Development of error-compensating UI for autonomous production cells

This contribution deals with the impact of human error on the overall system reliability in flexible manufacturing systems (FMS). Autonomous production cells are used to illustrate an error-compensating system design on the basis of Sheridan's (1997) paradigm of supervisory control. In order to specify human errors and their effects in terms of system disturbances, a taxonomy of system disturbances is recommended. This taxonomic approach was derived by a value benefit analysis and is based on HEDOMS (Human Error and Disturbance Occurrence in Manufacturing Systems) with slight modifications and Reason's GEMS (Generic Error Modelling System). The taxonomy is used for data acquisition. Next, a risk priority equivalent to FMEA (Failure Mode and Effect Analysis) is introduced to structure the data according to their relevance. Then, Vicente's and Rasmussen's guidelines (1987) for an ecological interface design are related to the paradigm of supervisory control. On the basis of these guidelines four case studies are presented to show their successful applicability for interface design in FMS.     

Development of error-compensating UI for autonomous production cells

This contribution deals with the impact of human error on the overall system reliability in flexible manufacturing systems (FMS). Autonomous production cells are used to illustrate an error-compensating system design on the basis of Sheridan's (1997) paradigm of supervisory control. In order to specify human errors and their effects in terms of system disturbances, a taxonomy of system disturbances is recommended. This taxonomic approach was derived by a value benefit analysis and is based on HEDOMS (Human Error and Disturbance Occurrence in Manufacturing Systems) with slight modifications and Reason's GEMS (Generic Error Modelling System). The taxonomy is used for data acquisition. Next, a risk priority equivalent to FMEA (Failure Mode and Effect Analysis) is introduced to structure the data according to their relevance. Then, Vicente's and Rasmussen's guidelines (1987) for an ecological interface design are related to the paradigm of supervisory control. On the basis of these guidelines four case studies are presented to show their successful applicability for interface design in FMS.     

Model-based low-level control in flexible manufacturing systems

Low-level (supervisory) control of flexible manufacturing systems (FMS) assures conflict-free operation and enforces production requirements such as priorities. It forms a crucial link between medium and higher-level decision making, on the one hand, and the various machine-controllers and servomechanisms on the other. In the absence of a suitable control methodology, ad hoc development is the current practice and compromised results at high cost are far too common. Here we described a model-based framework for a new, systematic approach to supervisory control.     

A Petri-Net Approach to Modular Supervision With Conflict Resolution for Semiconductor Manufacturing Systems

In a semiconductor manufacturing system, particular human operations may violate desired requirements and lead to destructive failure. For such human-in-the-loop systems, this paper proposes a supervisory framework which guarantees that manual operations meet required specifications so as to prevent human errors in operation using Petri nets. Moreover, a modular technique with an intersection mechanism is proposed in order to cope with the state-space explosion problem of large-scale systems. A rapid thermal process in semiconductor manufacturing systems is provided to show the practicability of the proposed approach. Note to Practitioners - This work was motivated by the requirement of remote monitoring and supervision of semiconductor manufacturing systems. In such human-in-the-loop and large-scale systems, certain human operations may violate desired safety requirements and result in catastrophic failure. Moreover, the overall complexity of most existing Petri net modeling and analysis approaches significantly increases with the size of the considered systems. This paper suggests a modular supervisory scheme for modeling and synthesis of supervisory agents using Petri nets. The proposed method contributes a promising tool for preventing abnormal operations from being carried out to semiconductor manufacturing systems which, if appropriately modified, may be also applied to other types of discrete event systems.     

A CONWIP model for FMS control

Production inventory control is one of the most important aspects of a flexible manufacturing system (FMS) design. CONstant Work In Process (CONWIP), which is a hybrid of push-and-pull type systems, offers an alternative to effective utilization of the expensive FMS equipment while still meeting customer requirements. In the selection of an FMS control method, material handling often becomes one of the capacity constraints which forms the basis of various research interests. In this paper, a structure-based model for a CONWIP-controlled FMS is proposed, and within it, the node type characteristics concept is used to describe the constraints in FMS. Furthermore, simulation is used to determine the card number based on the structure-based model. The simulation results demonstrate that the model is suitable for the design and operation of FMS. The model can be used as a manufacturing execution system of enterprise resources planning. An architecture for this integrated design based on Internet/Intranet systems is also proposed.     

Integrating Task- and Work Domain-Based Work Analyses in Ecological Interface Design: A Process Control Case Study

In this paper, we present a case study wherein several work analysis methods were incorporated in the design of a graphical interface for a petrochemical production process. We follow this case from the application of the work analysis methods, through the consolidation of information requirements, to the design of a novel interface that integrates the requirements. The findings confirm earlier assertions that task-based and work domain-based analysis frameworks identify unique and complementary requirements for effective information systems that are intended to support supervisory control of complex systems. It further provides the first industrial demonstration of ecological interface forms based on integrated task-and work domain-based work requirements.     

