Two experiments are described, in the first of which subjects rank-ordered, and in the second subjectively quantified, a set of sentences in the form of rough quantifiers (eg, "a large part of ..., etc"). It was found that there was remarkably high concordance between subjects in rank ordering, but that numerical equivalents are notably more variable. Some recommendations are made for improving verbal communication.
This article discusses the limits within which the working environment should be maintained. The limits are listed in a table. When the limits are exceeded, there is likely to be a fall in efficiency, an increased susceptibility to accidents, and a reduced attendance at work.
In view of the problems facing human factors specialists, how do they feel about the present status of their profession and its future prospects? A small number of highly qualified practitioners were asked their opinions about various questions which have been discussed in two previous articles in this series. In a 1979 survey they agreed that designers rarely solicit human engineering assistance and resist human engineering inputs; that the behavioural research reported in the literature is of relatively little value in system development work; that government does not monitor human engineering in system development very effectively. In a survey performed for this article, specialists were generally optimistic about the future of their discipline but concerned about government funding and job support under the Reagan administration; felt that engineering and public acceptance of human factors is increasing slowly; were ambivalent about any significant improvement in methodology; and considered that the scope of human factors work would expand in the future. The need for human factors should increase in the future and the future looks reasonably promising if specialists learn to deal with a rapidly changing technological environment.
For the results of ergonomic research to be of value it must be validated on the shop floor and this involves field experiments. The aim of this article is to formulate some generally applicable ideas on the problems and strategies involved in field research. The points to be made derive from experience of research in the field extending over some 20 years. It is hoped that a realistic assessment of the problems will help contribute to their solution.
The performance of man, for a given level of ability, will be affected by his hygro-thermal, electro-ionic, visual and psychological microclimates. This paper presents the results of studies which demonstrate the effect of the hygro-thermal micro-climate on worker performance. The effects of the other micro-climates on worker performance are also discussed. For tasks with mainly physical activity performance depends upon metabolic heat. For tasks with mainly psychological activities there have, until now, been no specified criteria for determining the effects of the environment on performance. Consideration of the results of studies conducted in working environments clearly shows that environmental conditions can effect the efficiency of workers and hence that there are sound economic arguments for optimising working conditions.
Ergonomics has the aim of promoting efficiency, comfort and health. In research and practice, efficiency and comfort are generally the main criteria; one assumes too easily that the health promoting effect goes parallel. Disease of the musculoskeletal system are a major source of health related absenteeism in industry. A study revealed that the ergonomic situation of the work place is connected, in many cases, with the occurrence of physical symptoms of these diseases. Bad design of machines, tools, furniture and other equipment from an ergonomic point of view has a great influence on the state of health of the users. To improve this situation more integration of engineering and human sciences is needed. Education of engineers in ergonomic principles is therefore of great importance.
The application of Human Factors or ergonomics principles to American system development occurs in a highly unstructured, problem-solving environment in which inputs compete with each other for acceptance. Factors determining whether human engineering inputs will be accepted include: the specification (or lack thereof) of personnel performance requirements; the advantages supplied by the human engineering recommendation; the costs involved in implementing it; the funding supplied by the customer for the new system; and his oversight of human engineering efforts. Human Factors efforts are required in at least five of the six major phases of system development: System Planning; Predesign; Detail Design; Production; Test and Evaluation; and Operations. Each phase introduces behavioural questions that must be answered if the system is to be designed properly. Each question demands specific techniques and skills of the human engineer.
This note describes the results of research into anthropometric measurement of children in Mazandaran province/Iran. Seventeen anthropometric measurements were taken from 1758 randomly selected subjects. Data obtained were used in school furniture design.
In 2006-2008 we performed a case study for the purpose of assessing the industrial application of the seven part Control Centre (CC) design standard ISO 11064 to identify positive and negative experiences among stakeholders in the Norwegian petroleum sector. We mainly focussed on ISO 11064 Part 1, because this was the most commonly used among the identified stakeholders. ISO 11064 is generally appreciated and applied in the industry, but we did observe a significant variance in use between the different parts of the standard. We also identified potential areas for improvements, like scope and application adaptation. Thus we suggest a more goal-based approach based on one normative part only.
