Two posture analysis approaches and their application in a modified Rapid Upper Limb Assessment evaluation

This paper presents two posture risk quantification methods: first, an event-based method where the most common and the worst postures are estimated in a task; second, a time-based method where posture distributions are calculated from random samples of observed postures in the task. A ‘click-on-screen’ posture data entry method was developed for the time-based posture analysis method to make the observation process easier and to reduce possible posture categorization bias. Both methods were used to quantify various work posture parameters among a study cohort of 733 subjects from a prospective epidemiological study of upper extremity musculoskeletal disorders. Composite posture indices using a modified Rapid Upper Limb Assessment (RULA) method were also computed using data obtained by the two posture analysis methods. Results showed that both methods were able to distinguish jobs with large differences in certain posture measures. However, they did not produce the same results and could not be used interchangeably. Risk evaluation criteria should be developed, either for specific posture parameters or as a composite index, with a well-defined postural analysis method, so that users can follow exact procedures and obtain comparable results. The event-based method is easy to use and may suit practitioners better, while the time-based method adds more information to the measurement and may suit users who want more detailed information about posture exposure.     

Variation in upper limb posture and movement during word processing with and without mouse use

Work postures and movements of the upper limb were analysed for 12 ‘mouse’ operators and 12 ‘non-mouse’ computer operators employed in word-processing work. Measurements were carried out during correction of a given text. ‘Mouse’ operators spent 64% of the working time with the operative wrist deviating more than 15° towards the ulnar side, while ‘non-mouse’ operators spent 96% of the time with the corresponding wrist in neutral position towards radial deviation. The rotation in the shoulder was at all times in neutral position towards inward rotation for ‘non-mouse’ operators, while ‘mouse’ operators worked 81% of the time with the shoulder rotated outward more than 30°. ‘Mouse’ operators corrected a longer text during the given time. Our observations showed long periods of strenuous working postures for ‘mouse’ operators compared to ‘non-mouse’ operators. We believe that further investigations need to be carried out on the effects of word-processing techniques and to develop ergonomic work station designs for the ‘mouse’ and other non-keyboard input devices.     

Context based image analysis with application in dietary assessment and evaluation

Multimedia Tools and Applications - Dietary assessment is essential for understanding the link between diet and health. We develop a context based image analysis system for dietary assessment to...     

The risk of distal upper limb disorder in cleaners: A modified application of the Strain Index method

This paper presents a modified application of the Strain Index (SI) method, in evaluation of effort-related variables in cleaning activities (n=40). EMG data were analyzed in the wrist flexor and extensor muscles. Effort-related variables were calculated to each record in four trigger levels (effort values were considered when the amplitude of the signal is above the trigger level for at least 0.5 s). Differences in effort time, intensity, frequency of efforts and in the resulting SI score were observed in the same activity when these variables are calculated with different trigger levels. Vacuuming, cleaning walls, floor scrapping, dusting offices and dusting horizontal surfaces were the most critical cleaning activities in terms of distal upper extremity (DUE) risk disorders; operating mono-disc and scrubber drier floor machines, dry and wet mopping and floor sweeping are among the cleaning activities with comparatively lower risk to DUE disorders. Global values of the cleaning activities (n=40) were calculated: Mean effort-intensity of 59.5% MVE; mean effort duration of 52.6% effort time; mean effort frequency of 7.8 peaks min⁻¹; mean SI score of 8.7 (for a task duration <1 h). The use of EMG data to evaluate effort related variables was found to be an useful alternative to observational methods, when efforts are not clearly associated to hand/wrist movements and when non-cyclical high-frequency activities makes virtually impossible the evaluation of effort variables (intensity, frequency and duration). However, the application of this method requires the definition of an appropriate trigger level and of an activation time.Relevance to industryJob Strain Index (SI) has been widely applied in industry, but not to cleaning activities. Difficulties may occur when observational or self-report methods are applied to activities where hand/wrist efforts are not associated to clear hand/wrist movements and when non-cyclical high-frequency activities make evaluation of effort variables difficult. This study presents a modified application of the original method to calculate wrist exertion variables and it is based on the analysis of EMG data.     

