Optimal design of a decoupled multiple-loop pallet system for cyclic flexible manufacturing plants

IEEE Trans. Automat. Sci. Eng.

2013

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For flexible manufacturing systems, there are normally some durations in which a number of machines are idle and do not process any parts. Devising a control policy to turn off the idle machines and reduce their level of energy consumption is a significant contribution towards the green manufacturing paradigm. This paper addresses the design of such a control strategy for a closed-loop flow shop plant based on a one-loop pallet system. The main goal is to coordinate running of the machines and motion of pallets to gain the minimal energy consumption in idle machines, as well as to obtain the desired throughput for the plant. To fulfill this goal, first mathematical conditions, which economically characterize the on-off control for machines, are presented. Constrained to these conditions and the mathematical models describing the pallet system, a mixed integer nonlinear minimization problem with the energy monitor as the objective function is then developed. Provided that the problem computation time can be managed, the optimal control for the operation of the plant and the minimal energy consumption in the idle machines are computed. To deal with the time complexity, a linearized form of the model and a heuristic approach are introduced. These methods are applied to some examples of industrial size, and their impacts in practice are discussed and verified by using a discrete event simulation tool.Note to Practitioners-Control of a flexible manufacturing plant in order to produce a set of part types in a determined production cycle time is a challenging problem. In addition, the problem is more complicated if energy efficiency is considered as an important key in the plant control design. This study provides methods which tackles this complex problem for an industrial size of a pallet-constrained flow shop. The outcome is an optimal switching control strategy, which reduces energy consumption for idle processing machines and maintains a desired throughput for the flow shop plant.Index Terms-Energy model, flow shop plant, heuristic algorithm, optimization, pallet system.

Section: A a Cyclic Flow Shop Plant Based On A One-loop Pallet Systemmentioning

confidence: 99%

Section: B Verification and Robust Analysis Of The On-off Controlmentioning

confidence: 99%

Energy Reduction in a Pallet-Constrained Flow Shop Through On–Off Control of Idle Machines

Mashaei

IEEE Trans. Automat. Sci. Eng.

2013

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“…In [18], the authors developed the mathematical models, which characterize the dynamic behavior of a cyclic pallet system. Employing these models as the constraints in an optimization problem, the problem solution gives the level of queues at any given time in the cyclic period.…”

Section: Mathematical Models Of the Cyclic Pallet Systemmentioning

confidence: 99%

Green and lean control of cyclic pallet systems

Mashaei

2011 IEEE International Conference on Automation Science and Engineering

Abbestam

2011

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Reduction of energy consumed by a manufacturing system to turn raw parts to finished products is a big step towards the green and lean production. In this study the energy efficiency of a one-loop pallet system, a main tool to handle and locate various part types in a cyclic production line, is investigated. The main goal is to obtain the minimal energy consumption in the pallet system drive unit through an optimally controlled and coordinated motion of pallets. To achieve the mentioned goal, first the mean value of the pallet system energy consumption is mathematically modeled. Later, this energy model is utilized as an objective function within an optimization model including constraints on system crucial properties such as cyclic and dynamic behavior, queueing policy, and buffer size. The solution of the optimization problem gives the optimal values of the system control variables, namely, number of pallets and conveyor velocity. To demonstrate the application of this optimization model in practice, three case studies are introduced. The results of these studies show that a significant amount of the energy consumption may be saved by applying the suggested green control.

“…The main issue in the control design is to maximize flow efficiency with a nearly fixed number of handling resources and technologies (the number of carriers such as pallets and AGVs may be variable). Flow enhancement, [5], [6], [7], [8], makespan minimization [9], [10], reduction of the cycle time and Work-In-Process (WIP), [11], [12], [13], [14] are some instances for the control design. On the other hand, the main objective in the plant design is to minimally design a handling system (maximize handling resource utilization) for a given flow rate, [2], [3], [4].…”

Section: Introductionmentioning

confidence: 99%

Concurrent design and control of automated material handling systems

Mashaei¹,

2013 IEEE International Conference on Automation Science and Engineering (CASE)

2013

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Lean and agile design and control of an automated material handling system are investigated in this paper. The demands for a minimal number of handling resources and their maximal utilization emphasize the importance of a concurrent structure and control design for a handling mechanism in the conceptual phase. To provide this concurrency, a universal model based on mathematical linear constraints is developed to define a set of part movements without concerning a specific handling technology. Furthermore, an objective characterizing optimal part movements, according to the lean and agile paradigms, is formulated in the conceptual design phase. Control measures, which are obtained by solving the mixed integer linear model including the objective and constraints, provide important keys for designers to conceptualize a proper design of an automated material handling system. To show the application of developed approach, a case study is presented and discussed.