Estimated insulation (Icl) of clothing worn by workers daily exposed to air temperatures between 0 and 15 degrees C was compared with the corresponding insulation calculated for thermal neutrality using the IREQ-model (IREQneutral, ISO/TR 11079). The goal was to determine possible limitations of the applicability of the IREQ-model and to stress to necessities and possibilities to improve the model. Sixteen female and 59 male workers (16-56 yr) were monitored during their work. According to their cold stress at the workplace they were allocated to three groups (33 persons were exposed to constant temperatures of more than 10 degrees C, 32 to less than 10 degrees C, and 10 persons experienced frequent temperature changes of 13 degrees C. Another categorization concerned workload (8 persons worked at metabolic rates of less than 100 W/m2, 50 persons worked at 101-164 W/m2, and 17 worked at more than 165 W/m2, respectively). The analysis of the differences between estimated worn insulation (Icl) and calculated IREQneutral revealed that the IREQ-model applies for air temperatures up to 15 degrees C and for temperature changes of 13 degrees C (at least) but needs to be improved with respect to gender. The IREQ model does not apply sufficiently for high and largely varying workloads (165 W/m2 and more). However, these situations are beyond the currently available possibilities to protect workers adequately with conventional clothing material. A suitable short-term measure is a more even work flow by avoiding activities with very high and low metabolic rates.
The ergonomics aspects of the design of a domestic telephone are outlined as a case study. The main usage points investigated were: handset relationship to ear and mouth together with adequate finger clearance at the cheek; general comfort when picking up and holding the handset; replacing the handset correctly in order to operate the hook-switch; establishing an acceptable compromise for dial and keypad angle at 15 degrees ; and devising a wall mounted unit.
120 shift rotas of the police were collected and analysed. The frequency distribution of the shift cycles, the duration of shifts, the start and end of shifts, the maximal number of consecutive night shifts, as well as the frequency of different kinds of free weekends, were determined. The shift systems are compared with recommendations for the design of shift rotas which are based on physiological, psychological and social criteria.
In this study, we validated comfort and limit temperatures of four sleeping bags with different levels of insulation defined according to EN 13537. Six male subjects and four female subjects underwent totally 20 two-hour exposures in four sleeping bags at four intended testing temperatures: 11.2, 3.8, 2.1 and -9.0 °C. The subjective perceptions and physiological responses of these subjects were reported and analyzed. It was found that the EN 13537 defined comfort temperature and limit temperature were underestimated for sleeping bags MA3, HAG and MAM. The predictions are so conservative that further revision may be required to meet the requirements of both manufacturers and consumers. In contrast, for the sleeping bag MA0 with a low level of insulation, the limit temperature defined by EN 13537 was slightly overestimated. In addition, two individual case studies (-28.0 and -32.0 °C) demonstrated that low toe temperatures were widely observed among the male and female subjects, although the mean skin temperatures were almost within the thermoneutrality range (32.0-34.0 °C). It seems that the IREQ model (ISO 11079) overestimated both the comfort and limit temperatures of the sleeping bags. Finally, traditional sleeping bags may be required to be re-designed to provide consumers both whole body comfort as well as local thermal comfort at feet/toes or users need to be made aware of the higher need for their insulation.
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In this chapter, various factors are considered briefly which are relevant to the general problem of work organisation, including work study, biological work measurement, work-rest schedules, operator variability, learning, shiftwork and human ageing.
A description is given of the International Standards Organisation with particular reference to Technical Committee 159 which deals with ergonomics. The Subcommittees and Working Groups are covered and the paper concludes with a look at the future directions of standards work.
This paper will explore and discuss the spatial recommendations, and the supporting research evidence, for in-patient bed spaces. The bed space is defined as the area around an individual bed that offers privacy either as a single room or a cubicle. A document review from 1866 to 2008 found that the recommendations for bed space width had increased by 1.1m over 44 years, from 2.4m (1961) to 3.6m (2005). However, a small scoping project in the United Kingdom revealed that the bed space areas in recently built hospitals (medical and surgical wards) were less than the recommendations. These data are discussed in the context of healthcare Evidence-Based Design to consider three patient safety issues (falls, noise and infection transmission). A role for ergonomics is proposed in the design, planning and evaluation stages as a methodology bridge between clinicians and architects (participatory ergonomics) and as an expert adviser to address design issues of patient safety and environmental functionality.