Characterization of a capacitive tactile shear sensor for application in robotic and upper limb prostheses

This paper presents the characterization of a novel tactile sensor designed to measure shear forces. The sensor design is targeted for use in robotic and prosthetic hands, where haptic feedback or ability to detect shear forces associated with slip are critical. The presented sensor utilizes the principle of differential capacitance to measure the mechanical deflection of the sensor element. The dynamic range of the sensor can be varied by encapsulating the sensor terminal within silicone of varying hardness. The design features ease of mass production, low per-unit-cost, novel overload protection and low wire count, while still preserving the ability to achieve reasonable spatial resolutions and array densities. Mathematical and COMSOL multiphysics models of the sensor are presented, in addition to results from practical experiments. Sensors with a full scale displacement range of ±0.525 mm were produced and the differential capacitance was measured. Shear force transduction was characterized over the range of 0 N–4 N with the sense terminal encapsulated by silicone with a shore A hardness of 20. The effect of elastomer hardness on the sensor's dynamic range was analyzed. The differential capacitance, when measured at each fixed interval, was found experimentally to have a maximum standard deviation of 4.28e?16 F over a ±2 N range. A maximum standard deviation of 1.35e?15 F was measured across characterized full scale sensor range of ±4 N. The sensor design has a sensitivity of 1.967 fF/N of applied force and the sensor output was found to be approximately linear. The coefficient of determination, r², was found to be 0.941.     

Two new upper bounds of the solution for the continuous algebraic Riccati equation and their application

In this paper, for the solution of the continuous algebraic Riccati equation(CARE), we derived two new upper matrix bounds. Compared with the existing results, the newly obtained bounds are less conservative and more practical, which means that the condition for the existence of the upper bounds derived here is much weaker. The advantage of the results is shown by theoretical analysis and numerical examples. Moreover, in redundant optimal control, when we increase the columns of the input matrix, some sufficient conditions are presented to strictly decrease the largest singular value of the feedback matrix by utilizing these upper bounds.We also give some examples to illustrate the effectiveness of these sufficient conditions.     

Comparison of three computer office workstations offering forearm support: impact on upper limb posture and muscle activation

The aims of the study were: 1) to determine whether resting the forearms on the work surface, as compared to chair armrests, reduces muscular activation; 2) to compare the sensitivity of different electromyographic (EMG) summary parameters. Eighteen healthy subjects performed computer work (with keyboard and mouse alternately) for 20 min while resting their forearms on a work surface adjustable in height (Workstation A), on the chair's armrests with an adjustable workstation (Workstation B) or on their chair's armrests with a non-adjustable workstation (Workstation C). The EMG amplitude of the trapezius and deltoid muscles was little influenced by the workstations, whereas their EMG variability increased with Workstation A, which was interpreted as a positive effect. However, the EMG amplitude of the mouse-side extensor digitorum muscle was higher with Workstation A. Alternating between resting the forearms on the work surface and on the chairs' armrests could solicit different muscles during computer work, and could be considered as a strategy for preventing musculoskeletal disorders. The new exposure variation analysis summary parameters used were sensitive to small workstation changes, thus supporting their use in future studies.     

Repetitive task indicator as a tool for assessment of upper limb musculoskeletal load induced by repetitive task

A unified repetitive task indicator (RTI) has been proposed, characterizing the upper limb load resulting from repetitive work. Within RTI, the work task is described using parameters which refer to the duration of particular sequences of the work cycle and force exerted, taking into account the posture of the upper limb. On the basis of theoretical and experimental studies, undertaken by the author and on the basis of results of experimental studies conducted in other international research laboratories, available in the literature, an analysis was conducted with the aim of developing and verifying the RTI. A comparison of the RTI with indicators of internal load was performed for eight published study cases. The experimental study cases used for verification purposes were conducted for various variants of load (various types and levels of the external force and duration of cycle periods) and for various physiological indicators of internal load. Strong correlations between RTI and indicators of internal load expressed by the unified indicator (IL), showed considerable credibility of the RTI. Results of the verification are noteworthy, given the wide range of cases examined, differing in terms of the conditions under which they were done, the population examined and internal load indicators used. Thus, this analysis indicates that the proposed RTI reflects well the upper limb load occurring as a result of performing repetitive work.     

A methodology to assess the upper extremity strength in a chair egress posture

In this paper a method is presented which can be used to analyse the force distribution resulting from the application of force on the left and right armrest of a chair during the action of sitting down or standing up. The peak data for both hands can be combined to obtain the maximum for a trial on a specific chair configuration. This method is useful to assess the upper extremity limitations of an elderly or disabled population when rising from a seated position. The method involved the instrumentation, with strain gauges, of armrests of a prototype lounge chair obtained from a manufacturer of seating for the elderly. Provision for hand placement was included and the system was appropriately calibrated. The methodology presented may have a variety of applications, such as the assessment of seating requirements for the elderly or disabled, and the relative evaluation of a range of seats for nursing homes, clinics, hospitals and rehabilitation or recreational lounges.     

Multistrategy learning approaches to generate and tune fuzzy control structures and their application in manufacturing

Intelligence is strongly connected with learning adapting abilities, therefore such capabilities are considered as indispensable features of intelligent manufacturing systems (IMSs). A number of approaches have been described to apply different machine learning (ML) techniques for manufacturing problems, starting with rule induction in symbolic domains and pattern recognition techniques in numerical, subsymbolic domains. In recent years, artificial neural network (ANN) based learning is the dominant ML technique in manufacturing. However, mainly because of the black box nature of ANNs, these solutions have limited industrial acceptance. In the paper, the integration of neural and fuzzy techniques is treated and former solutions are analysed. A genetic algorithm (GA) based approach is introduced to overcome problems that are experienced during manufacturing applications with other algorithms.     

