Ergonomics of using a mouse or other non-keyboard input device

Ten years ago, when the Health and Safety (Display Screen Equipment) Regulations (HSE, 1992) were drafted, the majority of computer interaction occurred with text driven interfaces, using a keyboard. It is not surprising then that the guidance accompanying the DSE Regulations included virtually no mention of the computer mouse or other non-keyboard input devices (NKID). In the intervening period, graphical user interfaces, incorporating ‘windows, icons and pull down menus’ (WIMPS), with a heavy reliance on pointing devices such as the mouse, have transformed user computer interaction. Accompanying this, however, have been increasing anecdotal reports of musculoskeletal health problems affecting NKID users. While the performance aspects of NKID (e.g. accuracy and speed) have been the subject of detailed research, the possible implications for user health have received comparatively little attention. The research presented in this report was commissioned by the Health and Safety Executive to improve understanding of the nature and extent of NKID health problems. This investigation, together with another project examining mobile computing (Heasman et. al., 2000), was intended to contribute to a planned review and updating of the DSE Regulations and accompanying guidance

The effect of personalised adjustments to computer workstations on the efficiency and physical comfort of computer operators

The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept

An Assessment of Unmanned Aircraft System Pilot Discomfort and Fatigue

The rapid growth of unmanned aircraft system (UAS) use in both the military and civil sectors has uncovered an array of challenges within the field. In terms of human factors and ergonomics, the influence of the unique physical design of the control stations used to pilot the unmanned aircraft on local muscular fatigue and discomfort are of great concern. This study was conducted to assess the influence of two display configurations, Side-by-Side (SS) and Stacked (ST), and two chairs, Ergonomic (EC) and Captain’s (CC), on mean and median power frequencies, root mean square amplitude, posture, discomfort, workload, and seat pressure. Sixteen participants [age: 24.75 ± 2.96 years; gender: 4 female/ 12 male; height: 177.56 ± 9.09 cm; weight: 81.37 ± 16.43 kg] completed four, 2-hour simulated UAS flights for all chair/display combinations. Eight participants piloted one, 6-hour simulated UAS flight in the display/chair combination which best minimized discomfort and fatigue in the two-hour flights, EC/SS. During the two-hour flights, muscle activity, discomfort, posture, workload, and seat pressure findings indicated increased muscular fatigue and discomfort over time. Generally, the EC/SS condition appeared to best mitigate muscular fatigue and postures associated with increased risk for the development of musculoskeletal disorders. Six-hour flight data failed to provide additional insights on the influence of extended duration flights on the dependent variables of this study. Finally, linear regression analysis revealed muscle activity can likely be predicted during UAS piloting tasks using the dependent variables in this study; however, the study failed to provide evidence that models built from two-hour data can accurately predict muscle activity out to six hours

MUSCULOSKELETAL SYMPTOMS AND LAPTOP COMPUTER USE AMONG COLLEGE STUDENTS

Laptop computers are widely used by college students for academic and leisure activities (Cortes, Hollis, Amick, & Katz, 2002). However, there is limited research that identifies risk factors for musculoskeletal discomfort during laptop computer use in this population. This dissertation includes two studies: Study 1: This survey study explores characteristics of laptop computer use and relationships between laptop-related risk factors and discomfort; Study 2: This randomized cross-over study examines the effects of three most common laptop workstation setups on upper body postures, discomfort, and task productivity.Thirty students were recruited from the University of Pittsburgh. The survey was a self-administered questionnaire. Subjects¡¯ posture were videotaped while typing for 10 minutes in six laptop workstation setups (desktop sitting, chair sitting, lying prone, lying supine, floor sitting, and lap sitting), and the three most common workstation setups were analyzed. Body angles were digitized at 10-time points and averaged using ImageJ. Typing style was identified using the Keyboard-Personal Computer Style Instrument. Discomfort was determined using a 10-cm VAS. Task productivity was assessed by typing speed and accuracy. Data were analyzed by ANOVAs and Bonferroni post-hoc comparisons.Subjects were primarily female (83.3%), with a mean age of 26.0¡¾7.3, and white (63.3%). Survey results showed that the most common workstation setups were desktop sitting, followed by lying supine and chair sitting. There were no statistically significant relationships between laptop-related factors (duration and type of workstation setup) and discomfort. Most body angles were significantly different between the three workstation setups: neutral wrists and ulnar deviation, upright trunk, and greater shoulder flexion during desktop sitting; greater neck flexion, wrist extension, and ulnar deviation during chair sitting; less neck flexion and greater wrist flexion and trunk extension during lying supine. For typing style, subjects showed large differences in static postures among the workstation setups. Less discomfort and faster typing speed were observed during desktop sitting, followed by lying supine, and then chair sitting. Overall more neutral postures and less discomfort were observed during desktop sitting, followed by lying supine and chair sitting. These findings highlight the importance of laptop workstation setup choice for preventing potential musculoskeletal problems