This article relates the beginning of ergonomics research at Bisra and how it subsequently evolved. Examples are given of experiments undertaken by the Human Factors Section to solve problems relating to the steel industry. A future article will deal with the human factors work at Bisra from 1964-1971.
This second article about the work of the Bisra Human Factors Section relates to changes in the Section's activity following the renationalisation of the industry and describes some of the present work and plans for the future.
This paper, the first of two, gives an account of legislation and regulations made in the USA requiring hazardous pharmaceutical and other household products to be packaged in child-resistant containers. Human factors test procedures and standards, in terms of which child-resistance is defined, are described. An account is given of those hazardous substances which regulations in the USA require should be packed in child-resistant containers. The paper concludes with a description of the effects of the regulations and of child-resistant containers in reducing mortality and morbidity associated with the ingestion of poisonous substances, particularly aspirin, in the USA. The second paper will briefly describe the effects of legislation made in England and Wales requiring certain pharmaceutical products to be packaged in child-resistant containers. It will also give an account of experiments, carried out in England and Sweden, describing the difficulties and inconvenience which the elderly and disabled experience when they attempt to use such containers.
This article presents a brief overview of the research performed at tge Human Factors Division of The University of Michigan Transportation Research Institute between 1977 and 1986. The focus of the research has been on human factors (ergonomics) aspects of road safety. Specifically, the research has dealt with the following issues: vehicle headlighting, vehicle rear lighting and signalling, vehicle displays and controls, vehicle components, conspicuity of vehicles, legibility of traffic signs and licence plates, driver reaction time, driver performance, stopping sight distance, driver seated position, individual differences (drivers with disabilities, older drivers), methods for measuring blood alcohol concentration, societal violence and traffic accidents, cross-cultural comparison of driver risk-perception, and theoretical issues.
This article describes a project which was undertaken to assess the British Standard 5810: 1979 Access for the Disabled to Buildings, with a view to it being improved at the next review. This code of practice 'concentrates on the essential provisions that need to be incorporated in buildings to ensure that they are conveniently usable by disabled people'. The aim of the project was to make suggestions for improvements to the Standard, both qualitatively and in its range of provision, by discovering what additional data, if any, architects require, what level of detail they need and the preferred method of presentation. Research was also undertaken to ascertain whether the information contained in the Standard is based on empirical data. The project involved a literature search, sending postal questionnaires to architects and visiting architectural practices to complete structured interviews. The method used, the results and the conclusions on how the British Standard could be improved are described.
The Consumer Protection Act 1987 imposes new demands on manufacturers regarding the safety of their products. They can be sued directly by any person injured by their defective goods and prosecuted if they fail to meet the new comprehensive general safety requirement and any other safety provision. Product designers and ergonomists need a sound understanding of and involvement in the legal aspects of product safety. It is now essential to take into account what may reasonably be done with goods, or foreseeable conditions of use, in order to satisfy the test of what is "reasonably safe" and meet the level of safety which "persons generally are entitled to expect" under the law. Any significant progress in product safety will now come through developments in technical standards which will be harmonised throughout the European Community. It is essential that ergonomics considerations be taken into account during the drafting of product specifications if users' interests are to be safeguarded more effectively. Ergonomists will be required to make an even greater contribution in the field of product safety, therefore, by assisting in the determination of the new statutory safety criteria. They are uniquely qualified to ensure that the product user is fully considered at the design and assessment stages which can now be looked upon as an essential pre-requisite of the law and not just sound engineering policy.
The International Standard ISO 7933 (1989) Hot environments--Analytical determination and interpretation of thermal stress using calculation of required sweat rate has been proposed for the evaluation of climatic stress within the European system of CEN standards. Comparison of results of studies performed in climatic chambers and those in the field with the predictions of ISO 7933 show that there are considerable problems in using this index in practice. In its present state of development, ISO 7933 seems to be rather a step towards a useable index for evaluating climatic conditions rather than an established climatic index which is applicable in practice. Within the CEN standards, the deficiencies of ISO 7933 are reflected mainly by a restriction of the limits of application within EN 12 515 (1997) which is based on ISO 7933.
