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Title:A hierarchical control strategy for aircraft thermal systems
Author(s):Williams, Matthew A.
Advisor(s):Alleyne, Andrew G.
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Modeling and Control
Large-scale systems
Aircraft thermal systems
Model predictive control
Thermal energy
Abstract:Aircraft systems present an interesting control problem given the fact that there exist multiple objectives, actuators, and physical dependencies throughout the system. For decades the onboard systems of aircraft have worked in isolation seeking to achieve their goals while giving little to no consideration to actions or constraints of other systems. As aircraft become more electric, aircraft systems can no longer work in isolation without regard to the constraints and limitations of other systems. Current generation aircraft are experiencing complications between electrical and thermal management systems that have emerged as a result of the increasing prevalence of electrical systems onboard aircraft. Due to these trends, new strategies for controlling aircraft systems are required so that decision making and communication can occur between the vehicle, system, subsystem, and component levels of an aircraft. This thesis looks at establishing the groundwork for the development of next-generation control for aircraft systems. Since testing aircraft systems would be a costly endeavor, models of an aircraft’s electrical, thermal, hydraulic, and pneumatic systems are developed for computer based simulation. A five-level hierarchical control strategy is proposed that seeks to minimize objectives at the vehicle, system, subsystem, component, and physical level. This thesis looks specifically at the system and subsystem-levels of the hierarchy while focusing on the thermal system of the aircraft. At the system level a model predictive controller is developed for minimizing total energy consumption while maintaining the temperature of thermal zones within some bounds. Control decisions made by the system-level controller are passed to a subsystem controller that is formulated as a mixed integer quadratic programming problem which seeks to minimize power consumption while meeting the command of the system-level controller. The subsystem-level controller is responsible for determining the optimal operational mode for each thermal subsystem. An example system consisting of a passenger cabin, fuel tank, vapor compression system, air cycle machine, and ram air cooling loop is used to demonstrate the capabilities of the proposed system and subsystem-level controllers. Controller parameters are analyzed to determine the effect on total power consumption and temperature regulation. Preliminary results show that the two-level hierarchical controller is capable of maintaining temperatures within constraints while minimizing total power consumption.
Issue Date:2014-09-16
Rights Information:Copyright 2014 Matthew A. Williams
Date Available in IDEALS:2014-09-16
Date Deposited:2014-08

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