Tarefas de manipulação manual de cargas : selecção de métodos de avaliação de risco

Dissertação de mestrado em Engenharia HumanaA Manipulação Manual de Cargas está presente num conjunto significativo de tarefas que uma extensa multiplicidade de operadores tem de realizar nos seus postos de trabalho, ocorrendo transversalmente, desde a indústria transformadora, à construção, passando pelos serviços. Contudo, esta manipulação manual constitui um determinante factor de risco para o desenvolvimento de Lesões Músculo-Esqueléticas relacionadas com o Trabalho. Este risco pode ser minimizado através de uma intervenção ergonómica baseada na identificação e na avaliação dos factores de risco associados a esse tipo de tarefas. Para tal, existem diversos métodos que permitem identificar e avaliar o risco de lesões músculo-esqueléticas na manipulação manual de cargas. Pretendeu-se com este estudo elaborar um Guião, que permita, de forma simples, apoiar a selecção e de aplicação do método mais apropriado para avaliar esse risco num posto de trabalho específico. Da análise bibliográfica realizada foram analisados vários métodos distintos, sendo que 10 deles foram incluídos no Guião. A fase seguinte envolveu a realização de um questionário de contextualização do presente estudo. Um dos principais resultados que foi possível inferir do questionário indica que grande parte dos técnicos conhece, por vezes com detalhe, alguns dos métodos mas, em simultâneo, desconhecem a forma de aplicação dos mesmos, ou sentem alguma dificuldade em seleccionar o método mais apropriado. Tendo em consideração este resultado, foi desenvolvida uma ferramenta informática cujo objectivo consiste em apresentar de forma intuitiva o Guião desenvolvido e permita que a selecção do método de avaliação do risco seja feita de forma apropriada. Depois, a partir de uma amostra de possíveis utilizadores finais deste produto, testou-se a sua usabilidade, com a administração de um inquérito por questionário, de modo a avaliar: (1) a eficácia, estimada pela taxa de sucesso dos utilizadores mediante uma tarefa pré-definida; (2) a eficiência, medindo o tempo dispendido para atingir os objectivos; e (3) o grau de satisfação dos utilizadores, relativamente à empatia, aprendizagem, controlo, ajuda e eficiência do Guião. Os dados obtidos, apontam para uma avaliação global positiva da aplicação informática. O facto de o Guião não permitir realizar os cálculos directamente relativos à aplicação dos métodos foi o aspecto negativo mais apontado pelos utilizadores. Relativamente aos aspectos positivos mais referenciados, estes estão relacionados com a facilidade de consulta do Guião, com o seu aspecto gráfico, bem como com o facto de este produto constituir um meio de informação sobre os métodos considerados. Espera-se que este trabalho permita uma maior difusão dos métodos seleccionados e que a sua escolha seja facilitada, permitindo também minimizar os riscos inerentes às tarefas de Manipulação Manual de Cargas.Manual Handling of Loads is present in a significantly group of tasks that a wide variety of workers has to realize in their workplaces, occurring transversally, from the transforming industry, to the construction industry, passing through services. However, this manual handling constitutes a determinant risk factor for development of work-related musculoskeletal disorders. This risk can be minimized through an ergonomic intervention based on the identification and evaluation of risk factors associated with this type of tasks. For that purpose, there are several methods for identifying and evaluating the risk for musculoskeletal disorders in the manual handling loads. With this study it was intended to develop a simple Guide, with a simple structure, in order to be used as a decision-making support for the selection and application of the most appropriate method to assess this risk at a particular workplace. The undertaken literature review has analyzed several different methods, being 10 of them included in the Guide. The next stage involved the realization of a questionnaire of contextualization of the present study. One of the main results that could be obtained from the questionnaire indicated that most of the practitioners know, sometimes in detail, some of the methods but, simultaneously, they do not know how to implement them or, at least, feel some difficulty in selecting the most appropriate method. Taking this result into account, it was developed a multimedia tool whose purpose was to provide an intuitive way to the developed Guide and to allow that the methods selection for risk assessment is done properly. Afterward, using a sample of possible final users of this product, its usability was tested, using the administration of a questionnaire, in order to evaluate: (1) the efficacy, estimated by the success rate of users by means of a pre-defined task; (2) the efficiency, measuring the needed time to achieve the goals; and (3) the degree of satisfaction of the users, relatively to empathy, learning, control, helpfulness and efficiency of the Guide. The obtained data, points to a global positive evaluation of the multimedia tool. The fact that the Guide does not allow to carry out the calculations directly relative to the application of the methods was the negative aspect more frequently pointed by the users. Concerning the more evidenced positive aspects, these are related with the facility in consulting the Guide, with its graphic appearance, as well as the fact that this product constitutes a mean of information about the considered methods. It is expected that this work will permit a wider dissemination of the selected methods and that its choice becomes easier, also allowing minimizing the risks inherent to the manual handling tasks