Two modified spectral conjugate gradient methods and their global convergence for unconstrained optimization

In this paper, two modified spectral conjugate gradient methods which satisfy sufficient descent property are developed for unconstrained optimization problems. For uniformly convex problems, the first modified spectral type of conjugate gradient algorithm is proposed under the Wolfe line search rule. Moreover, the search direction of the modified spectral conjugate gradient method is sufficiently descent for uniformly convex functions. Furthermore, according to the Dai–Liao's conjugate condition, the second spectral type of conjugate gradient algorithm can generate some sufficient decent direction at each iteration for general functions. Therefore, the second method could be considered as a modification version of the Dai–Liao's algorithm. Under the suitable conditions, the proposed algorithms are globally convergent for uniformly convex functions and general functions. The numerical results show that the approaches presented in this paper are feasible and efficient.     

Risk evaluation approaches in failure mode and effects analysis: A literature review

Failure mode and effects analysis (FMEA) is a risk assessment tool that mitigates potential failures in systems, processes, designs or services and has been used in a wide range of industries. The conventional risk priority number (RPN) method has been criticized to have many deficiencies and various risk priority models have been proposed in the literature to enhance the performance of FMEA. However, there has been no literature review on this topic. In this study, we reviewed 75 FMEA papers published between 1992 and 2012 in the international journals and categorized them according to the approaches used to overcome the limitations of the conventional RPN method. The intention of this review is to address the following three questions: (i) Which shortcomings attract the most attention? (ii) Which approaches are the most popular? (iii) Is there any inadequacy of the approaches? The answers to these questions will give an indication of current trends in research and the best direction for future research in order to further address the known deficiencies associated with the traditional FMEA.     

Preventing upper limb work-related musculoskeletal disorders (UL-WMSDS): new approaches in job (re)design and current trends in standardization

In industrialized countries, upper limb work-related musculoskeletal disorders (UL-WMSDs) are the most common form of occupational diseases. They are generating a growing population of workers with reduced working capacity. The link between these pathologies and different aspects of work organization has been convincingly proven. Recent experiences in Europe supporting the combination of traditional work design methods used in manufacturing companies with ergonomics methods are reported briefly, with special focus on the use of the occupational repetitive action (OCRA) method for risk assessment and management of manual repetitive tasks. The combined approach strives to achieve the goal of maintaining a satisfactory level of productivity while respecting ergonomics criteria and, definitely, workers' health. New ergonomics standards provide for interaction between job and machinery designers and ergonomists in the design of work processes and workplaces. These standards generally refer only to the healthy adult working population and do not always provide criteria for protecting particular working populations, such as that represented by workers affected by UL-WMSDs. The results of preliminary studies concerning productive re-employment of workers with UL-WMSDs allow the introduction of some criteria for implementing current ergonomics standards in this connection. One aim of this paper is to summarize experiences of close cooperation between ergonomists, machinery designers and job designers to guarantee productivity and the prevention of musculoskeletal disorders. A second aim is to examine current ergonomics standards in the field of manual physical work (designed for healthy workers) and to suggest preliminary criteria for their implementation taking into account the capabilities and needs of specific sub-groups of the working population.     

Fuzzy complex numbers and their application for classifiers performance evaluation

There are a variety of measures to describe classification performance with respect to different criteria and they are often represented by numerical values. Psychologists have commented that human beings can only reasonably manage to process seven or-so items of information at any one time. Hence, selecting the best classifier amongst a number of alternatives whose performances are represented by similar numerical values is a difficult problem faced by end users. To alleviate such difficulty, this paper presents a new method of linguistic evaluation of classifiers performance. In particular, an innovative notion of fuzzy complex numbers (FCNs) is developed in an effort to represent and aggregate different evaluation measures conjunctively without necessarily integrating them. Such an approach well maintains the underlying semantics of different evaluation measures, thereby ensuring that the resulting ranking scores are readily interpretable and the inference easily explainable. The utility and applicability of this research are illustrated by means of an experiment which evaluates the performance of 16 classifiers using different benchmark datasets. The effectiveness of the proposed approach is compared to conventional statistical approach. Experimental results show that the FCN-based performance evaluation provides an intuitively reliable and consistent means in assisting end users to make informed choices of available classifiers.     

