International Journal of Human Factors Modelling and Simulation (13 papers in press)
Predictive simulation of human circular gait
by Yujiang Xiang, Paul Owens
Abstract: This paper presents a one-stride formulation to simulate human circular gait using a skeletal model. The formulation is based on a previously presented asymmetric walking formulation (Xiang et al. 2011). The circular walking motion is analyzed using the proposed motion prediction method. The global moments due to active forces are decomposed at pelvis to retrieve correct zero moment point (ZMP) and ground reaction forces (GRF). The predicted GRF are compared to those of straight walk. Some insights on human circular gait are obtained. It is found that the transverse GRF of outer step is much larger than that of inner step for a circular gait, and the turning motion has larger jerk for the ZMP trajectory compared to the straight walk, i.e., it has more potential to fall. In addition, the straight walking is validated with the experimental data, and the peak knee joint angle values of the circular gait are compared with the data in the literature.
Keywords: Circular gait; Jerk; Turning; Fall; Optimization.
Projection of Anthropometric Correlation for Virtual Population Modelling
by John Rasmussen, Rasmus Plenge Waagepetersen, Kasper Pihl Rasmussen
Abstract: A new statistical method for generation of virtual populations based on anthropometric parameters is developed. The method addresses the problem that most anthropometric information is reported in terms of summary data such as means and standard deviations only, while the underlying raw data, and therefore the correlations between parameters, are not accessible. This problem is solved by projecting correlation from a data set for which raw data are provided.rnThe method is tested and validated by generation of pseudo females from males in the ANSUR anthropometric dataset. Results show that the statistical congruency of the pseudo population with an actual female population is more than 90\% for more than 90\% of the possible parameter pairs. The method represents a new opportunity to generate virtual populations for specific geographic regions and ethnicities based on summary data only.
Keywords: Anthropometry; Human factors; Statistics; Principal component analysis; PCA; Correlation.
Ergonomic Risk Assessment in DHM tools Employing Motion Data Exposure Calculation and Comparison to Epidemiological Reference Data
by Ida-Märta Rhén, Mikael Forsman, Roland Örtengren, Dan Högberg, Ali Keyvani, Dan Lämkull, Lars Hanson
Abstract: Digital human modelling (DHM) allows ergonomic risk assessment to be performed at early stages of design and development. Such assessment is typically based on observational methods, which do not take advantage of the potential of DHM tools to provide precise posture and motion data. This paper describes and illustrates an alternative assessment approach employing DHM tools, inspired by risk assessment based on direct measurements. A literature survey established a reference database of epidemiological associations between exposure and wrist-related disorders. This approach is illustrated by a DHM simulation of a car assembly task. Wrist posture and motion were simulated and compared to the database, predicting the prevalence of work-related musculoskeletal disorders on the basis of direct measurements.
Keywords: biomechanical load; digital human modelling; wrist; repetitive strain injuries; direct measurements; exposure-response relationship; work-related musculoskeletal disorders; physical workload.
Driver Response to Steering Perturbations: Mechanical Arm Admittance and Grip Pressure
by Antonin Joly, Rencheng Zheng, Kimihiko Nakano
Abstract: The monitoring of the driver condition has been studied extensively to develop advanced driver assistance systems aimed at reducing the driving burden. Whereas, the available methods for acquiring information about the condition of the driver are limited to the analysis of driving performances and the monitoring of the visual behaviour via cameras. The lack of approaches for monitoring the condition of driver is caused by the nature of the sensor, as nonintrusive methods are largely preferred when designing an assistance system. In this study, we propose to estimate the condition of the drivers via the relationship between mechanical arm admittance, which provides the dynamics of the arm through a relation between a force input and a position output, and grip pressure of the drivers in the frequency range of [0.1 0.5 Hz]. The effects of perturbation amplitude and between subject variations were investigated. A total of ten participants performed driving simulations to determine these characteristics. Participants were instructed to firmly grab the steering wheel in a ten-to-two position while wearing grip sensors gloves. Experimental results show that mechanical arm admittance is a power function of the grip pressure of the participants. A non-linear response was obtained with larger admittance with larger perturbation amplitudes.
Keywords: human factors; driver monitoring; mechanical arm admittance; grip pressure.
A Quantitative Assessment of Variations in the Palm Surface Area as a Percentage of Total Body Surface Area within the General Population
by Tina C. Liu, Rajan Bhatt, Kimberly D. Farrell, Stephen Baek, Yuk Ming Liu, Karim Abdel-Malek, Jasbir Arora
Abstract: Healthcare professionals who treat burn patients determine fluid requirements for resuscitation based on an estimation of burned body surface area (BBSA) as a percentage of total body surface area (TBSA). Hence, it is important to get an accurate assessment of these values. An overestimation or underestimation of the BBSA percentage can lead to medical complications, negatively affecting a patients quality of care. Conventional methods to estimate the BBSA percentage include segmenting the three dimensional body surface into a two dimensional burn chart or estimating the area relative to the palm of the hand with the assumption that the palm represents 1% of the TBSA. These methods introduce inaccuracies due to unreliable assumptions and estimations. For example, methods that rely on a burn chart overgeneralize that the body type of a patient to fit the established body sections in the chart, and methods that use the palm of the hand rely on incorrect assumptions regarding the palm surface area. This paper demonstrates specifically that the assumption that a patients palm can be estimated as 1% of the TBSA is not reliable. In addition, it summarizes, evaluates, and quantifies these inaccuracies, and compares and contrasts the variations for different genders.