A relatively neglected topic in manual materials handling (MMH) research is the impact of the accuracy of task parameter measurements on the application of various assessment methods. A laboratory experiment was conducted to investigate the accuracy of NIOSH equation parameter measurements made by eight subjects following a 4-h training session. Five individual tasks were measured; two were single tasks and three were part of a multiple-component simulated palletizing operation. Significant differences between reference parameter measurements and average measurements made by subjects were found. The sensitivity analysis showed that frequency and horizontal location are the most important parameters. These parameters also tended to have the highest measurement errors. Recommendations for increasing the effectiveness of training programs for NIOSH equation users based on the results of the study are presented.
Hand-held power tools used for fastening operations exert high dynamic forces on the operator's hand-arm, potentially causing injuries to the operator in the long run. This paper presents a study that analyzed the vibrations exerted by two hand-held power tools used for fastening operations with the operating exhibiting different postures. The two pneumatic tools, a right-angled nut-runner and an offset pistol-grip, are used to install shearing-type fasteners. A tri-axial accelerometer is used to measure the tool's vibration. The position and orientation of the transducer mounted on the tool follows the ISO-5349 Standard. The measured vibration data is used to compare the two power tools at different operating postures. The data analysis determines the number of years required to reach a 10% probability of developing finger blanching. The results indicate that the pistol-grip tool induces more vibration in the hand-arm than the right-angled nut-runner and that the vibrations exerted on the hand-arm vary for different postures.
Upper limb disorders (ULDs) in the workplace represent a significant cause of ill health in Great Britain. As part of the Health and Safety Commission's strategy for the prevention of musculoskeletal disorders (MSDs), the well known guidance document on ULDs--"Work-related Upper Limb Disorders: a Guide to Prevention" (HSG60), (HMSO, London.), has been extensively revised. This revision (Upper limb disorders in the workplace. HSG60 (rev), HSE Books, Sudbury.) includes the development of new risk assessment tools that can be used by employers to identify ULD risk factors in work activities and more importantly to take action to reduce or eliminate ULD risks. The risk assessment tools form part of a seven stage management approach that underpins the new guidance. This paper outlines the development of the risk assessment tools contained in the revised guidance.
In recent years the use of new technical equipment and the Internet by middle-aged people has increased. This paper presents middle-aged people's (45 years old or older) usage of new technical equipment and analyses how their (2704 persons) symptoms are associated with the equipment. Over 70% of Finland's middle-aged population use mobile phones daily and less than 30% use desktop computers at leisure. For example, over 80% of middle-aged people had sometimes or often experienced pain, numbness or aches in the neck and about 70% had aches in the hip and lower back. The use of new technical equipment among the group of people who are outside working life was smaller than the people's usage in general. In the future, when new technical equipment is developed, it is important to take into account, that people (outside working life) do not use, e.g., the Internet as much as people in general. The working environment will be much more ergonomic also at home and the Internet services will be easy to use for almost everyone, even those who have little experience or knowledge of computers and the Internet.
The primary objectives of this study were to describe and analyze the hand force exertion patterns of experienced nursing home nurses and nursing students during dynamic medicine cart pushing tasks in Initial, Sustained, Turning, and Stopping motion phases. A 2 × 2 × 2 factorial experiment was conducted with 22 participants to estimate the effects of lane congestion, precision cart control, and floor surface on horizontal hand forces. Root mean squared (RMS) lane deviation patterns were also described to provide an indicator of cart handling difficulty across the different study conditions. Descriptive statistics revealed that nurses exerted greater mean hand force (10%) and made more (12%) lane deviation than students and that the highest two-hand forces of 147N were measured in the Turning phase on carpet. Strong correlations between work experience group, body mass, and BMI required that force data for nurses and students be collapsed in analytical models where no group differences existed. Predicted pushing forces on carpeted floor surface were significantly greater than on tile in Initial (14N), Sustained (14N) and Turning (18N), except in stopping where pulling forces were 37N lower. High lane congestion predicted significant peak force increases of 4N and 7N in Sustained and Turning, respectively, but decreased by 20N in Initial. High precision control led to significant decreases in two-hand forces that ranged from 4 to 20N across motion phases. Complex interactions among the experimental factors suggest that work environment (lane congestion and floor surface) and work demands (precision control) should be included in the evaluation of pushing tasks and considered prior to making renovations to nursing home environments.