Design of Work-Rest Schedules for VDT Operators.

The number of musculoskeletal and psychological discomforts is increasing as a result of continuing growth of VDT work. Although ergonomic improvements in workstation design can be applied, an effective work-rest schedule is an economical way to reduce these problems. The objective of this research was to determine an effective work-rest schedule for VDT operators. In addition to a discomfort questionnaire, performance and electromyography measurements from trapezius and flexor carpi radialis were used. Three different work-rest schedules were applied: 60-minute work/10-minute rest, 30-minute work/5-minute rest, and for the third schedule, the subjects received four breaks from VDT work each hour additional to a 14-minute break after two hours. Three of these breaks were 30 seconds in length and the fourth break was 3 minutes in length. The research also considered the effect of type of VDT task. Subjects were asked to enter alphanumeric data for data entry task and to solve addition/subtraction problems as mental task. The results indicated that effect of schedule was different on discomfort levels and performance of the subjects. Similarly, the type of task had different effects on discomfort, performance, and muscular tension levels. The 15/micro schedule was superior to the other schedules in terms of discomfort levels of the neck, back, and elbow/arm, eyestrain, speed, accuracy, and performance for both tasks. The lowest levels of trapezius muscle tension for data entry and flexor carpi radialis for mental tasks were resulted in the 15/micro schedule. The effect of the type of task was significantly different with 60/10 schedule on discomfort in shoulder and chest, bluffed vision, and headache; with 30/5 schedule on shoulder, chest and elbow/arm discomforts; and with 15/micro on discomforts in shoulder and hand/wrist. The schedule effect was different on data entry task for neck, lower back, elbow/arm discomforts and on mental task for headache. Mental task resulted in a higher psychological discomfort, lower physical discomfort, and lower performance than data entry task. The results of the study suggest that the 15/micro schedule is superior to the longer and infrequent rest break schedules considering upper extremity discomfort, eyestrain, speed, accuracy, and performance of the subjects

Evaluating the Ergonomics of Healthcare Providers using Kinematic Motion Analysis, Electromyography, and Musculoskeletal Modeling