Keywords: palm surface area; burn size; body surface area; hand surface area; burn area estimation.
Pedestrian Simulators for Traffic Research: State of the Art and Future of a Motion Lab
by Ilja Feldstein, Christian Lehsing, Andre Dietrich, Klaus Bengler
Abstract: While classical driving simulators have for decades been a valuable tool for the investigation of human behavior and validation of advanced driver assistance systems (ADAS), the development of pedestrian simulators is still in its beginning stages. However, with an increasing complexity of ADAS, it is not sufficient anymore to evaluate those uniquely from the perspective of a driver using driving simulators. Mainly based on motion tracking and virtual reality (VR) technology, pedestrian simulators are used to investigate human behavior from the pedestrian perspective especially in urban traffic scenarios in a reproducible, safe, and cost-efficient way. They enable research on pedestrian behavior in potentially hazardous traffic situations (e.g., crossing scenarios). Becoming an increasingly valuable tool for car manufacturers and original equipment manufacturers (OEMs) in the development process of ADAS, e.g., pedestrian detection and avoidance, the importance of these simulators will grow given the emergence of autonomous and silent cars (e.g., electric vehicles) in the near future.
This paper will help researchers starting off in this research field to get a general idea and also some primary technological input. It explains the potential and possible areas of application of this particular simulator paradigm and gives a detailed overview of some of the technologically most advanced virtual reality simulators used by various research institutes for pedestrian investigations. More specifically, the technology used in the pedestrian simulator developed at the Technical University of Munich is thoroughly described, and components such as head-mounted display, motion capture system, and simulation software are discussed.
Finally, the approach of linking a driving simulator to a pedestrian simulator so that both participants can meet simultaneously in the same virtual environment is introduced. This promising approach facilitates social interaction regarding mutual behavior adaption in the virtual environment of a driving simulation. Experimental evaluations that use this multiple simulator setup can address a broader variety of research questions in traffic-related areas where the interaction between different classes of road users can be assessed as opposed to the reaction to programmed agents used in conventional driving simulators. Regarding data validity, especially in urban scenarios where interaction plays a significant role, the approach of two human beings encountering each other in a safe and reproducible traffic environment shows its potential.
Keywords: pedestrian simulator; virtual reality (VR); head-mounted display (HMD); motion capture; road crossing investigation; linked simulation; social interaction in traffic.
Special Issue on: Quantifying Human Factors Towards Analytical Human-in-the-Loop
Relevance of Air-Traffic Controllers Tacit Knowledge in Enhancing Air-Traffic Control and Safety in Ghanaian Airspace
by Mohammed-Aminu Sanda
Abstract: This study explored the cognitive and workload demands of air-traffic control activity and the tacit knowledge used by air-traffic controllers to cope with the stress associated with such demands in ensuring air-traffic safety in Ghana. Guided by the systemic structural theory of activity, it was found that the air-traffic control activity entailed several challenges, whereby variety of tasks demand significant cognitive efforts, requiring use of tacit knowledge by the air-traffic controllers to augment their operational performances in order to enhance air-traffic safety. It is concluded that the functional efficiency and effectiveness of human work in the air-traffic control activity can be enhanced by understanding and integrating air-traffic controllers tacit knowledge in the job design. By implication, this understanding can be incorporated in designing an operator-efficient and effective work system for air-traffic controllers in order enhance their management capacity of air-traffic safety in Ghana.
Keywords: Air-traffic control activity; Air-traffic controller; Tacit knowledge; Air-traffic safety; Ghana.
Bayesian Network for the Prediction of Situation Awareness Errors
by Jean-Marc Salotti
Abstract: A new method is proposed to predict situation awareness errors in training simulations. It is based on Endsleys model and the 8 situation awareness demons that she described. The predictions are determined thanks to a Bayesian network and Noisy-Or nodes. A maturity model is introduced to come up with the initialization problem. The NASA behavioural competency model is also used to take individual differences into account.
Keywords: Situation awareness; Bayesian network; noisy-or; behavioural competency.
Extracting Typical Incident Patterns from Text Data
by Toru Nakata
Abstract: To prevent industrial incidents, it is important to learn why and how past incidents occurred and escalated. Information regarding accidents is recorded primarily in natural language texts, which are not convenient for analysing incident progression. This paper proposes a method for recognising the typical flow of events in a large set of text reports. Our method transforms each sentence in reports about industrial incidents into a vector (bag-of-words) to facilitate the detection of similar contexts and stories. In this way, we can recognise the typical progression of accidents.
Keywords: incident analysis; text mining; bag of words; modelling; safetyrnengineering.
