Reference Governor Control Strategies for Nonlinear Systems

Reference governor control strategies provide an add-on supervisory layer to conventional feedback controllers in nonlinear systems, ensuring that state and input constraints are satisfied while pursuing desired performance objectives. By monitoring the nominal control signals and modifying reference commands in real time, the governor enforces constraints such as actuator limits, safety envelopes and admissible operating regions without redesigning the core stabilising controller. In nonlinear settings, the governor computes an admissible set of future trajectories, often via output admissible or invariant set calculations, and selects the maximal reference adjustment that avoids constraint violation. This approach lends itself to applications where safety and reliability are paramount, including aerospace manoeuvres, power-electronic converters and turbomachinery. The principal advantages of reference governors are their modularity—allowing existing controllers to remain unaltered—and their ability to guarantee constraint satisfaction under bounded disturbances or model uncertainties. Recent advances have focused on reducing computational burden through low-order approximations, extending admissible-set theory to systems with variable constraints, and integrating robust or adaptive elements to handle model mismatch in highly nonlinear environments. Practical implementations demonstrate that reference governors can preserve performance while enforcing tight safety margins, making them a compelling choice for modern constrained control tasks.

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Research from all publishers

Recent studies in diverse application domains have validated and extended reference governor methodologies for nonlinear control. In aerospace, flight envelope protection during high angle-of-attack manoeuvres was achieved by embedding both static and dynamic reference governors atop an eigenstructure-assigned baseline controller. This work demonstrated through numerical simulation that the governor could reshape pilot-commanded inputs to respect aerodynamic and actuator constraints, enhancing stability and preventing stall while requiring minimal redesign of the existing flight control laws. In power electronics, a novel governor concept employing a variable-time-constant PT1-element was introduced to manage constraints in battery emulator DC-DC converters. By linking the governor to a flatness-based feedback linearisation scheme, the control architecture generated smooth, constraint-aware voltage trajectories across a wide operating range and maintained fast dynamic response without undue conservatism. In turbomachinery, reference and limit governors were combined to protect turbofan engines against thermal and mechanical limits. The scheme adaptively adjusted both reference commands and constraint boundaries, exploiting output admissible sets for variable constraints and delivering enhanced thrust performance during transient conditions. Together, these works illustrate the global significance of reference governors in ensuring safe operation of nonlinear systems across flight, energy and industrial contexts, while emphasising modular implementation, computational efficiency and robust constraint enforcement.

Reference Governor Control Strategies for Nonlinear Systems publication trend

The graph below shows the total number of articles in reference governor control strategies for nonlinear systems across all publications each year (not limited to Nature Index journals).

Technical terms

Reference governor: A supervisory algorithm that modifies the reference input to a control system in real time, ensuring state and actuator constraints are never violated.

Nonlinear system: A dynamic system whose behaviour cannot be accurately described by linear equations, often requiring specialised analysis to guarantee stability and performance.

Invariant set: A region of the system’s state space within which trajectories remain once they enter, used to certify that constraints will hold indefinitely.

Constraint satisfaction: The requirement that all system states and inputs remain within predefined safe or admissible bounds during operation.

References

1. Flight Envelope Protection Control Based on Reference Governor Method in High Angle of Attack Maneuver. Mathematical Problems in Engineering (2015).
2. A Control Concept for Battery Emulators Using a Reference Governor With a Variable PT1-Element for Constraint Handling. IEEE Open Journal of Industry Applications (2022).
3. Reference and Limit Governors for Limit Protection of Turbofan Engines. Energies (2019).