核心概念
This paper develops a linear approach for analyzing the observability of nonlinear dynamical systems over finite fields using the Koopman operator framework. It constructs a minimal linear realization (LOR) that can reproduce all the output sequences of the original nonlinear system, and provides necessary and sufficient conditions for the observability of the nonlinear system through the LOR. The paper also establishes an upper bound on the number of outputs required for the unique reconstruction of the initial condition.
摘要
The paper addresses the observability problem for nonlinear dynamical systems over finite fields (DSFF), which is computationally challenging due to the need to solve nonlinear algebraic equations over finite fields.
Key highlights:
- It constructs a linear output realization (LOR) of the nonlinear DSFF using the Koopman operator framework, which is the smallest dimensional linear system that can reproduce all the output sequences of the original nonlinear system.
- It proves that the LOR is always observable, regardless of the observability of the original nonlinear DSFF.
- It provides necessary and sufficient conditions for the observability of the nonlinear DSFF through the LOR, showing that the DSFF is observable if and only if the map from the state space to the LOR state space is injective.
- It establishes that the maximum number of outputs required to uniquely reconstruct the initial condition is equal to the dimension of the LOR.
- It shows that the LOR is invariant under nonsingular state transformations of the original nonlinear DSFF.
The results provide a systematic approach to analyze the observability of nonlinear DSFF, and the insights on the relationship between the LOR and the original system can aid in the design of observers for such nonlinear systems.