The basic driver error: late detection

Over the past two or three decades we have been quite successful in reducing injuries of car occupants by the use of energy-absorbing techniques; but we have not been as successful in reducing the risks of having collisions. When drivers are asked why an accident occurred very often they claim that they saw the other road user too late to avoid collision. This paper discusses the basic road user error of failing to see another road user in time, why such errors happen, and how they can be reduced. A detection error is basic, because without detection no processing of information, no decision process including that road user, takes place. Among the many causes of detection error two of the more important are:

?a lapse of cognitive expectation, illustrated by the failure to scan for a particular class of road user, or to look in the appropriate direction;

?a difficulty with perceptual thresholds, illustrated by the failure to discern the relevant stimuli in lower levels of ambient illumination or in situations where vehicles approach in the peripheral visual field of road users.     

Types and tokens in road accident causation

Accidents are preceded by long histories containing multitudes of events that constitute promising targets for preventive action. These antecedent events can be classified into at least four groups that occur in this order: failure types; psychological precursors; unsafe acts; and breakdown of defences. It is argued that events directly preceding an accident, such as breakdown of defences and unsafe acts, are only haphazard tokens of the more permanent weaknesses within a system, called failure types. Elimination of a type will therefore have much more impact than the elimination of one or a few tokens. It is also argued that there exist only a limited number of failure types, which are responsible for all accidents. However, in the specific area of road accidents, it is not known which types cause most of the problems. Therefore, their relative importance can only be guessed. We guessed that hardware problems and maintenance are unimportant types; that education and regulations are of moderate importance; and that incompatible goals, conditions promoting unsafe behaviour, and organizational inadequacy are the types that cause most of the accidents. The latter therefore constitute the most promising targets for accident prevention.     

Relations between task and activity: elements for elaborating a framework for error analysis

The notion of error, when applied to an activity or the result of an activity, implies the notion of task: it expresses the deviation between the activity and the task being considered from an angle which is judged to be relevant. The task and the activity are the object of representations for the analyst (or specialist) and for the driver. Four representations are dealt with in this paper: the task and the activity for the specialist and the task and the activity for the driver. An interpretation is proposed for these tasks, and they are illustrated using some of the work already carried out in this field. The signification of deviations between these representations is then discussed, together with the advantage of studying these deviations in order to clarify error-producing mechanisms. Analysis in terms of task and activity raises methodological and practical problems which are touched upon; it does not exclude referring to psychological theoretical frameworks to which it is worthwhile linking it. This perspective raises questions which make it possible to enhance the study of errors: it could be completed at a later date by extending it to include other representation categories.     

Drivers' margins of safety considered as a focus for research on error

Accident statistics alone cannot provide a sound understanding of driver error, although they can assist the evaluation of remedial measures against errors and accidents. Roadside observation of drivers' errors can provide a valid index of their relative riskiness and of overall accident frequency, but only in route-specific applications. Field testing of hypotheses developed from theories of driver error is seen to be a far more valid and arguably more cost-effective method of improving road safety than relying on post hoc subjective assessments of error contributions to accident statistics. The distinction between driving task and envronmental factors which contribute to error production and those which constrain error correction is not well-documented in road accident studies. Yet it seems essential to make this distinction if we are to reach a sound understanding of research requirements in this field and hence identify and evaluate cost effective countermeasures against driver error. The bias which certain drivers appear to have towards inadequate safety margins is seen to provide an instructive theoretical framework for field studies of error production and error correction as contributory factors in traffic accident causation.     

The application of ANFIS prediction models for thermal error compensation on CNC machine tools

Thermal errors can have significant effects on CNC machine tool accuracy. The errors come from thermal deformations of the machine elements caused by heat sources within the machine structure or from ambient temperature change. The effect of temperature can be reduced by error avoidance or numerical compensation. The performance of a thermal error compensation system essentially depends upon the accuracy and robustness of the thermal error model and its input measurements. This paper first reviews different methods of designing thermal error models, before concentrating on employing an adaptive neuro fuzzy inference system (ANFIS) to design two thermal prediction models: ANFIS by dividing the data space into rectangular sub-spaces (ANFIS-Grid model) and ANFIS by using the fuzzy c-means clustering method (ANFIS-FCM model). Grey system theory is used to obtain the influence ranking of all possible temperature sensors on the thermal response of the machine structure. All the influence weightings of the thermal sensors are clustered into groups using the fuzzy c-means (FCM) clustering method, the groups then being further reduced by correlation analysis.A study of a small CNC milling machine is used to provide training data for the proposed models and then to provide independent testing data sets. The results of the study show that the ANFIS-FCM model is superior in terms of the accuracy of its predictive ability with the benefit of fewer rules. The residual value of the proposed model is smaller than ±4 μm. This combined methodology can provide improved accuracy and robustness of a thermal error compensation system.     

