Browsing by Subject "Robotic cell scheduling"

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    Pure cycles in two-machine dual-gripper robotic cells
    (Elsevier, 2017) Gultekin, H.; Dalgıç, Ö. O.; Akturk, M. S.
    We consider a robotic cell served by a dual-gripper robot that consists of identical CNC machines placed linearly and a material handling robot loading/unloading the machines and transporting the parts between them. Identical parts are to be processed in this system and the CNC machines are capable of performing all the operations that a part requires. We consider the problem of sequencing activities of the robot in order to maximize the throughput rate. As a consequence of the flexibility of the CNC machines, a new class of robot move sequences, named as pure cycles, arises. In a pure cycle, the robot loads and unloads each machine once and each part is processed on exactly one of the machines. Thereby, the problem is to determine the best pure cycle that maximizes the throughput rate. We first determine the feasibility conditions for the pure cycles and prove some basic results that reduces the number of feasible pure cycles to be investigated. We analyze 2-machine robotic cells in detail and prove that five of the cycles among a huge number of feasible pure cycles dominate the rest. We determine the parameter regions in which each of the five cycles is optimal. We also analyze the performance improvement that can be attained by using a dual gripper robot and provide managerial insights.
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    Scheduling in flexible robotic manufacturing cells
    (2006) Gültekin, Hakan
    The focus of this thesis is the scheduling problems arising in robotic cells which consist of a number of machines and a material handling robot. The machines used in such systems for metal cutting industries are highly flexible CNC machines. Although flexibility is the key term that affects the performance of these systems, the current literature ignores this. As a consequence, the problems considered in the current literature are either too limiting or the provided solutions are suboptimal for the flexible systems. This thesis analyzes different robotic cell configurations with different sources of flexibility. This study is the first one to consider operation allocation problems and controllable processing times as well as some design problems and bicriteria models in the context of robotic cell scheduling. Also, a new class of robot move cycles is defined, which is overlooked in the existing literature. Optimal solutions are provided for solvable cases, whereas complexity analyses and efficient heuristic algorithms are provided for the remaining problems.