Sliding mode control of uncertain time delay systems
Abstract
This thesis considers robust sliding mode control of uncertain time delay systems with unmatched parameter uncertainties and matched bounded external disturbances. Sliding mode control breaks down into two phases: sliding manifold design and controller design. Two types of sliding manifold design are considered: linear function of (i) current system states, and (ii) current and delayed system states as well as delayed control. Sufficient conditions in terms of Algebraic Riccati Inequalities and Linear Matrix Inequalities are given as functions of parameter uncertainties, external disturbances and time delays for the stability of system states restricted on the designed manifolds. Next (discontinuous) controllers are developed to globally attract system state trajectories to the designed manifolds. The control structure consists of three terms: an equivalent control for the underlying nominal system, a compensation term for the uncertainties, and a discontinuous term to ensure the reachability of the manifolds. The bounding techniques of the sliding mode controller design are then used to develop a combined classical (non-sliding) controller-observer design method for uncertain time delay systems. Two observer structures are developed to estimate system states, and a linear feedback control is given based on the observed states to asymptotically stabilize the combined plant-controller-observer. Lastly the methods are applied to Internal Combustion engine idle speed control problem. Simulation results show that the controllers can operate the engine at a low idle speed and smoothly reject typical load disturbances. This would provide better fuel economy and more comfortable drive than current production controllers.
Degree
Ph.D.
Advisors
DeCarlo, Purdue University.
Subject Area
Electrical engineering|Systems design
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