The Causes of Severe Accidents in the Andalusian Manufacturing Sector: The Role of Human Factors in Official Accident Investigations

This study examines the associations between worker characteristics and accident causation. It is based on the causes identified in the accidents investigated in the manufacturing sector of Andalusia (Spain) from 2004 to 2011 by the Labour Authority. The method used to assess the association between the categorical variables related to worker characteristics and types of causes is the phi coefficient test for each specific combination of categories of the variables. The main results are as follows. For young workers, the most likely causes include being assigned a task without the proper qualifications, using inappropriate work methods, and misunderstanding instructions. For low‐experience workers, the most likely cause is a lack of experience. For nonmanual qualified workers, the most likely causes include performing tasks without proper experience or personal protective equipment and performing nonroutine tasks. This differential causation found, depending on worker characteristics, can be used to design more effective preventive programs.     

Designing for transportation safety in the light of perception,attention, and mental models

Most recent research on error has concentrated on errors of planning, judgement, and action. This paper is concerned with errors in the acquisition of information which are caused by perceptual and attentional mechanisms. Failures to schedule attentional sampling of the environment will lead to accidents. Theoretical models exist for attention and for data acquisition. These models suggest how designers might approach human-machine systems so as to reduce error. A brief summary of the author's feelings about probabilistic risk assessment and related attempts to predict error is provided.     

The role of error in organizing behaviour

During recent years, the significance of the concept of human error has changed considerably. The reason for this has partly been an increasing interest of psychological research in the analysis of complex real-life phenomena, and partly the changes of modern work conditions caused by advanced information technology. Consequently, the topic of the present contribution is not a definition of the concept or a proper taxonomy. Instead, a review is given of two professional contexts for which the concept of error is important. Three cases of analysis of human-system interaction are reviewed: (1) traditional task analysis and human reliability estimation; (2) causal analysis of accidents after the fact; and, finally, (3) design of reliable work conditions in modern socio-technical systems. It is concluded that ‘;errors’ cannot be studied as a separate category of behaviour fragments; the object of study should be cognitive control of behaviour in complex environments.     

Human error and information systems failure: the case of the London ambulance service computer-aided despatch system project

Human error and systems failure have been two constructs that have become linked in many contexts. In this paper we particularly focus on the issue of failure in relation to that group of software systems known as information systems. We first review the extant theoretical and empirical work on this topic. Then we discuss one particular well-known case — that of the London ambulance service computer-aided despatch system (L) project — and use it as a particularly cogent example of the features of information systems failure. We maintain that the tendency to analyse information systems failure solely from a technological standpoint is limiting, that the nature of information systems failure is multi-faceted, and hence cannot be adequately understood purely in terms of the immediate problems of systems construction. Our purpose is also to use the generic material on IS failure and the specific details of this particular case study to critique the issues of safety, criticality, human error and risk in relation to systems not currently well considered in relation to these areas.     

Stability of the Kalman filter for continuous time output error systems

The stability of the Kalman filter is usually ensured by the uniform complete controllability regarding the process noise and the uniform complete observability of linear time varying systems. This paper studies the case of continuous time output error systems, in which the process noise is totally absent. The classical stability analysis assuming the controllability regarding the process noise is thus not applicable. It is shown in this paper that the uniform complete observability alone is sufficient to ensure the asymptotic stability of the Kalman filter applied to time varying output error systems, regardless of the stability of the considered systems themselves. The exponential or polynomial convergence of the Kalman filter is then further analyzed for particular cases of stable or unstable output error systems.     

Human error identification in human reliability assessment. Part 2: Detailed comparison of techniques

This is the second part of a two-part review of human error identification (HEI) approaches in human reliability assessment (HRA). Part 1 reviewed the probabilistic risk assessment (PRA) context in which HRA occurs, and then detailed 12 HEI techniques which have evolved in the field of HRA. Part 2 attempts to compare the way these techniques perform against a range of criteria relevant to HEI theoretical and empirical validity, and practical usefulness in applied HRA. It is hoped that these comparisons will help assessors in the selection of techniques for practical applications. The comparisons also point to research and development needs in the area of applied HEI.     

Analysis of time and frequency synchronization error for wireless systems using OFDM

1 Introduction The OFDM process includes the following two steps: splitting the high-rate serial bit stream into N parallel low-rate substreams, and modulating N substreams on N or-thogonal subcarriers by means of inverse fast Fourier transform (IFFT)[1―6]. Orthogonal superposition of subcarriers ensures the OFDM technique to have the higher bandwidth efficiency compared to other frequency division multiplexing[4]. Because OFDM can be arbitrarily combined with high-efficient digital m…     

Drivers' errors in,and out of,context

Error depends for its definition, commission, and the seriousness of its consequences on the circumstances in which it occurs. As such, it is argued, in this overview of a large number of contemporary papers on (driver) error, that an erroneous act is only a useful index of behaviour where the background to that act is properly understood. The role of error in the development of skill, and its relationship to accident causation and risk-taking is discussed from this point of view.     

Systems scenarios: a tool for facilitating the socio-technical design of work systems

Abstract

The socio-technical systems approach to design is well documented. Recognising the benefits of this approach, organisations are increasingly trying to work with systems, rather than their component parts. However, few tools attempt to analyse the complexity inherent in such systems, in ways that generate useful, practical outputs. In this paper, we outline the ‘System Scenarios Tool’ (SST), which is a novel, applied methodology that can be used by designers, end-users, consultants or researchers to help design or re-design work systems. The paper introduces the SST using examples of its application, and describes the potential benefits of its use, before reflecting on its limitations. Finally, we discuss potential opportunities for the tool, and describe sets of circumstances in which it might be used.

