Glossary · Control theory and process control
Robust control
Also known as: Robust controller design
German: Robuste Regelung
In control engineering, robust control is the design of controllers that keep stability and acceptable performance despite a specified range of uncertainty in the process model, disturbances or parameter variations.
- Control theory
In one sentence
Robust control designs controllers that stay stable and perform acceptably across a specified range of model uncertainty.
Example
A robust controller for a packaging machine axis is designed to stay stable for any load mass between 2 and 20 kg without retuning.
How it applies
- Engineering: Robust design starts with a description of the uncertainty, such as parameter ranges or unmodeled dynamics, and methods like H-infinity design or loop shaping with generous Stability margin values. Simpler practice: tune for the worst-case operating point and verify at the others.
- Verification: Test at the corners of the specified range, not only at nominal conditions. The uncertainty range is an Operating assumption and should be traceable.
- Documentation: State the range of conditions for which the controller was designed, such as loads, speeds and temperatures. Operating manuals should warn that behavior outside that range is not covered.
Robust control vs. adaptive control
Robust control uses one fixed design that tolerates uncertainty. Adaptive control changes its parameters as the process changes. Robust designs are easier to verify; adaptive designs can cover wider ranges.