Type of Document	Dissertation
Author	Ellis, Graham K.
URN	etd-02012006-141752
Title	H[infinity] and LQG optimal control for the rejection of persistent disturbances : analysis, design and experiment
Degree	PhD
Department	Mechanical Engineering
Advisory Committee	Advisor Name Title Robertshaw, Harry H. Committee Chair Baumann, William T. Committee Member Leonard, Robert G. Committee Member Russell, David L. Committee Member Wicks, Alfred L. Committee Member
Keywords	Control theory
Date of Defense	1992-02-05
Availability	restricted
Abstract This dissertation presents a discussion of the asymptotic behavior and estimation structure of the H∞ central controllers in terms of the well-known behavior of the LQG controller and gives some insight into the physics of the H ∞ controller that is often presented in an unclear manner in the current literature. The connections to LQ game theory that underlie this confusion are discussed. Augmented systems that are typically used in disturbance rejection problems are also analyzed. Additionally, a controlled output equation for disturbance rejection is developed based on the physics of the problem rather than the typical ad hoc approaches of the past. These controlled output equations are also appropriate for LQG compensators. In order to verify the proposed approach, an experiment in harmonic and narrowband disturbance rejection using a simply supported steel plate is presented. Discrete-time LQG, and continuous-time H∞ and LQG controllers that have been transformed to discrete-time are used to determine the attainable performance of each approach. The results indicate that the H ∞ controller provides more damping than either LQG approach and that discrete-time design procedures are necessary for maximum disturbance rejection.
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