Time-Delay Systems with Discrete and Distributed delays: Discontinuous Initial Conditions and Reachability Sets
This work addresses a fundamental stability issue in control theory for time-delay systems, which is incremental as it extends known results from discrete delays to mixed delays.
The paper tackled the problem of ensuring bounded reachability sets for time-delay systems with mixed discrete and distributed delays, developing novel sufficient conditions that can be directly tested on the system dynamics and identifying broad classes of systems that satisfy these conditions.
Time-invariant finite-dimensional systems, under reasonable continuity assumptions, exhibit the property that if solutions exist for all future times, the set of vectors reachable from a bounded set of initial conditions over bounded time intervals is also bounded. This property can be summarized as follows: forward completeness implies bounded reachability sets. By contrast, this property does not necessarily hold for infinite-dimensional systems in general, and time-delay systems in particular. Sufficient conditions for this property to hold that can be directly tested on the function defining the system dynamics are only known in the case of systems with pointwise (or discrete) delays. This paper develops novel sufficient conditions for the boundedness of the reachability sets of time-delay systems involving mixed pointwise and distributed delays. Broad classes of systems satisfying these conditions are identified.