Written information does not have to be flowing prose. Recent studies have shown that abandoning the prose format for alternatives such as logical trees and tabulated presentations can often improve comprehension. From our present knowledge, it seems unlikely that any one style will be universally optimal. Written information is used for many different purposes and in a wide variety of circumstances. This paper discusses some of the factors which need to be taken into account when selecting a particular way of writing to be understood.
This paper focuses on the relationship between the socio-technical system and the user-technology interface. It looks at specific aspects of the organisational context such as multiple user roles, job change, work processes and workflows, technical infrastructure, and the challenges they present for the interaction designer. The implications of trends such as more mobile and flexible working, the use of social media, and the growth of the virtual organisation, are also considered. The paper also reviews rapidly evolving technologies such as pervasive systems and artificial intelligence, and the skills that workers will need to engage with them.
Workstations at school are among several factors that contribute to musculoskeletal symptoms among school-aged children. The aim of this study was to investigate the effects of ergonomically designed workstations on schoolchildren's musculoskeletal symptoms as compared to conventional workstations. In the first 14-month phase of the study (2002-2003, two schools), 42 from the intervention and 46 from the control school participated. In the total follow-up of 26 months (2002-2004), 23 in the intervention group and 20 in the control group participated. Anthropometrics and musculoskeletal symptoms were measured. In general, the ergonomically designed school workstations did not decrease present neck-shoulder, upper back, low back and lower limbs strain and pain, compared to conventional ones during follow-ups.
Long-term vibration stress can contribute to degenerative changes in the joints of the human body, especially in the lumbar spine. An important factor in the development of these diseases is given by the forces transmitted in the joints. Because the forces can hardly be measured a biomechanical model was developed which simulates the human body in the standing and the sitting posture. The vibration properties of the model were adapted to the transfer function provided in the standards and the literature. With the model the compressive forces at the driving point of the body, in the leg joints, and in two motion segments of the spine were simulated under a vertical pseudo random vibration. Transfer functions between the accelerations of the ground or of the seat and the forces were computed. Furthermore, based on the transfer function between seat acceleration and compressive force in the spinal motion segment L3-L4 weighting factors were derived. By means of these factors characteristic vibration values were computed for 57 realistic vibration spectra measured on 17 machines and vehicles. The consideration of the forces resulted in a stronger weighting of low-frequency vibrations compared to the weighted acceleration as suggested by ISO 2631-1. In order to enable an assessment of the health risk a force-related guidance value was derived which amounts to 0.81 ms(-2) (rms).
Sensitivity of lateral motions relative to vertical motions were determined and compared to predictions provided by ISO 2631. Two experiments were executed where lateral and vertical motions were applied consecutively or simultaneously and where the magnitude of a single- or dual-axis test signal was adjusted until it was judged as equivalent to a preceding single-axis reference motion of the same frequency. Experiment 1: References consisted of vertical sinusoidal motions presented with 1.6-12.5 Hz and weighted accelerations of a(zw) = 0.3, 0.6 and 1.2 m s(-2) r.m.s., single-axis test signals were lateral motions of the same frequency. 26 subjects (15 men, 11 women, 20-56 yr) participated in the experiments. Accelerations adjusted for lateral vibrations above 1.6 Hz were considerably lower than predicted suggesting that the weighting factors provided in ISO 2631 are incorrect. Experiment 2: References consisted of single-axis vertical or lateral sinusoidal motions presented with 1.6-12.5 Hz and a weighted acceleration of a(zw) = 1.25 m s(-2) r.m.s. The dual-axis test signals consisted of a constant fraction of the reference acceleration (10, 25, 50, 75, 90%) and a perpendicularly oriented adjustable component. 31 subjects (15 men, 16 women, 19-51 yr) participated in the experiments. Both experiments revealed that ISO 2631 is qualitatively valid, the weighting of lateral motions above 1.6 Hz, however, should be increased in order to meet the actual sensitivity particularly in case of multi-axis vibrations.
