Understanding Perceived Complexity in Human Supervisory Control

Industrial processes are becoming more complex owing to technological developments and new opportunities. Technological developments, hardware and software, have become more reliable and system configurations more robust. However, the reliability of operator control actions has not improved at the same pace. Consequently human reliability has become the relatively weakest aspect of automated, operator-supervised systems. Hence, understanding how the human operator experiences increasing complexity may play an important role in task allocation and human–machine system design. In this paper the perceived complexity is studied within four typical operational environments in supervisory control. Mathematical formulations for these four operational environments are proposed, and their properties are analysed. A laboratory system is used to investigate the perceived complexity under various operational environments. The experimental results show a significantly different perceived complexity for the coupled and uncoupled operation environments. Extrapolation of the results revealed that the operator would have perceived the system as extremely complex if he/she would have to operate more than eight strongly interconnected subsystems extensively in 30 minutes. Implications of this study are also addressed.     

Role of a Common Frame of Reference in Cognitive Cooperation: Sharing Tasks between Agents in Air Traffic Control

This study deals with cognitive cooperation in the context of the design of cooperative computer support for sharing aircraft conflict detection and resolution tasks between human and machine in air traffic control. In order to specify some necessary cooperative capabilities of such a system, we have observed an artificial situation on a simulator where two radar controllers (RCs) had to cooperate for the management of a heavy traffic within a single sector. This paper reports the analysis of the verbal communications between the two RCs recorded during the simulation. The results enabled us to describe the elements of a common frame of reference (COFOR), elaborated and updated by the two RCs, as a crucial cooperative activity in this kind of situation. They also show the role of this COFOR in the implicit detection and resolution of interference between the RCs’ individual activities. Their contribution to design, associated with other investigations and the state of the art, is discussed.     

Features of Decision-Making in Process Control Tasks: The Relevance of the Work Context

This paper is centred on evaluating some significant features of decision-making in process control tasks. The study was carried out in a petrol refinery, specifically, with distillation console operators. Operator verbalisations were recorded during the completion of two specific tasks and later categorised by raters using a list of cognitive categories. The inter-rater reliability was calculated together with qualitative evaluations of the main overlaps among the categories. From the raters’ evaluations, flow diagrams were drawn that represented the plans and tactics developed by operators and the implied cognitive processes (evaluation, prediction, action, etc.). We found that the operators began the tasks with a primary global situation assessment that determined the choice of whether to cope with the task ‘step by step’ or ‘globally’. The results showed two patterns of decision sequences made in normal adjustment performance or in problem situations. Other findings are related to the importance of characteristics such as prediction, anticipation, feedback and the role of the alarms selected by a situation assessment and individual characteristics.     

Cognitive Automation for Tactical Mission Management: Concept and Prototype Evaluation in Flight Simulator Trials

This paper describes an approach to cognitive and cooperative operator assistance in the field of tactical flight mission management. A framework for a generic functional concept is derived from general considerations of human performance and cognitive engineering. A system built according to these human-centred design principles will be able to keep up with the change of situation parameters, in order to provide situational adapted operator assistance. Such a cognitive assistant system represents an approach to ensure the highest degree possible of situation awareness of the flight deck crew as well as a satisfactory workload level. This generic approach to mission management and crew assistance for military aircraft has been realised in different application domains such as military transport and air-to-ground attack. The Crew Assistant Military Aircraft is a functional prototype for the air transport application. Even applications in the domain of uninhabited aerial vehicles (UAV) are in reach. This paper mainly covers one state-of-the-art research and development activity in the domain of combat aircraft: the TMM – Tactical Mission Management System is an experimental solution for the air-to-ground attack role. The TMM has been implemented as a functional prototype in the mission avionics experimental cockpit (MAXC), a development flight simulator at ESG and evaluated with German Air Force pilots as subjects in simulator trials. Therefore, the TMM has been compared with a reference cockpit avionics configuration in terms of task performance, workload, situation awareness and operator acceptance. After giving an overview of the system concepts this paper reports on the experimental design and results of the simulator trial campaign.     