Obesity influence on perceived physical overload during vertical handling loads - A preliminary study

Obesity prevalence is increasing among the Portuguese workforce, similarly to other industrial countries. Obesity seems to negatively affect the individuals’ work capacity. Tasks with vertical handling loads, including lifting and lowering, are very common in occupational contexts. With the aim of studying the possible effect of obesity on workers’ physical overload during vertical handling loads, psychophysical data were collected from a total of 14 participants with different obesity levels (non-obese, high level of obesity and very high level). The participants were asked to go through 6 lifting trials with different occupational conditions and, for each task tested, they reported physical loading by using the Borg’ “Category Ratio-10” (CR-10) scale. The obtained results in this preliminary study are not conclusive about the obesity influence on perceived physical overload during vertical handling loads. Accordingly, this study should be continued, by considering a statistically valid sample and other psychophysical techniques that can complement the CR10 scale results

Estudio y análisis de un nuevo dispositivo para la rehabilitación de la articulación tibiotarsal

Introduction: Currently, there are several types of devices and techniques for the rehabilitation of the tibiotarsal joint. However, complete and effective rehabilitation still falls short of expectations, since the existing devices are not adaptable to the level of torque and the number of repetitions and sessions to be performed, as these depend on each patient and on the stage at which he is finds. Objetives: To improve a mechatronic device for the rehabilitation of the tibiotarsal joint, the Therapheet. Methods: This study presents a review of the tibiotarsal joint rehabilitation protocols, as well as the classification of devices used for this purpose. Thus, the purpose is to improve the Therapheet, developed at the Department of Mechanical Engineering of the University of Minho, obtaining a viable, functional and safe rehabilitation device, standing out from the rest on the market, since it allows the execution of the six rehabilitation exercises. Results: It was obtained a prototype of equipment for rehabilitation of the tibiotarsal joint was obtained, proposing changes for improvement according to the specificities and requirements for such a device, having been subjected to a series of preliminary tests to verify its functionality, performance and suitability. The equipment proved to be functional, in terms of executing the ankle rehabilitation movements, however, it still manifests some flaws in terms of the user's stability, sudden movements, and above all dysfunctions arising from excess mass that make up its structure and limitations pneumatic technology adopted. Conclusions: The control of the amplitude of the characteristic angles of the movements of the foot is still done manually, so it would be significant to implement an automated system that would allow the control of the range of amplitude, according to the patient's rehabilitation phase. One option would be the implementation of a new technology, such as the insertion of servomotors.Introdução: Atualmente existem vários tipos de dispositivos e técnicas para a reabilitação da articulação tibiotársica. No entanto, a reabilitação completa e eficaz ainda está aquém das expectativas, uma vez que os dispositivos existentes não são adaptáveis ao nível do binário e do número de repetições e sessões a executar, pois estas dependem de cada paciente e do estádio em que este se encontra. Objetivos: Melhorar um dispositivo mecatrónico, de reabilitação da articulação tibiotársica, o Therapheet. Métodos: Neste estudo é apresentada uma revisão dos protocolos de reabilitação da articulação tibiotársica, assim como a classificação dos dispositivos utilizados para este propósito. Assim, a finalidade é aperfeiçoar o Therapheet, desenvolvido no Departamento de Engenharia Mecânica da Universidade do Minho, obtendo-se um dispositivo de reabilitação viável, funcional e seguro, destacando-se dos restantes no mercado, uma vez que permite a executação dos seis exercícios de reabilitação. Resultados: Foi obtido um protótipo de equipamento para