Measuring hand anthropometric data for the development of good-fitting gloves is crucial. In pursuing higher accuracy in hand anthropometric measurements, scanning of hand surfaces with the aids of image analysis system to acquire measurements is an alternative to the manual methods. This study proposes a new hand measuring approach by using 2D and 3D scanning which are evaluated through comparisons of manual measurements. Thirty-three dimensions are measured by using (1) tape and calliper measurement; (2) 2D image analysis; (3) 3D image analysis based on ten captures; and (4) 3D image analysis based on three captures, respectively. Repeated-measures ANOVA, correlation analysis and RMSE are used to examine the results. The hand dimensions obtained from the four methods are highly linearly correlated. Hand data taken from 3D image analysis has no significant difference compared with manual measurements on hand and wrist circumferences, length and breadth dimension, regardless of the number of captures.
Two-dimensional, image-based anthropometric measurement systems offer an interesting alternative to traditional and three-dimensional methods in applications such as clothing sizing. These automated systems are attractive because of their low cost and the speed with which they can measure size and determine the best-fitting garment. Although these systems have appeal in this type of application, not much is known about the accuracy and precision of the measurements they take. In this paper, the performance of one such system was assessed. The accuracy of the system was analyzed using a database of 349 subjects (male and female) who were also measured with traditional anthropometric tools and techniques, and the precision was estimated through repeated measurements of both a plastic mannequin and a human subject. The results of the system were compared with those of trained anthropometrists, and put in perspective relative to clothing sizing requirements and short-term body changes. It was concluded that image-based systems are capable of providing anthropometric measurements that are quite comparable to traditional measurement methods (performed by skilled measurers), both in terms of accuracy and repeatability.
A number of studies have described mood change during sleep loss in the laboratory, however, an understanding of fluctuations in structural aspects of mood under such conditions is lacking. Sixty-two healthy young adults completed one of three possible conditions: one (n = 20) or two (n = 23) nights of sleep loss or the control condition which consisted of one (n = 9) or two (n = 10) nights of 9 h time in bed. The Mood Scale II was completed every two waking hours and data were analysed in terms of the frequency and intensity of mood reports. Overall, sleep loss conditions were associated with significantly less frequent happiness and activation and more frequent fatigue reports (p < 0.001). Intensity was also significantly reduced for activation and happiness, and increased for depression, anger and fatigue (p < 0.05). Interestingly, there were no significant differences in anger following two nights in the laboratory with or without sleep. Further, two nights in the lab with normal sleep was associated with significant increases in depression intensity (p < 0.05). Findings support the hypothesis of a mood regulatory function of sleep and highlight the relative independence of frequency and intensity and of positive and negative mood dimensions. Findings also suggest that the laboratory environment, in the absence of sleep loss, may have a significant negative impact on mood.
Three-dimensional (3D) anthropometry based on the laser scanning technique not only provides one-dimensional measurements calculated in accordance with the landmarks which are pre-located on the human body surface manually, but also the 3D shape information between the landmarks. This new technique used in recent ergonomic research has brought new challenges to resolving the application problem that was generally avoided by anthropometric experts in their researches. The current research problem is concentrating on how to shift and develop one-dimensional measurements (1D landmarks) into three-dimensional measurements (3D land-surfaces). The main purpose of this paper is to test whether the function of B-splines can be used to fit 3D scanned human heads, and to for further study to develop a computer aided ergonomic design tool (CAED). The result shows that B-splines surfaces can effectively reconstruct 3D human heads based on the laser scanning technique.
The purpose of this project was to investigate the amount of error in calculating cumulative lumbar spine kinetics using a posture matching approach (3DMatch) compared to a 3D coordinate electromagnetic tracking approach (FASTRAK). Six subjects were required to perform five repeats each of two symmetrical and two asymmetrical lifts while being simultaneously recorded from 4 camera views at viewing angles of 0 degrees , 45 degrees , 60 degrees and 90 degrees to the sagittal plane while wearing eight FASTRAK sensors to define an 8 segment rigid link model (RLM) of the head, arms, and trunk. Four hundred and eighty lifts (6 subjects x20 lifts x4 camera views) were analyzed using the 3DMatch posture-matching program to calculate the following cumulative loads at the L4/L5 joint: compression, anterior shear, posterior shear, reaction shear and extension moment. The errors in cumulative load calculation were determined as the difference between the values calculated for the same lifts using a 3D RLM that used electromagnetic motion tracking sensors (FASTRAK) positioned at the segment center of masses as model inputs. No significant difference (p<0.05) in the relative error for any of the cumulative loading variables between the four camera views and the 3D RLM approach was found. Furthermore the relative errors for cumulative compression, joint anterior shear, reaction anterior shear and extension moment were all below 12%. These results suggest that posture matching by trained users can provide reasonable 3D data to calculate cumulative low back loads with a biomechanical model.
