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Title:Robust Yaw/roll Control of High-Speed Containerships
Author(s):Magerko, John Alexander, Jr
Department / Program:Mechanical Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, System Science
Abstract:This thesis proposes a controller design for high-speed containerships with aggravated yaw/roll characteristics. With the trend of higher superstructures, low density cargo, and the deck loading of containerships, major problems have arisen in regard to roll motion stabilization. To minimize the yaw/roll coupling effect on the course-keeping mode, the multivariable (MV) approach was applied. The objective was to employ the minimum number of new sensors and actuators to obtain reasonable operating results. Hence, rudder-only control and rudder/fin control were introduced. Using comprehensive models that modeled yaw, sway, surge, and roll; and all significant coupling modes, a new performance index was established and an effective controller was designed to obtain the maximum results from rudder and fin input signals. This was a true first, for other researchers having ignored certain dynamics, were designing autopilots which were issuing inherently conflicting control signals. This thesis work demonstrated the effectiveness of each manner of control, as well as, the MV design approach itself.
The proposed controller design for high-speed containerships used various frequency-domain forms of the system to interpret state-space models and the Linear Quadratic Gaussian control design approach. The dual perspectives of time-domain and frequency-domain viewpoints allow a closer look at both the performance and robustness issues of control as done in classical single input/single output (SISO) control methods. For instance, the performance index once viewed in terms of frequency was shown to be an index penalizing key parameters such as the return difference matrix and its complement. Generalizing classical single-input and single-output methods, prescriptions for good multivariable feedback control were obtained and used to choose/modify the appropriate penalty matrices. Consequently, dynamic compensation resulted, allowing the use of generalized classical ideas on loop gain shaping to be applied. Further, the mu "norm" was introduced to obtain a nonconservative measure of stability robustness, thus allowing for the realization of a practical controller. And finally, due to the analytic nature of the approach, reliable and convenient computer tools were necessary and subsequently developed based on those found in Honeywell's HoneyX$\sp{\rm TM}$ library.
Issue Date:1988
Description:254 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.
Other Identifier(s):(UMI)AAI8823189
Date Available in IDEALS:2014-12-15
Date Deposited:1988

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