1,720,969 research outputs found
Feature selection techniques and comparative studies for large-scale manufacturing processes
No full textIn order to efficiently and effectively control an overall process in the process industry, a few important parameters should be identified from high-dimensional, non-linear, and correlated data. Feature selection techniques can be employed to extract a subset of process parameters relevant to product quality. The performance of these techniques depends on the precision of the prediction model formulated to quantify the relationship between the process parameters and the quality characteristics. Although the neural network-based partial least squares (NNPLS) method has been proven to be effective in prediction models for the aforementioned industrial process data, feature selection techniques appropriate for NNPLS models have yet to appear. Here, several techniques for scoring the relevance of process parameters to product quality are proposed and validated by applying three datasets. These experiments show that the proposed techniques can discriminate relevant process parameters from irrelevant ones.X114sciescopu
INTELLIGENT WORKSTATION CONTROLLER FOR COMPUTER-INTEGRATED MANUFACTURING - PROBLEMS AND MODELS
No full textA shop floor control system (SFCS), an integrated part of computer-integrated manufacturing, oversees the production required to fill orders. To effectively control these activities, it is necessary to define a control architecture and functional perspective of how a SFCS operates. In this paper, a hierarchical SFCS (shop, workstation, equipment) is adopted. The paper presents the problems and models necessary to develop an intelligent workstation controller (IWC) at the middle level of a SFCS. The IWC is responsible for selecting a specific process routing, allocating resources, scheduling and coordinating activities across the equipment, monitoring the progress of activities, detecting and recovering from errors, and preparing reports. The IWC fulfills this responsibility using three functions - planning, scheduling, and execution. Requirements for the development of the IWC are to create a process plan representation model, specify the evolution of a process plan from the shop down to the equipment, and define all of the functions to be integrated into an intelligent controller. A deadlock detection and resolution model is also presented to maintain the system in a deadlock-free state. Finally, the IWC software is created to demonstrate the architectural linkages with other controllers. As a result, the development of the IWC will save cost and time in developing control software for automated manufacturing systems.X1136sciescopu
Petri-net-based rapid development of a task execution module of equipment controller for distributed shop floor control
No full textAlthough many conceptual structures for shop floor control have been proposed, their implementation methodologies have not been satisfactorily achieved yet due to the cost and time required for developing new control software and modifying the existing software. This paper suggests a Petri-net-based tool to rapidly develop a task execution module in the equipment controller for distributed shop floor control. To develop a task execution module, the users have only to build an extended Petri-net model to represent information on how to control the equipment device. The C++ code of the task execution module for intra-activities is then automatically generated from the developed model and plugged into the equipment controller. A prototype task execution module exemplifies that an equipment controller can be constructed or modified easily by adding/deleting several modules in the proposed framework. Consequently, the proposed tool will help the distributed shop floor control system adaptively evolve according to various control environments. (C) 2001 Elsevier Science B.V. All rights reserved.X113sciescopu
Efficient feature-based process planning for sculptured pocket machining
No full textFeature is recently known as the core concept necessary to realize a fully integrated CAD/CAM system. The information contents in a feature can be easily conveyed from one application to another in the manufacturing domain. However the feature generated in one application may not be suitable for another without being modified with more information. The objective of the paper is to present the methodology of decomposing bulky features of the sculptured shape of pocket to be removed into compact features to be efficiently machined. It is possible to reactively and efficiently machine the sculptured shape of packet by segmenting horizontally and vertically a bulky feature and by applying variable cutting condition to each feature. (C) 1997 Elsevier Science Ltd.X116sciescopu
An intelligent workstation controller for integrated planning and scheduling of an FMS cell
No full textThis paper presents an experimental design developed to determine a combination of robust planning and scheduling rules for an intelligent workstation controller (MTC). The IWC is used as part of the control system for an automated flexible manufacturing system. A three-level hierarchical control structure (shop, workstation and equipment) is adopted in order effectively to control a shop-floor. At the top level is a shop controller which receives orders and their associated manufacturing information, and manages interactions among workstations. The IWC defines and resolves the production control activities necessary to coordinate a group of equipment controllers so as to ensure the completion of orders. Specifically, the IWC is responsible for selecting a specific process routeing for each part, allocating resources, scheduling and coordinating the activities across the equipment, monitoring the progress of activities, detecting and recovering from errors, and preparing reports.X113sciescopu
Adaptive and dynamic process planning using neural networks
No full textAlthough feature-based process planning plays a vital role in automating and integrating design and manufacturing for efficient production, its off-line properties prevent the shop floor controller from rapidly coping with dynamic shop floor status such as unexpected production errors and rush orders. This paper proposes a conceptual framework of the adaptive and dynamic process planning system that can rapidly and dynamically generate the needed process plans based on shop floor status. In particular, the generic schemes for constructing dynamic planning models are suggested. The dynamic planning models are constructed as neural network forms, and then embedded into each process feature in the process plan. The shop floor controller will execute them to determine machine, cutting tools, cutting parameters, tool paths and NC codes just before the associated process feature is machined. The dynamic nature of process planning enables the shop floor controller to increase flexibility and efficiency in unexpected situations.X1118sciescopu
Dynamic planning model for determining cutting parameters using neural networks in feature-based process planning
No full textAlthough feature-based computer-aided process planning plays a vital role in automating and integrating design and manufacturing for efficient production, its off-line properties prohibit the shop floor controllers from rapidly coping with unexpected production errors. The objective of the paper is to suggest a neural network-based dynamic planning model, by which the shop floor controllers determine cutting parameters in real-time based on shop floor status. At off-line is the dynamic planning model constructed as a neural network form, and then embedded into each removal feature. The dynamic planning model will be executed by the shop floor controllers to determine the cutting parameters. A prototype system is constructed to validate whether the dynamic planning model is capable of determining dynamically and efficiently the cutting parameters for a particular set of shop operating factors. Owing to the dynamic planning model, the shop floor controller will increase flexibility and robustness by rapidly and adaptively determining the cutting parameters in unexpected errors occurring.X115sciescopu
Integration framework of process planning based on resource independent operation summary to support collaborative manufacturing
No full textIn today's global manufacturing environment, manufacturing functions are distributed as never before. Design, engineering, fabrication, and assembly of new products are done routinely in many different enterprises scattered around the world. Successful business transactions require the sharing of design and engineering data on an unprecedented scale. This paper describes a framework that facilitates the collaboration of engineering tasks, particularly process planning and analysis, to support such globalized manufacturing activities. The information models of data and the software components that integrate those information models are described. The integration framework uses an Integrated Product and Process Data ( IPPD) representation called a Resource Independent Operation Summary (RIOS) to facilitate the communication of business and manufacturing requirements. Hierarchical process modelling, process planning decomposition and an augmented AND/OR directed graph are used in this representation. The Resource Specific Process Planning (RSPP) module assigns the required equipment and tools, selects process parameters, and determines manufacturing costs based on two-level hierarchical RIOS data. The shop floor knowledge ( resource and process knowledge) and a hybrid approach ( heuristic and linear programming) to linearize the AND/OR graph provide the basis for the planning. Finally, a prototype system is developed and demonstrated with an exemplary part. Java and XML ( Extensible Mark-up Language) are used to ensure software and information portability.X1114sciescopu
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