Positive systems

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Positive systems[1][2] constitute a class of systems that has the important property that its state variables are never negative, given a positive initial state. These systems appear frequently in practical applications,[3][4] as these variables represent physical quantities, with positive sign (levels, heights, concentrations, etc.).

The fact that a system is positive has important implications in the control system design,[5] as the system. It is also important to take this positivity into account for state observer design, as standard observers (for example Luenberger observers) might give illogical negative values.[6]

See also

Positive feedback

References