Date of Award
2019
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Computer Science
Committee Chair
Mikel D. Petty
Committee Member
Letha H. Etzkorn
Committee Member
Daniel M Rochowiak
Committee Member
Harry S Delugach
Committee Member
James J Swain
Subject(s)
Reinforcement learning., Materials handling., Discrete-time systems--Simulation methods.
Abstract
Applying machine learning methods to improve the efficiency of complex manufacturing processes, such as material handling, can be challenging. The interconnectedness of the multiple components that make up such processes and the typically large number of variables required to specify procedures and plans within them combine to make it very difficult to map the details of a real-world manufacturing process to an abstract mathematical representation suitable for machine learning methods. This work comprises both applied and theoretical results. On the applied side, machine learning, in particular reinforcement learning, was used to generate increasingly efficient plans for material handling to satisfy temporally varying product demands in a representative manufacturing facility. The essential steps in the research included defining a formal representation of a realistically complex material handling plan, specifying a set of suitable plan change operators as reinforcement learning actions, implementing a simulation-based multi-objective reward function that considers multiple components of material handling costs, and abstracting the many possible material handling plans into a state set small enough to enable reinforcement learning. Extensive experimentation with multiple starting plans showed that reinforcement learning could consistently reduce the material handling plans’ costs over time. This work may be among the first applications of reinforcement learning with a multi-objective reward function to a realistically complex material handling process. On the theoretical side, this work examines the effectiveness of balancing exploration and exploitation in a multi-objective plan-based reinforcement learning problem with different ε values. It also shows that with careful selection of actions and state input, a neural network-based state function approximator can learn action values of a continuous reinforcement learning material handling problem.
Recommended Citation
Govindaiah, Swetha, "Reinforcement learning applied to manufacturing material handling" (2019). Dissertations. 176.
https://louis.uah.edu/uah-dissertations/176