Proactive eye-gaze (PEG) is a behavioural pattern where eye fixations precede actions, such as reaching. With the proliferation of eye-tracking technology, PEG shows promise for predicting human actions, which has many applications, for example, within industrial human-robot collaboration (HRC). This study investigates PEG in repetitive assembly tasks. Eye-tracking data from four experienced workers were recorded and analysed. The study recorded 57 assembly sessions, identifying 3793 fixations, of which 35% were proactive gazes. The mean PEG interval was 795 ms. Contrary to the hypothesis, PEG was found to be as strong, if not stronger, in repetitive tasks compared to previous studies investigating PEG in other contexts. These findings suggest PEG could be a reliable predictor of worker actions in repetitive tasks, enhancing coordination in HRC.
Modern manufacturing systems seem to be shifting from mass production to mass customisation, which means that systems must be able to manage changes in customer demands and requirements, new technology as well as environmental demands. This in turn leads to an increase in product variants that need to be assembled. To handle this issue, well designed and presented information is vital for assembly workers to perform effective and accurate assembly tasks. In this thesis the main focus has been to find factors that affect human performance in manual assembly. A literature review was made on the subject of manufacturing and usability as well as basic cognitive abilities used to utilise information, such as memory. This investigation identified applicable factors for assessing human cognitive performance within the research field of manufacturing. The thesis further investigates how some of these factors are handled in manual assembly, using case studies as well as observational studies. The results show that how material and information are presented to the assembler needs to be considered in order to have a positive effect on the assembly operation. In addition, a full factorial experimental study was conducted to investigate different ways of presenting material and information at the workstation while using mixed assembly mode with product variants. The material presentation factor involved the use of a material rack compared to using an unstructured kit as well as a structured kit and the information presentation factor involved using a text and number instruction compared to a photograph instruction. The results showed that using a kit is favourable compared to the traditional material rack, especially when using a structured kit combined with photographic instruction. Furthermore, the use of unstructured kits can lead to better productivity and reduced perceived workload, compared to a material rack. Although they are perhaps not as good as using a structured kit, they most likely bring a lower cost, such as man-hour consumption and space requirements. However, the number of components in an unstructured kit needs to be considered in order to keep it on a manageable level. As a conclusion, several scenarios were developed in order to understand how different assembly settings can be used in order to improve human performance at the assembly workstation.
Current product and production development tends to become more complex where principal design decisions are made in very early development phases when product data only exist in virtual formats. To support this virtual product realisation process there exist a number of tools and technologies. Considering ergonomics and human factors in an increasingly complex process with often complex tools requires competent people able to handle multidisciplinary development challenges in a proactive manner. To answer the need for educational programs to cover these issues the School of Engineering Science at University of Skövde has developed a new master (second cycle) program Virtual Ergonomics and Design. The aim with the program is to give students and future product and production developers, necessary knowledge and skills to effectively use virtual tools for analysis, development, and verification of ergonomics and integrate ergonomics and user aspects into the product realisation process. This is achieved through a number of courses that partly forms a core within the subject Virtual product realisation but also provides in-depth knowledge in ergonomics. Students will in a possible future role as design or production engineers have a great influence on ergonomics in manufacturing departments but also better perception of ergonomics, higher motivation and knowledge of support tools and methods for ergonomics integration.
The higher level of product variation in the automotive industry leads to an increasing workload for the assembler that has to search, fetch and assemble all the variants. This puts high demands on the information that is given to the assembler to fulfil the assembly task. This paper describes the impact of information overload and sources, and their influence on the assembler. Through observations conducted in the Swedish automotive industry, the study has shown that the assembly personnel perceive the kit as structured information and that structured kits are able to present distinct information at a certain place to the assembler, which in turn reduces the searching, resulting in decreased cognitive workload.
In manual assembly, a strategy to meet the goal of efficient production is the increased use of kitting as a material supply principle. Even though kitting is already implemented in industry, there are still uncertainties regarding the effects of introducing kits, particularly from a human factors perspective.
