Robust control methods are designed to function properly provided that uncertain parameters or disturbances are found within some (typically compact) set.
High-gain feedback is a simple example of a robust control method; with sufficiently high gain, the effect of any parameter variations will be negligible.
From the closed-loop transfer function perspective, high open-loop gain leads to substantial disturbance rejection in the face of system parameter uncertainty.
Robust control systems often incorporate advanced topologies which include multiple feedback loops and feed-forward paths.
The control laws may be represented by high order transfer functions required to simultaneously accomplish desired disturbance rejection performance with the robust closed-loop operation.
High-gain feedback is the principle that allows simplified models of operational amplifiers and emitter-degenerated bipolar transistors to be used in a variety of different settings.