Clinical trials among worker populations: a model for an anamnestic survey of upper limb pathologies and its practical application methods

Following a brief review of the principal clinical characteristics of musculoskeletal disorders of the upper limbs, the authors propose a protocol for a structured anamnestic examination featuring a series of set questions. The anamnestic model is based on a detailed listing of the symptoms to be analysed, which are divided into four categories: pain, paraesthesia, symptoms attributable to hyposthenia, and neurovegetative disorders. Regarding pain and paraesthesia, the authors list the localization, pattern of onset, duration and number of episodes, irradiation and treatment. The patients can thus be classified as anamnestic cases based on the following criteria: presence of pain or paraesthesia during the last 12 months, with episodes lasting for at least 1 week or occurring at least once a month, with no previous acute trauma. For hyposthenia, the authors report on the conditions under which the disorder may develop. The neurovegetative disorders considered are modifications in colour of the fingers and reaction to exposure to low temperatures. The structure of the proposed anamnestic chart permits all findings to be easily encoded for subsequent storage in a dedicated database. The appendix contains an annotated facsimile of the anamnestic chart.     

Part-whole relationship categories and their application inobject-oriented analysis

Part decomposition and conversely, the construction of composite objects from individual parts have long been recognized as ubiquitous and essential mechanisms involving abstraction. This applies, in particular, in areas such as CAD, manufacturing, software development and computer graphics. Although the part-of relationship is distinguished in object oriented modeling techniques, it ranks far behind the concept of generalization/specialization and a rigorous definition of its semantics is still missing. We first show in which ways a shift in emphasis on the part-of relationship leads to analysis and design models that are easier to understand and to maintain. We then investigate the properties of part-of relationships in order to define their semantics. This is achieved by means of a categorization of part-of relationships and by associating semantic constraints with individual categories. We further suggest a precise and, compared with existing techniques, less redundant specification of constraints accompanying part-of categories based on the degree of exclusiveness and dependence of parts on composite objects. Although the approach appears generally applicable, the object oriented Unified Modeling Language (UMF) is used to present our findings. Several examples demonstrate the applicability of the categories introduced     

The effect of handle design on upper extremity posture and muscle activity during a pouring task

In this study, the effect of container handle parameters on shoulder and upper limb muscle activity and joint posture during a pouring task is investigated. Results indicated that a low handle position and a vertical handle slope minimised the loading of the shoulder muscles. A high and sloped handle minimised the muscle activity and wrist deviation of the lower arm. The effects of diameter were not significant for most dependent variables during the lifting phase of the task; however, beneficial effects were seen with the smallest handle diameter during the pouring phase. A trade-off existed between the shoulder and the hand/wrist posture with the different handles. The findings of significance with relatively small effect size suggest a high sensitivity of the system to any changes. In the real world, speed, space and work conditions are important factors that influence how a task is performed. This emphasises the importance of proper handle design.

Practitioner Summary: In this study, the effect of container handle design on the muscle activity and postures of the upper extremity during a pouring task were analyzed using the experimental data collected from electromyography and motion tracking systems. The low handle height and vertical handle slope design yielded the lowest shoulder muscle activity.     

Anticipatory assistance-as-needed control algorithm for a multijoint upper limb robotic orthosis in physical neurorehabilitation

Robotic devices are becoming a popular alternative to the traditional physical therapy as a mean to enhance functional recovery after stroke; they offer more intensive practice opportunities without increasing time spent on supervision by the treating therapist. An ideal behavior for these systems would consist in emulating real therapists by providing anticipated force feedback to the patients in order to encourage and modulate neural plasticity. However, nowadays there are no systems able to work in an anticipatory fashion. For this reason, the authors propose an anticipatory assistance-as-needed control algorithm for a multijoint robotic orthosis to be used in physical ABI neurorehabilitation. This control algorithm, based on a dysfunctional-adapted biomechanical prediction subsystem, is able to avoid patient trajectory deviations by providing them with anticipatory force-feedback. The system has been validated by means of a robotic simulator.Obtained results demonstrate through simulations that the proposed assistance-as-needed control algorithm is able to provide anticipatory actuation to the patients, avoiding trajectory deviations and tending to minimize the degree of actuation. Thus, the main novelty and contribution of this work is the anticipatory nature of the proposed assistance-as-needed control algorithm, that breaks with the current robotic control strategies by not waiting for the trajectory deviations to take place. This new actuation paradigm avoids patient slacking and increases both participation and muscle activity in such a way that neural plasticity is encouraged and modulated to reinforce motor recovery.     

Execution and perception of upper limb exoskeleton for stroke patients: a systematic review

Intelligent Service Robotics - Due to the lack of therapists and the demand for objective rehabilitation training indicators, the upper limb rehabilitation exoskeleton (ULR-EXO) has attracted more...     

Projective morphoogies and their application in structural analysis of digital images

A formalism of projective morphology is proposed, which allows one to compare structural models and structural objects in images irrespective of the dependence on the specific features of the application domain. The main problems of structural analysis of digital images are considered, and the methods for solving them within the framework of projective morphologies are described.