Further results on almost disturbance decoupling with global asymptotic stability for nonlinear systems

As a complement to some new breakthroughs on global almost disturbance deco upling problem with stability for nonlinear systems, in a recent note, we i dentified a class of unstable zero dynamics that are allowed to be affected by disturbances. The class of the unstable zero dynamics identified in tha t note is linear and have all the poles at the origin. In this paper, we en large such a class of zero dynamics to include any linear system with all i ts poles in the closed left-half plane. The condition on the way the distur bance affects this part of zero dynamics is also identified. This enlargeme nt is due to a new scaling technique that views each pair of jw axis zeros as a "generalized integrator" and transforms the zero dynamics into a numbe r of chains of "generalized integrators". (C) 1999 Elsevier Science Ltd. Al l rights reserved.