Intelligent support for activity management (ISAM): an architectureto support distributed supervisory control

Distributed supervisory control is the monitoring and control of complex, dynamic, highly automated systems by a team of human operators. As such, it is an example of a cooperative work environment. The goal of this paper is to analyze the nature of cooperative work in distributed supervisory control environments and describe implications for computer support. In particular, we argue that flexible support for activity management is a key requirement for computer support for distributed supervisory control, and we propose the intelligent support for activity management (ISAM) architecture as one infrastructure for doing so. The design and implementation of ISAM draws from previous work on intelligent operator's associate systems and computer-supported cooperative work (CSCW) systems. A graphical user interface to ISAM and an evaluation study of this system in the context of team supervisory control are also described     

Discrete event and hybrid systems in robotics and automation: anoverview

Discrete event and hybrid systems modeling has been used extensively in automation, robotics, and manufacturing applications. Different frameworks for dynamic supervisory controllers are used in flexible manufacturing systems (FMS) and automated processes. This article presents an overview of some existing strategies that are used to control systems in real-time based on sensory data     

Agent-based FMS control

Future manufacturing systems will be integrated into the networks of distributed resources, and at the same time, such systems will be capable of processing both knowledge and material. It will probably be required that manufacturing systems be agile, flexible, and fault-tolerant. Petri nets (PN) and object-oriented design (OOD) are used together in order to develop the integrated agent-based FMS control system. The flexible manufacturing system (FMS) consists of machines, workstations, and automated material handling system, distributed buffer storage sites and computer-based supervisory control, all which can be modeled as an agent in OOD with PN. This paper introduces the design of an agent-based FMS control system through PNs and evaluates the performance using timed placed Petri nets (TPPN). In order to do so, the agent control design, FMS structure has been evaluated in detail and the agent definitions have been submitted. The system includes the sharing and distribution of tasks among agents and the mentioned structure has been simulated by TPPN. The simulation procedure has been realized through Petri Net 2.0—MATLAB Demo Program [Mahulea CF, Motcovschi MH, Pastravanu O. Department of Automatic Control Industrial Informatics, Technical University “Gh. Asachi” of Iasi, Blvd., Mangeron 53A, 6600 Iasi, Romania, 〈http://www.ac.tuiasi.ro/pntool,pntool@ac.tuiasi.ro〉, 2004.]. Each case is modeled, and then the agent's machine processing time is considered in this program. As for the evaluation of the study, the system performance is assessed through the waiting time of the parts in queue and the task distributions.     

A knowledge-based decision support system for the management of parts and tools in FMS

Flexible manufacturing systems (FMS) are very complex systems with large part, tool, and information flows. The aim of this work is to develop a knowledge-based decision support system (KBDSS) for short-term scheduling in FMS strongly influenced by the tool management concept to provide a significant operational control tool for a wide range of machining cells, where a high level of flexibility is demanded, with benefits of more efficient cell utilization, greater tool flow control, and a dependable way of rapidly adjusting short-term production requirements. Development of a knowledge-based system to support the decision making process is justified by the inability of decision makers to diagnose efficiently many of the malfunctions that arise at machine, cell, and entire system levels during manufacturing. In this context, this paper proposes three knowledge-based models to ease the decision making process: an expert production scheduling system, a knowledge-based tool management decision support systems, and a tool management fault diagnosis system. The entire system has been created in a hierarchical manner and comprises more than 400 rules. The expert system (ES) was implemented in a commercial expert system shell, Knowledge Engineering System (KES) Production System (PS).     

Human factors approach for evaluation and redesign of human–system interfaces of a nuclear power plant simulator

Nuclear power production is a safety-critical process where ultimate execution of process change decisions lie with the operators. Thus it is important to provide the best possible decision support through effective supervisory control operator interfaces. This requires a human factors/ergonomics approach in the modernization of analog instrumentation and control systems of the existing nuclear power plants. In this article, we describe how this approach is being used for modernization of the ANGRA I power plant. Using a cognitive task analysis (CTA) approach, we observed operators working on an advanced control room of a nuclear power plant digital simulator and noted several opportunities for improvement in the human/system interfaces related to the graphics design, alarm systems and procedure integration. A redesigned prototype was constructed as an alternative to the current simulator and hardcopy procedure manuals. The design improves upon the graphical layout of system information and provides better integration of procedures, automation and alarm systems. The design was validated by expert opinion and a scenario-based comparison.