Practitioner Summary: The paper presents a novel, applied methodological tool, named the ‘Systems Scenarios Tool’. We believe this tool can be used as a point of reference by designers, end-users, consultants or researchers, to help design or re-design work systems. Included in the paper are two worked examples, demonstrating the tool’s application.     

Boundedness conditions for relative error in fast simulation of reliability of non-Markovian systems

A general model is considered that describes the functioning of non-Markovian systems. A new method is proposed for fast simulation of failure probability. The method allows obtaining estimates with a bounded relative error under some weak conditions. This method is used to evaluate the reliability of a specific class of systems. Numerical examples are considered. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 63–80, July–August 2006.     

Robustness design of fuzzy controllers for nonlinear multiple time-delay singularly perturbed systems: using dither as auxiliary

The stabilisation problem is considered in this study for nonlinear multiple time-delay singularly perturbed (NDSP) systems. First, a neural-network (NN) model is employed to approximate the reduced-order model of the NDSP plant. Then, a linear differential inclusion (LDI) state-space representation is established for the dynamics of the NN model. Based on this LDI state-space representation, a robustness design of fuzzy control is proposed to stabilise the NDSP system. If the designed fuzzy controller cannot stabilise the NDSP system, a dither (as an auxiliary of the fuzzy controller) is simultaneously introduced to stabilise the NDSP system. If the frequency of dither is high enough, the outputs of the dithered system and its corresponding mathematical model, the relaxed system, can be made as close as desired. This makes it possible to obtain a rigorous prediction of the stability of the dithered system by establishing that of the relaxed system. Finally, this study provides a numerical example with simulations to illustrate the concepts discussed throughout this article.     

Integration of task networks and cognitive user models using coloured Petri nets and its application to job design for safety and productivity

Changes of task demands due to unforeseen events and technological changes can cause variations in job design such as modifications to job procedures and task allocation. Failure to adapt to job design variations can lead to human errors that may have severe consequences for system safety. Existing techniques for task modelling cannot adequately model how task networks can be adapted to changing work conditions and task demands. Therefore, there is a need to integrate task networks with cognitive user models that indicate how operators process information, make decisions, or cope with suspended tasks and errors. The work described here presents a tool for integrating task and cognitive models using coloured Petri nets. The cognitive user model comprises two modules of attention management (selective and divided attention), a module of memory management of suspended tasks and a module of work organization. Performance Shaping Factors (e.g., workload, fatigue and mental-tracking load) are calculated at any point in time to take into account the context of work (e.g., competing activities, errors and suspended tasks). Different types of human error can be modelled for rule-based behaviours required in proceduralized work environments. Simulation analysis and formal analysis techniques can be applied to process control tasks to verify job procedures, workload management strategies and task allocation schemes in response to technological changes and unfamiliar events.     

Examining virtual reality as a platform for developing mental models of industrial systems

Industrial systems can be complex and not intuitive to perceive. Therefore, students in technology and engineering programs can benefit from developing mental models of industrial systems during their journey in college. However, more often than not, these students do not have access to industrial facilities; thus, developing mental models for systems is a challenge. This paper examines the merit of an Immersive Virtual Reality (IVR) framework application in creating proper mental models for industrial systems in technology and engineering students. Two IVR applications were developed. One IVR application afforded interaction with components of a prefabricated industrial cooling water system (CWVR). In the other application, students designed and built industrial systems with IVR (system designer VR [SDVR]). SDVR facilitated constructive-generative engagement. A group of 33 students was divided into two; one group (the Design, experimental group) was tasked with building a system with SDVR and interacting with the cooling water system in CWVR. The other group was tasked with directly interacting with the CWVR without building a system with SDVR (the Interaction, comparison group). Students' mental models of the cooling water system in CWVR were evaluated following completing the interaction experience with CWVR. The results demonstrate that the causal model notion of the mental model of the cooling water system was significantly higher in the Design, experimental group. The results suggest that designing a rich IVR application that facilitates constructive-generative engagements may carry merit in informing student mental models of complex technical concepts.     

Alarm-initiated activities: an analysis of alarm handlingby operators using text-based alarm systems in supervisory control systems

Alarms constitute a significant aspect of the operator-system interface in human supervisory control tasks: they have the potential to display information that is of critical importance to overall system safety and integrity. This paper considers the trend toward the use of visual display terminals for the presentation of alarms, specifically in the use of scrolling text displays. It is suggested that this form of information display may not best serve all aspects of alarm handling. To illustrate why this is so, an analysis of human alarm handling activities is presented. The focus on text-based displays and annunciators allows the authors to concentrate on a number of problems associated with the alarm design using a specific medium. From this discussion, the alarm initiated activities model is developed. By considering the activities that people engage in when dealing with alarms, an insight is offered into the information requirements that can be used to inform the design of alarm systems.