic toy. The work presented here prepares for a broad application of GAs in industrial settings by providing a user-oriented modelling environment. After stating the problem in a functiou-oriented way, any scheduling-related problem can be transformed into the GA-amenable form and solved. Key issues with GAs are coding and speed of evaluation. Three basic GA problem types are identified and the coding is explained. Results on evaluation speed obtained so far are presented. 108
No-Wait Task Assignment in Flexible Manufacturing Cells A. Agnefls, F. Nicolo', M. Lucertini, pp 373.377
The problem of task assignment for a class of flexible manufacturing ceils is considered. The cell is designed for cyclic production of one product, characterized by a sequence of operations of given length and each requiring a robot: the problem is therefore to allocate the o~eratious to the robots in order to maximize the throughput` The problem of f'mding a task assignment such that the parts are never in a waiting state is discussed. If such an assignment exists, the maximum theoretical throughput is achieved. The complexity of the problem for some structures of the system is illustrated by means of graph-theoretical modes.
109 Computer Meddling in Die Casting Applications C.A. Leonfo D. Frayce, Y. Lauze, pp 379-382 In .~e context of die casting, computer modelling facifitates the design and manufacturing of complex pans. It can help to reduce production costs through design and process fo~timization, and s.horten. product development time. This paper ocuses on moneumg me two roam aspects of die casting-turbulent metal flow and nonisothermal solidification-undertaken by means of the finite element method (FEM). Flow and sofidification patterns are generated and can then be used to evaluate and optimize cavity design, predict potential defects, and formulate manufacturing requirements. Theoretical aspects related to the CASTFILL filling model and CASTSOL