Energy conscious machine and robot speed decisions in two machine robotic cell scheduling

Güzel, Betül Necibe
Minimizing cycle time has always been a critical objective in manufacturing cells. Recently, energy efficient and environmentally conscious manufacturing practices have received increasing attention from researchers and practitioners. Therefore, in this thesis we consider a 2-machine manufacturing cell with a material handling robot where two conflicting objectives exist: minimization of cycle time and energy consumption. It is a flow type cell where identical parts are first processed on the first machine and then on the second machine. All handling operations between part buffers and machines and loading/unloading operations are done by a robot. Most of the research on robotic cell scheduling problems focus on robot activity sequencing decisions and assume that robot and machines operate at a fixed pace. However, both robot’s speed and machines’ processing times are controllable and they affect the cycle time and energy consumption performance of a cell. To the best of our knowledge, this is the first study that consider robot and machine speed controllability at the same time. We study three well known cyclic robot activity sequences and develop mathematical models that find efficient solutions for the problem. Our analysis on mathematical models show that energy optimization with robot speed and machine processing time control leads to schedules in which robot’s arrival to a machine for unloading operation and part completion time on the machine are synchronized. Furthermore, we provide a numerical study that explores which robotic activity sequence is better when and how much energy saving can be achieved by employing robot speed and processing time control strategies.


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Citation Formats
B. N. Güzel, “Energy conscious machine and robot speed decisions in two machine robotic cell scheduling,” M.S. - Master of Science, Middle East Technical University, 2021.