Problem-Driven Approach to the Design of Information Technology Systems Supporting Complex Cognitive Tasks

The present paper proposes a methodological framework for the design and evaluation of information technology systems supporting complex cognitive tasks. The aim of the methodological framework is to permit the design of systems which: (1) address the cognitive difficulties met by potential users in performing complex problem-solving tasks; (2) improve their potential users’ problem-solving performance; and (3) achieve compatibility with potential users’ competences and working environment. After a short review of the weaknesses of existing systems supposed to support complex cognitive tasks, the theoretical foundations of the proposed methodology are presented. These are the ergonomic work analysis of French ergonomists, cognitive engineering, cognitive anthropology–ethnomethodology and activity theory. The third section of the paper describes the generic ergonomic model, which constitutes a frame of reference useful for the analyst of the work situation to which the information technology system is addressed. In the fourth section, the proposed methodology is outlined, and in the fifth a case study demonstrating an application of the methodology is summarised. In the epilogue, the differences between the proposed methodological framework and other more conventional approaches are discussed. Finally, directions for future developments of the problem-driven approach are proposed.     

Extension of the Nicholls-Lee-Nichols algorithm to three dimensions

A new algorithm for clipping a line segment against a pyramid in E ³ is presented. This algorithm avoids computation of intersection points that are not end points of the output line segment. It also solves all cases more effectively. The performance of this algorithm is shown to be consistently better than that of existing algorithms, including the Cohen–Sutherland, Liang–Barsky, and Cyrus–Beck algorithms.     

Model checking: a hardware design perspective

Current practices in the verification of commercial hardware designs (digital, synchronous, and sequential semiconductors) are described. Recent advances in verification by the mathematical technique called model checking are described, and requirements for the successful application of model checking in commercial design are discussed.     

On the Right Track: Systematic Implementation of Ergonomics in Railway Network Control

At a time of change for the railway networks of Europe we have been developing tools to assess ergonomics aspects of railway network control. This is within the Railway Ergonomics Control Assessment Package (RECAP). Among the developments have been an audit instrument (REQUEST), tools to assess situation awareness (RESA) and staff loading (RELOAD), and workshops to predict opportunities for human error and organisational failure across rail network operations. This research is discussed with respect to the context of UK railway operations and the need for an expanding tradition of cognitive ergonomics fieldwork. From the findings we draw some conclusions about the roles filled by signallers, electrical controllers and zone controllers within a perspective of distributed cognitive/social networks.     

Display Design of Process Systems Based on Functional Modelling

The prevalent way to present information in industrial computer displays is by using piping and instrumentation diagrams. Such interfaces have sometimes resulted in difficulties for operators because they are not sufficient to fulfil their needs. A systematic way that supports interface design therefore has to be considered. In the new design framework, two questions must be answered. Firstly, a modelling method is required to describe a process system. Such a modelling method can define the information content that must be displayed in interfaces. Secondly, how to communicate this information to operators efficiently must be considered. This will provide a basis for determining the visual forms that the information should take. This study discusses interface design of human–machine systems from these two points of view. Based on other scholars’ work, a comprehensive set of functional primitives is summarised as a basis to build a functional model of process systems. A library of geometrical presentations for these primitives is then developed. To support effective interface design, the concept of ‘functional macro’ is introduced and a way to map functional model to interface display is illustrated by applying several principles. To make our ideas clear, a central heating system is taken as an example and its functional model is constructed. Based on the functional model, the information to be displayed is determined. Several functional macros are then found in the model and their corresponding displays are constructed. Finally, by using the library of geometrical presentations for functional primitives and functional macros, the display hierarchy of the central heating system is developed. Reusability of functional primitives makes it possible to use the methodology to support interface design of different process systems.     

