LMIs in Control/pages/Continuous time Quadratic stability
To study stability of a LTI system, we first ask whether all trajectories of system converge to zero as . A sufficient condition for this is the existence of a quadratic function , that decreases along every nonzero trajectory of system . If there exists such a P, we say the system is quadratically stable and we call a quadratic Lyapunov function.
The system coefficient matrix takes the form of
where is a known matrix, which represents the nominal system matrix, while
is the system matrix perturbation, where
- are known matrices, which represent the perturbation matrices.
- which represent the uncertain parameters in the system.
- is the uncertain parameter vector, which is often assumed to be within a certain compact and convex set : : that is
The uncertain system is quadratically stable if and only if there exists ,
where such that
The following statements can be made for particular sets of perturbations.
Consider the case where the set of perturbation parameters is defined by a regular polyhedron as
The uncertain system is quadratically stable if and only if there exists ,
where such that
Consider the case where the set of perturbation parameters is defined by a polytope as
The uncertain system is quadratically stable if and only if there exists ,
where such that
If feasible, System is Quadratically stable for any
https://github.com/Ricky-10/coding107/blob/master/PolytopicUncertainities