Adaptive tracking of a class of uncertain nonlinear systems subject to unknown dead-zone input nonlinearities: the symmetric and the non-symmetric cases

Quite successfully adaptive control strategies have been applied to dynamical systems subject to dead-zone nonlinearities. However, adaptive tracking of systems with non-symmetric dead-zones characteristics has not been fully discussed with minimal knowledge of the dead-zones parameters. First, we develop a new adaptive control algorithm for systems involving unknown symmetric dead-zones control inputs. We show that the developed adaptive algorithm does not require any knowledge of the extreme values of the dead-zone parameters. For nonlinear systems subject to non-symmetric dead-zones, we propose another adaptive scheme that requires only the information of bounds of the dead-zone slopes. A numerical example is introduced to show the effectiveness of the theoretical results.