Monitoring muscle fatigue following continuous load changes

Department of Human Factors EngineeringPrevious studies related to monitoring muscle fatigue during dynamic motion have focused on detecting the accumulation of muscle fatigue. However, it is necessary to detect both accumulation and recovery of muscle fatigue in dynamic muscle contraction while muscle load changes continuously. This study aims to investigate the development and recovery of muscle fatigue in dynamic muscle contraction conditions following continuous load changes. Twenty healthy males conducted repetitive elbow flexion and extension using 2kg and 1kg dumbbell, by turns. They performed the two tasks of different intensity (2kg intensity task, 1kg intensity task) alternately until they felt they could no longer achieve the required movement range or until they experienced unacceptable biceps muscle discomfort. Meanwhile, using EMG signal of biceps brachii muscle, fatigue detections were performed from both dynamic measurements during each dynamic muscle contraction task and isometric measurements during isometric muscle contraction right before and after each task. In each of 2kg and 1kg intensity tasks, pre, post and change value of EMG amplitude (AEMG) and center frequency were computed respectively. They were compared to check the validity of the muscle fatigue monitoring method using Wavelet transform with EMG signal from dynamic measurements. As a result, a decrease of center frequency in 2kg intensity tasks and an increase of center frequency in 1kg intensity tasks were detected. It shows that development and recovery of muscle fatigue were detected in 2kg and 1kg intensity tasks, respectively. Also, the tendency of change value of center frequency from dynamic measurements were corresponded with that from isometric measurements. It suggests that monitoring muscle fatigue in dynamic muscle contraction conditions using wavelet transform was valid to detect the development and recovery of muscle fatigue continuously. The result also shows the possibility of monitoring muscle fatigue in real-time in industry and it could propose a guideline in designing a human-robot interaction system based on monitoring user's muscle fatigue.clos

Human centred manufacturing: methodology for ergonomic previsional evaluation of manual assembly operations

The challenge of flexibility and productivity for manufacturing operations needs a new concept based on “human-centered manufacturing process”. This concept must consider basically the ergonomics of workplaces and workload balancing. The application of this concept is achievable through the detailed knowledge of the interaction between human and workplace, in particular as far as the mechanical load (or work load) arising from product design and from manufacturing process definition (included tools and equipment). The measurement of workload then is a fundamental for new (and existing) workplaces. In this paper is described the methodology that considers the procedure and instruments for measuring ergonomic parameters and the use of EAWS method to assess the ergonomic risk level of the workplace summarized by a score. EAWS considers postural aspects and dynamics of work activity. Design or modification of the workplace can be defined on base of the results obtained by the methodology application

Supporting people-centred design through information and empathy

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.People-centred design is a design approach that takes the intended end users into consideration throughout the development process, resulting in more appropriate design output in terms of meeting peoples needs and wants. There is recognised value in the use of user-based information, and in establishing empathy with those being designed for, yet there is a distinct lack of literature addressing both aspects and the potential for associated support mechanisms for designers. The combination of information and empathy is the focus of this research. This thesis presents studies carried out to investigate the potential for ‘supporting people-centred design through information and empathy’, focusing upon the early stages of design development. The main aims of this research were to understand designers’ processes and where users fit into these, and to suggest means of support that could promote user focus whilst remaining a practical and appropriate complement to established methods. The under-explored nature of this area required empirical research engaging in practical ways with designers, which was achieved through in-depth probe studies and follow-up interviews with 10 designers; active participation in two four-month real-life design projects; the examination and co-creation of resource tool concepts during two workshops, each with 20 design participants; and ‘MHIRROR’ (Means of Human Information Retrieval, Representation, Organisation and Reflection), a mixed media human information resource was developed and trialed with six experienced inclusive design practitioners. These qualitative explorations with designers and within real-life projects facilitated understanding of the potential for human information resources to support the design process. The thesis has made original contribution to knowledge in terms of the formation of a framework for the manipulation and integration of human information into the design process; the iterative design and embodiment of a working prototype resource MHIRROR, and it has provided insights into the value of information and empathy resource combinations and their potential to promote people-centred design.This study is funded by the Engineering and Physical Sciences Research Council (EPSRC)

Esoscheletro e Riduzione del Sovraccarico Biomeccanico per l’Arto Superiore

Le malattie muscolo-scheletriche (MSD) sono tra le patologie prevalenti nel territorio Italiano (dati INAIL) e, pertanto i fattori di rischio ad esse correlati devono essere attentamente analizzati. Lo sviluppo scientifico e la tecnologia offrono sul mercato nuovi strumenti per contrastare questo fenomeno. La fase di analisi e sperimentazione di questi nuovi dispositivi o modelli procedurali è di fondamentale importanza per verificare l’accettabilità, l’usabilità e la reale efficacia nel contesto produttivo.Lo studio di seguito riportato aveva come finalità quella di analizzare e di verificare la funzionalità e l’applicabilità di un prototipo di esoscheletro per arti superiori nel contesto automotive.Lo studio è stato eseguito presso il laboratorio di ergonomia di FIAT CHRYSLER AUTOMOBILES - ErgoLab, con la finalità di definire l’applicabilità di un dispositivo di supporto, un esoscheletro passivo, in attività tipiche di una linea di produzione automotive

