54 research outputs found
Supervised and unsupervised learning in vision-guided robotic bin picking applications for mixed-model assembly
Mixed-model assembly usually involves numerous component variants that require effective materials supply. Here, picking activities are often performed manually, but the prospect of robotics for bin picking has potential to improve quality while reducing man-hour consumption. Robots can make use of vision systems to learn how to perform their tasks. This paper aims to understand the differences in two learning approaches, supervised learning, and unsupervised learning. An experiment containing engineering preparation time (EPT) and recognition quality (RQ) is performed. The findings show an improved RQ but longer EPT with a supervised compared to an unsupervised approach
Redesign of parts and simulation of flexible assembly cell for safety water shower assembly
A Design for Assembly (DSA) method is used to analyze the safety water shower assembly and to redesign the components with emphasis on meeting the criteria of allowing for flexible Assembly Cell (FAS). An Expert System is developed to select the right Assembly using VP-Expert. This thesis contrasts the old and new safety water shower assembly designs and describes the design of a final Flexible Assembly Cell. A PUMA 550 robot was investigated for use in the cell design. The flexible Assembly cell is simulated on silicon graphics using the IGRIP software. The economics of each part presentation method is considered. Flexible assembly cell has the advantage of high reliability, faster cycle time, low operating cost in the long run relative to the manual assembly process
Materials Handling in Production Systems: Design and Performance of Kit Preparation
This thesis focuses on processes for kit preparation, which are applied with the materials supply principle of kitting in production systems for mixed-model assembly. With kitting, assembly processes are supplied with portions of pre-sorted components, and each portion makes up a kit that holds the components needed for one assembly object at one or several assembly processes. When kitting is applied, picking activities, which are otherwise performed at assembly processes, are instead carried out in a process for kit preparation. Kit preparation involves collecting components designated for a particular assembly object into a single unit load that is delivered to assembly.Kitting is widely seen as beneficial for quality and flexibility in assembly processes when there are a large variety of components. Performance effects in assembly processes normally associated with kitting largely depend on the performance of kit preparation. Previous research indicates that a picking system’s design greatly impacts its performance. While research that has dealt with kit preparation points out several design aspects that can affect its performance, the available knowledge is far from exhaustive. The purpose of this thesis is to contribute to the knowledge of how kit preparation design aspects govern kit preparation performance.Case research, experiments, and modelling have been used to study how flexibility, kit quality and man-hour efficiency are affected by kit preparation design aspects related to work organisation, layout, policies, packaging, equipment, picking information, automation and control. Two case research studies respectively address kit preparation flexibility and kit quality, identifying how kit preparation design aspects can be configured to support these two performance areas. Two experiments focus on how picking information systems and confirmation methods affect kit preparation man-hour efficiency. One modelling study focuses on how collaborative robots can support man-hour efficient kit preparation. Through involvement in three research projects and an extensive review of the literature, this research has been guided by the needs of industry and by previously established knowledge.This thesis contributes to theory and to practice in the form of knowledge about relationships between kit preparation design aspects and the performance areas flexibility, kit quality and manhour efficiency. The theoretical contribution consists of building upon and underpinning the limitedknowledge about the topic that has been previously available, while also adding new knowledge. This includes, for example, glasses with integrated computer displays, RFID-scanning wristbands, and collaborative robots, and how they are linked to kit preparation performance. The practical contribution consists of concise yet holistic descriptions of relationships between kit preparation design and performance, which industry can readily adopt with some consideration to the situation’s characteristics
Lean manual assembly 4.0: A systematic review
In a demand context of mass customization, shifting towards the mass personalization of products, assembly operations face the trade-off between highly productive automated systems and flexible manual operators. Novel digital technologies—conceptualized as Industry 4.0—suggest the possibility of simultaneously achieving superior productivity and flexibility. This article aims to address how Industry 4.0 technologies could improve the productivity, flexibility and quality of assembly operations. A systematic literature review was carried out, including 234 peer-reviewed articles from 2010–2020. As a result, the analysis was structured addressing four sets of research questions regarding (1) assembly for mass customization; (2) Industry 4.0 and performance evaluation; (3) Lean production as a starting point for smart factories, and (4) the implications of Industry 4.0 for people in assembly operations. It was found that mass customization brings great complexity that needs to be addressed at different levels from a holistic point of view; that Industry 4.0 offers powerful tools to achieve superior productivity and flexibility in assembly; that Lean is a great starting point for implementing such changes; and that people need to be considered central to Assembly 4.0. Developing methodologies for implementing Industry 4.0 to achieve specific business goals remains an open research topic
The co-incident flow of work pieces and cutting tools in a restricted category of flexible machining cells
The work reported in this thesis describes research carried out into the detailed design
and operation of Flexible Machining Cells (FMC) incorporating automated work and tool
flow, dual flow. Three modes of cell management are considered for dual flow cells,
where the author examines both their operational and economic performance.
A framework is defined for investigating these dual flow cells, and a structured approach
providing a novel and detailed modelling capability is described. The question of how
this approach compares to single flow modelling and the additional or alternative
requirements for dual flow modelling is examined via the following key areas; the
specification of material handling requirements, tool transportation and issue and finally,
the control required to examine the interaction between the two flows operating
concurrently.
The framework is tested for its industrial applicability via an industrial case study. A
major aim of this study is to examine the view that a hybrid cell management strategy,
competitive management, could outperform the other strategies examined.
The aim of this methodology is to provide a solution for the control of FMCs. Emphasis
is placed on the ease of control and how the loading and control rules selection can
maximise economic enhancement of a cells performance
Design of tool management systems for flexible manufacturing systems
The objective of this thesis is to study the design and analysis of tool management system
in the automated manufacturing systems.
The thesis is focused on two main areas, namely design and experiment. In the first part
of the thesis, the design facility created has been reported. The model has been designed using
a hybrid approach in which the power of both algorithmic and knowledge based approaches is
utilised. Model permits detail, more accurate and complete solutions for the management of
tools in a generic manufacturing system.
In the second part of the thesis, to add more understanding to the tool management
problems, the interactions of the major tool management design parameters have been
investigated using a well known design technique, the Taguchi method. For this purpose, a large
number of design experiments have been configured where some have been suggested by the
Taguchi method and some have been created by the author to add more confidence, using a
large body of real industrial data. The experiments results give deeper understanding of TMS
problems and allow design guide-lines to be drawn for the designers.
The design approach and the experiments have been proven to be an accurate and valid
tool for the design of tool management systems for automated manufacturing systems. This is
indicated in the conclusion of the thesis
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