reabilitação da articulação tibiotársica, propondo alterações de melhoria de acordo com as especificidades e os requisitos necessários para um dispositivo deste tipo, tendo sido submetido a uma série de testes preliminares para verificar a sua funcionalidade, desempenho e adequabilidade. O equipamento demonstrou ser funcional, a nível de execução dos movimentos de reabilitação do tornozelo, no entanto, ainda manifesta algumas falhas ao nível da estabilidade do utilizador, movimentos bruscos, e sobretudo disfunções provenientes de excesso de massa que compõe a sua estrutura e de limitações da tecnologia pneumática adotada. Conclusões: O controlo da amplitude dos ângulos característicos dos movimentos do pé ainda é feito manualmente, pelo que seria significativa a implementação de um sistema automatizado que possibilitasse o controlo da graduação da amplitude, de acordo com a fase de reabilitação do paciente. Uma opção seria a implementação de uma nova tecnologia, como a inserção de servomotores.Introducción: Actualmente, existen varios tipos de dispositivos y técnicas para la rehabilitación de la articulación tibiotarsal. Sin embargo, la rehabilitación completa y efectiva aún no cumple con las expectativas, ya que los dispositivos existentes no son adaptables al nivel de torque y al número de repeticiones y sesiones a realizar, ya que dependen de cada paciente y la etapa en la que se encuentra. Objetivos: Mejorar un dispositivo mecatrónico para la rehabilitación de la articulación tibiotarsal, el Therapheet. Métodos: Este estudio presenta una revisión de los protocolos de rehabilitación de la articulación tibiotarsal, así como la clasificación de los dispositivos utilizados para este propósito. Por lo tanto, el propósito es mejorar un dispositivo mecatrónico desarrollado en el Departamento de Ingeniería Mecánica de la Universidad de Minho, el Therapheet, obteniendo un dispositivo de rehabilitación viable, funcional y seguro, que se destaque del resto en el mercado, ya que permite la ejecución de los seis ejercicios de rehabilitación. Resultados: Se obtuvo un prototipo de equipo para la rehabilitación de la articulación tibiotarsal, proponiendo cambios para mejorar de acuerdo con las especificidades y requisitos de dicho dispositivo, habiendo sido sometido a un serie de pruebas preliminares para verificar su funcionalidad, rendimiento e idoneidad. El equipo demostró ser funcional, en términos de ejecución de los movimientos de rehabilitación de tobillo, sin embargo, todavía presenta algunos defectos en términos de estabilidad del usuario, movimientos bruscos y, sobre todo, disfunciones derivadas del exceso de masa que conforman su estructura y limitaciones. Tecnología neumática adoptada. Conclusións: El control de la amplitud de los ángulos característicos de los movimientos del pie todavía se realiza manualmente, por lo que sería importante implementar un sistema automatizado que permita el control del rango de amplitud, de acuerdo con la fase de rehabilitación del paciente. Una opción sería la implementación de una nueva tecnología, como la inserción de servomotores.This work has been supported by FCT – Fundação para a Ciência e Tecnologia with-in the R&D Units Project Scope: UIDP/04077/2020. It has been also supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Differences in muscular activity between obese and non-obese workers during manual lifting

The prevalence of obesity is increasing throughout the workforce. Manual lifting tasks are common and can produce significant muscle loading. This study compared muscular activity between obese and non-obese subjects, using surface Electromyography (EMG), during manual lifting. Six different lifting tasks (with 5, 10 and 15 kg loads in free and constrained styles) were performed by 14 participants with different obesity levels. EMG data normalization was based on the percentage of Maximum Contraction during each Task (MCT). Muscle Activation Times (AT) before each task were also evaluated. The study suggests that obesity can increase MCT and delay muscle AT. These findings reinforce the need to develop further studies focused on obesity as a risk factor for the development of musculoskeletal disorders

Occupational safety & ergonomics training of future industrial engineers: a project-based learning approach