This paper presents initial steps in the development of a method to be used for the evaluation of kitting. This from an information source point of view and for studying effects related to productivity and quality. The methodology is projected to act as a foundation for how to carry out a subsequent comprehensive case study. The purpose of the case study is to explore how kitting affects the cognitive workload compared to the ordinary material rack combined with part numbers used in the current manufacturing industry. This is done by measuring productivity; time spent on assembling a product, and quality; number of assembly errors. One step in the methodology development process, which is described in this paper, was to conduct a pilot study, primarily to test the methodology related to the selection of measurement parameters, as well as for getting experiences from running the methodology with real test subjects.
This paper concerns the handling of information in assembly work environments. Several studies involving both literature reviews, case studies andobservations were conducted to find factors that affect human performance in manual assembly. The main experiment with 36 subjects used a mixed method design with a quantitative study, including time and errors as dependant measures,a qualitative study, including workload ratings, and a questionnaire. The experiment involved the assembly of a pedal car and the components werepresented using structured kits, unstructured kits and material racks. Assembly information was presented as text & component numbers or photographs, and situations with and without component variation were considered. Among theresults it was found that assembly times and workload ratings were lower when using a kit, whereas using a material rack resulted in perceived decreased workflow and increased stress and frustration. Assembly times and workload ratings were lower when using photographs, whereas using text and numbers increased mental workload.
This paper presents an experimental study aimed at investigating interaction effects affecting personnel in manual assembly. The main experiment with 36 subjects used a mixed method design which included a quantitative study, including time and errors as dependent measures, and a qualitative study, including workload ratings and a questionnaire. The overall task in the experiment was to assemble components on a pedal car. The main factors involved were assembly information (text & component numbers or photographs), material presentation (using structured kits, unstructured kits and material racks) and component variation (situations with and without component variation). It was found that performance, measured in assembly time, was best when combining photographs with no component variants and when using an unstructured kit.
This study investigate different ways of presenting material and information at workstations while using mixed assembly mode with product variants. The experimental set up annotated an assembly line involving 36 subjects. The material presentation factor involved the use of a material rack compared to using an unstructured kit as well as a structured kit. The information presentation factor involved using a text and number instruction compared to a photograph instruction, and situations with and without component variation were considered. Results show that assembly times and workload ratings were lower when using a kit, whereas using a material rack resulted in perceived decreased workflow and increased stress and frustration. Moreover, assembly times and workload ratings were lower when using photographs, whereas using text and numbers increased mental workload. The results could be useful when planning work places and production systems in order to obtain a better workflow and an increased human performance.
Modern manufacturing information systems allow fast distribution of, and access to, information. One of the main purposes with an information system within manual assembly is to improve product quality, i.e. to ensure that assembly errors are as few as possible. Not only must an information system contain the right information, it must also provide it at the right time and in the right place. The paper highlights some of the concerns related to the design and use of information systems in manual assembly. The paper describes a study that focuses on the correlation between active information seeking behaviour and assembly errors. The results are founded on both quantitative and qualitative methods. The study indicates that by using simplified information carriers, with certain characteristics, the assembly personnel more easily could interpret the information, could to a higher degree be prompted (triggered) about product variants and could also be able to prepare physically and mentally for approaching products arriving along the assembly line. These conditions had positive influence on quality, i.e. gave a reduction of assembly errors.
Work-related musculoskeletal disorders (WMSDs) constitute a large part of work absences among industry workers, together with all the health and economic problems that it carries. Exoskeletons developed for overhead operations can potentially be a solution to reduce risks for WMSDs. However, some companies are still hesitant to implement exoskeletons in their workplace, since the effects of using exoskeletons are still not fully proved. Digital human modeling (DHM) could help with this dilemma by facilitating studies of the viability of the exoskeletons for specific work tasks. This paper proposes a DHM based framework to implement the study of upper body exoskeletons focused on overhead assembly operations. The framework emphasizes the kinematics and forces interaction between the human and the exoskeleton.
