Plant model uncertainty can be a fundamental limiting factor in determining what can be achieved with feedback.
To quantify the multivariable stability margins and performance of a system, use the singular values of the closed-loop transfer functions of the system.
In loop-shaping controller synthesis, you specify
the shape of the open-loop response you want, and use
compute a controller that approximates that shape.
This example shows how to use
address robustness and performance tradeoffs.
When the initial results from
not satisfactory, refine the target loop shape.
Mixed-sensitivity loop shaping combines performance and stability robustness specifications into one cost function that penalized both sensitivity and complementary sensitivity.