A set simulation approach to the computation of invariant sets for nonlinear systems

Given a nonlinear discrete-time system, previous works exist that compute invariant sets as finite unions of boxes. Set inversion algorithms based on interval arithmetic are used to obtain inner approximations of the one step set starting in an invariant target set. In this paper a complementary approach based on set simulation is proposed. An invariant set can be obtained if a set trajectory that initiates in a given set, reaches this set again in a given number of steps at most. The first advantage of the proposed method is that there is no need to know an initial invariant set. The second one is that for a given system, a high convergence rate of the trajectories tends to reduce the computational effort of the method. The main disadvantage is that the algorithm does not guarantee that an invariant set is obtained. It just guarantees a response in finite time.