Impact of automated decision aids on performance,operator behaviour and workload in a simulated supervisory control task

In studies reporting automation effects on overall system performance and on the operator, the methods used to measure workload often did not appropriately reflect the complexity of this construct. The present study addresses the impact of automation on operator workload and behaviour in process control fault management. Workload effects were assessed with subjective, cardiovascular and secondary task performance indicators. Interactions with the interface of the process control simulation directed at gathering information and controlling the system were recorded. Automation made operators more efficient, allowing faster fault management with less information sampling and control actions. Subjective workload ratings were significantly lower in the assisted conditions as compared to manual, which was not reflected in cardiovascular and secondary task measures. Participants' information sampling activity did not differ between medium and high level of automation. Results suggest that participants paid constantly high attention to their task even with highly automated support.     

Effects of different physical workload parameters on mental workload and performance

The design and evaluation of an occupational task should include an assessment of mental workload, since excessive levels of mental workload can cause errors or delayed information processing. Physically demanding work that is performed concurrently with a cognitive task may impact mental workload by impairing mental processing or decreasing performance. The primary objective of this study was to determine whether there is a differential effect of various types of physical activity on both mental workload and cognitive performance. Objective and subjective assessment tools (heart rate variability and visual analog scale) were used as indicators of mental workload, while correct responses during an arithmetic task reflected levels of performance. Thirty participants (ages 18-24 years) performed a combination of tasks inducing both physical and mental workload. Type of physical effort, frequency of movement, and force exertion level were manipulated to alter the workload associated with the physical activity. Changes in subjective ratings generally corresponded to changes in both performance on the arithmetic task and objective mental workload assessment. Some discrepancies occurred at the highest physical force exertion level as participants perceived an increase in effort to maintain the same level of performance. Further research is needed to determine the force exertion threshold, beyond which the physical effort required interferes with mental workload and/or cognitive performance.

Relevance to industry

Technological advancements have increased the requirement for many workers to execute cognitive tasks concurrently with physical activity. When designing and evaluating such situations it is important to determine the interactive effects of these activities. A simple, uni-dimensional tool is suggested as a screening tool to identify situations requiring excessive or increased mental workload that many degrade performance or place additional stress on the individual.     

From field operators to central control room operators An integrated educational,research and consultancy approach

The Auebe food industry in the Netherlands has planned to modify their factories in view of the recovery of proteins out of potatoes. After modification of the first factory some human factor problems were recognized which led the project management to ask for ergonomic advice from an external team, consisting of the three authors.

The problem was approached in the following way. Firstly, two-day courses were set up to introduce ergonomics to the whole design team. The lectures were illustrated with examples of poor ergonomic design observed in the modified factory. During the course the participants were asked to suggest improvements for some of these situations.

The second step in approaching the problem was an investigation into the functioning of the operators in the modified factory. It appeared that most of the problems could be reduced to the incongruity between technical and social aspects in the original design. On the one hand there is a central control room operator which is supposed to have a complete overview of the process. On the other hand there are field operators each of which is responsible for its part of the plant. Communication is often difficult because of the distance, the noise, and ambiguities in the respective responsibilities of the operators. Comparison of the five shifts showed that reasonable functioning was difficult and in fact only possible if a friendly relation existed between operators in the control room and in the field. In addition the style of leadership of the shift supervisor had a strong influence.

In the third place the design team for the second factory was advised to let every operator supervise his part of the plant from a common control room. When he has to leave for observations or actions in the field one of his colleagues can take over. With some technical adjustments, such a system can be realized. Hence the final concept of automation can be characterized by geographical centralization and organizational decentralization.     

Effect of workload history on task performance

OBJECTIVE: This study investigated the effects of workload history (specifically, sudden shifts in workload) on performance. BACKGROUND: In 1993 the National Research Council identified workload transition as an important concern for human factors researchers. The study of workload history suggests that what an individual has been doing prior to a point in time has an effect on subsequent performance. One trend emerging from workload history studies is that a general decrement in performance is most likely to occur following a decrease in task demand. METHOD: The 198 participants were randomly assigned to a high-to-low or low-to-high condition. Participants performed a version of the Bakan Vigilance Task while correct responses, response times, and total errors were recorded. RESULTS: Results supported previous research suggesting a workload decrease results in a performance decrement. More importantly, this study reports that either a sudden increase or decrease could lead to a loss in accuracy and a slowing of response time in a longer time course. CONCLUSION: An explanation of the decrement is offered in terms of adaptation models. In addition, a follow-up study suggested that the decrement is a result of something inherent in the workload shift rather than an effect of fatigue. APPLICATION: Workload history (more specifically, a workload shift) has significant implications for many work environments. These implications are particularly salient in occupations where individuals are confronted with varying levels of workload demand, especially safety-sensitive occupations.     