Title from PDF of title page viewed May 10, 2019Dissertation advisor: Gregory W. KingVitaIncludes bibliographical references (pages 107-118)Thesis (Ph.D.)--School of Computing and Engineering and School of Medicine. University of Missouri--Kansas City, 2018Work-related musculoskeletal disorders (MSDs) in healthcare providers have been heavily reported, and are a major cause of occupational discomfort, disability, and occupational absence. Current evaluation methodology of occupational posture in healthcare professionals includes qualitative methods such as survey-based instruments that report on the characteristics of existing pain, or observational instruments where still photographs or videos of occupational postures are evaluated by independent raters to assess risk or exposure to musculoskeletal disorders. This research program used marker-based kinematic motion capture, surface electromyography, and musculoskeletal modeling to evaluate occupational postures in eye care providers and dental operators. Reclining the patient during refraction and strabismus exams reduced the amount of procedural time that eye care providers’ necks were in non-neutral postures. For eye care providers performing the slit lamp exam, it was observed that moving the patient forward and adjusting slit lamp biomicroscope height led to reduced non-neutral neck postures as indicated by a reduction in sagittal plane neck flexion range of motion, upper trapezius muscle activity and the percentage of procedural time with non-neutral neck flexion. Additionally, the use of an elbow rest when holding up exam lenses at the slit lamp reduced the procedural time that the anterior deltoid muscle was active, indicating a lower likelihood of shoulder musculoskeletal disorders. For dental operators, this research investigated the effect of using two kinds of Galilean magnification loupes on neck postures in dental hygienists performing sub-gingival probing. It was observed that both loupes reduced the range of motion of sagittal plane neck flexion in dental hygienists when compared to no magnification. The use of two kinds of through-the-lens Galilean loupes used by ophthalmic surgeons was also evaluated using motion capture, electromyography, and musculoskeletal modeling. A musculoskeletal model of a 50th percentile adult male demonstrated that holding a human head balanced at the working neck flexion of a lighter loupe required a smaller angular torque than a heavier loupe. Since this lower torque was a function of both neck flexion and loupe weight, neck muscle activity was evaluated at three different neck flexions for both loupes. It was observed that using a lighter loupe with a larger angle of declination led to a decrease in upper trapezius muscle activity. Postural adjustment, patient positioning, equipment re-positioning and supportive equipment choice (such as elbow rests for slit lamp examinations, or magnification loupes for periodontal probing and ophthalmic surgery) may be easy to implement methods that can reduce the exposure of healthcare providers to work-related musculoskeletal disorders.Introduction -- Background -- Evaluating posture in eye care providers performing refraction and strabismus exams using kinematic motion capture and electromyography -- Postural evaluation of eye care providers at the Slit Lamp using kinematic motion capture and electromyography -- Using motion capture technology to measure the effects of magnification loupes on dental operator posture: a pilot study -- Effect of magnification loupe weight and angle of declination on neck muscle effort in ophthalmic surgeons -- Conclusion -- Appendice

Evaluating the Ergonomics of Healthcare Providers using Kinematic Motion Analysis, Electromyography, and Musculoskeletal Modeling

Title from PDF of title page viewed May 10, 2019Dissertation advisor: Gregory W. KingVitaIncludes bibliographical references (pages 107-118)Thesis (Ph.D.)--School of Computing and Engineering and School of Medicine. University of Missouri--Kansas City, 2018Work-related musculoskeletal disorders (MSDs) in healthcare providers have been heavily reported, and are a major cause of occupational discomfort, disability, and occupational absence. Current evaluation methodology of occupational posture in healthcare professionals includes qualitative methods such as survey-based instruments that report on the characteristics of existing pain, or observational instruments where still photographs or videos of occupational postures are evaluated by independent raters to assess risk or exposure to musculoskeletal disorders. This research program used marker-based kinematic motion capture, surface electromyography, and musculoskeletal modeling to evaluate occupational postures in eye care providers and dental operators. Reclining the patient during refraction and strabismus exams reduced the amount of procedural time that eye care providers’ necks were in non-neutral postures. For eye care providers performing the slit lamp exam, it was observed that moving the patient forward and adjusting slit lamp biomicroscope height led to reduced non-neutral neck postures as indicated by a reduction in sagittal plane neck flexion range of motion, upper trapezius muscle activity and the percentage of procedural time with non-neutral neck flexion. Additionally, the use of an elbow rest when holding up exam lenses at the slit lamp reduced the procedural time that the anterior deltoid muscle was active, indicating a lower likelihood of shoulder musculoskeletal disorders. For dental operators, this research investigated the effect of using two kinds of Galilean magnification loupes on neck postures in dental hygienists performing sub-gingival probing. It was observed that both loupes reduced the range of motion of sagittal plane neck flexion in dental hygienists when compared to no magnification. The use of two kinds of through-the-lens Galilean loupes used by ophthalmic surgeons was also evaluated using motion capture, electromyography, and musculoskeletal modeling. A musculoskeletal model of a 50th percentile adult male demonstrated that holding a human head balanced at the working neck flexion of a lighter loupe required a smaller angular torque than a heavier loupe. Since this lower torque was a function of both neck flexion and loupe weight, neck muscle activity was evaluated at three different neck flexions for both loupes. It was observed that using a lighter loupe with a larger angle of declination led to a decrease in upper trapezius muscle activity. Postural adjustment, patient positioning, equipment re-positioning and supportive equipment choice (such as elbow rests for slit lamp examinations, or magnification loupes for periodontal probing and ophthalmic surgery) may be easy to implement methods that can reduce the exposure of healthcare providers to work-related musculoskeletal disorders.Introduction -- Background -- Evaluating posture in eye care providers performing refraction and strabismus exams using kinematic motion capture and electromyography -- Postural evaluation of eye care providers at the Slit Lamp using kinematic motion capture and electromyography -- Using motion capture technology to measure the effects of magnification loupes on dental operator posture: a pilot study -- Effect of magnification loupe weight and angle of declination on neck muscle effort in ophthalmic surgeons -- Conclusion -- Appendice

