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Application of Fuzzy Logic to Multi-Objective Scheduling Problems in Robotic Flexible Assembly Cells
Khalid Abd,
Kazem Abhary,
Romeo Marian
Issue:
Volume 1, Issue 3, June 2013
Pages:
34-41
Received:
29 May 2013
Published:
20 June 2013
Abstract: This paper is aimed at developing a methodology to solve a multi-objective problem in robotic flexible assembly cells. The proposed methodology is based on three main steps: (1) scheduling of the RFACs using different common rules, (2) normalisation of the scheduling outcomes, and (3) selection of the optimal scheduling rules, using a fuzzy inference system. In this paper, four rules, namely short processing time, long processing time, earlier due date and random, are examined. Four objectives are considered simultaneously: scheduling length, total transportation time, utilisation rate and workload rate. A realistic case study is provided for demonstrating applicability of the suggested methodology. The results show that the methodology is practical and works in RFACs settings.
Abstract: This paper is aimed at developing a methodology to solve a multi-objective problem in robotic flexible assembly cells. The proposed methodology is based on three main steps: (1) scheduling of the RFACs using different common rules, (2) normalisation of the scheduling outcomes, and (3) selection of the optimal scheduling rules, using a fuzzy inferen...
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Development of a Model for Simultaneous Cost-Risks Reduction in JIT Systems Using Multi-External and Local Backup Suppliers
Faraj El Dabee,
Romeo Marian,
Yousef Amer
Issue:
Volume 1, Issue 3, June 2013
Pages:
42-52
Received:
14 May 2013
Published:
30 June 2013
Abstract: In many organisations, Just-In-Time (JIT) implementation plays a significant role in minimizing their excessive costs, and increasing their efficiency. However, the risks accompanying JIT strategies are often overlooked and affect system processes disrupting the entire chain of supply. This paper proposes an inventory model that can simultaneously reduce costs and risks in JIT systems. This model is developed in order to ascertain an optimal ordering strategy for procuring raw materials by using multi-external suppliers and local backup supplier to reduce the total cost of the products, and at the same time to reduce the risks associated with JIT supply within production systems. The effectiveness of the developed model is tested using an example problem with inbuilt disruption. A comparison between the cost of using the JIT system and using the inventory system shows the superiority of the use of the inventory policy.
Abstract: In many organisations, Just-In-Time (JIT) implementation plays a significant role in minimizing their excessive costs, and increasing their efficiency. However, the risks accompanying JIT strategies are often overlooked and affect system processes disrupting the entire chain of supply. This paper proposes an inventory model that can simultaneously ...
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Ant Colony Optimization with Genetic Operations
Issue:
Volume 1, Issue 3, June 2013
Pages:
53-58
Received:
12 June 2013
Published:
30 June 2013
Abstract: This paper attempts to overcome stagnation problem of Ant Colony Optimization (ACO) algorithms. Stagnation is undesirable state which occurs at a later phases of the search process. Excessive pheromone values attract more ants and make further exploration hardly possible. This problem has been addressed by Genetic operations (GO) incorporated into ACO framework. Crossover and mutation operations have been adapted for use with ant generated strings which still have to provide feasible solutions. Genetic operations decrease selection pressure and increase probability of finding the global optimum. Extensive simulation tests were made in order to determine influence of genetic operation on algorithm performance.
Abstract: This paper attempts to overcome stagnation problem of Ant Colony Optimization (ACO) algorithms. Stagnation is undesirable state which occurs at a later phases of the search process. Excessive pheromone values attract more ants and make further exploration hardly possible. This problem has been addressed by Genetic operations (GO) incorporated into ...
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Ant Colony Optimization with Re-Initialization
Issue:
Volume 1, Issue 3, June 2013
Pages:
59-63
Received:
19 June 2013
Published:
30 June 2013
Abstract: This contribution introduces an Ant Colony Optimization (ACO) algorithm with re-initialization mechanism. The whole search process is broken by re-initialization into shorter semi-independent steps called “macro cycles”. The length of macro cycle depends on pheromone accumulation and can be adjusted by a user parameter. It is shown that re-initialization mechanism prevents ACO algorithm from pheromone saturation and consecutive stagnation. This approach avoids overhead caused by algorithm run with excessive pheromone values where further exploration is hardly possible. The solution offers lower CPU cost of the search process and enables automation of heuristic search especially in changing environments like dynamic networks. The efficiency of proposed method is demonstrated on a path minimization problem on 50 node graph.
