The robotic mobile fulfillment system (RMFS) utilizes robots to automate logistics handling. Although robots can replace workers, there are serious limitations and conflicts that make the system inefficient, resulting...
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The robotic mobile fulfillment system (RMFS) utilizes robots to automate logistics handling. Although robots can replace workers, there are serious limitations and conflicts that make the system inefficient, resulting in a limited number of robots in the system. A conflict-free scheduling approach is studied, demonstrating better system efficiency, breaking the limit on the number of robots, and accommodating more robots in operation compared to the traditional strategy. A mathematical model aiming to minimize the total completion time is presented. An A $<^>\ast$ algorithm is modified for path planning, and an approach with two avoidance rules and six priority rules is proposed for conflict-free scheduling. Based on a case study involving four layout scales, the conflict-free scheduling is suitable for layouts with a higher number of robots, pillars, and a unidirectional path networks. More robots can be accommodated within the system, and even a threefold increase (45 to 150) will not result in a decrease in system efficiency, reducing the total completion time by 49.3%. In the largest layout system, the number of robots doubled (160 to 320) and the total completion time was reduced by 26.1%. This indicates the great potential for the conflict-free scheduling approach in future logistic applications, which could reduce resource consumption for scheduling and increase system efficiency.
Consider an m-machine production line for processing identical parts served by a mobile robot. The problem is to find the minimum cycle time for 2-cyclic schedules, in which exactly two parts enter and two parts leave...
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Consider an m-machine production line for processing identical parts served by a mobile robot. The problem is to find the minimum cycle time for 2-cyclic schedules, in which exactly two parts enter and two parts leave the production line during each cycle. This work treats a special case of the 2-cyclic robot scheduling problem when the robot route is given and the operation durations are to be chosen from prescribed intervals. The problem was previously proved to be polynomially solvable in O(m(8)log m) time. This paper proposes an improved algorithm with reduced complexity O(m(4)). (C) 2010 Elsevier B.V. All rights reserved.
In this paper we consider the problem of no-wait cyclic scheduling of identical parts in an m-machine production line in which a robot is responsible for moving each part from a machine to another. The aim is to rind ...
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In this paper we consider the problem of no-wait cyclic scheduling of identical parts in an m-machine production line in which a robot is responsible for moving each part from a machine to another. The aim is to rind the minimum cycle time for the so-called 2-cyclic schedules, in which exactly two parts enter and two parts leave the production line during each cycle. The earlier known polynomial-time algorithms for this problem are applicable only under the additional assumption that the robot travel times satisfy the triangle inequalities. We lift this assumption on robot travel times and present a polynomial-time algorithm with the same time complexity as in the metric case, O(m(5) log m). (C) 2008 Elsevier B.V. All rights reserved.
Recently, Pablo Saez (2009) [1] has developed a quadratic algorithm for a 2-cyclic robotic scheduling problem. In this note we uncover that the algorithm handles a special version of the problem only and fails to solv...
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Recently, Pablo Saez (2009) [1] has developed a quadratic algorithm for a 2-cyclic robotic scheduling problem. In this note we uncover that the algorithm handles a special version of the problem only and fails to solve the general 2-cyclic robotic scheduling problem. (C) 2009 Elsevier B.V. All rights reserved.
This study addresses cyclic scheduling in robotic flowshops with bounded work-in-process (WIP) levels. The objective is to minimize the cycle time or, equivalently, to maximize the throughput, under the condition that...
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This study addresses cyclic scheduling in robotic flowshops with bounded work-in-process (WIP) levels. The objective is to minimize the cycle time or, equivalently, to maximize the throughput, under the condition that the WIP level is bounded from above by a given integer number. We present several strongly polynomial algorithms for the 2-cyclic robotic flowshop scheduling problems for various WIP levels. (C) 2010 Wiley Periodicals, Inc. Naval Research Logistics 58: 1-16, 2011
This note discusses the pioneering role and main contributions of V.S. Tanaev in the field of cyclic robotic flowshop scheduling. Open questions (either explicitly or implicitly) posed in his papers and kept unsolved ...
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This note discusses the pioneering role and main contributions of V.S. Tanaev in the field of cyclic robotic flowshop scheduling. Open questions (either explicitly or implicitly) posed in his papers and kept unsolved up to date are exposed.
Consider an m-machine production line for processing identical parts served by a mobile robot. The problem is to find the minimum cycle time for 2-cyclic schedules, that is, schedules in which exactly two parts enter ...
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Consider an m-machine production line for processing identical parts served by a mobile robot. The problem is to find the minimum cycle time for 2-cyclic schedules, that is, schedules in which exactly two parts enter and two parts leave the production line during each cycle. This work treats a special case of the 2-cyclic robot scheduling problem when the robot route is given and operation durations are chosen from prescribed intervals. A strongly polynomial algorithm of time complexity O(m (8)log m) is proposed.
In this survey we review the current complexity status of basic cyclic scheduling models. We start with the formulations of three fundamental cyclic scheduling problems, namely the cyclic jobshop, cyclic flow-shop, an...
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In this survey we review the current complexity status of basic cyclic scheduling models. We start with the formulations of three fundamental cyclic scheduling problems, namely the cyclic jobshop, cyclic flow-shop, and cyclic project scheduling problems. We present state-of-the-art results on the computational complexity of the problems, paying special attention to recent results on the unsolvability (NP-hardness) of various cyclic problems arising from the scheduling of robotic cells. (c) 2010 Elsevier Ltd. All rights reserved.
We consider the original routing algorithm invented by Romanovskii (1967) for solving a cyclic project scheduling problem and establish its close relationship with the well-known routing algorithm by Dantzig, Blattner...
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ISBN:
(纸本)9781424441358
We consider the original routing algorithm invented by Romanovskii (1967) for solving a cyclic project scheduling problem and establish its close relationship with the well-known routing algorithm by Dantzig, Blattner and Rao (1967). Though Romanovskii's and Dantzig-Blattner-Rao's algorithms can only treat fixed numerical data, we show that they both can be extended to solve problems with interval-valued input data.
An arrangement of the multi-set {1, 1, 2, 2, ... , n, n} is said to be "split-pair" if for all i < n, between the two occurrences of i there is exactly one i + 1. We enumerate the number of split-pair arr...
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An arrangement of the multi-set {1, 1, 2, 2, ... , n, n} is said to be "split-pair" if for all i < n, between the two occurrences of i there is exactly one i + 1. We enumerate the number of split-pair arrangements and in particular show that the number of such arrangements is (-1)(n+1) 2(n)(2(2n) - 1)B-2n where B-i is the ith Bernoulli number. (c) 2007 Elsevier Inc. All rights reserved.
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