The course aims to provide control techniques for dynamical systems subject to uncertainty and/or nonlinearities. The main topics are: 1) Robust control of linear time invariant systems; 2) Analysis of classical nonlinear feedback control systems 3) Feedback controller design for nonlinear systems.
To acquire analytical and numerical tools for the analysis and control of uncertain and/or nonlinear systems
Prerequisites
Basic elements of linear control systems
Teaching Methods
Lectures and practice
Type of Assessment
Oral exam
Course program
1. ROBUST CONTROL OF LINEAR TIME INVARIANT SYSTEMS
Signals norm (L-2) and systems norms (H₂ and H∞).System gains and input-output Lq stability of feedback systems (small gain). Examples.
Nominal performance of feedback control systems in terms of weighted H∞ norm of sensitivity function S. Robust stability of feedback control systems in terms of weighted H∞ norm of closed loop function W. Examples.
Robust stability and robust performance in terms of weighted H∞ norm of S and W. Controller design via loopshaping for minimum phase nominal plants and extension to plants with unstable poles-zeroes. Examples.
2. ANALYSIS OF CLASSICAL NONLINEAR FEEDBACK CONTROL SYSTEMS
Absolute stability problem of Lur’e control systems: Aizerman and Kalman conjectures. Frequency techniques, circle and Popov criteria. Examples. Input-output stability and relation between circle criterion and small gain theorem.
Periodic solutions in nonlinear feedback control systems: harmonic balance and describing functions. Periodic solutions computation via describing function method, accuracy and stability prediction.
3. FEEDBACK CONTROLLER DESIGN FOR NONLINEAR SYSTEMS
Linear state and output dynamic feedback controllers for nonlinear plants. Examples.
Input-state feedback linearization on nonlinear control plants: controller design and robustness. Input-output feedback linearization on nonlinear control plants: controller design, relative degree, zero dynamics, minimum phase condition. Examples.