Gene

Quantum mechanics

Control (management)

Engineering

MIMO

Bandwidth (computing)

Feedback loop

Operational amplifier

Control engineering

Computer security

Robustness (evolution)

Minimum phase

Perturbation (astronomy)

Transfer function

Telecommunications

Biochemistry

Amplifier

Computer science

Physics

Artificial intelligence

Chemistry

Channel (broadcasting)

Control theory (sociology)

Phase margin

Electrical engineering

IEEE Control Systems

This article provides a tutorial introduction to disk margins. These are robust stability measures that account for simuitaneous gain and phase perturbations in a feedback system. The article first reviews the classical (gain only and phase -only) margins and their limitations. This motivates the use of disk margins, which are defined using a set of perturbations that has simuitaneous gain and phase variations. A necessary and sufficient condition is provided to compute the disk margin for a single -input, single -output feedback system. Frequency -dependent disk margins can also be computed, yielding additional insight. The article concludes with a discussion of stability margins for multiple -input, multiple output (MIMO) feedback systems. A typical approach is to assess robust stability "loop -at -a -time," with a perturbation introduced into a single channel and all other channels held at their nominal values. MIMO disk margins provide a useful extension to consider simultaneous variations in multiple channels. This multiloop analysis can provide a more accurate robustness assessment as compared to the one -loop -at -a -time approach.

An Introduction to Disk Margins [Lecture Notes]