Doubt on the relationship between the sensitivity and the complementary sensitivity function

1. What is a complementary sensitivity function?
2. What is the function of sensitivity?
3. What is the sensitivity transfer function?

What is a complementary sensitivity function?

The complementary sensitivity function, T, at a point is the closed-loop transfer function around the feedback loop measured at the specified location. It is related to the open-loop transfer function, L, and the sensitivity function, S, at the same point as follows: T = L 1 − L = S − 1.

What is the function of sensitivity?

A sensitivity function serves to express some output probability of interest in terms of a specific parameter probability, and therefore provides for studying the effect of varying this parameter probability on that particular output probability.

What is the sensitivity transfer function?

The system sensitivity function is defined as the ratio of percentage change in the closed-loop transfer function to percentage change in the plant transfer function, i.e., assuming unity feedback (H(s)=1), STG=∂T/T∂G/G=∂T∂GGT=11+KG(s)