As industries push for continuous technological innovation, the need to balance work demands and human capabilities and to ensure the workers' safety is now more pressing than ever. Therefore, the training of future industrial engineers must promote the development of different skills, including in the Occupational Safety & Ergonomics (OS&E) domain. Based on this assumption, Project-Based Learning (PjBL) is an active learning methodology where students develop projects in teams as a means of building effective professional skills and knowledge. The current study aims at evaluating the impact of PjBL in effective learning on OS&E, based on the participants' perceptions. PjBL has been applied in the 7th semester of the Integrated MSc in Industrial Engineering and Management at a Portuguese University. In the last years, different companies in the northern region of Portugal have participated in this PjBL, welcoming the students to develop the projects. The current study included a documental analysis that was also developed, considering the final technical reports developed by the students during a scholar semester. In addition, a questionnaire for data collection was developed and applied to the participants. The sample (n=64) included university students who participated in the referred PjBL, their teachers, and the supervisors of the companies where the Project was developed. Globally, the participants' perceptions reveal that the PjBL participants attribute a positive evaluation to this learning methodology, concerning the development of technical (on OS&E) and transversal skills.FCT - Fundação para a Ciência e a Tecnologia(UIDB/00319/2020

Physical ergonomic improvement and safe design of an assembly workstation through collaborative robotics

One of the key interesting features of collaborative robotic applications is the potential to lighten the worker workload and potentiate better working conditions. Moreover, developing robotics applications that meets ergonomic criteria is not always a straightforward endeavor. We propose a framework to guide the safe design and conceptualization of ergonomic-driven collaborative robotics workstations. A multi-disciplinary approach involving robotics and ergonomics and human factors shaped this methodology that leads future engineers through the digital transformation of a manual assembly (with repetitive and hazardous operations) to a hybrid workstation, focusing on the physical ergonomic improvement. The framework follows four main steps, (i) the characterization of the initial condition, (ii) the risk assessment, (iii) the definition of requirements for a safe design, and (iv) the conceptualization of the hybrid workstation with all the normative implications it entails. We applied this methodology to a case study in an assembly workstation of a furniture manufacturing company. Results show that the methodology adopted sets an adequate foundation to accelerate the design and development of new human-centered collaborative robotic workstations.This work has been supported by NORTE-06-3559-FSE-000018, integrated in the invitation NORTE-59-2018-41, aiming the Hiring of Highly Qualified Human Resources, co-financed by the Regional Operational Programme of the North 2020, thematic area of Competitiveness and Employment, through the European Social Fund (ESF)

Digitalization of musculoskeletal risk assessment in a robotic-assisted assembly workstation

The ergonomic assessment of adopted working postures is essential for avoiding musculoskeletal risk factors in manufacturing contexts. Several observational methods based on external analyst observations are available; however, they are relatively subjective and suffer low repeatability. Over the past decade, the digitalization of this assessment has received high research interest. Robotic applications have the potential to lighten workers’ workload and improve working conditions. Therefore, this work presents a musculoskeletal risk assessment before and after robotic implementation in an assembly workstation. We also emphasize the importance of using novel and non-intrusive technologies for musculoskeletal risk assessment. A kinematic study was conducted using inertial motion units (IMU) in a convenience sample of two workers during their normal performance of assembly work cycles. The musculoskeletal risk was estimated according to a semi-automated solution, called the Rapid Upper Limb Assessment (RULA) report. Based on previous musculoskeletal problems reported by the company, the assessment centered on the kinematic analysis of functional wrist movements (flexion/extension, ulnar/radial deviation, and pronation/supination). The results of the RULA report showed a reduction in musculoskeletal risk using robotic-assisted assembly. Regarding the kinematic analysis of the wrist during robotic-assisted tasks, a significant posture improvement of 20–45% was registered (considering the angular deviations relative to the neutral wrist position). The results obtained by direct measurements simultaneously reflect the workload and individual characteristics. The current study highlights the importance of an in-field instrumented assessment of musculoskeletal risk and the limitations of the system applied (e.g., unsuitable for tracking the motion of small joints, such as the fingers)

Ergonomics and human factors as a requirement to implement safer collaborative robotic workstations: a literature review