Reducing cognitive workload of a computer-based procedure system

The use of procedure systems is an important safety management strategy in coping with emergency or abnormal situations in a process control system. With the digitalization trend in these complex and large-scale systems, most aspects of a process control system are also computerized. In addition to the primary tasks, operators now have to do extra secondary tasks when using the computerized systems. In this research, three design features aimed to reduce the cognitive workload are evaluated on our research platform, SimCBP and SimPlant. These two systems work in tandem to simulate a Computer-Based Procedure (CBP) system and a simplified nuclear power plant. From the results of the experiments, the design of embedded controls/parameters is found to be efficient but its counterpart has implications for the design of training materials. Navigation aid, although not statistically significant, is important because of the subjective responses and the need of cross-referencing. The simplified flowchart display format, like other researches on the use of this format, revealed mixed results. Implications and directions for future studies are also proposed.     

Level of automation effects on performance, situation awareness and workload in a dynamic control task

Various levels of automation (LOA) designating the degree of human operator and computer control were explored within the context of a dynamic control task as a means of improving overall human/machine performance. Automated systems have traditionally been explored as binary function allocations; either the human or the machine is assigned to a given task. More recently, intermediary levels of automation have been discussed as a means of maintaining operator involvement in system performance, leading to improvements in situation awareness and reductions in out-of-the-loop performance problems. A LOA taxonomy applicable to a wide range of psychomotor and cognitive tasks is presented here. The taxonomy comprises various schemes of generic control system function allocations. The functions allocated to a human operator and/or computer included monitoring displays, generating processing options, selecting an 'optimal' option and implementing that option. The impact of the LOA taxonomy was assessed within a dynamic and complex cognitive control task by measuring its effect on human/system performance, situation awareness and workload. Thirty subjects performed simulation trials involving various levels of automation. Several automation failures occurred and out-of-the-loop performance decrements were assessed. Results suggest that, in terms of performance, human operators benefit most from automation of the implementation portion of the task, but only under normal operating conditions; in contrast, removal of the operator from task implementation is detrimental to performance recovery if the automated system fails. Joint human/system option generation significantly degraded performance in comparison to human or automated option generation alone. Lower operator workload and higher situation awareness were observed under automation of the decision making portion of the task (i.e. selection of options), although human/system performance was only slightly improved. The implications of these findings for the design of automated systems are discussed.     

Analysis of the mental workload of city traffic control operators while monitoring traffic density: A field study

IntroductionIt is important to evaluate when and why the mental workload of operators increases during system operation. The city traffic control center (TCC) is a complex work system, and it is important to describe MW as a condition related to this. The purpose of this study is to evaluate the mental workload of operators while monitoring traffic loads in the city TCC.MethodsElectroencephalography and electrooculography data were collected from 16 operators while performing their daily work, in four conditions: resting state, low traffic density, high traffic density, and recovery. The Simplified-Subjective Workload Assessment Technique (S-SWAT) was used to evaluate the subjective workload of operators.ResultsThe findings indicate that operators experience a larger mental workload during high traffic density than during low traffic density (p < 0.001). TCC stressors led to significant changes in EEG bands, such as theta, alpha, and eye activity. Significant differences were observed for subjective ratings of MW (p < 0.001).ConclusionAlthough the working situations of TCC operators are repeated daily, their mental fatigue and stress level gradually increase, leading to deterioration in their mental health. It may be necessary periodically to monitor their mental health and to consider their organizational behavior during traffic density monitoring.Relevance to industrycomplex work systems have increased the requirement for many operators to conduct mental tasks in real work conditions such as city traffic density monitoring. When evaluating such workplaces, it is important to identify situations requiring increased mental workload that might impose additional stress on operators, decreasing their performance. Based on the results, the traffic control center director would be aware of the MW condition of the operators.     

