Nonlinear Control Systems
ECE611 · Colorado State University
Fall 2026 | Fort Collins, CO
Why I took it
Governors and exciters leave the linearization the moment the machine actually moves. I already work on Simulink models for a digital exciter; I wanted the ECE611 toolkit — Lyapunov, phase portraits, and nonlinear feedback design — so those models are not just linearized A matrices I hope stay valid.
What I'm learning
Nonlinear systems
Nonlinear and time-varying systems, vector spaces and norms, and the conditions for existence and uniqueness of solutions — the background Khalil assumes before you talk about stability.
Stability analysis
Phase portraits, Lyapunov theorems, Popov and circle criteria for nonlinear feedback, and passivity and small gain for operators — how to argue stability without eigenvalues of a local linearization.
Controller design
Jacobian linearization and gain scheduling, feedback linearization, and direct nonlinear design methods, including computer projects that force the theory onto a system you can simulate.