Recently, the concept of Industry 5.0 has been introduced to complement, among other things, Industry 4.0’s focus on efficiency and productivity with a focus on humans in digital design and production processes. The inclusion of human interaction with digital realities, extended reality (XR) technologies, such as augmented reality (AR) and virtual reality (VR), can play an essential role in Industry 5.0. While rapid advances in XR technologies are solidifying and finding their place in the product and production development process, terminology and classification scheme remain under-determined. As a result, there have been numerous classifications of XR technologies from different perspectives, but little widespread agreement. They have been classified by their level of immersion or how well they meet a specific purpose (such as training). In addition to that, the classifications are usually made for one particular field (e.g. marketing, healthcare, engineering, architecture, among others). Therefore, to set the basis for future research, it is essential to identify and outline the dimensions that intervene in product and production design in regards to XR facilitated collaboration. With the ideas proposed in this paper, we want to identify basic concepts that classify a collaborative XR system by analyzing how users interact with the environment and other users. Our motivation is that collaborative design involves not only the physical dimension but also a social dimension. Defining when an XR system contributes to increasing social and/or physical presence could clarify and simplify its categorization.
In the design process of products and production systems, the activity to systematically evaluate initial alternative design concepts is an important step. The digital human modeling (DHM) tools include several different types of assessment methods in order to evaluate product and production systems. Despite this, and due to the fact that a DHM tool in essence is a computer-supported design and analysis tool, none of the DHM tools provide the functionality to, in a systematic way, use the results generated in the DHM tool to compare design concepts between each other. The aim of this paper is to illustrate how a systematic concept evaluation method is integrated in a DHM tool, and to exemplify how it can be used to systematically assess design alternatives. Pugh´s method was integrated into the IPS software with LUA scripting to systematically compare design concepts. Four workstation layout concepts were generated by four engineers. The four concepts were systematically evaluated with two methods focusing on human well-being and two methods focusing on system performance and cost. The result is very promising. The demonstrator illustrates that it is possible to perform a systematic concept evaluation based on human well-being, overall system performance, and other parameters, where some of the data is automatically provided by the DHM tool and other data manually. The demonstrator can also be used to evaluate only one design concept, where it provides the software user and the decision maker with an objective and visible overview of the success of the design proposal from the perspective of several evaluation methods.
The type of ergonomics assessment methods typically used in digital human modelling (DHM) tools and automated assessment processes were rather developed to be used by ergonomists to assess ergonomics by observing the characteristics of the work. Direct measurement methods complement observation methods. Direct measurement methods have a design that suits being implemented into DHM tools. A drawback of direct measurement methods is that they traditionally do not include action levels. However, action levels in direct measurement methods have recently been suggested. The aim of this paper is to illustrate how these recent physical load exposure calculations and recommendations can be integrated in a DHM tool and in an automated assessment process. A demonstrator solution was developed that inputs exposure data from simulations in the DHM tool IPS IMMA as well as exposure data that originate from tracking real workers’ motions, using the motion capture system Xsens MVN. The demonstrator was applied in two use cases: one based on predicted human motions and one based on captured human motions. In the demonstrator, head posture, upper left and right arm posture and velocity, as well as left and right wrist velocity were calculated. Exposure data were compared with action levels, and extreme action levels were indicated by colouring the information. The results are promising, and the demonstrator illustrates that it is possible to follow the trends in Industry 4.0 and Industry 5.0 to automate and digitalize ergonomics assessment processes in industry.
In the context of in-plant materials supply, the materials feeding principle of kitting is often discussed as an alternative to the more common continuous supply (also known as line stocking). However, there are few detailed studies describing the relative effects of kitting and continuous supply. The current paper identifies the relative effects of kitting and continuous supply, and provides insight into how these effects arise. The paper draws on empirical data from two case studies in the Swedish automotive assembly industry. In each of the cases, continuous supply has been replaced by kitting, enabling comparison of kitting and continuous supply in the same production environment. The performance areas studied include man-hour consumption, product quality, flexibility, inventory levels, and space requirements. Interviews with production engineers, assemblers, and operators responsible for kit preparation at each company contribute to a broad yet detailed view of the relative effects of the two materials feeding principles.
This paper presents an experimental study made on the use of different kinds of information sources in manual assembly. The general idea is that only the necessary information should be presented to the worker and it should be presented where and when the worker needs it as this is believed to both save time and unload cognitive strain. To account for the latter two aspects of this thought, where and when, this paper investigates the use of a handheld unit as an information source in manual assembly. Having a mobile information system, such as a Personal Digital Assistant (PDA), that can be carried with you at all times, as opposed to a stationary one, such as a computer terminal, is hypothesized to greatly improve productivity and quality. Experimental results show that the use of a PDA significantly improves quality whereas productivity does not significantly improve.