A contractive approach to separable Lyapunov functions for monotone systems. (August 2019)

• Record Type: Journal Article
• Authors: Coogan, Samuel
• Is Part Of: Automatica. Volume 106(2019)
• Page Start: 349
• Page End: 357
• Publication Date: 2019-08
• Subjects: Automatic control -- Periodicals; Automation -- Periodicals; 629.805
• DOI: 10.1016/j.automatica.2019.05.001
• Languages: English
• ISSNs: 0005-1098

Abstract

Abstract: Monotone systems preserve a partial ordering of states along system trajectories and are often amenable to separable Lyapunov functions that are either the sum or the maximum of a collection of functions of a scalar argument. In this paper, we consider constructing separable Lyapunov functions for monotone systems that are also contractive, that is, the distance between any pair of trajectories exponentially decreases. We assume the system evolves in a forward invariant rectangular domain, and the distance between trajectories is defined in terms of a Finsler type metric characterized by a possibly state-dependent norm. When this norm is a weighted one-norm, we obtain conditions which lead to sum-separable Lyapunov functions, and when this norm is a weighted infinity-norm, symmetric conditions lead to max-separable Lyapunov functions. In addition, we consider two classes of Lyapunov functions: the first class is separable along the system's state, and the second class is separable along components of the system's vector field. The latter case is advantageous for many practically motivated systems for which it is difficult to measure the system's state but easier to measure the system's velocity or rate of change.