There is a worldwide interest in implementing collaborative robots (Cobots) to reduce work-related Musculoskeletal Disorders (WMSD) risk. While prior work in this field has recognized the importance of considering Ergonomics & Human Factors (E&HF) in the design phase, most works tend to highlight workstations’ improvements due to Human-Robot Collaboration (HRC). Based on a literature review, the current study summarises studies where E&HF was considered a requirement rather than an output. In this article, the authors are interested in understanding the existing studies focused on Cobots’ implementation with ergonomic requirements, and the methods applied to design safer collaborative workstations. This review was performed in four prominent publications databases: Scopus, Web of Science, Pubmed, and Google Scholar, searching for the keywords ‘Collaborative robots’ or ‘Cobots’ or ‘HRC’ and ‘Ergonomics’ or ‘Human factors’. Based on the inclusion criterion, 20 articles were reviewed, and the main conclusions of each are provided. Additionally, the focus was given to the segmentation between studies considering E&HF during the design phase of HRC systems and studies applying E&HF in real-time on HRC systems. The results demonstrate the novelty of this topic, especially of the real-time applications of ergonomics as a requirement. Globally, the results of the reviewed studies showed the potential of E&HF requirements integrated into HRC systems as a relevant input for reducing WMSD risk.This work has been supported by FCT–Fundação para a Ciência e Tecnologia and MIT Portugal Program under the doctoral Grant SFRH/BD/151365/2021. This work has been also supported by NORTE-06-3559-FSE-000018, integrated in the invitation NORTE-59-2018-41, aiming the Hiring of Highly Qualified Human Resources, co-financed by the Regional Operational Programme of the North 2020, thematic area of Competitiveness and Employment, through the European Social Fund. Additionally, has been also supported by FCT within the Project “I-CATER–Intelligent robotic Coworker Assistant for industrial Tasks with an Ergonomics Rationale”, Ref. PTDC/EEIROB/3488/2021, and within R&D Units Project Scope: UIDB/00319/2020

Towards an ergonomic assessment framework for industrial assembly workstations - a case study

Work-related musculoskeletal disorders (WMSD) are one of the main occupational health problems. The best strategy to prevent them lies on ergonomic interventions. The variety of industrial processes and environments, however, makes it difficult to define an all-purpose framework to guide these ergonomic interventions. This undefinition is exacerbated by recurrent introduction of new technologies, e.g., collaborative robots. In this paper, we propose a framework to guide ergonomics and human factors practitioners through all stages of assessment and redesign of workstations. This framework was applied in a case study at an assembly workstation of a large furniture enterprise. Direct observation of work activity and questionnaires were applied to characterize the workstations, the process, and the workers’ profiles and perceptions. An ergonomic multi-method approach, based on well-known and validated methods (such as the Finnish Institute of Occupational Health and Rapid Upper Limb Assessment), was applied to identify the most critical risk factors. We concluded that this approach supports the process redesign and tasks’ allocation of the future workstation. From these conclusions, we distill a list of requirements for the creation of a collaborative robot cell, specifying which tasks are performed by whom, as well as the scheduling of the human-robot collaboration (HRC).This work has been supported by NORTE-06-3559-FSE-000018, integrated in the invitation NORTE-59-2018-41, aiming the Hiring of Highly Qualified Human Resources, co-financed by the Regional Operational Programme of the North 2020, thematic area of Competitiveness and Employment, through the European Social Fund (ESF). This work has been also supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Human–robot interaction in industrial settings: perception of multiple participants at a crossroad intersection scenario with different courtesy cues

In environments shared with humans, Autonomous Mobile Robots (AMRs) should be designed with human-aware motion-planning skills. Even when AMRs can effectively avoid humans, only a handful of studies have evaluated the human perception of mobile robots. To establish appropriate non-verbal communication, robot movement should be legible and should consider the human element. In this paper, a study that evaluates humans’ perceptions of different AMR courtesy behaviors at industrial facilities, particularly at crossing areas, is presented. To evaluate the proposed kinesic courtesy cues, we proposed five tests (four proposed cues—stop, deceleration, retreating, and retreating and moving aside—and one control test) with a set of participants taken two by two. We assessed three different metrics, namely, the participants’ self-reported trust in AMR behavior, the legibility of the courtesy cues in the participants’ opinions, and the behavioral analysis of the participants related to each courtesy cue tested. The retreating courtesy cue, regarding the legibility of the AMR behavior, and the decelerate courtesy cue, regarding the behavioral analysis of the participants’ signs of hesitation, are better perceived from the forward view. The results obtained regarding the participants’ self-reported trust showed no significant differences in the two participant perspectives.NORTE-06-3559-FSE-000018, integrated in the invitation NORTE-59-2018-41, aimed at the Hiring of Highly Qualified Human Resources, co-financed by the Regional Operational Programme of the North 2020, thematic area of Competitiveness and Employment, through the European Social Fund (ESF). This work was also supported by FCT–Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020