Relevance to industry

Human factors/ergonomics are not playing the role they deserve in the design of process control systems making them less controllable than they could be if human factors were adequately incorporated. The use of human factors approach in the design of process control systems throughout the industry presents many opportunities for improvements with regard to system effectiveness, efficiency, reliability and safety.     

Scale transformations and information presentation in supervisory control

It is commonly accepted that designers of supervisory control systems cannot comprehensively anticipate operators’ information needs. In order to compensate the lack between the information presented by the supervisory control system and the information needed, operators tailor the information presentation.Currently, there is a lack of theoretical understanding of tailoring activities and hence fundamental principles for the design of supervisory control systems that support tailoring activities in a systematic manner.Any data being presented to the operator is on one of the four different scale types proposed by Stevens. The scale type of data is determined by how values are assigned to the dimensions of the system being supervised and each scale type specifies a set of operations that can be legitimately applied to data on this scale type.Based on the concept of scale transformation the paper proposes systematic principles for operator-initiated adaptation of the interpretation of system properties as presented by the supervisory control system. The value of the approach is illustrated by means of examples.     

Expert systems: An application in flexible manufacturing

Flexible manufacturing systems (FMS) are needed to provide manufacturing operations with the capability to adjust, in real time, to changes in the manufacturing environment. Realization of the goals of flexible manufacturing is governed by the ability of the FMS to maintain adequate information on the factory to assist in generating scenarios from product planning to operations and performance. This leads to a view where the factory is represented as an integrated information system. To facilitate the analysis of information requirements and the design of information systems for flexible manufacturing, an expert support system (ESS) which can be used to model and study the various structures is described. This ESS uses the information cell model to build these information structures. Petri net representations of these structures and their interactions are then constructed. The ESS may now be used to exercise these models and study their performance using time and cost measures.     

The MPC elucidator: a case study in the design for human-automationinteraction

In this paper, we describe the design of a decision support system for operators of model-based predictive controllers (MPC). MPC is a form of advanced automatic control that is increasingly common in process operations due to its ability to control and optimize large sections of a process. A cognitive task analysis revealed that current operating displays, which rely on displaying tables of numeric information across several display pages, do not effectively support human operator monitoring, diagnosis, and control of MPC. This case study shows how we applied representation aiding and workspace management design principles to better support the human-automation interaction requirements of monitoring, understanding, and adjusting these complex, semi-autonomous; process controllers. We show how effective user interface design can significantly reduce the complexity of operating with advanced automation, and can lead to improved understanding of how the automation works     

An object-oriented model for FMS control

The flexible manufacturing system (FMS) is a distributed network of heterogeneous programmable manufacturing machinery, such as assembly lines and numerically controlled machines. Despite these interconnected, programmable hardware elements, the success of building a truly flexible manufacturing system has been limited so far, owing to the lack of flexibility in its control software layer. In integrating heterogeneous machinery, many existing FMS control software systems depend structurally on specific machinery and job-scheduling strategies, and thus it is difficult to incorporate new developments in FMS organization and operational requirements. In searching for an open architecture for the FMS control software system, this paper presents an object-oriented FMS data model. Among others, it represents each physical cluster of related machinery (called a flexible manufacturing cell) as an object. To facilitate the integration of heterogeneous physical cells, such cell objects share a common protocol of interacting with the main control process through inheritance from the abstract cell class. Other related physical and abstract entities in FMS are also modelled as objects, with their similarity and difference captured in inheritance hierarchies. To verify the proposed approach experimentally, a prototype FMS control software system named FREE (FMS Runtime Executive Environment) has been implemented on top of a commercial object-oriented database system.     

过程系统体系结构及信息集成

体系结构是指导大型复杂综合自动化系统的原则和框架,信息集成是分布式综合自动化系统成功运行的基础.以石化企业为背景,综合研究了过程企业体系结构和信息集成问题.提出了包含信息、功能、组织、产品和资源等五个视图及需求分析,初步设计和详细设计三个主要阶段的体系结构.进一步探讨了过程企业方法库、管理数据库、实时数据库和装置模型库的构建方法,提出了基于C0RBA标准的分布式信息集成模型.     

Adaptive-intelligent control of robots and technological equipment of intelligent manufacturing

Methods of adaptive-intelligent control of robots and technological equipment of intelligent manufacturing (IM) with incomplete information on the plant conditions are discussed. Flexible algorithms are proposed for programming and sensor correction of movements which provide adaption to obstacles and uncertainly factors. Robust and adaptive control algorithms which compensate the uncontrollable disturbances and ensure the wanted character of transient process are synthesized. The conversational means and computeraided design technology for multi-microprocessor adaptive control systems of robots and technological equipment are described. The results of using the proposed methods in adaptive-intelligent control systems of robots and flexible manufacturing systems (FMS) for powder metallurgy, laser processing are presented.