Quantifying the roles of human error (HE) and his/her state-of-health (SH): use of the double-exponential-probability-distribution-function (DEPDF)
by Ephraim Suhir
Abstract: The probabilistic predictive modeling (PPM) approach in human-in-the-loop (HITL) related aerospace problems enables one to predict, quantify, assure and even specify the probability of the outcome of an aerospace mission or a situation, when the performance of a never-perfect human, never-100%-reliable instrumentation (equipment), never absolutely predictable response of the object of control (aero- or spacecraft), uncertain and often harsh environment, as well as the interaction (interfaces) of these uncertainties, contribute jointly to the likelihood of such an outcome. As to the human factor (HF), it includes (but might not be limited to) two major aspects: possible human-error (HE) and his/her state-of-health (SH). While the reliability of the navigation instrumentation (equipment) could be evaluated using the well known suitable and more or less well established modeling means, the role of the HF could be considered, when quantification of the human role in the HITL effort is critical, by using the double-exponential-probability-distribution-function (DEPDF). In the previously published paper suggesting the use of such a distribution the role of the HE aspect of the HF was considered indirectly, through the level and the role of the human capacity factor (HCF). In this analysis the HE characteristic is introduced directly. This has been done assuming and suggesting that mean-time-to-failure (MTTF) of a human, when performing his/her professional duties, can be used as an adequate criterion of his/her failure-free performance: when this performance is error-free, the MTTF, although never zero, is infinitely long, and is very short in an opposite extreme case. The suggested DEPDF considers that both high MTTF and high HCF result in a higher probability of a failure-free human performance, but, unlike in the previously suggested DEPDF, enables one to separate the MTTF as the direct HF characteristic from other critical HCF features, such as, e.g., level of training, ability to operate under time pressure, mature thinking, etc. Similarly, the suggested state-of-health (SH) characteristic is separated in the suggested DRPDF formulation from the general mental workload (MWL) level to emphasize the importance of human SH that could affect his/her perception of the otherwise more or less objective MWL. In any event, the major objective of this paper is to generate thinking on how to advance the state-of-the-art in the todays aerospace human psychology, and, particularly, on how to quantify, by both modeling and experimentation, the HITL related effort, when the HF and equipment/instrumentation performance contribute jointly to the outcome (success and safety) of an aerospace mission or an extraordinary situation. Future work will be aimed predominantly at these efforts.
Keywords: human factor; reliability; aerospace engineering; avionics psychology; mission success and safety.
Morphological analysis in systemic-structural activity theory
by Gregory Bedny, Inna Bedny
Abstract: Currently the most common ergonomic experiments often don\'t have sufficient external validity. To overcome this negative factor it\'s important to develop formalized and analytical methods of studying human performance. In this work authors describe the morphological analysis of tasks offered by Systemic-Structural Activity Theory. Morphological analysis is a general method for non-quantified modeling of various objects. In Systemic-Structural Activity Theory it is a systemic qualitative description of the structure of designed and often not yet existing activity. Such morphological analysis facilitates farther quantitative analysis of the operators\' performance. It allows not just to optimize the methods of performance but also to improve equipment and HCI design.
Keywords: Systemic-Structural Activity Theory; experimental and analytical methods of study; qualitative systemic analysis; Morphological analysis;.
Human Performance Modelling for Image Analyst Decision Support Design
by Holly Zelnio, Mary Fendley
Abstract: The critical element in human in the loop military systems, image analysts must make decisions quickly. Improving analyst performance remains a priority of military leadership. This model, and previous findings of synthetic aperture radar (SAR) human in the loop experiments were used to design and test a decision support system (DSS) for analyzing electro-optical (EO) and SAR images. Cognitive task analysis was used to develop an operator function model of the analyst classification task. Findings indicate that a DSS increased decision confidence and time. Interestingly, analyst trust is higher when employed in the analysis of EO images, yet aided performance was more accurate on SAR images. As uncovered through human performance modelling, analyst accuracy, confidence and time aided by a trusted DSS is crucial to analyst performance. These results suggest while the developed DSS improved analyst confidence and accuracy, it did not do so while concurrently decreasing task time.
Keywords: human in the loop; decision support system; DSS; synthetic aperture radar; SAR; analyst classification; analyst performance; cognitive bias; operator function model; OFM; confidence; trust.
Towards a Framework for Reliability and Safety Analysis of Complex Space Missions
by John Evans, Frank Groen, Lui Wang, Shira Okon, Rebekah Austin, Arthur Witulski, Nagabhushan Mahadevan, Steven Cornford, Martin Feather, Nancy Lindsey
Abstract: Long duration and complex mission scenarios are characteristics of NASAs human exploration of Mars, and will provide unprecedented challenges. Systems reliability and safety will become increasingly demanding and management of uncertainty will be increasingly important. NASAs current pioneering strategy recognizes and relies upon assurance of crew and asset safety. In this regard, flexibility to develop and innovate in the emergence of new design environments and methodologies, encompassing modeling of complex systems, is essential to meet the challenges
Keywords: Model Based Mission Assurance; Model Based Systems Engineering; Assurance Case; Failure Modes and Effects Analysis; Fault Tree Analayis; Bayesian Nets; Reliability.