Trapping Regions for Quadratic Systems with Generalized Lossless Nonlinearities
For researchers analyzing boundedness of quadratic dynamical systems, this provides a broader and more effective method for computing trapping regions, particularly for systems where existing techniques are inadequate.
This work extends trapping region analysis to quadratic systems with generalized lossless nonlinearities, enabling optimal ellipsoidal trapping region computation where prior methods failed or produced larger bounds. The approach yields trapping regions an order of magnitude smaller for an unsteady aerodynamics model and correctly identifies global asymptotic stability in an academic example.
A trapping region is a compact set that is forward invariant with respect to the dynamics. Existence of a trapping region certifies boundedness of trajectories, and the size of the set provides an estimate of the ultimate bound. Prior work on trapping region analysis has focused on quadratic systems with energy-preserving (lossless) nonlinearities. In this work, we focus on a generalization of the lossless property and present an efficient parameterization that enables optimal trapping region computation for a broader class of quadratic systems than afforded by existing methods. We also formulate conditions for ellipsoidal trapping regions, whereas spherical regions have been the focus of prior works. Three numerical examples are used to demonstrate the proposed framework: (1) a four dimensional system for which the prior state-of-the art is incapable of identifying a trapping region; (2) a low-order unsteady aerodynamics model for which the proposed approach yields trapping regions approximately an order of magnitude smaller than prevailing methods; and (3) a two-state academic example in which the proposed approach correctly identifies a globally asymptotically stable equilibrium point.