Abstract: This contribution introduces an Ant Colony Optimization (ACO) algorithm with re-initialization mechanism. The whole search process is broken by re-initialization into shorter semi-independent steps called “macro cycles”. The length of macro cycle depends on pheromone accumulation and can be adjusted by a user parameter. It is shown that re-initiali...
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Adaptive Control Design for a Mimo Chemical Reactor
Yasabie Abatneh,
Omprakash Sahu
Issue:
Volume 1, Issue 3, June 2013
Pages:
64-70
Received:
24 June 2013
Published:
10 July 2013
Abstract: The major disadvantage of non-adaptive control systems is that these control systems cannot cope with fluctuation in the parameters of the process. One solution to this problem is to use high levels of feedback gain to decrease the sensitivity of the control system. However high gain controllers have two major problems: large signal magnitude and closed loop instability. The solution to this problem is to develop a control system that adapts to changes in the process. This paper presents the design of adaptive controller to a Multi Input Multi Output (MIMO) chemical reactor. The proposed adaptive controller is tested by using Math lab Simulink program and its performance is compared to a conventional controller for a different situation. The paper demonstrated that while the adaptive controller exhibits superior performance in the presence of noise the convergence time is typically large and there is a large overshoot. The results from the case study indicate that the use of adaptive controller can be extended to process with inverse response. For such process the adaptive controller will be superior to the conventional controller even without parameters change in the process. Although the conventional controller has the smaller response time, it is incapable of eliminating the inverse response.
Abstract: The major disadvantage of non-adaptive control systems is that these control systems cannot cope with fluctuation in the parameters of the process. One solution to this problem is to use high levels of feedback gain to decrease the sensitivity of the control system. However high gain controllers have two major problems: large signal magnitude and c...
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Optimization of Goal Targeting in 1 on 1 Soccer Robots Using Safe Points (Experimental Research)
Yahya Hassanzadeh-Nazarabadi,
Abolfazl Saravani,
Bahareh Alizadeh
Issue:
Volume 1, Issue 3, June 2013
Pages:
71-74
Received:
1 July 2013
Published:
20 July 2013
Abstract: Due to the fact that targeting the goal is the last part of soccer robot’s aggressive decision chains, aiming styles and their lack of proficiency are discussed. Then targeting based on safe points is explained and implemented. Accordingly, this method has perfect accuracy. It brings new standpoint in aiming and it’s capable of moving the barrier of its related knowledge.
Abstract: Due to the fact that targeting the goal is the last part of soccer robot’s aggressive decision chains, aiming styles and their lack of proficiency are discussed. Then targeting based on safe points is explained and implemented. Accordingly, this method has perfect accuracy. It brings new standpoint in aiming and it’s capable of moving the barrier o...
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An Analysis of the Reciprocal Collision Avoidance of Cooperative Robots
A. Fratu,
M. Dambrine,
L. Vermeiren,
A. Dequidt
Issue:
Volume 1, Issue 3, June 2013
Pages:
75-84
Received:
14 May 2013
Published:
30 July 2013
Abstract: This paper presents a formal approach that addresses the reciprocal robots collision avoidance, where two robots need to avoid collisions with each other, while moving in a common workspace. Based on our formulation, each physical robot acts fully independently, communicating with the corresponding virtual prototype and imitating its behavior. Each physical robot reproduces the pathway of its virtual prototype. With a view to collision avoidance, it is necessary to detect a possible collision. This action includes the potentially intersecting regions test of the corresponding virtual prototypes. The estimation of the collision-free actions on the virtual robots and the collaborative work of the physical robots which imitate their virtual prototypes are the original ideas. Based on potentially intersecting regions of the virtual robots, we identified a collision-free motion corridor for two cooperative robots. Using the definition of velocity obstacles, we derived sufficient conditions for the collision-free motion of the two virtual robots. We tested the present approach on several complex simulation scenarios involving two virtual robots and estimating collision-free actions for each of them during the cooperative tasks. The focus of this paper is the identification of the collision-free actions for two virtual robots and their behavioral imitation by the physical robots.
Abstract: This paper presents a formal approach that addresses the reciprocal robots collision avoidance, where two robots need to avoid collisions with each other, while moving in a common workspace. Based on our formulation, each physical robot acts fully independently, communicating with the corresponding virtual prototype and imitating its behavior. Each...
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