Nyquist criterion: Closed-Loop Stability

This lecture covers the Nyquist criterion for determining the stability of closed-loop systems without computing poles. It explains how to shape open-loop behavior by adjusting the controller, design methods based on experimental data, and optimizing performance while ensuring stability. The concept of closed-loop transfer functions is discussed, along with the Nyquist plot and Cauchy's Argument Principle. The Nyquist criteria are detailed, emphasizing the importance of evaluating clockwise encirclements and unstable poles. The relationship between Nyquist plots and the right half-plane zeros is explored, highlighting the significance of plotting along the imaginary axis. The lecture concludes with insights into why only the imaginary axis is plotted and the symmetry of Nyquist plots around the real axis.