Seated working posture : a research thesis with experimental methodology and literature review

Masters Degree in Applied ScienceMuch has been written about seated working posture - particularly in the late 19th and early 20th centuries, and the furniture associated with achieving what is commonly referred to as the "German Square" postural geometry (after Mandal, 1974). The physical sciences aspects of chair, desk and associated furniture ancillary to the task required of the seated worker, have been described in the scientific literature and the standards and guideline publications of the authorities of many countries of the western world. The most important contribution of multi-adjustable furniture to the reduction of postural discomfort and musculo-skeletal complaints is recognised. As a result a variety of standards and guidelines concerning some of these aspects exists in countries such as the United Kingdom, Canada, United States of America, Germany, Australia and the Scandinavian countries. The International Organisation for Standardisation published document TC136/SC7 in 1978, consolidating such existing standards. Less emphasis has been placed on the interface of the information exchange and the comfort, performance and preferences of the seated worker; ie., the practically, the comfort and the intrinsic safety of the working posture prescribed by the model established by the many standards. Existing specifications and guidelines differ in their orientation towards operator performance and comfort of the operator, in as much as some purport to be "furniture standards", for example C.E.N, Comite European de Normalisation, Paris, 1980, while others purport to be "postural standards", for example, International Organisation for Standardisation document TC 136/SC7 (1978). The standards are uniform in matters of upright trunk and 90° upper and lower limb geometry, but are divided in the lineal dimensions applied to eye height above the floor, shoulder acromion to home row of keys (or pen-grip position of the dominant hand and fingers), and eye distance to copy

A survey and evaluation of microbased computer aided design systems for design education and practice in Scotland primarily in the area of product design: their application, problems and potential solutions

The initial premise of the research centred around the relatively new adoption by the Product Design sector of Computer Aided Design technology. Problems were expected to occur in applying the hardware and understanding the terminology of the software by this sector which prides itself In its artisan skills. The aim of the work was to determine the extent of the adoption of Computer Aided Design and to clarify the problem areas. The research determined, by study of more experienced but similar Computer Aided Design users, that the expected problems Were not insurmountable and were being overcome by the constant improvements of computer hardware and software. However, the problems that were pinpointed actually involved the human issues encountered In working with a Computer Aided Design system and involved issues such as the management skills required, working conditions and understanding of the advantages and disadvantages of Computer Aided Design. The research focused on what had to be considered and what should be known about Computer Aided Design so that it could be effectively used in Product Design. The research was undertaken to establish general solutions to the introduction of Computer Aided Design into companies. These solutions are intended to provide a guide to potential and current users on how to improve the effectiveness of the use of Computer Aided Design systems in Product Design. The research has identified the themes and topics that should be covered in training staff on the use and potential of Computer Aided Design systems