Paraskevi Th. Zacharia and Andreas C. Nearchou
This paper considers the assembly line worker assignment and balancing problem of type-2 (ALWABP-2) with fuzzy task times. This problem is an extension of the (simple) SALBP-2 in…
Abstract
Purpose
This paper considers the assembly line worker assignment and balancing problem of type-2 (ALWABP-2) with fuzzy task times. This problem is an extension of the (simple) SALBP-2 in which task times are worker-dependent and concurrently uncertain. Two criteria are simultaneously considered for minimization, namely, fuzzy cycle time and fuzzy smoothness index.
Design/methodology/approach
First, we show how fuzzy concepts can be used for managing uncertain task times. Then, we present a multiobjective genetic algorithm (MOGA) to solve the problem. MOGA is devoted to the search for Pareto-optimal solutions. For facilitating effective trade-off decision-making, two different MO approaches are implemented and tested within MOGA: a weighted-sum based approach and a Pareto-based approach.
Findings
Experiments over a set of fuzzified test problems show the effect of these approaches on the performance of MOGA while verifying its efficiency in terms of both solution and time quality.
Originality/value
To the author’s knowledge, no previous published work in the literature has studied the biobjective assembly line worker assignment and balancing problem of type-2 (ALWABP-2) with fuzzy task times.
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Elias Xidias and Paraskevi Zacharia
A fleet of mobile robots has been effectively used in various application domains such as industrial plant inspection. This paper proposes a solution to the combined problem of…
Abstract
Purpose
A fleet of mobile robots has been effectively used in various application domains such as industrial plant inspection. This paper proposes a solution to the combined problem of task allocation and motion planning problem for a fleet of mobile robots which are requested to operate in an intelligent industry. More specifically, the robots are requested to serve a set of inspection points within given service time windows. In comparison with the conventional time windows, our problem considers fuzzy time windows to express the decision maker’s satisfaction for visiting an inspection point.
Design/methodology/approach
The paper develops a unified approach to the combined problem of task allocation and motion planning for a fleet of mobile robots with three objectives: (a) minimizing the total travel cost considering all robots and tasks, (b) balancing fairly the workloads among robots and (c) maximizing the satisfaction grade of the decision maker for receiving the services. The optimization problem is solved by using a novel combination of a Genetic Algorithm with pareto solutions and fuzzy set theory.
Findings
The computational results illustrate the efficiency and effectiveness of the proposed approach. The experimental analysis leverages the potential for using fuzzy time windows to reflect real situations and respond to demanding situations.
Originality/value
This paper provides trade-off solutions to a realistic combinatorial multi-objective optimization problem considering concurrently the motion and path planning problem for a fleet of mobile robots with fuzzy time windows.
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Paraskevi Zacharia, Nikos Aspragathos, Ioannis Mariolis and Evaggelos Dermatas
The purpose of this paper is to present a flexible automation system for the manipulation of fabrics lying on a work table and focuses on the design of a robot control system…
Abstract
Purpose
The purpose of this paper is to present a flexible automation system for the manipulation of fabrics lying on a work table and focuses on the design of a robot control system based on visual servoing and fuzzy logic for handling flexible sheets lying on a table. The main contribution of this paper is that the developed system tolerates deformations that may appear during robot handling of fabrics due to buckling without the need for fabric rigidization.
Design/methodology/approach
The vision system, consisting of two cameras, extracts the features that are necessary for handling the fabric despite possible deformations or occlusion from the robotic arm. An intelligent controller based on visual servoing is implemented enabling the robot to handle a variety of fabrics without the need for a mathematical model or complex mathematical/geometrical computations. To enhance its performance, the conventional fuzzy logic controller is tuned through genetic algorithms and an adaptation mechanism and the respective performance is evaluated. The experiments show that the proposed robotic system is flexible enough to handle various fabrics and robust in handling deformations that may change fabric's shape due to buckling.
Findings
The experiments show that the proposed robotic system is flexible enough to handle various fabrics and robust in handling deformations that may change fabric's shape due to buckling.
Research limitations/implications
It is not possible to cover all the aspects of robot handling of flexible materials in this paper, since there are still several related issues requiring solutions. Considering the future research work, the proposed approach can be extended to sew fabrics with curved edges and correcting the distortions presented during robot handling of fabrics.
Practical implications
The paper includes implications for robot handling a variety of fabrics with low and medium bending rigidity on a working table. The intent of this paper deals with buckling in context of achieving a successful seam tracking and not the correction strategy against folding or wrinkling problems.
Originality/value
This paper fulfils an identified need to study the fabrics' behavior towards robot handling on a working table.
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Examines the thirteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…
Abstract
Examines the thirteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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Examines the twelfth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects…
Abstract
Examines the twelfth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.