Evaluation of operation state for operators in NPP Main control room using human behavior recognition

The cognitive state of the main control room (MCR) operator is the state of cognitive progress. This paper proposes a video analysis method to assist in the analysis of the operation state. A behavioral coding method is presented for the feature extraction of the MCR operator, and the time-line analysis method is used to continuously sample the operator’s postures and actions. OpenPose algorithm and ST-GCN method are used for the recognition of the operator’s behavior. The level of consciousness and cognition is analyzed based on the operator’s body language and used to evaluate the level of mental stress in performance shaping factors (PSF). A case is presented for the feasibility analysis of the operation state evaluation method. The results of the video analysis help recognize the operator’s bad or error behavior and improve the operator’s operation state.

     

Cooling-aware workload placement with performance constraints

Power optimization in data centers requires either to raise the temperature of the cold air supplied by the air conditioner or to reduce the power consumption of the servers by careful workload allocation. Both the approaches must satisfy a number of constraints, mainly temperature at the server intakes, which should not exceed a critical threshold, and capacity and response time requirements. To tackle these issues, we formulate an optimization problem in which the total data center power has to be minimized subject to the constraints imposed by performance requirements and thermal specifications of the servers. At the heart of the optimization problem is an analytical model which takes into account the complex relationship between the performance of servers, the allocation of workloads, the temperature of the air supplied by the conditioning unit and the heat distribution in the server room. For the easy evaluation of this relationship, we adopt a simplified yet accurate heat flow model, which we extensively validate using the data collected in several months of Computational Fluid Dynamics simulations. Extensive tests on 90 randomly generated scenarios suggest that the proposed coupled thermal-performance model can lead to a power saving of 21%. Finally, a case study is presented which is based on 1164 workload traces collected from the data center of a large telco operator. The cooling-aware workload placement suggests a saving of 8% with respect to a performance-only based strategy.     

Collaborative control for a robotic wheelchair: evaluation of performance, attention, and workload

Powered wheelchair users often struggle to drive safely and effectively and, in more critical cases, can only get around when accompanied by an assistant. To address these issues, we propose a collaborative control mechanism that assists users as and when they require help. The system uses a multiple-hypothesis method to predict the driver's intentions and, if necessary, adjusts the control signals to achieve the desired goal safely. The main emphasis of this paper is on a comprehensive evaluation, where we not only look at the system performance but also, perhaps more importantly, characterize the user performance in an experiment that combines eye tracking with a secondary task. Without assistance, participants experienced multiple collisions while driving around the predefined route. Conversely, when they were assisted by the collaborative controller, not only did they drive more safely but also they were able to pay less attention to their driving, resulting in a reduced cognitive workload. We discuss the importance of these results and their implications for other applications of shared control, such as brain-machine interfaces, where it could be used to compensate for both the low frequency and the low resolution of the user input.     

Task workload and cognitive abilities in dynamic decision making

Researchers often treat workload as a task-dependent variable. To evaluate the effect of workload on individuals' performance, researchers commonly use several methods, such as varying the complexity or number of tasks that test participants are asked to handle or placing individuals under time constraints. Only rarely have researchers investigated workload as a variable dependent on individuals' cognitive abilities. This study investigated workload during dynamic decision making in terms of its dependence on both task workload and cognitive abilities. The findings demonstrate detrimental effects of both high task workload and low cognitive abilities. Further, the results show that high workload is more detrimental in individuals with low cognitive abilities than in individuals with high cognitive abilities. Potential applications of this research include the design of new workload studies and new training protocols in which psychometric tests are used.     

Effects of control order,augmented feedback,input device and practice on tracking performance and perceived workload

Virtual interfaces to advanced human-machine systems will present operators with a variety of perceptual-motor challenges. To inform the virtual interface design processes, the present experiments examined the effects of track order, level of knowledge of performance, type of control device, and the extent of practice on tracking performance and associated mental workload. Tracking was assessed by root mean square error. Subjective workload was measured using both the NASA Task Load Index (TLX) and the Subjective Workload Assessment Technique (SWAT). Results indicated non-linear effects, where tracking error and subjective workload both increased non-proportionally with track order. Trackball use resulted in more accurate performance and was judged to be of lower subjective workload than input using a mouse. Augmented knowledge of performance had little effect on either performance or workload. There were a number of interactions affecting performance that were replicated in perceived workload. Over acquisition trials, second-order tracking exhibited continuous improvement. This capability was retained even after a 30-day rest interval. Decrease in workload followed performance improvement in both initial acquisition and subsequent retention phases. The two subjective workload scales were essentially equivalent in terms of their sensitivity to task manipulations. These results support the direct association between workload and performance and confirms the use of workload in helping to evaluate the influence of diverse task-related demands. The implications for the design of virtual interfaces to real-world systems are examined in the light of these findings.     