Direct manipulation of FFD: efficient explicit solutions and decomposible multiple point constraints

Published online: 25 July 2001     

Goal-Oriented Requirements Engineering: A Unifying Framework

The study of contemporary requirements engineering (RE) methodologies indicates that modelling of organisational goals constitutes a central activity of the RE process. In particular, goals provide the rationale and drive the elaboration of the requirements that operationalise them. They also provide the criteria against which the completeness and correctness of the requirements specification is validated. In other words, requirements implement goals in the same way that programs implement design specifications. Despite the significance of goals in RE, research in the field is fragmented. No research has so far taken place in order to define the overall role that goals play in RE. This paper puts forward a unifying view of goal analysis in the context of RE. This allows the identification of similarities and differences between the different conceptions of goal used by different approaches and promotes the understanding of the overall role of goal analysis in RE. Based on this understanding the various approaches can be put together, thus leading to a stronger goal-driven RE framework that takes advantage of the contributions from the many streams of goal-oriented research.     

CATALOG: a system for detection and rendering of internal log defects using computer tomography

This paper describes the design and implementation of a machine vision system CATALOG for detection and classification of some important internal defects in hardwood logs via analysis of computer axial tomography (CT or CAT) images. The defect identification and classification in CATALOG consists of two phases. The first phase comprises of the segmentation of a single CT image slice, which results in the extraction of 2D defect-like regions from the CT image slice. The second phase comprises of the correlation of the 2D defect-like regions across CT image slices in order to establish 3D support. The segmentation algorithm for a single CT image is a complex form of multiple-value thresholding that exploits both, the prior knowledge of the wood structure within the log and the gray-level characteristics of the image. The algorithm for extraction of 2D defect-like regions in a single CT image first locates the pith of the log cross section, groups the pixels in the segmented image on the basis of their connectivity and classifies each 2D region as either a defect-like region or a defect-free region using shape, orientation and morphological features. Each 2D defect-like region is classified as a defect or non-defect via correlation across corresponding 2D defect-like regions in neighboring CT image slices. The 2D defect-like regions with adequate 3D support are labeled as true defects. The current version of CATALOG is capable of 3D reconstruction and rendering of the log and its internal defects from the individual CT image slices. CATALOG is also capable of simulation and rendering of key machining operations such as sawing and veneering on the 3D reconstructions of the logs. The current version of CATALOG is intended as a decision aid for sawyers and machinists in lumber mills and also as an interactive training tool for novice sawyers and machinists. Received: 1 August 1997 / Accepted: 25 August 1999     

A Location Model for Communicating and Processing of Context

Location is one of the most important elements of context in ubiquitous computing. In this paper we describe a location model, a spatial-aware communication model and an implementation of the models that exploit location for processing and communicating context. The location model presented describes a location tree, which contains human-readable semantic and geometric information about an organisation and a structure to describe the current location of an object or a context. The proposed system is dedicated to work not only on more powerful devices like handhelds, but also on small computer systems that are embedded into everyday artefact (making them a digital artefact). Model and design decisions were made on the basis of experiences from three prototype setups with several applications, which we built from 1998 to 2002. While running these prototypes we collected experiences from designers, implementers and users and formulated them as guidelines in this paper. All the prototype applications heavily use location information for providing their functionality. We found that location is not only of use as information for the application but also important for communicating context. In this paper we introduce the concept of spatial-aware communication where data is communicated based on the relative location of digital artefacts rather than on their identity. Correspondence to: Michael Biegl, Telecooperation Office (TecO), University of Karlsruhe, Vincenz-Prieβritz-Str. 1 D-76131 Karlsruhe, Germany. Email: michael@teco.edu     

Industrial bank check processing: the A2iA CheckReaderTM

This paper presents the current state of the A2iA CheckReaderTM – a commercial bank check recognition system. The system is designed to process the flow of payment documents associated with the check clearing process: checks themselves, deposit slips, money orders, cash tickets, etc. It processes document images and recognizes document amounts whatever their style and type – cursive, hand- or machine printed – expressed as numerals or as phrases. The system is adapted to read payment documents issued in different English- or French-speaking countries. It is currently in use at more than 100 large sites in five countries and processes daily over 10 million documents. The average read rate at the document level varies from 65 to 85% with a misread rate corresponding to that of a human operator (1%). Received October 13, 2000 / Revised December 4, 2000