Garment fit and resultant air volume is a crucial factor in thermal insulation, and yet, it has been difficult to quantify the air volume of clothing microclimate and relate it to the thermal insulation value just using the information on the size of clothing pattern without actual 3D volume measurement in wear condition. As earlier methods for the computation of air volume in clothing microclimate, vacuum over suit and circumference model have been used. However, these methods have inevitable disadvantages in terms of cost or accuracy due to the limitations of measurement equipment. In this paper, the phase-shifting moiré topography was introduced as one of the 3D scanning tools to measure the air volume of clothing microclimate quantitatively. The purpose of this research is to adopt a non-contact image scanning technology, phase-shifting moiré topography, to ascertain relationship between air volume and insulation value of layered clothing systems in wear situations where the 2D fabric creates new conditions in 3D spaces. The insulation of vests over shirts as a layered clothing system was measured with a thermal manikin in the environmental condition of 20 degrees C, 65% RH and air velocity of 0.79 m/s. As the pattern size increased, the insulation of the clothing system was increased. But beyond a certain limit, the insulation started to decrease due to convection and ventilation, which is more apparent when only the vest was worn over the torso of manikin. The relationship between clothing air volume and insulation was difficult to predict with a single vest due to the extreme openings which induced active ventilation. But when the vest was worn over the shirt, the effects of thickness of the fabrics on insulation were less pronounced compared with that of air volume. In conclusion, phase-shifting moiré topography was one of the efficient and accurate ways of quantifying air volume and its distribution across the clothing microclimate. It is also noted that air volume becomes more crucial factor in predicting thermal insulation when clothing is layered.
A method used to determine the probable population accommodation of a helmet sizing system is described. The method involves the use of 3D laser scanning, as a means of measuring helmet standoff distance (distance between the inside of the helmet and the skull), and the selection of a representative sample of test subjects. The laser scanner and the software developed to calculate standoff distance proved to be an excellent tool for the assessment of helmet fit. The main advantages include ease of use and visualization of problem areas. This 3D-analysis method gives designers objective evidence of the need for design changes as well as an idea of what these changes should be. A comparison was made between standoff distance results obtained from the scanner and those obtained using a physical measurement method (a probe). Although discrepancies were found between the two, sources of errors intrinsic to both methods make it difficult to determine which of the two methods yielded the truest standoff distance. Analysis of the comparison data shows laser scanning to be slightly more conservative than the probe method for standoff distance purposes, i.e. erring on the side of safety.
Body dimensions are based on landmarks of the body, but the magnitude of error in landmark determination is not well known. Therefore, a study was performed in which 40 subjects were marked five times in total by one highly skilled marker and a novice marker. Immediately after marking, a skilled measurer determined 34 body dimensions that were based on the mark locations. Intra- and inter-observer errors in landmarking of 35 landmarks, as well as those in 34 body dimensions were quantified. The error in landmarking was defined as the distance between two marks made on the same landmark by the same marker (intra-observer error) or by two different markers (inter-observer error). To make the first mark invisible when the second mark was made, the first mark was made using an invisible ink pen under black light. Landmarks with large intra-observer errors also had large inter-observer errors. Errors in body dimensions were smaller than landmarking errors in 23 measurements, which suggested that the magnitude of landmarking error would be underestimated from errors in body dimensions. In 15 body dimensions, measurements based on marks made by two different markers were not comparable according to the ISO 20685 criterion. Examination of body dimensions and landmarks with large inter-observer errors suggested that reducing inter-observer landmarking errors was necessary to reduce inter-observer measurement errors, and that a possible solution was to explicitly define landmarks with large errors in more detail so that anthropometrists can pinpoint them on the skin. Quantitative data on the intra- and inter-observer landmarking errors in the present study may be useful as a reference when evaluating and comparing the performance of software for calculating landmark locations for 3D anthropometry.