DQN-based OpenCL workload partition for performance optimization

The Journal of Supercomputing - This paper proposes a deep Q network (DQN)-based method for the workload partition problem in OpenCL. The DQN, a reinforcement learning algorithm, optimizes the...     

Impact of workload and system parameters on next generation clusterscheduling mechanisms

Scheduling of processes onto processors of a parallel machine has always been an important and challenging area of research. The issue becomes even more crucial and difficult as we gradually progress to the use of off-the-shelf workstations, operating systems, and high bandwidth networks to build cost-effective clusters for demanding applications. Clusters are gaining acceptance not just in scientific applications that need supercomputing power, but also in domains such as databases, web service, and multimedia which place diverse Quality-of-Service (QoS) demands on the underlying system. Further, these applications have diverse characteristics in terms of their computation, communication, and I/O requirements, making conventional parallel scheduling solutions, such as space sharing or gang scheduling, unattractive. At the same time, leaving it to the native operating system of each node to make decisions independently can lead to ineffective use of system resources whenever there is communication. Instead, an emerging class of dynamic coscheduling mechanisms that attempt to take remedial actions to guide the system toward coscheduled execution without requiring explicit synchronization offers a lot of promise for cluster scheduling. Using a detailed simulator, this paper evaluates the pros and cons of different dynamic coscheduling alternatives while comparing their advantages over traditional gang scheduling (and not performing any coordinated scheduling at all). The impact of dynamic job arrivals, job characteristics, and different system parameters on these alternatives is evaluated in terms of several performance criteria. In addition, heuristics to enhance one of the alternatives even further are identified, classified, and evaluated. It is shown that these heuristics can significantly outperform the other alternatives over a spectrum of workload and system parameters and is thus a much better option for clusters than conventional gang scheduling     

Impact of speech presentation level on cognitive task performance: implications for auditory display design

Speech displays and verbal response technologies are increasingly being used in complex, high workload environments that require the simultaneous performance of visual and manual tasks. Examples of such environments include the flight decks of modern aircraft, advanced transport telematics systems providing invehicle route guidance and navigational information and mobile communication equipment in emergency and public safety vehicles. Previous research has established an optimum range for speech intelligibility. However, the potential for variations in presentation levels within this range to affect attentional resources and cognitive processing of speech material has not been examined previously. Results of the current experimental investigation demonstrate that as presentation level increases within this 'optimum' range, participants in high workload situations make fewer sentence-processing errors and generally respond faster. Processing errors were more sensitive to changes in presentation level than were measures of reaction time. Implications of these findings are discussed in terms of their application for the design of speech communications displays in complex multi-task environments.     

Impact of speech presentation level on cognitive task performance: implications for auditory display design

Speech displays and verbal response technologies are increasingly being used in complex, high workload environments that require the simultaneous performance of visual and manual tasks. Examples of such environments include the flight decks of modern aircraft, advanced transport telematics systems providing in-vehicle route guidance and navigational information and mobile communication equipment in emergency and public safety vehicles. Previous research has established an optimum range for speech intelligibility. However, the potential for variations in presentation levels within this range to affect attentional resources and cognitive processing of speech material has not been examined previously. Results of the current experimental investigation demonstrate that as presentation level increases within this ‘optimum’ range, participants in high workload situations make fewer sentence-processing errors and generally respond faster. Processing errors were more sensitive to changes in presentation level than were measures of reaction time. Implications of these findings are discussed in terms of their application for the design of speech communications displays in complex multi-task environments.     

Impact of human operators on communication network dependability

There is a scarcity of scientific literature about the characteristics of the control work and its demands in the critical domain of telecommunication. The motivation of the paper is to shed light on the context and content of the human operators’ work in maintaining the dependability of telecommunication networks. A case study was accomplished in a large telecommunication company. The research focused on clarifying the impact of human operators on the dependability of telecommunication network. Interviews confirmed earlier assumption among members of the communication network operations (CNO) community that the human operator has an important impact on the network dependability. Specific sources of errors in daily work were identified and strategies of avoiding erroneous action were described. By utilising core-task analysis and modelling approach, we defined generic control demands of the CNO work domain, and operators’ ways of coping with these demands. Regarding human dependability of communication network operations, a combination of resilient and proactive ways of acting is needed. Due to daily changes in the network and the continuous increase of its complexity, specifically change management on both organisational and work practice levels was required. The study is restricted to one Finnish telecommunication company, which limits possible empirical generalisation of the findings.