Self-tuning systems have been a hallmark of the aerospace industry for decades, as this sort of feedback is necessary to generate optimal multi-variable control for non-linear processes.
In the telecommunications industry, adaptive communications are often used to dynamically modify operational system parameters to maximize efficiency and robustness.
Professor Jack Dongarra, an American computer scientist, claims self-tuning boosts performance, often on the order of 300%.
Control quality is described by a generalised characteristic which is usually a complex and not completely known or stable function of the primary parameters.
Self-tuning systems with parameter determination can reliably operate in environments characterised by wide variations of exogenous conditions.
Different self-tuning systems without parameter determination exist that are based on controlling transitional processes, frequency characteristics, etc.
All of those are examples of closed-circuit self-tuning systems, whereby parameters are automatically corrected every time the quality characteristic value falls outside the allowable bounds.