Robust control is a branch of control theory that focuses on designing controllers that maintain stability and performance despite uncertainty in the system.
In real-world systems, models are never perfect. Parameters vary, disturbances occur, sensors are noisy, and dynamics may be partially unknown. Robust control explicitly accounts for these uncertainties during controller design.
In practical systems:
Parameters may change over time (temperature, aging, wear).
External disturbances affect behavior.
Exact mathematical models are unavailable.
Instead of designing a controller for one model we design for a family of models or plants. The goal is:
Stability for all plants
Acceptable performance for all plants
Parametric uncertainty
Unmodeled dynamics (High-frequency dynamics ignored in modeling)
Disturbances (Wind, load changes, noise)
Structured vs. unstructured uncertainty (Structured: known form, unknown parameters; Unstructured: unknown high-frequency dynamics)