An Ergonomic Assessment of Different Postures and Children Risk during Evacuations

Crawling is recommended for avoiding high heat and toxic fumes and for obtaining more breathable air during evacuations. Few studies have evaluated the effects of crawling on physical joints and velocity, especially in children. Based on motion capture technology, this study proposes a novel method of using wearable sensors to collect exposure (e.g., mean duration, frequency) on children’s joints to objectively quantify the impacts of different locomotion methods on physical characteristics. An on-site experiment was conducted in a kindergarten with 28 children (13 boys and 15 girls) of different ages (4–6 years old) who traveled up to 22 m in three different postures: upright walking (UW), stoop walking (SW), and knee and hand crawling (KHC). The results showed that: (1) The level of joint fatigue for KHC was heavier than bipedal walking (p 0.05). (2) The physical characteristics of the children in the different postures observed in this study were different (p 0.05) and gender (p > 0.05) of the children on the joints in any of the three postures. To conclude, KHC causes more damage to body joints compared to bipedal walking, as evidenced by higher exposure (mean duration, frequency), whereas UW and SW are similar in terms of the level of joint fatigue. The above findings are expected to provide a useful reference for future applications in the children’s risk assessment and in the prevention design of buildings

Study on the influence of indoor environment on perceived comfort in elderly care buildings

北九州市立大学博士(工学)The paper takes a human-centered approach and aims to achieve perceived comfort. It applies physiological sensing technology and eye tracking technology to the study of perception-environment and quantifies the unobservable variable of perceived comfort through human factors technology. By analyzing the physiological indicators of different perceptual states obtained through measurements, and synchronously verifying the representativeness of the changes in various physiological indicators through subjective questionnaires, comfort states are determined, and corresponding spatial indicators and parameters are derived. Through experiments conducted in residential and restaurant spaces, one-way perceived comfort, room brightness under single functional behavior, spatial distance, appropriate sound pressure levels, comfortable temperature, humidity, and the use of warm and safe decorative materials are obtained as spatial indicators and features.doctoral thesi

Estresores visuales y cognitivos en oficinas con tecnologías de la información y las comunicaciones

El trabajo con Tecnologías de la Información y las Comunicaciones (TIC) es un caso paradigmático de sistema de trabajo en que la adopción de una nueva tecnología introduce nuevos riesgos asociados: visuales, musculo-esqueléticos y cognitivos. Se diseñó una Evaluación Post Ocupacional en las oficinas administrativas de la sede central de la Universidad de Mendoza, realizando un diagnóstico de los riesgos visuales, cognitivos y posturales asociados al trabajo de oficina con TIC. Nuestros resultados muestran un promedio de iluminación en el plano de trabajo inferior a lo indicado por la legislación vigente, normativa que  por otro lado requiere ser revisada y actualizada. Un 32% de los participantes se encontró fuera del rango aceptable de carga de trabajo. Se exploró el hipotético rol de distractor ambiental de las fuentes de deslumbramiento presentes en el campo visual de los trabajadores, encontrándose una correlación lineal estadísticamente significativa entre nivel de iluminación vertical y magnitud del efecto Stroop. Este estudio exploratorio describió el comportamiento de nuestras variables de interés en presencia de factores de confusión propios de una situación real de trabajo, proponiéndose un modelo general de puesto de trabajo con TIC a partir del grado de correlación entre las variables relevadas

Analysis on Drivers\u27 Vision-psychology under the Influence of Color Difference after Pavement Pothole Repair

Pavement pothole repair, as one of the commonest methods used in routine road maintenance works, is effective to extend the pavement service life and increase its transport capacity. However, there are significant color differences between the old and new pavements after pothole repair, and there are few studies about the impact of color differences on driving safety. Thus, using multiple typical pavements with the pothole repair, we aim to reveal the impact of the color differences between the old and new materials on the driving safety, and to improve the safety and comfort of drivers. Tobii eye tracker and the ErgoLAB physiological recorder were used to test the driver\u27s visual parameters when the vehicles run under the pothole repair environment, including drivers\u27 gaze frequency, gaze duration, saccade range and heart rate variability. Results show that the color differences of the road after pothole repair have a significant influence on the drivers\u27 vision and psychology, resulting in reduced driving safety and stability. Compared with the unrepaired road section, the gaze frequency and duration of drivers on pothole sections are significantly increased. The speed of saccade is also increased, and the saccade range is reduced. Meanwhile, the average heart rate of drivers on the pothole sections is increased by 10-20%, indicating that drivers\u27 attention and heart rate fluctuate greatly when passing through potholes, which can easily cause emotional tension and misjudgment, and thereby reduce the safety of driving. The obtained conclusions provide a significant reference for subsequent research