ADAPTIVE-CONTROL OF SYSTEMS WITH UNKNOWN NONSMOOTH NONLINEARITIES

In this paper we unify our recent results in adaptive control of syste ms with unknown non-smooth nonlinearities such as dead-zone, backlash and hysteresis characteristics at the input or output of a linear dyna mics. Our adaptive inverse approach employs an adaptive controller str ucture consisting of an adaptive inverse for cancelling the effect of an unknown non-linearity and a fixed (or adaptive) linear control law for a known (or unknown) linear dynamics, Despite the bilinear depende nce on the unknown parameters, a linearly parametrized error system is constructed which enables us to design robust adaptive laws for updat ing the controller parameters to ensure closed loop signal boundedness and improve system tracking performance.