Presenting information in manual assembly

Ever since industrialization, manufacturing companies have competed with each other in trying to make the best and the cheapest product and the automotive industry is definitely no exception. The arms race between truck and car manufacturers has pushed manufacturing technology and production practice to where it is today. However, whereas companies have traditionally competed with the engineering excellence and technology of their products, the human effort in production is often neglected. After all, there are still many tasks that require the flexibility and intelligence of a human worker. This thesis focuses entirely on the information context of assembly workers. It investigates and discusses their general information behaviour in terms of information need, syntax of information, information sources and technology as well as basic cognitive abilities used to utilize information such as attention and memory. The thesis presents relevant literature on the subject of information behaviour and pinpoints potential hazards of information design in manual assembly. It also identifies three hypotheses that suggest improved productivity and quality of work as a result of certain changes in the information landscape. One hypothesis deals with the layout of information, a second deals with the syntax used to identify parts and a third deals with the information medium used to convey information. Analysis of empirical data gathered shows, among other things, that using unstructured and batched information favours productivity of work; using a syntax with semantic content as opposed to traditional article numbers without any semantic content also improves productivity of work; and using a mobile information unit betters the quality of work. The purpose of the thesis is to present the beginnings of a road map towards the greater understanding of information presentation in manual assembly. As previous research on this application area has been scarce, it draws upon existing theories found in other sciences, primarily cognitive science and its applications such as Human-Computer Interaction (HCI), information theory and human error

Incorporating cognitive aspects in digital human modelling

To build software which, at the press of a button, can tell you what cognition related hazards there are within an environment or a task, is probably well into the future if it is possible at all. However, incorporating existing tools such as task analysis tools, interface design guidelines and information about general cognitive limitations in humans, could allow for greater evaluative options for cognitive ergonomics. The paper will discuss previous approaches on the subject and suggest adding design and evaluative guiding in DHM that will help a user with little to no knowledge of cognitive science, design and evaluate a human-product interaction scenario

Experimental study of cognitive aspects affecting human performance in manual assembly

This full factorial experimental study aimed to investigate different ways of presenting material and information at the workstation while using mixed assembly mode with product variants. The experimental set up annotated an assembly line involving 36 subjects (19 women and 17 men) partly assembling a pedal car. 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. Both quantitative and qualitative results were obtained, including time and errors as dependant measures, and workload ratings as well as a questionnaire as support measurements. Among the results 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. 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

Applying cognitive science to digital human modelling for user centred design

To build software which, at the press of a button, can tell you what cognition related hazards there are within an environment or a task, is probably well into the future if it is possible at all. However, incorporating existing tools such as task analysis tools, interface design guidelines and information about general cognitive limitations in humans, could allow for greater evaluative options for cognitive ergonomics. The paper discusses previous approaches to the subject and suggests adding design and evaluative guiding in Digital Human Modelling that will help a user with little or no knowledge of cognitive science to design and evaluate a human- product interaction scenario

Interaction effects affecting human performance in manual assembly

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

Cognitive aspects affecting human performance in manual assembly

This paper concerns the handling of information in assembly work environments. Several studies involving both literature reviews, case studies and observations 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 were presented 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 the results 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

Using mobile information sources to increase productivity and quality

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

Kitting as an information source in manual assembly

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

An assembly line information system study

Assembly line information systems are designed to provide assembly workers with appropriate information that allows the assembly of the product in good time and good quality. In this context product quality might be defined relative to the number of internal rejects or products which need some kind of reworking before being in a deliverable condition. This paper describes a pilot study of a heavy diesel engine assembly line where considerable variety is presented to the assembly workers in the form of engines destined for trucks, buses, marine applications and stationary power generation each of which has to comply with a variety of national and international standards. Internal rejects might for example occur through the fitting of subassemblies that are unsuited to the eventual application, and although an extensive information system is currently in place the level of internal rejects is considered to be unsatisfactory. The objectives of the study were to understand how the assembly workers interact with information systems and the impact this has on product quality and productivity. A single line was studied for ten days during which 2600 engines were assembled. At four of the assembly stations the existing information system was changed to reduce the amount of information to be assimilated by the workers, the timing of its presentation and its location. The use of simple colour-coded cards and symbols resulted in the reduction of internal rejects by 40% on two of the assembly stations and to zero on the other two stations. It is believed that changing the information system has changed the workers' behaviour through a reduction in cognitive stress levels. The pilot study has provided useful insights into the basis for modifying information systems and a further study of the final assembly of heavy trucks is planned with an ultimate aim of determining a rationale for the design of information systems for use within the assembly of customised products

Editorial [Production and Manufacturing Research]

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